tire pressure myth?
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jaxtell671
08-31-2006, 05:51 PM
i was taking care of one of my friends cars the other day and i noticed her tire pressure was a little low. i filled the tires to the max psi pressure of 44psi listed on the side of her tires. when i told her the air was low she said that she only filled it to around 35 because she had heard that filling it to the max psi rating would cause increased tread wear. is she right or is that just some bull that she heard somewhere?
G-man422
08-31-2006, 05:53 PM
If you overfill it(or its too low), you get uneven tread wear, but not More tread wear. Usually you dont fill it to max psi though, because it makes fo a rougher ride (sometimes) and air has to have some room to expand, and compress.
TheSilentChamber
08-31-2006, 06:29 PM
Yeah, dont fill it to the max psi unless your putting the max load on them, in which case you should switch to a higher load rated tire.
Moppie
08-31-2006, 07:06 PM
Wow.
Did you actualy read what it said on the tyre wall?
Unless its a very large truck, or they are extremely low profile tyres then 44psi is WAY to much.
In fact its dangerously to much, and I hope your friend is good at controlling skids.
Most cars only need between 28 and 38psi, with 32-34psi being a good amount to put in if your not sure.
Did you actualy read what it said on the tyre wall?
Unless its a very large truck, or they are extremely low profile tyres then 44psi is WAY to much.
In fact its dangerously to much, and I hope your friend is good at controlling skids.
Most cars only need between 28 and 38psi, with 32-34psi being a good amount to put in if your not sure.
GreyGoose006
08-31-2006, 07:27 PM
no... there are such things as tires that run at 44psi. michelin's harmony tires say to run at 44psi. i believe the majority of minivans, and light weight wuss-UVs run at 44 psi. it cuts down on rolling resistance.
i have a friend who has a suburban that he put 90 (yes 90) psi industrial tires on.
tires should be inflated to what it says on the sidewall, which is recomended pressure, not max pressure (it may say max, but it isnt)
i have a friend who has a suburban that he put 90 (yes 90) psi industrial tires on.
tires should be inflated to what it says on the sidewall, which is recomended pressure, not max pressure (it may say max, but it isnt)
Igovert500
08-31-2006, 07:56 PM
For every day driving, I've always filled my cars to the recommended tire pressure on the plaque in the driver's door jam (I think every car has one) which is generally in the range of what Moppie said.
Keep in mind when tires warm up the air inside expands and can raise the tire pressure something like 5psi. So if you are inflating them to the max psi rating, when they are cold, that is VERY bad.
Keep in mind when tires warm up the air inside expands and can raise the tire pressure something like 5psi. So if you are inflating them to the max psi rating, when they are cold, that is VERY bad.
bluevp00
08-31-2006, 10:00 PM
Overfilling the tire will cause tire wear in the middle of the tire (it bulges out in the middle when theres too much air in it). But filling within the limits of what it says on the tire should be alright. Myself, I go by what it says in the owners manual (if you're using OEM size tires), the people who made the car usually know best PSI to use.
UncleBob
08-31-2006, 10:50 PM
no... there are such things as tires that run at 44psi. michelin's harmony tires say to run at 44psi. i believe the majority of minivans, and light weight wuss-UVs run at 44 psi. it cuts down on rolling resistance.
i have a friend who has a suburban that he put 90 (yes 90) psi industrial tires on.
tires should be inflated to what it says on the sidewall, which is recomended pressure, not max pressure (it may say max, but it isnt)
the only pressure listed on the side wall, is the maximum pressure. You are incorrect. You should never fill it up to the pressure listed on the tire UNLESS you are loading the vehicle enough to require that amount of pressure.
Over inflating the tires will not only cause a rough ride, it will cause the tire to wear severely in the center of the tread.
The vehicle manufacturers recommended pressure is the best information to follow....regardless of the tire in question (assuming its within the weight rating designed for the vehicle). Believe it or not, the vehicle manufacturer has a pretty good idea what they are doing. The tire manufacture doesn't know what vehicle you're putting the tire onto.
Simply put, you will have a better ride, better handling, better traction and longer tire longevity, if you follow the vehicle recommendations. You may get one or two mpg better with severe overinflation, but at the cost of tire wear, you're not saving yourself any money. And if you get in an accident due to it....
i have a friend who has a suburban that he put 90 (yes 90) psi industrial tires on.
tires should be inflated to what it says on the sidewall, which is recomended pressure, not max pressure (it may say max, but it isnt)
the only pressure listed on the side wall, is the maximum pressure. You are incorrect. You should never fill it up to the pressure listed on the tire UNLESS you are loading the vehicle enough to require that amount of pressure.
Over inflating the tires will not only cause a rough ride, it will cause the tire to wear severely in the center of the tread.
The vehicle manufacturers recommended pressure is the best information to follow....regardless of the tire in question (assuming its within the weight rating designed for the vehicle). Believe it or not, the vehicle manufacturer has a pretty good idea what they are doing. The tire manufacture doesn't know what vehicle you're putting the tire onto.
Simply put, you will have a better ride, better handling, better traction and longer tire longevity, if you follow the vehicle recommendations. You may get one or two mpg better with severe overinflation, but at the cost of tire wear, you're not saving yourself any money. And if you get in an accident due to it....
Moppie
09-01-2006, 01:31 AM
tires should be inflated to what it says on the sidewall, which is recomended pressure, not max pressure (it may say max, but it isnt)
Wow.
Ok, go find a bottle of turpentine and drink as much of it as you can.
It might say Poison on the side, but it isn't.
Wow.
Ok, go find a bottle of turpentine and drink as much of it as you can.
It might say Poison on the side, but it isn't.
G-man422
09-01-2006, 07:44 AM
My michellins have a 44psi max, but i usually fill them to about 38-40psi.
curtis73
09-01-2006, 01:54 PM
Every car I know of has a sticker inside the driver's door that lists the recommended inflation pressure. That is based on the floatation of the tire, the weight of the vehicle, and several other factors. For the most part, 99% of your driving will be done with a couple passengers. Every once in a while you'll make a run to Home Depot and get 10 bags of mulch, but there is no need to put more air in for 10 miles.
The number on the sidewall is NOT a recommended inflation, its max. There is no way michelin can recommend a pressure for a tire that might be used on a light truck or a Camry in the same size.
Weight suspension in a tire is a function of pressure and interior volume... Period. That's why CAR manufacturers put those stickers in the door jamb. Auto manufacturers choose a size of tire that will be satisfactory under its max pressure to suspend the weight of the car. It doesn't matter if Toyota puts a Michelin tire or a Firestone tire as original equipment on a Camry, the sticker still says 32 psi. They know it takes about 32 psi to suspend a 3000-lb car. That's also why a 1-ton truck gets tires that hold 80 psi.
Read up on everything tire tech at www.tirerack.com (http://www.tirerack.com) in their tire tech section. I could type up something here, but you know me... It would be 30 pages long. :)
The number on the sidewall is NOT a recommended inflation, its max. There is no way michelin can recommend a pressure for a tire that might be used on a light truck or a Camry in the same size.
Weight suspension in a tire is a function of pressure and interior volume... Period. That's why CAR manufacturers put those stickers in the door jamb. Auto manufacturers choose a size of tire that will be satisfactory under its max pressure to suspend the weight of the car. It doesn't matter if Toyota puts a Michelin tire or a Firestone tire as original equipment on a Camry, the sticker still says 32 psi. They know it takes about 32 psi to suspend a 3000-lb car. That's also why a 1-ton truck gets tires that hold 80 psi.
Read up on everything tire tech at www.tirerack.com (http://www.tirerack.com) in their tire tech section. I could type up something here, but you know me... It would be 30 pages long. :)
jaxtell671
09-01-2006, 02:42 PM
thanks for all the advice, yeah i did notice that it ran a bit stiffer but i didn't really mind that. but from now on i think i'll just fill it to around 40.
curtis73
09-01-2006, 02:54 PM
Although I don't really recommend this for other people's cars (just my own :)), you can try different inflation pressures and then lay a good trail of rubber. Pressures too high will create darker black streaks in the center. Pressures too low will create darker streaks near the edges of the tread.
The other way is to just buy a $1.99 tread depth gauge and monitor tread depth on the edges and center of the tread.
The other way is to just buy a $1.99 tread depth gauge and monitor tread depth on the edges and center of the tread.
GreyGoose006
09-01-2006, 11:58 PM
the thing is, the sidewalls on my tires say reccomended...
lets assume that the number printed really is the max, the manufacturers would tell you about 10 psi less to be on the safe side. there is going to be a margin of safety on any tire.
as for the door jamb, its a great idea... that is if you havent switched the brand or size or performance rating of the tire you were using when the car was bought. say you upgrade to wider tires, and get a summer compound, since you live in florida (for example). the whole thing about the door jamb is now not true. even if you keep the tire size and load rating the same, but switch brands, you need to adjust the pressure. the pressure on the sidewall is GENERALLY accepted as a good place to start when filling your tires. i wouldnt suggest going over it, but you are perfectly safe while you are at the pressure listed.
oh, and by the way, yes, michelin harmony tires do recommend using 44 psi. my dad has them on his '05 Oddesy and my mom has them on her '92 Accord. BOTH say 44 psi.
lets assume that the number printed really is the max, the manufacturers would tell you about 10 psi less to be on the safe side. there is going to be a margin of safety on any tire.
as for the door jamb, its a great idea... that is if you havent switched the brand or size or performance rating of the tire you were using when the car was bought. say you upgrade to wider tires, and get a summer compound, since you live in florida (for example). the whole thing about the door jamb is now not true. even if you keep the tire size and load rating the same, but switch brands, you need to adjust the pressure. the pressure on the sidewall is GENERALLY accepted as a good place to start when filling your tires. i wouldnt suggest going over it, but you are perfectly safe while you are at the pressure listed.
oh, and by the way, yes, michelin harmony tires do recommend using 44 psi. my dad has them on his '05 Oddesy and my mom has them on her '92 Accord. BOTH say 44 psi.
UncleBob
09-02-2006, 01:28 AM
the thing is, the sidewalls on my tires say reccomended...
lets assume that the number printed really is the max
you seem to be rather insistant that you understand this better than everyone, when a awful lot of people say otherwise.
If you'd like some credentials....I work at a tire store. We're not making this stuff up.
I'd suggest you read your sidewalls again. I think you have misread what it says.
as for the door jamb, its a great idea... that is if you havent switched the brand or size or performance rating of the tire you were using when the car was bought. say you upgrade to wider tires, and get a summer compound, since you live in florida (for example). the whole thing about the door jamb is now not true.
Here is the large part of the confusion, and its a very common misconception.
The PSI of the tire is MOSTLY ruled by the WEIGHT the tire is supporting.
In other words. No matter what tire you used to have, do have, was stock, isn't stock, width, weight rating ect ect: assuming the weight of the vehicle, and its weight relation (level of CG, weight distribution, etc) it will be the SAME recommended PSI no matter what tire is involved.
Here is a simple analogy. You take a party balloon and blow it up. Now you hold it to the floor with your hand and smoosh it so that it flattens out. The obvious result will be, the more pressure (weight) you apply to the balloon, the more it will smoosh. A tire is the exact same thing. The more weight you add, the more the tire will be squished. The way you compensate for this is by adding PSI so that you have a happy median between too squished, and not squished enough (where it would only ride on the center of the tread area)
Now if you have a very stiff tire, it can support more weight BECAUSE it can support more PSI. If you run a semi-truck tire at 2psi will will eventually overheat the sidewalls just like any other tire, although granted, it will take away, because the structure doesn't have enough support to support a significant load.
The number you see on the stickers on door jams is just that: Its the manufacturers calculated psi necessary for the WEIGHT of the vehicle, and its various likely additional loads. A 1 ton truck, for example, will have some grey area. Because when the truck is empty, vs having a full load to its maximum weight capacty in the back, the required PSI for these two extremes will be quite different. This is where, if you wish to be savy about your tires, that you need to take some guesses at the proper level of inflation. But if you maxed out those 90psi capable tires and never have a load in the back, you will wear them out very fast.
lets assume that the number printed really is the max
you seem to be rather insistant that you understand this better than everyone, when a awful lot of people say otherwise.
If you'd like some credentials....I work at a tire store. We're not making this stuff up.
I'd suggest you read your sidewalls again. I think you have misread what it says.
as for the door jamb, its a great idea... that is if you havent switched the brand or size or performance rating of the tire you were using when the car was bought. say you upgrade to wider tires, and get a summer compound, since you live in florida (for example). the whole thing about the door jamb is now not true.
Here is the large part of the confusion, and its a very common misconception.
The PSI of the tire is MOSTLY ruled by the WEIGHT the tire is supporting.
In other words. No matter what tire you used to have, do have, was stock, isn't stock, width, weight rating ect ect: assuming the weight of the vehicle, and its weight relation (level of CG, weight distribution, etc) it will be the SAME recommended PSI no matter what tire is involved.
Here is a simple analogy. You take a party balloon and blow it up. Now you hold it to the floor with your hand and smoosh it so that it flattens out. The obvious result will be, the more pressure (weight) you apply to the balloon, the more it will smoosh. A tire is the exact same thing. The more weight you add, the more the tire will be squished. The way you compensate for this is by adding PSI so that you have a happy median between too squished, and not squished enough (where it would only ride on the center of the tread area)
Now if you have a very stiff tire, it can support more weight BECAUSE it can support more PSI. If you run a semi-truck tire at 2psi will will eventually overheat the sidewalls just like any other tire, although granted, it will take away, because the structure doesn't have enough support to support a significant load.
The number you see on the stickers on door jams is just that: Its the manufacturers calculated psi necessary for the WEIGHT of the vehicle, and its various likely additional loads. A 1 ton truck, for example, will have some grey area. Because when the truck is empty, vs having a full load to its maximum weight capacty in the back, the required PSI for these two extremes will be quite different. This is where, if you wish to be savy about your tires, that you need to take some guesses at the proper level of inflation. But if you maxed out those 90psi capable tires and never have a load in the back, you will wear them out very fast.
2.2 Straight six
09-02-2006, 01:38 AM
you seem to be rather insistant that you understand this better than everyone, when a awful lot of people say otherwise.
If you'd like some credentials....I work at a tire store. We're not making this stuff up.
you can't argue with that.
if you want more proof that tyre running pressure is decided by vehicle weight and is decided by the vehicle manufacturer i suggest you look at some large trucks like semis, dump trucks etc..
i've seen a lot of them here with the tyre pressure labeled on each individual wheelarch. this is decided by the manufacturer, not the operator, not the driver, not the tyre company, not even that guy with the moustache that lives 5 doors down.
maybe you shouldn't argue with the experts here, Curtis, Moppie, UncleBob and some others are the experts here. they know more about cars that you could imagine, so don't argue.
you're outnumbered in opinion when it comes to what that number represents anyway.
If you'd like some credentials....I work at a tire store. We're not making this stuff up.
you can't argue with that.
if you want more proof that tyre running pressure is decided by vehicle weight and is decided by the vehicle manufacturer i suggest you look at some large trucks like semis, dump trucks etc..
i've seen a lot of them here with the tyre pressure labeled on each individual wheelarch. this is decided by the manufacturer, not the operator, not the driver, not the tyre company, not even that guy with the moustache that lives 5 doors down.
maybe you shouldn't argue with the experts here, Curtis, Moppie, UncleBob and some others are the experts here. they know more about cars that you could imagine, so don't argue.
you're outnumbered in opinion when it comes to what that number represents anyway.
KiwiBacon
09-02-2006, 05:09 AM
44psi is dangerous for a light car.
Your contact patch is severely reduced, which reduces grip.
Here's how I set my tyre pressure:
Drive at your normal open road cruising speed, pull over and feel the temperature of the tyre.
Warmer on the sides means the pressure is too low.
Warmer in the middle means the pressure is too high.
Get it right and you'll get even tyre wear and even temperature distribution.
For reference this gives me 40psi running 600kg on each 225/85R16 LT tyre.
Your contact patch is severely reduced, which reduces grip.
Here's how I set my tyre pressure:
Drive at your normal open road cruising speed, pull over and feel the temperature of the tyre.
Warmer on the sides means the pressure is too low.
Warmer in the middle means the pressure is too high.
Get it right and you'll get even tyre wear and even temperature distribution.
For reference this gives me 40psi running 600kg on each 225/85R16 LT tyre.
JustSayGo
10-03-2006, 10:12 PM
In the name of Democracy! The guys in white sheets made sure they always outnumbered their victims and began their meetings reading from the Bible. They believed they were right and that their work was what God and the majority wanted done.
Seems to me 2.2 may be trying to pull his experts under his sheet.
There are small car tires that are safe and recomended inflated to 44lbs
Tires are constructed in ways that maximum tire presure is determined by a calculated formula which is based on their individual design.
Tires are capable of supporting the greatest load at their maximum inflation pressure.
Tires are designed to provide the greatest wear and fuel milage at the maximum inflation pressure.
Tires are designed to provide even wear over a range of pressure and varios load.
Tires are run lower than max inflation to improve ride comfort.
Due to construction, Tires can and have worn more on the outside edges because of over or max inflation. Bands in tires can be designed and constructed in ways that prevent the center of the tread from expanding as much as the edges when the tire is inflated. Tires are a very sophisticated balloon.
Some of the most significant evidence presented against the Ford Motor Company in their Explorer roll over because of tire failure law suite (which they lost seriosly big $$$), delt with stickers on the door that were lower pressure than the tire manufacture had recomrnded.
Tire expence is the second greatest operating expence, fuel being the first. Tire manufacture factory reps do tire tests together with fleet vehicle owners to determine the best tire pressure decal to place on the body at each wheel for that fleet. The pressures on the stickers are updated and adjusted periodicly as conditions change and newer tests dictate need. The tire pressure is ultamatly decided by the fleet owner. I have been part of the testing, inflating, and putting the sticers on, for the largest fleet in the world and another extreemly well recognized large fleet. I have had extensive training and conversation with the major tire reps. Each rep is preaching the same info.
Competition between tire manufactures supplying fleets is fierce. They send their best reps to fleets to measure and optimize expence. Tire sales reps who visit tire stores advise on how to sell the most tires by giving the public what they want most.
Fleets pay their techs to maintain tire pressure so often that the pressure is maintained well within 5% of their determined inflation pressure.
Maintaining tire pressure is critical. When ever I did side jobs, regardless of replacing brakes, clutch, or tune-up, I always aired the tires to the max inflation, partly because of my fleet background and because often I found the tires had deflated to only 18-20lbs when max was 32-36lbs. Little wonder that some told me, "you know, my car always drives better after you have worked on it." "I don't understand how this type of repair can make my car feel different and drive better?"
Even after inflating so many tires for too many years, I am somewhat amazed at my own newest tires that are nitrogen filled to 28lbs (max may be 36lbs) after more than a year they still gave 28lbs. Heat does not change pressure of nitrogen filled tires.
Manufactures recomend very close to the max and never stop talking about maintaning pressure.
In the case of your girlfriend, I recomend giving her what She wants!
Seems to me 2.2 may be trying to pull his experts under his sheet.
There are small car tires that are safe and recomended inflated to 44lbs
Tires are constructed in ways that maximum tire presure is determined by a calculated formula which is based on their individual design.
Tires are capable of supporting the greatest load at their maximum inflation pressure.
Tires are designed to provide the greatest wear and fuel milage at the maximum inflation pressure.
Tires are designed to provide even wear over a range of pressure and varios load.
Tires are run lower than max inflation to improve ride comfort.
Due to construction, Tires can and have worn more on the outside edges because of over or max inflation. Bands in tires can be designed and constructed in ways that prevent the center of the tread from expanding as much as the edges when the tire is inflated. Tires are a very sophisticated balloon.
Some of the most significant evidence presented against the Ford Motor Company in their Explorer roll over because of tire failure law suite (which they lost seriosly big $$$), delt with stickers on the door that were lower pressure than the tire manufacture had recomrnded.
Tire expence is the second greatest operating expence, fuel being the first. Tire manufacture factory reps do tire tests together with fleet vehicle owners to determine the best tire pressure decal to place on the body at each wheel for that fleet. The pressures on the stickers are updated and adjusted periodicly as conditions change and newer tests dictate need. The tire pressure is ultamatly decided by the fleet owner. I have been part of the testing, inflating, and putting the sticers on, for the largest fleet in the world and another extreemly well recognized large fleet. I have had extensive training and conversation with the major tire reps. Each rep is preaching the same info.
Competition between tire manufactures supplying fleets is fierce. They send their best reps to fleets to measure and optimize expence. Tire sales reps who visit tire stores advise on how to sell the most tires by giving the public what they want most.
Fleets pay their techs to maintain tire pressure so often that the pressure is maintained well within 5% of their determined inflation pressure.
Maintaining tire pressure is critical. When ever I did side jobs, regardless of replacing brakes, clutch, or tune-up, I always aired the tires to the max inflation, partly because of my fleet background and because often I found the tires had deflated to only 18-20lbs when max was 32-36lbs. Little wonder that some told me, "you know, my car always drives better after you have worked on it." "I don't understand how this type of repair can make my car feel different and drive better?"
Even after inflating so many tires for too many years, I am somewhat amazed at my own newest tires that are nitrogen filled to 28lbs (max may be 36lbs) after more than a year they still gave 28lbs. Heat does not change pressure of nitrogen filled tires.
Manufactures recomend very close to the max and never stop talking about maintaning pressure.
In the case of your girlfriend, I recomend giving her what She wants!
Alastor187
10-03-2006, 11:34 PM
...Heat does not change pressure of nitrogen filled tires...
Isothermal tires? :disappoin
Isothermal tires? :disappoin
KiwiBacon
10-04-2006, 01:25 AM
In the name of Democracy! The guys in white sheets made sure they always outnumbered their victims and began their meetings reading from the Bible. They believed they were right and that their work was what God and the majority wanted done.
Seems to me 2.2 may be trying to pull his experts under his sheet.
There are small car tires that are safe and recomended inflated to 44lbs
Tires are constructed in ways that maximum tire presure is determined by a calculated formula which is based on their individual design.
Tires are capable of supporting the greatest load at their maximum inflation pressure.
Tires are designed to provide the greatest wear and fuel milage at the maximum inflation pressure.
Tires are designed to provide even wear over a range of pressure and varios load.
Tires are run lower than max inflation to improve ride comfort.
Which part of "contact patch" do you not understand?
The higher the tyre pressure, the smaller the contact patch, the less grip you have.
44psi in a passenger car is dangerously high, your contact patch is approximately 50% smaller than it should be and your grip is seriously compromised.
In addition you will wear out the centre of the tyre tread, causing replacement to be required much sooner and increasing the owners running costs.
Maximum inflation pressure is only for use at the maximum weight the tyre can carry.
Seems to me 2.2 may be trying to pull his experts under his sheet.
There are small car tires that are safe and recomended inflated to 44lbs
Tires are constructed in ways that maximum tire presure is determined by a calculated formula which is based on their individual design.
Tires are capable of supporting the greatest load at their maximum inflation pressure.
Tires are designed to provide the greatest wear and fuel milage at the maximum inflation pressure.
Tires are designed to provide even wear over a range of pressure and varios load.
Tires are run lower than max inflation to improve ride comfort.
Which part of "contact patch" do you not understand?
The higher the tyre pressure, the smaller the contact patch, the less grip you have.
44psi in a passenger car is dangerously high, your contact patch is approximately 50% smaller than it should be and your grip is seriously compromised.
In addition you will wear out the centre of the tyre tread, causing replacement to be required much sooner and increasing the owners running costs.
Maximum inflation pressure is only for use at the maximum weight the tyre can carry.
UncleBob
10-04-2006, 02:45 AM
There are small car tires that are safe and recomended inflated to 44lbs
correction, there are small car tires that have a WEIGHT RATING that can acheive 44 psi. Simular, but not the same
Tires are constructed in ways that maximum tire presure is determined by a calculated formula which is based on their individual design.
bullshit. To put it nicely.
I assume you're talking about runflat tires? If you think they are incapable of overinflation damage because they have such stiff sidewalls, you'd be quite wrong.
As kiwi pointed out, weight/psi = contact patch. No matter how stiff the side walls are. Really.
Tires are capable of supporting the greatest load at their maximum inflation pressure.
100% agree. Thats the entire purpose of the listed maximum weight the tire can support....which is also listed with the maximum psi. They go hand in hand.
Tires are designed to provide the greatest wear and fuel milage at the maximum inflation pressure.
Wrong. Tires are designed to have the greatest wear mileage at the proper inflation for the vehicle weight.
Best mileage would be at maximum inflation the tire could support, but would cause the tires to wear accessively
Tires are designed to provide even wear over a range of pressure and varios load.
only if the vehicle weight corresponded with the tire psi.
Its been stated over and over. psi = weight capacity. Its a very simple formula
Tires are run lower than max inflation to improve ride comfort.
this is definitely true.
Due to construction, Tires can and have worn more on the outside edges because of over or max inflation. Bands in tires can be designed and constructed in ways that prevent the center of the tread from expanding as much as the edges when the tire is inflated. Tires are a very sophisticated balloon.
Let turn the tables here on this belief. If a tire is so stiff that it will keep an even form across the contact patch regardless of psi....
why does it need any psi?
comprenda?
Some of the most significant evidence presented against the Ford Motor Company in their Explorer roll over because of tire failure law suite (which they lost seriosly big $$$), delt with stickers on the door that were lower pressure than the tire manufacture had recomrnded.
correct. That was firestones argument. Ford set the psi in the door jam lower than was realistic for the vehicle weight, for two reasons. One was ride quality. The second might surprise you, it was to prevent roll overs. The CG was a contention with the engineers, so this was one tiny aspect that they manipulated to lower it to help prevent roll overs. Funny eh?
The part that I find amusing about such arguements about the firestone/ford thing, is that 99.9% of car owners don't even know about the sticker in their door jam, so its really quite mute on whats printed on it. Most people wait til their tires are so flat its riding on the rim before they do anything about it. Thats my experience anyway.
Manufactures recomend very close to the max.
uh. No they don't. Most manufacturers don't put that crappy a tire on their cars.
correction, there are small car tires that have a WEIGHT RATING that can acheive 44 psi. Simular, but not the same
Tires are constructed in ways that maximum tire presure is determined by a calculated formula which is based on their individual design.
bullshit. To put it nicely.
I assume you're talking about runflat tires? If you think they are incapable of overinflation damage because they have such stiff sidewalls, you'd be quite wrong.
As kiwi pointed out, weight/psi = contact patch. No matter how stiff the side walls are. Really.
Tires are capable of supporting the greatest load at their maximum inflation pressure.
100% agree. Thats the entire purpose of the listed maximum weight the tire can support....which is also listed with the maximum psi. They go hand in hand.
Tires are designed to provide the greatest wear and fuel milage at the maximum inflation pressure.
Wrong. Tires are designed to have the greatest wear mileage at the proper inflation for the vehicle weight.
Best mileage would be at maximum inflation the tire could support, but would cause the tires to wear accessively
Tires are designed to provide even wear over a range of pressure and varios load.
only if the vehicle weight corresponded with the tire psi.
Its been stated over and over. psi = weight capacity. Its a very simple formula
Tires are run lower than max inflation to improve ride comfort.
this is definitely true.
Due to construction, Tires can and have worn more on the outside edges because of over or max inflation. Bands in tires can be designed and constructed in ways that prevent the center of the tread from expanding as much as the edges when the tire is inflated. Tires are a very sophisticated balloon.
Let turn the tables here on this belief. If a tire is so stiff that it will keep an even form across the contact patch regardless of psi....
why does it need any psi?
comprenda?
Some of the most significant evidence presented against the Ford Motor Company in their Explorer roll over because of tire failure law suite (which they lost seriosly big $$$), delt with stickers on the door that were lower pressure than the tire manufacture had recomrnded.
correct. That was firestones argument. Ford set the psi in the door jam lower than was realistic for the vehicle weight, for two reasons. One was ride quality. The second might surprise you, it was to prevent roll overs. The CG was a contention with the engineers, so this was one tiny aspect that they manipulated to lower it to help prevent roll overs. Funny eh?
The part that I find amusing about such arguements about the firestone/ford thing, is that 99.9% of car owners don't even know about the sticker in their door jam, so its really quite mute on whats printed on it. Most people wait til their tires are so flat its riding on the rim before they do anything about it. Thats my experience anyway.
Manufactures recomend very close to the max.
uh. No they don't. Most manufacturers don't put that crappy a tire on their cars.
UncleBob
10-04-2006, 03:00 AM
here's a mind bender for car people.
What is the proper inflation psi based off of......on a bike tire?
It has a round profile, which is desired to support lean angles. The contact patch will obviously get bigger the less psi you have, but there is some major issues with a under-inflated tire on a motorcycle. Stability becomes very bad at some point.
Its a little mind teaser for those that have never dealt with bike tire inflation. Do the same rules apply, as I've listed above, for cars? Is weight the ultimate consideration, even though it won't ultimately cause an "even" contact patch across the tire? What ARE the factors involved here?
What is the proper inflation psi based off of......on a bike tire?
It has a round profile, which is desired to support lean angles. The contact patch will obviously get bigger the less psi you have, but there is some major issues with a under-inflated tire on a motorcycle. Stability becomes very bad at some point.
Its a little mind teaser for those that have never dealt with bike tire inflation. Do the same rules apply, as I've listed above, for cars? Is weight the ultimate consideration, even though it won't ultimately cause an "even" contact patch across the tire? What ARE the factors involved here?
Moppie
10-04-2006, 03:03 AM
In the name of Democracy! The guys in white sheets made sure they always outnumbered their victims and began their meetings reading from the Bible. They believed they were right and that their work was what God and the majority wanted done.
Seems to me 2.2 may be trying to pull his experts under his sheet.
Riiight, except your the one giveing some very irrational reasoning, and backing it up with rethoric.
Prehaps we should all join you in your sheet?
Oh! Thats right, we have knowledge, experiance and rational thought on our side.
Iv added some comments in red:
There are small car tires that are safe and recomended inflated to 44lbs
Yip, thier called space saver spare tyres. They run a very high side wall, and a very small contact patch. They also have a very limited life.
Tires are constructed in ways that maximum tire presure is determined by a calculated formula which is based on their individual design.
I would hope some engineering and calculating went to it
Tires are capable of supporting the greatest load at their maximum inflation pressure.
As has already been stated. Max load needs max pressure, right again.
Tires are designed to provide the greatest wear and fuel milage at the maximum inflation pressure.
Yip, true again, high pressure equals small contact patch, equals lower roller resistance, equals better fuel milage. It also means the tyre will wear faster since not all of its contact patch is being used, the small part that is wears more, and un-evenly across the face of the tyre. You can also get problems from the tyre over heating. And of course its very dangerous, since the car has less traction that it was designed to have.
Tires are designed to provide even wear over a range of pressure and varios load.
Of course, assuming the pressure matchs the load.
Tires are run lower than max inflation to improve ride comfort.
Yip, common problem with used Jap imports sold here in NZ and else where in the world. The recomended prssure is one for driving around Japan, and for a market that generaly values comfort over performance. They also have radicaly different speed limits, to the rest of the world, with most cars never getting above 60kph in thier life. So, they have lower tyre pressures recomended by the manufactors. They also carry less weight in thier cars, as the population generaly weights less. The exact same car, sold here in NZ, where the speed limits are much higher, and its very easy to drive long distances at 100kph, and as a population we weigh more, and carry more, comes with a manufactors put a tyre pressure recomendation that can be 4-6psi higher.
Basicly what works in Japan, becomes dangerously under inflated here in NZ.
Some local manufactors that took to importing and renewing and then selling thier own brand of car from Japan even goto the trouble of replacing the Japanese tyre prssure recomendation plate.
Due to construction, Tires can and have worn more on the outside edges because of over or max inflation. Bands in tires can be designed and constructed in ways that prevent the center of the tread from expanding as much as the edges when the tire is inflated. Tires are a very sophisticated balloon.
Yip, another good reason not to over inflate your tyres, and why a pressure guage is very important to keep in your car if your serious about getting the pressure right. Nothing worse than uneven wear on a tyre.
Some of the most significant evidence presented against the Ford Motor Company in their Explorer roll over because of tire failure law suite (which they lost seriosly big $$$), delt with stickers on the door that were lower pressure than the tire manufacture had recomrnded.
Not relevant to the thread, but ok.
Tire expence is the second greatest operating expence, fuel being the first. Tire manufacture factory reps do tire tests together with fleet vehicle owners to determine the best tire pressure decal to place on the body at each wheel for that fleet. The pressures on the stickers are updated and adjusted periodicly as conditions change and newer tests dictate need. The tire pressure is ultamatly decided by the fleet owner. I have been part of the testing, inflating, and putting the sticers on, for the largest fleet in the world and another extreemly well recognized large fleet. I have had extensive training and conversation with the major tire reps. Each rep is preaching the same info.
And just what is this info? Im very familar with fleet work, I help look after a small fleet of trucks. Im also well aware that the pressure recomended by the manufactor is not always right, for all situation. There is often a trade off in tyre life, vs performance, or comfort. As a general rule on every car Iv owned I taken the manufactors recomendation, and added about 4psi, then adjusted it to suit, based on driving feel, tyre temps (measured) and wear across the contact patch. At the moment I run 32 on the front of my car, where 28 is recomended.
Competition between tire manufactures supplying fleets is fierce. They send their best reps to fleets to measure and optimize expence. Tire sales reps who visit tire stores advise on how to sell the most tires by giving the public what they want most.
Fleets pay their techs to maintain tire pressure so often that the pressure is maintained well within 5% of their determined inflation pressure.
Sounds like good business practice, but has nothing to do with this thread
Maintaining tire pressure is critical. When ever I did side jobs, regardless of replacing brakes, clutch, or tune-up, I always aired the tires to the max inflation, partly because of my fleet background and because often I found the tires had deflated to only 18-20lbs when max was 32-36lbs. Little wonder that some told me, "you know, my car always drives better after you have worked on it." "I don't understand how this type of repair can make my car feel different and drive better?"
On a large car, or one with low profile tryes then 32-36psi is about right. Infact some very, very low profile tyres (50% and below) recomended pressure can be 42psi or more, or the very low side wall is unable to surport the weight of the vechile, and maintian its shape in corners.
But 32-36psi is certianly not max pressure. Unless your talking about the manufacotors recomended max, pressure, and not the max pressure printed on the tyres side wall, which is what the thread started is refering to.
Even after inflating so many tires for too many years, I am somewhat amazed at my own newest tires that are nitrogen filled to 28lbs (max may be 36lbs) after more than a year they still gave 28lbs. Heat does not change pressure of nitrogen filled tires.
Being an inert gas Nitrogen dosn't experiance the same changes in volume with changes in temprature that breathable air does because of its Oxygen content. There are better gases to use, Ill be damned if I can remember what they are though.
Manufactures recomend very close to the max and never stop talking about maintaning pressure.
Tyre manufactors or car manufactors?
Because they both recomend a different max pressure, for the tyre manufactor its the point at which the tyre can't hold any more weight, and adding more becomes dangerous.
For the car manufactors its the point at the which the car, when fully loaded will be surported by a tyre with a complete contact patch, and provide the car manufactors idea of the ideal ride and performance.
There is nothing terriably wrong with following the car manufactors recomended max, although if have very little weight in your car you may be compromising total tyre grip by slightly reduceing its contact patch.
If you follow the tyre manufactors recomended max your are an idiot unless its matchs the cars max, and you are also carrying the cars maximum pay load.
But since the tyres recomended max is usualy 20-30% more than the max of the car its fitted to, all you end up doing is reducing the tyres contact patch to a very dangerous level.
In the case of your girlfriend, I recomend giving her what She wants!
Congratulations, you have a just given a recomdation that will lead to a dangerous situation for his girlfriend, and anyone else who has to share the road with her.
And is all based on reasoning that draws a very different conclusion. :rolleyes: :rolleyes:
Seems to me 2.2 may be trying to pull his experts under his sheet.
Riiight, except your the one giveing some very irrational reasoning, and backing it up with rethoric.
Prehaps we should all join you in your sheet?
Oh! Thats right, we have knowledge, experiance and rational thought on our side.
Iv added some comments in red:
There are small car tires that are safe and recomended inflated to 44lbs
Yip, thier called space saver spare tyres. They run a very high side wall, and a very small contact patch. They also have a very limited life.
Tires are constructed in ways that maximum tire presure is determined by a calculated formula which is based on their individual design.
I would hope some engineering and calculating went to it
Tires are capable of supporting the greatest load at their maximum inflation pressure.
As has already been stated. Max load needs max pressure, right again.
Tires are designed to provide the greatest wear and fuel milage at the maximum inflation pressure.
Yip, true again, high pressure equals small contact patch, equals lower roller resistance, equals better fuel milage. It also means the tyre will wear faster since not all of its contact patch is being used, the small part that is wears more, and un-evenly across the face of the tyre. You can also get problems from the tyre over heating. And of course its very dangerous, since the car has less traction that it was designed to have.
Tires are designed to provide even wear over a range of pressure and varios load.
Of course, assuming the pressure matchs the load.
Tires are run lower than max inflation to improve ride comfort.
Yip, common problem with used Jap imports sold here in NZ and else where in the world. The recomended prssure is one for driving around Japan, and for a market that generaly values comfort over performance. They also have radicaly different speed limits, to the rest of the world, with most cars never getting above 60kph in thier life. So, they have lower tyre pressures recomended by the manufactors. They also carry less weight in thier cars, as the population generaly weights less. The exact same car, sold here in NZ, where the speed limits are much higher, and its very easy to drive long distances at 100kph, and as a population we weigh more, and carry more, comes with a manufactors put a tyre pressure recomendation that can be 4-6psi higher.
Basicly what works in Japan, becomes dangerously under inflated here in NZ.
Some local manufactors that took to importing and renewing and then selling thier own brand of car from Japan even goto the trouble of replacing the Japanese tyre prssure recomendation plate.
Due to construction, Tires can and have worn more on the outside edges because of over or max inflation. Bands in tires can be designed and constructed in ways that prevent the center of the tread from expanding as much as the edges when the tire is inflated. Tires are a very sophisticated balloon.
Yip, another good reason not to over inflate your tyres, and why a pressure guage is very important to keep in your car if your serious about getting the pressure right. Nothing worse than uneven wear on a tyre.
Some of the most significant evidence presented against the Ford Motor Company in their Explorer roll over because of tire failure law suite (which they lost seriosly big $$$), delt with stickers on the door that were lower pressure than the tire manufacture had recomrnded.
Not relevant to the thread, but ok.
Tire expence is the second greatest operating expence, fuel being the first. Tire manufacture factory reps do tire tests together with fleet vehicle owners to determine the best tire pressure decal to place on the body at each wheel for that fleet. The pressures on the stickers are updated and adjusted periodicly as conditions change and newer tests dictate need. The tire pressure is ultamatly decided by the fleet owner. I have been part of the testing, inflating, and putting the sticers on, for the largest fleet in the world and another extreemly well recognized large fleet. I have had extensive training and conversation with the major tire reps. Each rep is preaching the same info.
And just what is this info? Im very familar with fleet work, I help look after a small fleet of trucks. Im also well aware that the pressure recomended by the manufactor is not always right, for all situation. There is often a trade off in tyre life, vs performance, or comfort. As a general rule on every car Iv owned I taken the manufactors recomendation, and added about 4psi, then adjusted it to suit, based on driving feel, tyre temps (measured) and wear across the contact patch. At the moment I run 32 on the front of my car, where 28 is recomended.
Competition between tire manufactures supplying fleets is fierce. They send their best reps to fleets to measure and optimize expence. Tire sales reps who visit tire stores advise on how to sell the most tires by giving the public what they want most.
Fleets pay their techs to maintain tire pressure so often that the pressure is maintained well within 5% of their determined inflation pressure.
Sounds like good business practice, but has nothing to do with this thread
Maintaining tire pressure is critical. When ever I did side jobs, regardless of replacing brakes, clutch, or tune-up, I always aired the tires to the max inflation, partly because of my fleet background and because often I found the tires had deflated to only 18-20lbs when max was 32-36lbs. Little wonder that some told me, "you know, my car always drives better after you have worked on it." "I don't understand how this type of repair can make my car feel different and drive better?"
On a large car, or one with low profile tryes then 32-36psi is about right. Infact some very, very low profile tyres (50% and below) recomended pressure can be 42psi or more, or the very low side wall is unable to surport the weight of the vechile, and maintian its shape in corners.
But 32-36psi is certianly not max pressure. Unless your talking about the manufacotors recomended max, pressure, and not the max pressure printed on the tyres side wall, which is what the thread started is refering to.
Even after inflating so many tires for too many years, I am somewhat amazed at my own newest tires that are nitrogen filled to 28lbs (max may be 36lbs) after more than a year they still gave 28lbs. Heat does not change pressure of nitrogen filled tires.
Being an inert gas Nitrogen dosn't experiance the same changes in volume with changes in temprature that breathable air does because of its Oxygen content. There are better gases to use, Ill be damned if I can remember what they are though.
Manufactures recomend very close to the max and never stop talking about maintaning pressure.
Tyre manufactors or car manufactors?
Because they both recomend a different max pressure, for the tyre manufactor its the point at which the tyre can't hold any more weight, and adding more becomes dangerous.
For the car manufactors its the point at the which the car, when fully loaded will be surported by a tyre with a complete contact patch, and provide the car manufactors idea of the ideal ride and performance.
There is nothing terriably wrong with following the car manufactors recomended max, although if have very little weight in your car you may be compromising total tyre grip by slightly reduceing its contact patch.
If you follow the tyre manufactors recomended max your are an idiot unless its matchs the cars max, and you are also carrying the cars maximum pay load.
But since the tyres recomended max is usualy 20-30% more than the max of the car its fitted to, all you end up doing is reducing the tyres contact patch to a very dangerous level.
In the case of your girlfriend, I recomend giving her what She wants!
Congratulations, you have a just given a recomdation that will lead to a dangerous situation for his girlfriend, and anyone else who has to share the road with her.
And is all based on reasoning that draws a very different conclusion. :rolleyes: :rolleyes:
Moppie
10-04-2006, 03:06 AM
Its a little mind teaser for those that have never dealt with bike tire inflation. Do the same rules apply, as I've listed above, for cars? Is weight the ultimate consideration, even though it won't ultimately cause an "even" contact patch across the tire? What ARE the factors involved here?
A little help:
Remember that weight is a factor of force AND mass :)
In mid corner a bike can generate some very high forces, and tyre pressures need to reflect that. ;)
A little help:
Remember that weight is a factor of force AND mass :)
In mid corner a bike can generate some very high forces, and tyre pressures need to reflect that. ;)
UncleBob
10-04-2006, 03:10 AM
A little help:
Remember that weight is a factor of force AND mass :)
In mid corner a bike can generate some very high forces, and tyre pressures need to reflect that. ;)
oooh....I like the way you think!
you are correct that weight involves force and mass....but here's the kicker. A higher force in the corners would cause the contact patch to get bigger.
Thats a good thing....up to a point :wink:
Remember that weight is a factor of force AND mass :)
In mid corner a bike can generate some very high forces, and tyre pressures need to reflect that. ;)
oooh....I like the way you think!
you are correct that weight involves force and mass....but here's the kicker. A higher force in the corners would cause the contact patch to get bigger.
Thats a good thing....up to a point :wink:
Moppie
10-04-2006, 04:49 AM
oooh....I like the way you think!
I spent a long time riding a push bike as a kid, and plenty of time playing with tyre pressures while doing so :smokin:
Air serves two purposes in a tyre.
It holds the weight of the vechile the tyre is attached to, AND it helps the tyre hold its shape.
And of course the shape a tyre has dictates its contact patch on the road surface, which of course dictates how much grip it will have.
Different tyres, used in different aplications, rely on different shapes, which require different air pressures in oder to hold up under the forces exerted on them by a vehcile.
With relation to bike tyre pressures vs car tyre pressures, think about the different jobs they do, and how they have to do it.
And, an extra little hint, very low profile tyres on a car have to behave in a similar manner as tyres on a bike with a large side wall contact patch (although that might confuse some people).
I spent a long time riding a push bike as a kid, and plenty of time playing with tyre pressures while doing so :smokin:
Air serves two purposes in a tyre.
It holds the weight of the vechile the tyre is attached to, AND it helps the tyre hold its shape.
And of course the shape a tyre has dictates its contact patch on the road surface, which of course dictates how much grip it will have.
Different tyres, used in different aplications, rely on different shapes, which require different air pressures in oder to hold up under the forces exerted on them by a vehcile.
With relation to bike tyre pressures vs car tyre pressures, think about the different jobs they do, and how they have to do it.
And, an extra little hint, very low profile tyres on a car have to behave in a similar manner as tyres on a bike with a large side wall contact patch (although that might confuse some people).
534BC
10-04-2006, 11:56 AM
I don't know much abouit bike tires other than what I can see that they are large, round, round and someone once told me that when spinning they want to "stand up" gyro or something.
I once picked up a load with an old backhoe with car tires on the front end (aired to 100 pounds) and the rim beads were touching the insides of the treads, lol.
We measured it and laughed. Does that count for anything?
I once picked up a load with an old backhoe with car tires on the front end (aired to 100 pounds) and the rim beads were touching the insides of the treads, lol.
We measured it and laughed. Does that count for anything?
UncleBob
10-04-2006, 12:30 PM
bike tires follow many of the same principles as car tires.
Weight is still a key factor, but it has more to do with tire performance.
Since there is no tire shape that you are trying to maintain, maxing out the tire pressure on any bike will increase your mileage because it reduces the contact patch, with no side effects to the tire. It in fact, increases tire life. Less contact patch means less heat for the tire.
The side effect, of course, is traction. Less contact patch will of course reduce traction, but the heat is an important factor also. Bike tires are much stickier than car tires, but they require a certain amount of heat to work optimally.
So for high performance riding, you drop the tire pressures to increase traction. The tire will wear faster because of this. The range you have availible to play with is quite large, say 20psi to 42psi.
The handling disadvantage with low pressure is it takes more steering effort to get a bike leaned over. The larger contact patch makes it resists the angle changes more. This doesn't prevent a bike from handling well, but many riders dislike the added steering effort.
I run my rear tire at 20-30psi, depending on what I'm doing. This is quite low compared to most. The reason being, the turbo makes rear wheel traction a challenge. But just by dropping my tire pressure, it will take every bit of HP I can throw at it. Quite impressive when you put it in car terms, of power to weight ratio....no car could keep traction with that level of P/W, without using special tires and chasis tuning.
__________________
Weight is still a key factor, but it has more to do with tire performance.
Since there is no tire shape that you are trying to maintain, maxing out the tire pressure on any bike will increase your mileage because it reduces the contact patch, with no side effects to the tire. It in fact, increases tire life. Less contact patch means less heat for the tire.
The side effect, of course, is traction. Less contact patch will of course reduce traction, but the heat is an important factor also. Bike tires are much stickier than car tires, but they require a certain amount of heat to work optimally.
So for high performance riding, you drop the tire pressures to increase traction. The tire will wear faster because of this. The range you have availible to play with is quite large, say 20psi to 42psi.
The handling disadvantage with low pressure is it takes more steering effort to get a bike leaned over. The larger contact patch makes it resists the angle changes more. This doesn't prevent a bike from handling well, but many riders dislike the added steering effort.
I run my rear tire at 20-30psi, depending on what I'm doing. This is quite low compared to most. The reason being, the turbo makes rear wheel traction a challenge. But just by dropping my tire pressure, it will take every bit of HP I can throw at it. Quite impressive when you put it in car terms, of power to weight ratio....no car could keep traction with that level of P/W, without using special tires and chasis tuning.
__________________
GreyGoose006
10-04-2006, 11:56 PM
Let them fill their tires as they see fit.Those guys sound like they are clutching at their chest with both hands and sticking one leg outta bed. They have a fairly clear understanding of 1975 tire technology and refuse to ackowledge the improvements that TIRE manufactures are continuosly making every day.
I pretty sure that none of the major TIRE manufactures will be consulting these guys asking for their recomendations on tire inflation any time soon.
Thirty years ago American cars weighed 4-6,000lbs and all tires said 28-32 lbs max inflation on the sidewall. Todays cars weigh around 3,000 lbs and in many cases have much wider tires than the typical 70's auto. There has been a trend of gradually increasing tire inflation recomendations by TIRE manufactures over the past 30 years. Now we have tires that say 44lbs max PSI on them on realetivly light weight vehicles. Tire pressures are cold and should not be adjusted as heat increases tire pressure.
Modern automobile tires are far more sophisticated than comparing them to an illustrative example of a party balloon having limited structure. Modern technology of tire construction continues to reduce irregular tire wear problems that over years past were blamed totally on tire inflation. Engineers who design tires are blending construction and inflation together to develope and produce longer lasting, safer, and more fuel efficient tires. Before a tire design ever leaves the computer drawing board, the engineers know what the tire should do at the tire pressure it has been designed to work at.
If your tires are the size recommended by the AUTO manufacture, the max tire pressure molded into the side wall by the TIRE manufacture will not create a liability to them or cause the tire to dervolope undisirable characteristics, contact patch, or otherwise reduce safety.
this was posted in the caprice forum when i mentioned the hot debate going on over here.
i'm sorry, but if the sidewall of my tire says 44psi. (it does), i'm gonna inflate it to 44psi. if it says 15, i'll happily put 15psi. in it.
as soon as you change from the tires that came on the car, you can ignore the doorjamb's sugestion.
my car is an '84 caprice classic.
it CAME w/ 205 wide tires that inflated to 25psi.
police 9c1 caprices came w/ 225 wide tires. i'm guessing they were at 25psi.
i put new 235 wide 44psi. tire on.
i inflate them to 44 psi.
if i inflated 44psi. tires to 25psi., all i'd be doing is decreasing my gas mileage, and causing accelerated tire wear and premature tire failure.
at $85 ea.
i'll inflate to 44psi thank you.
I pretty sure that none of the major TIRE manufactures will be consulting these guys asking for their recomendations on tire inflation any time soon.
Thirty years ago American cars weighed 4-6,000lbs and all tires said 28-32 lbs max inflation on the sidewall. Todays cars weigh around 3,000 lbs and in many cases have much wider tires than the typical 70's auto. There has been a trend of gradually increasing tire inflation recomendations by TIRE manufactures over the past 30 years. Now we have tires that say 44lbs max PSI on them on realetivly light weight vehicles. Tire pressures are cold and should not be adjusted as heat increases tire pressure.
Modern automobile tires are far more sophisticated than comparing them to an illustrative example of a party balloon having limited structure. Modern technology of tire construction continues to reduce irregular tire wear problems that over years past were blamed totally on tire inflation. Engineers who design tires are blending construction and inflation together to develope and produce longer lasting, safer, and more fuel efficient tires. Before a tire design ever leaves the computer drawing board, the engineers know what the tire should do at the tire pressure it has been designed to work at.
If your tires are the size recommended by the AUTO manufacture, the max tire pressure molded into the side wall by the TIRE manufacture will not create a liability to them or cause the tire to dervolope undisirable characteristics, contact patch, or otherwise reduce safety.
this was posted in the caprice forum when i mentioned the hot debate going on over here.
i'm sorry, but if the sidewall of my tire says 44psi. (it does), i'm gonna inflate it to 44psi. if it says 15, i'll happily put 15psi. in it.
as soon as you change from the tires that came on the car, you can ignore the doorjamb's sugestion.
my car is an '84 caprice classic.
it CAME w/ 205 wide tires that inflated to 25psi.
police 9c1 caprices came w/ 225 wide tires. i'm guessing they were at 25psi.
i put new 235 wide 44psi. tire on.
i inflate them to 44 psi.
if i inflated 44psi. tires to 25psi., all i'd be doing is decreasing my gas mileage, and causing accelerated tire wear and premature tire failure.
at $85 ea.
i'll inflate to 44psi thank you.
Moppie
10-05-2006, 12:11 AM
i'm sorry, but if the sidewall of my tire says 44psi. (it does), i'm gonna inflate it to 44psi. if it says 15, i'll happily put 15psi. in it.
as soon as you change from the tires that came on the car, you can ignore the doorjamb's sugestion.
my car is an '84 caprice classic.
it CAME w/ 205 wide tires that inflated to 25psi.
police 9c1 caprices came w/ 225 wide tires. i'm guessing they were at 25psi.
i put new 235 wide 44psi. tire on.
i inflate them to 44 psi.
if i inflated 44psi. tires to 25psi., all i'd be doing is decreasing my gas mileage, and causing accelerated tire wear and premature tire failure.
at $85 ea.
i'll inflate to 44psi thank you.
Wow.
Have you read anything in this thread?
Or you just out to kill yourself in you car?
as soon as you change from the tires that came on the car, you can ignore the doorjamb's sugestion.
my car is an '84 caprice classic.
it CAME w/ 205 wide tires that inflated to 25psi.
police 9c1 caprices came w/ 225 wide tires. i'm guessing they were at 25psi.
i put new 235 wide 44psi. tire on.
i inflate them to 44 psi.
if i inflated 44psi. tires to 25psi., all i'd be doing is decreasing my gas mileage, and causing accelerated tire wear and premature tire failure.
at $85 ea.
i'll inflate to 44psi thank you.
Wow.
Have you read anything in this thread?
Or you just out to kill yourself in you car?
corning_d3
10-05-2006, 01:10 AM
Some people just can't grasp the concept... Just hope your not behind or meeting them on the highway when they pop a tire.
KiwiBacon
10-05-2006, 01:15 AM
Some people just can't grasp the concept... Just hope your not behind or meeting them on the highway when they pop a tire.
Or when they spin out in a corner after hitting a small ripple that wouldn't upset a tyre at normal pressure.
Or when they spin out in a corner after hitting a small ripple that wouldn't upset a tyre at normal pressure.
corning_d3
10-05-2006, 01:20 AM
I've been there. I was toying with the pressures on my monte, and noticed too much pressure in the back was almost as bad as a defective strut in rippled corners! I now run 40 up front(it's heavy), and 34 in back for best all around wear and mileage..
2.2 Straight six
10-05-2006, 01:31 AM
i'm sorry, but if the sidewall of my tire says 44psi. (it does), i'm gonna inflate it to 44psi. if it says 15, i'll happily put 15psi. in it.
think about it, the tyres on YOUR car are not made solely for YOUR car (that model) they are put on OTHER cars, which will have DIFFERENT weight.
now, contact patch is in proportion to vehicle weight and tyre inflation pressure. if your car weighs 3,000lb and you run it at 44psi then your contact patch will be different to a 3,500lb car running 44psi.
you see, it doesn't matter about the tyre's max in this case, the manufacturer uses these tyres and test them on the vehicle, they then look at ride comfort, contact patch etc and THEY determine what pressure should be run, to give a good balance in those areas.
hence the reasoning that you should not inflate a tyre to the max pressure (as listed on the sidewall, since they're used on different cars, with different inflation pressures the tyre manufacturer can't say what pressure YOU should run, they can only tell you the max pressure the tyre can hold for its laod rating) and that you should follow what the car manufacturer reccomends.
but if you want to over-inflate them, then get killed because your contact patch isn't sufficient then by all means do so. but don't tell people you should run them at the max when it's not true for everday driving.
think about it, the tyres on YOUR car are not made solely for YOUR car (that model) they are put on OTHER cars, which will have DIFFERENT weight.
now, contact patch is in proportion to vehicle weight and tyre inflation pressure. if your car weighs 3,000lb and you run it at 44psi then your contact patch will be different to a 3,500lb car running 44psi.
you see, it doesn't matter about the tyre's max in this case, the manufacturer uses these tyres and test them on the vehicle, they then look at ride comfort, contact patch etc and THEY determine what pressure should be run, to give a good balance in those areas.
hence the reasoning that you should not inflate a tyre to the max pressure (as listed on the sidewall, since they're used on different cars, with different inflation pressures the tyre manufacturer can't say what pressure YOU should run, they can only tell you the max pressure the tyre can hold for its laod rating) and that you should follow what the car manufacturer reccomends.
but if you want to over-inflate them, then get killed because your contact patch isn't sufficient then by all means do so. but don't tell people you should run them at the max when it's not true for everday driving.
redstang423
10-05-2006, 01:53 AM
Here are a few things that have been overlooked.
Nitrogen DOES!!! increase pressure with temperature. All gases (not fuel type gases) ideally follow the Ideal Gas Law (granted, all depart this law to some degree, but follow it more or less). It is an equation defined by PV=nRT. P is the pressure of the gas. V is volume of the gas - basically unchanging in our idea of a tire. n is the number of moles of the gas (technical way of saying how much) - again, this is unchangning. R is the universal gas constant, again unchanged. T is temperature. So what the equation tells you is as the temperature increases pressure INCREASES. It does NOT remain the same as long as the tire remains sealed closed.
A bike (at least a motorcycle) is intended to be turned by leaning, rather than turning the handlebars. This causes all the forces of cornering to be directed directly though the vertical plane of the bike, from the rider's head to feet. It is not like a car where when you turn, you get thrown to the side and the tires must provide the friction in the lateral direction. Because of this, tires and their pressures are calcuated differently.
The "maximum" pressure is not truly the maximum pressure the tire can run. All engineers build in a factor of safety to nearly everything they do. Take a folding chair for instance, with a weight limit of 250 lbs. You WILL have some person that weighs 275 sit in it. It will not break. These safety factors are everywhere in engineering designs. They may be very low for something like a Formula Car, but very high for every day products that anyone can use. For the tires, there would be a reasonably large factor of safety, because idiots will inflate it beyond the "max" pressure. The tire can't explode on someone even if they slightly overload it. Additionally, most people don't understand pressure will increase when the tire (and air inside) gets hotter after use. Otherwise, someone could fill several PSI under the "max" when the tire is cold, and experience failure after they use it for a few minutes.
-Jeff
Nitrogen DOES!!! increase pressure with temperature. All gases (not fuel type gases) ideally follow the Ideal Gas Law (granted, all depart this law to some degree, but follow it more or less). It is an equation defined by PV=nRT. P is the pressure of the gas. V is volume of the gas - basically unchanging in our idea of a tire. n is the number of moles of the gas (technical way of saying how much) - again, this is unchangning. R is the universal gas constant, again unchanged. T is temperature. So what the equation tells you is as the temperature increases pressure INCREASES. It does NOT remain the same as long as the tire remains sealed closed.
A bike (at least a motorcycle) is intended to be turned by leaning, rather than turning the handlebars. This causes all the forces of cornering to be directed directly though the vertical plane of the bike, from the rider's head to feet. It is not like a car where when you turn, you get thrown to the side and the tires must provide the friction in the lateral direction. Because of this, tires and their pressures are calcuated differently.
The "maximum" pressure is not truly the maximum pressure the tire can run. All engineers build in a factor of safety to nearly everything they do. Take a folding chair for instance, with a weight limit of 250 lbs. You WILL have some person that weighs 275 sit in it. It will not break. These safety factors are everywhere in engineering designs. They may be very low for something like a Formula Car, but very high for every day products that anyone can use. For the tires, there would be a reasonably large factor of safety, because idiots will inflate it beyond the "max" pressure. The tire can't explode on someone even if they slightly overload it. Additionally, most people don't understand pressure will increase when the tire (and air inside) gets hotter after use. Otherwise, someone could fill several PSI under the "max" when the tire is cold, and experience failure after they use it for a few minutes.
-Jeff
GreyGoose006
10-05-2006, 10:39 AM
which is why i inflate to the pressure on the sidewall.
that pressure was calculated to be safe on the average car driving down the road. why would you inflate to a lower pressure to increase the contact patch for regular driving?
unless your drive to work sees lots of drivin at 150+ for extended time, lots of HARD acceleration, and high speed cornering at the limit of traction, the number on the sidewall is perfectly safe fo everyday driving.
that being said,
if i had the tires from my car on a miata (about half the weight), i WOULD take into consideration the fact that 44psi might be too much.
if i had my tires on an F-350 and was going to be towing a trailer full of horses, i might inflate to a different pressure.
thing is, tires come w/ a load rating.
this is the load that they were designed to carry safely.
i bought tires that were slightly above the weight of my car.
this way, i can happily inflate to the pressure on the sidewall, and be done with it.
redstang basically said what i was thinking but couldnt verbalize.
tires wont "explode" as many have said, under normal conditions.
there is a safety net built in by all engineers, and it happens to be quite large in the case of tires.
also, for those people who put nitrogen in their tires thinking it helps...
you are getting ripped off.
assuming that nitrogen helped with anything in the first place, tires would have to be filled exclusively w/ nitrogen. no air.
that means that all the normal air must be vacuumed out prior to filling w/ nitrogen.
also, the main reason for using nitrogen is that it expands LESS. no gas remains at the same volume regardless of heat... its called PHYSICS. these laws have been in place for cenuries.
lastly,
you do realize that this inferior stuff called air, contiains 78.084% nitrogen by mass?
that pressure was calculated to be safe on the average car driving down the road. why would you inflate to a lower pressure to increase the contact patch for regular driving?
unless your drive to work sees lots of drivin at 150+ for extended time, lots of HARD acceleration, and high speed cornering at the limit of traction, the number on the sidewall is perfectly safe fo everyday driving.
that being said,
if i had the tires from my car on a miata (about half the weight), i WOULD take into consideration the fact that 44psi might be too much.
if i had my tires on an F-350 and was going to be towing a trailer full of horses, i might inflate to a different pressure.
thing is, tires come w/ a load rating.
this is the load that they were designed to carry safely.
i bought tires that were slightly above the weight of my car.
this way, i can happily inflate to the pressure on the sidewall, and be done with it.
redstang basically said what i was thinking but couldnt verbalize.
tires wont "explode" as many have said, under normal conditions.
there is a safety net built in by all engineers, and it happens to be quite large in the case of tires.
also, for those people who put nitrogen in their tires thinking it helps...
you are getting ripped off.
assuming that nitrogen helped with anything in the first place, tires would have to be filled exclusively w/ nitrogen. no air.
that means that all the normal air must be vacuumed out prior to filling w/ nitrogen.
also, the main reason for using nitrogen is that it expands LESS. no gas remains at the same volume regardless of heat... its called PHYSICS. these laws have been in place for cenuries.
lastly,
you do realize that this inferior stuff called air, contiains 78.084% nitrogen by mass?
redstang423
10-05-2006, 12:17 PM
Greygoose, you should still inflate tires, regardless of any weight classifactions (assuming appropriate for your vehicle), to the car manufacturer's recommended pressures. Pressure is equal to force over area. The force would be the weight of the car seen by each wheel, leaving pressure to control the area, or contact patch of the tire. Automakers do significant testing to figure out what the best settings for that particular vehicle would be, factoring in everything from comfort to safety (proper amount of contact area) to tread wear of the stock sized (in terms of dimensions) tire. While you are free to fill to whatever pressure suits your fancy, departing too much from the recommendations can throw off the handling and safety characteristics of your vehicle. Its very similar to why when Escalades first came out with its small (on a relative scale) wheels and people started putting 22" wheels on it, Cadillac discouraged it since it would alter the inteded handling characteristics of the vehicle, possibly making it unsafe.
Moppie
10-05-2006, 02:40 PM
which is why i inflate to the pressure on the sidewall.
that pressure was calculated to be safe on the average car driving down the road. why would you inflate to a lower pressure to increase the contact patch for regular driving?
unless your drive to work sees lots of drivin at 150+ for extended time, lots of HARD acceleration, and high speed cornering at the limit of traction, the number on the sidewall is perfectly safe fo everyday driving.
So when your driving down the road at your sedate old mans pace, and someone pulls out in front of you, and you stand on the brakes, only to find that because you've over inflated your tyres instead of stopping you drive straight into them, what are you going to do?
For the final time, the number written on your tyres side wall is a max pressure for max loading, for that tyre.
It is not a recomended pressure for all cars. It is only there as a tested maximum pressure for that tyre, assuming its carrying a very heavy load.
that pressure was calculated to be safe on the average car driving down the road. why would you inflate to a lower pressure to increase the contact patch for regular driving?
unless your drive to work sees lots of drivin at 150+ for extended time, lots of HARD acceleration, and high speed cornering at the limit of traction, the number on the sidewall is perfectly safe fo everyday driving.
So when your driving down the road at your sedate old mans pace, and someone pulls out in front of you, and you stand on the brakes, only to find that because you've over inflated your tyres instead of stopping you drive straight into them, what are you going to do?
For the final time, the number written on your tyres side wall is a max pressure for max loading, for that tyre.
It is not a recomended pressure for all cars. It is only there as a tested maximum pressure for that tyre, assuming its carrying a very heavy load.
GreyGoose006
10-05-2006, 03:33 PM
So when your driving down the road at your sedate old mans pace, and someone pulls out in front of you, and you stand on the brakes, only to find that because you've over inflated your tyres instead of stopping you drive straight into them, what are you going to do?
For the final time, the number written on your tyres side wall is a max pressure for max loading, for that tyre.
It is not a recomended pressure for all cars. It is only there as a tested maximum pressure for that tyre, assuming its carrying a very heavy load.
hey moppie, you are EXACTLY right. EXACTLY RIGHT.
there is no problem with what you are saying... that is if i were using the standard tires on my car. guess what, IM NOT!!!
see, there are these things called "HIGH PRESSURE TIRES". they are meant to operate at HIGHER PRESSURES than standard tires. the reason for these tires is that it decreases rolling resistance, and allows for more precise handling and decreased tire weight.
next time your ecectricity goes out due to a tree falling on a line, go look around for those Govt. vehicles that show up.
on the sidewall of these tires, it says "90 PSI"
that means that you are to inflate the tires to 90 psi.
one of these govt F-250s dosent weigh significantly more than a standard F-250, so why the high pressure???
TIRE WEAR...
at 90 psi, the tires wear less and need to be replaced less often.
granted, they are $200 ea. but to the govt, it is worth it.
i am POSITIVE that if you went and bought 90 psi tires, and only inflated them to 25 psi, they would look nearly half way flat, decrease your mileage SIGNIFICANTLY, like cut it in half, and wear the tires out in about two weeks.
my tires are called "HIGH PRESSURE CAR TIRES" and are meant to be inflated to 44 psi.
you know, tire technology HAS advanced since the 70's and as a result, the pressure ratings on sidewalls is becoming the deciding factor when inflating your tires. any time you change wheel size tire size tire profile wheel width, lower your car, or even buy now tires, the door jamb is now DEFUNCT.
i agree that on a stock vehicle, you should go by the doorjamb, or the owners manual... STOCK.
MY TIRES ARENT STOCK!!! and my doorjamb is 23 years old. it makes a difference.
oh, and as for the grandfatherly pace i drive at,
im 19.
For the final time, the number written on your tyres side wall is a max pressure for max loading, for that tyre.
It is not a recomended pressure for all cars. It is only there as a tested maximum pressure for that tyre, assuming its carrying a very heavy load.
hey moppie, you are EXACTLY right. EXACTLY RIGHT.
there is no problem with what you are saying... that is if i were using the standard tires on my car. guess what, IM NOT!!!
see, there are these things called "HIGH PRESSURE TIRES". they are meant to operate at HIGHER PRESSURES than standard tires. the reason for these tires is that it decreases rolling resistance, and allows for more precise handling and decreased tire weight.
next time your ecectricity goes out due to a tree falling on a line, go look around for those Govt. vehicles that show up.
on the sidewall of these tires, it says "90 PSI"
that means that you are to inflate the tires to 90 psi.
one of these govt F-250s dosent weigh significantly more than a standard F-250, so why the high pressure???
TIRE WEAR...
at 90 psi, the tires wear less and need to be replaced less often.
granted, they are $200 ea. but to the govt, it is worth it.
i am POSITIVE that if you went and bought 90 psi tires, and only inflated them to 25 psi, they would look nearly half way flat, decrease your mileage SIGNIFICANTLY, like cut it in half, and wear the tires out in about two weeks.
my tires are called "HIGH PRESSURE CAR TIRES" and are meant to be inflated to 44 psi.
you know, tire technology HAS advanced since the 70's and as a result, the pressure ratings on sidewalls is becoming the deciding factor when inflating your tires. any time you change wheel size tire size tire profile wheel width, lower your car, or even buy now tires, the door jamb is now DEFUNCT.
i agree that on a stock vehicle, you should go by the doorjamb, or the owners manual... STOCK.
MY TIRES ARENT STOCK!!! and my doorjamb is 23 years old. it makes a difference.
oh, and as for the grandfatherly pace i drive at,
im 19.
UncleBob
10-05-2006, 03:35 PM
I guess we can continue to repeat ourselves into infinity. I'm too lazy to quote what I've already said.
This is going nowhere fast.
This is going nowhere fast.
Steel
10-05-2006, 06:11 PM
Actually, you'd be hard pressed to tell the difference between 40 psi and 90 psi in a 10-ply rated E load tire by just looking at it if the truck is unloaded.
Anyway i can guarantee you that the pressure rating written on the side of your tire is the max COLD pressure. And if you want to fill it to that point, that's fine. You're right in that it decreases rolling resistance, and the other guys are right in saying that it also decreases your traction and ride quality. But if you need to squeeze 3 really fat peaple in with a couple dead bodies in the back and some... lead pipes... you'll be all set for the load. I fill my civic tires to 37psi all around because i do a LOT (~23k miles a year) of highway driving and the highways are in generally good condition. If i know it's going to be snowy then i lower them a bit.
People always worry aobut overfilling tires, but that's really tough to do. I've seen customer cars with 50-55 psi in all the tires, 10psi over max and no bad side effects. USually the worst that happens is when they hit a pothole with tight tires like that is the the tire will bubble on the sidewall and need to be replaced. Usually saves the rim from damage too (unless its low profile... but i dont need to worry aobut taht with 185-70-13's :D) The big problem is UNDERFILLING them and having blowouts. You see people riding damn near on the rim all the time, and THAT scares me.
Another think - the ~100% nitrogen filled tires = waste of money. The air you breathe is 78% nitrogen. Though it is true that pressure will increase even with 100 N2 tires, its generally not as much as ROA (regular 'ol air). That and don't forget that auto manufactures AND tire manufacturers take into account the fact that the tires heat up and the pressure rises, so now you're working against them. So in conclusion, there is no advantage to N2 filled tires, unless you're the guy that came up with the idea.
Anyway i can guarantee you that the pressure rating written on the side of your tire is the max COLD pressure. And if you want to fill it to that point, that's fine. You're right in that it decreases rolling resistance, and the other guys are right in saying that it also decreases your traction and ride quality. But if you need to squeeze 3 really fat peaple in with a couple dead bodies in the back and some... lead pipes... you'll be all set for the load. I fill my civic tires to 37psi all around because i do a LOT (~23k miles a year) of highway driving and the highways are in generally good condition. If i know it's going to be snowy then i lower them a bit.
People always worry aobut overfilling tires, but that's really tough to do. I've seen customer cars with 50-55 psi in all the tires, 10psi over max and no bad side effects. USually the worst that happens is when they hit a pothole with tight tires like that is the the tire will bubble on the sidewall and need to be replaced. Usually saves the rim from damage too (unless its low profile... but i dont need to worry aobut taht with 185-70-13's :D) The big problem is UNDERFILLING them and having blowouts. You see people riding damn near on the rim all the time, and THAT scares me.
Another think - the ~100% nitrogen filled tires = waste of money. The air you breathe is 78% nitrogen. Though it is true that pressure will increase even with 100 N2 tires, its generally not as much as ROA (regular 'ol air). That and don't forget that auto manufactures AND tire manufacturers take into account the fact that the tires heat up and the pressure rises, so now you're working against them. So in conclusion, there is no advantage to N2 filled tires, unless you're the guy that came up with the idea.
UncleBob
10-05-2006, 06:16 PM
I see overinflation damage all the time at the shop. Not nearly as often as I see underinflation damage and lack-of-rotation damage....frankly, the average car owner just doesn't pay any attention to their tires. I would take a guess that the AVERAGE car I see is at least 1 quart low on oil also for the same reason, and I see at least two cars a week that are 3+ quarts low on oil a week. Finding abusive owners is definitely not hard to do.
But the point is, its not some type of mystical rare thing.
But the point is, its not some type of mystical rare thing.
2.2 Straight six
10-05-2006, 06:25 PM
I see overinflation damage all the time at the shop. Not nearly as often as I see underinflation damage and lack-of-rotation damage....frankly, the average car owner just doesn't pay any attention to their tires. I would take a guess that the AVERAGE car I see is at least 1 quart low on oil also for the same reason, and I see at least two cars a week that are 3+ quarts low on oil a week. Finding abusive owners is definitely not hard to do.
But the point is, its not some type of mystical rare thing.
stuff like that cracks me up, when i talk to people about seized engines (lack of oil) and they say "but why haven't they made engines that don't seize?"
umm....they do, you just have to put oil in them...
But the point is, its not some type of mystical rare thing.
stuff like that cracks me up, when i talk to people about seized engines (lack of oil) and they say "but why haven't they made engines that don't seize?"
umm....they do, you just have to put oil in them...
UncleBob
10-05-2006, 06:30 PM
stuff like that cracks me up, when i talk to people about seized engines (lack of oil) and they say "but why haven't they made engines that don't seize?"
umm....they do, you just have to put oil in them...
I tell yah, I'm simply stupified by the level of engineering these days. I really don't have any idea how a plain bearing motor can live for 15K+ miles running on the same oil, and half of that is under half its oil capacity. I can't tell you how many times I pulled less than 1/2 a quart out of the oil pan. The reason they brought the car in, was because the "oil change" light was coming on when they went around corners. That being the oil PRESSURE light.
Makes you appreciate a well designed engine. If a motor can live through that and still make it to 200K miles. Then if you actually MAINTAINED the car in a proper manor, I'm sure it would see a million miles without a hickup
umm....they do, you just have to put oil in them...
I tell yah, I'm simply stupified by the level of engineering these days. I really don't have any idea how a plain bearing motor can live for 15K+ miles running on the same oil, and half of that is under half its oil capacity. I can't tell you how many times I pulled less than 1/2 a quart out of the oil pan. The reason they brought the car in, was because the "oil change" light was coming on when they went around corners. That being the oil PRESSURE light.
Makes you appreciate a well designed engine. If a motor can live through that and still make it to 200K miles. Then if you actually MAINTAINED the car in a proper manor, I'm sure it would see a million miles without a hickup
GreyGoose006
10-05-2006, 06:35 PM
the million mile mark is not all that much anyway.
tons of volvo 240's and such make it to the million mile mark.
its all in the maintenance, and of course engine design
old pinto's were said to be able to run for five minutes at WOT w/ little or no oil in them.
i know someone who emptied the oil out and drained the radiator, then drove at 80 on the highway in an attempt to blow the engine. He went for 2-3 minutes before the thing started clacking so bad and lost power.
still ran tho lol.
tons of volvo 240's and such make it to the million mile mark.
its all in the maintenance, and of course engine design
old pinto's were said to be able to run for five minutes at WOT w/ little or no oil in them.
i know someone who emptied the oil out and drained the radiator, then drove at 80 on the highway in an attempt to blow the engine. He went for 2-3 minutes before the thing started clacking so bad and lost power.
still ran tho lol.
UncleBob
10-05-2006, 09:44 PM
I don't care what motor engineering you got, no oil = siezed motor. You might "survive" the abuse of running it down to 1/2 a quart of badly burnt oil that has gone so far that it lost all its viscosity and then regained it due to all the soot, but damage was done and will be back to haunt you.
Eventually....
Eventually....
GreyGoose006
10-05-2006, 10:04 PM
oh sure, but when you are trying to kill an engine...
corning_d3
10-06-2006, 01:12 AM
I witnessed an '84 4-banger mustang go 20 miles with no oil, plug or filter. Then it snapped the cam in two....
KiwiBacon
10-06-2006, 02:29 AM
which is why i inflate to the pressure on the sidewall.
that pressure was calculated to be safe on the average car driving down the road. why would you inflate to a lower pressure to increase the contact patch for regular driving?
The point is, when your "normal driving" limits are exceeded, it's too late to get out and air down your tyres.
Your grip is reduced, the chances of impact are so much higher.
Tyre air pressure is one of the first things an accident investigator will check.
Of course by the time an accident investigator is checking over your car, it's usually involved in an accident that killed someone.
that pressure was calculated to be safe on the average car driving down the road. why would you inflate to a lower pressure to increase the contact patch for regular driving?
The point is, when your "normal driving" limits are exceeded, it's too late to get out and air down your tyres.
Your grip is reduced, the chances of impact are so much higher.
Tyre air pressure is one of the first things an accident investigator will check.
Of course by the time an accident investigator is checking over your car, it's usually involved in an accident that killed someone.
UncleBob
10-06-2006, 02:34 AM
hey! No hijacking our hijacked thread! :D
I think talking about dumb car owners and blown up engines is way more entertaining....The stories I got....alas....
I think talking about dumb car owners and blown up engines is way more entertaining....The stories I got....alas....
GreyGoose006
10-06-2006, 11:29 AM
the tire issue is gone.
lets agree that i'm right and the rest of you are wrong...
LOL.
okay just kidding.
seriously though, some engines can take all kinds of abuse that they were never meant to take.
Then it snapped the cam in two....
holy shiznits thats cool.
what kind of forces are required to snap a cam?
a LOT.
lets agree that i'm right and the rest of you are wrong...
LOL.
okay just kidding.
seriously though, some engines can take all kinds of abuse that they were never meant to take.
Then it snapped the cam in two....
holy shiznits thats cool.
what kind of forces are required to snap a cam?
a LOT.
GreyGoose006
10-06-2006, 11:35 AM
The point is, when your "normal driving" limits are exceeded, it's too late to get out and air down your tyres.
Your grip is reduced, the chances of impact are so much higher.
Tyre air pressure is one of the first things an accident investigator will check.
Of course by the time an accident investigator is checking over your car, it's usually involved in an accident that killed someone.
oh, and to get back on topic, yes, but how often do you find yourself skidding out of control for no apparent reason...
with a little caution and level headed vehicle control, you can manage just fine in any emergency.
many times i have been driving around and somebody pulls out from behind a bus and stops right in front of me. i dont SLAM on the brakes and slide into him because my wheels ae locked up (no abs)
its more of an ever increasing pressure on the pedal to prevent front wheel lockup... that way you can still steer and avoid the situation entirely.
i'll be driving 45 on the bypass and some jerk hauling 5 horses pulls right out.
again, if you dont panic, and know a little bit about car control, accidents can be avoided, and you will never have to exceed the limits of your cars control
:2cents:
Your grip is reduced, the chances of impact are so much higher.
Tyre air pressure is one of the first things an accident investigator will check.
Of course by the time an accident investigator is checking over your car, it's usually involved in an accident that killed someone.
oh, and to get back on topic, yes, but how often do you find yourself skidding out of control for no apparent reason...
with a little caution and level headed vehicle control, you can manage just fine in any emergency.
many times i have been driving around and somebody pulls out from behind a bus and stops right in front of me. i dont SLAM on the brakes and slide into him because my wheels ae locked up (no abs)
its more of an ever increasing pressure on the pedal to prevent front wheel lockup... that way you can still steer and avoid the situation entirely.
i'll be driving 45 on the bypass and some jerk hauling 5 horses pulls right out.
again, if you dont panic, and know a little bit about car control, accidents can be avoided, and you will never have to exceed the limits of your cars control
:2cents:
2.2 Straight six
10-06-2006, 04:42 PM
what kind of forces are required to snap a cam?
a LOT.
varies, when removing them it doesn't take a lot. if you loosen the cam retainers wrong (like removing the ones on the left completely without touching those on the right) they can snap under the force of the valve springs. you need to loosen the retainers slowly and equally.
a LOT.
varies, when removing them it doesn't take a lot. if you loosen the cam retainers wrong (like removing the ones on the left completely without touching those on the right) they can snap under the force of the valve springs. you need to loosen the retainers slowly and equally.
Knap
10-06-2006, 05:01 PM
The correct pressures for conditions and circumstances should be used. Low pressures are more dangerous (accident reports) despite the "ultimate" grip re race use. Higher pressures give better steering response. Although max pressure on sidewall is more likely to give higher wear, to a certain extent radials do not balloon and the burst pressure is say 100psi. In view of additional pressure for high speed use and potential drop in pressure if not monitored, keeping them marginally higher than recommended for the conditions, which could include wet roads, is not a great sin, although this is unlikely to be max pressure on sidewall.
2.2 Straight six
10-06-2006, 05:16 PM
the burst pressure is say 100psi.
if you're running 50psi and hit a big enough bump at a high enough speed the pressure will surge and can blow your tyres out. i've seen it happen on tyres running 32psi. i was in the car when it hit a speed bump at ~120mph.
if you're running 50psi and hit a big enough bump at a high enough speed the pressure will surge and can blow your tyres out. i've seen it happen on tyres running 32psi. i was in the car when it hit a speed bump at ~120mph.
KiwiBacon
10-06-2006, 05:43 PM
oh, and to get back on topic, yes, but how often do you find yourself skidding out of control for no apparent reason...
with a little caution and level headed vehicle control, you can manage just fine in any emergency.
many times i have been driving around and somebody pulls out from behind a bus and stops right in front of me. i dont SLAM on the brakes and slide into him because my wheels ae locked up (no abs)
its more of an ever increasing pressure on the pedal to prevent front wheel lockup... that way you can still steer and avoid the situation entirely.
i'll be driving 45 on the bypass and some jerk hauling 5 horses pulls right out.
again, if you dont panic, and know a little bit about car control, accidents can be avoided, and you will never have to exceed the limits of your cars control
:2cents:
You're obviously invincible, far be it from us to convince you otherwise.
Have you tried a temp check to see how even your wear is going to be?
The max pressure for the BFG's on my truck is 65psi.
40psi is the correct pressure for the 600kg I have on each wheel to get even wear.
Lighter trucks run them around 30psi to get even wear.
You may notice a trend here.
with a little caution and level headed vehicle control, you can manage just fine in any emergency.
many times i have been driving around and somebody pulls out from behind a bus and stops right in front of me. i dont SLAM on the brakes and slide into him because my wheels ae locked up (no abs)
its more of an ever increasing pressure on the pedal to prevent front wheel lockup... that way you can still steer and avoid the situation entirely.
i'll be driving 45 on the bypass and some jerk hauling 5 horses pulls right out.
again, if you dont panic, and know a little bit about car control, accidents can be avoided, and you will never have to exceed the limits of your cars control
:2cents:
You're obviously invincible, far be it from us to convince you otherwise.
Have you tried a temp check to see how even your wear is going to be?
The max pressure for the BFG's on my truck is 65psi.
40psi is the correct pressure for the 600kg I have on each wheel to get even wear.
Lighter trucks run them around 30psi to get even wear.
You may notice a trend here.
GreyGoose006
10-06-2006, 07:06 PM
every time i get off the highway at a rest stop or something i check my tires by holding my hand on them and visually glancing to see that they are at the correct pressure.
usually, unless the wether is exceedingly hot, the tires are no warmer than what i'd say is 85-90* in the summer, and 80-85 in the winter.
dont worry, i'm not invincible, just levelheaded.
just last week i broke my wrist when i flew over the handlebars of my bycicle.
the bike was/is ~10 years old, and the bolt that holds the angle block inside the head tube snapped from fatigue. the front wheel turned 90* to my direction of travel and i flew off. my flying skills are a little rusty, so i hit the ground pretty hard.
dont worry tho, i'm freshening up on those 31337 flying skillz.
usually, unless the wether is exceedingly hot, the tires are no warmer than what i'd say is 85-90* in the summer, and 80-85 in the winter.
dont worry, i'm not invincible, just levelheaded.
just last week i broke my wrist when i flew over the handlebars of my bycicle.
the bike was/is ~10 years old, and the bolt that holds the angle block inside the head tube snapped from fatigue. the front wheel turned 90* to my direction of travel and i flew off. my flying skills are a little rusty, so i hit the ground pretty hard.
dont worry tho, i'm freshening up on those 31337 flying skillz.
534BC
10-06-2006, 07:21 PM
I have yet posted my opinion on this matter, I do have one. Just haven't been able to articulate it yet. I do see that it seems everyone is complicationg the matter quite a bit. Here's a question though before I do.
To all who religiously use the setting on the door panel:
Do you ever reduce your pressure when your 3 fat friends get out of the car?
sorry, I couldn't resist, lol.
To all who religiously use the setting on the door panel:
Do you ever reduce your pressure when your 3 fat friends get out of the car?
sorry, I couldn't resist, lol.
534BC
10-06-2006, 07:29 PM
I'll exgerate it a bit more using truck tires and weight and pressure. Must say that it is true that a higher than recommended inflation/weight may reduce traction and it may even be due to a reduced contact patch.
Speaking of rest-stops; When the truck driver unloaded his trailer , I always wonder why he let out a lot of air pressure,.? NOT
A tire is not like a air bag, nor is it like a balloon. It does not get it's shape from weight / pressure relationships that we are talking about.
Speaking of rest-stops; When the truck driver unloaded his trailer , I always wonder why he let out a lot of air pressure,.? NOT
A tire is not like a air bag, nor is it like a balloon. It does not get it's shape from weight / pressure relationships that we are talking about.
UncleBob
10-06-2006, 07:29 PM
Do you ever reduce your pressure when your 3 fat friends get out of the car?
sorry, I couldn't resist, lol.
that is a note worthy point, and I agree with the general issue: there is some room to play
But running tires that the door panel says should be 25psi at 44psi is a lot more extreme than what you're discribing
sorry, I couldn't resist, lol.
that is a note worthy point, and I agree with the general issue: there is some room to play
But running tires that the door panel says should be 25psi at 44psi is a lot more extreme than what you're discribing
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