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Dumb Question, How much air pressure should be in my tires


prosports1977
02-08-2009, 05:27 PM
I have a 1999 grand am GT the tires are Goodyear eagle GT HR, Max PSI 44.

I dont have to ever drive in snow in my state.

THanks

goodoldpapa
02-08-2009, 08:22 PM
Mine is an '03 and it takes 30 psi when cold. The label is located on the rear edge of the driver's door.

xeroinfinity
02-09-2009, 07:00 PM
You are suposed to add what it says on the tire.
The door sticker is for the stock tires Good Year RT or some other cheapo'.

Every tire is a little different. I use GY Assurance and if I ran 30psi it would ruin my tires. Typicaly I have 40psi cold, not even sure what the max is.
If you have to much it'll ride rougher, not enough and you can damage a rim/tire if you hit a chuck hole. :2cents:

73stingray
02-09-2009, 09:57 PM
All I've ever seen on any tire is the max pressure, which is usually up around 45 for these cars. The door plate is the normal cold pressure for stock type tires but depending on your driving habits you might want more or less. I usually run 34 in the summer (when I tend to drive a little faster) and 30-32 in the winter. Long term tire wear is a pretty good indicator if you're in the right range. Too much pressure and the center will wear faster, not enough and the edges will wear faster.

'97ventureowner
02-09-2009, 10:16 PM
You are suposed to add what it says on the tire.
The door sticker is for the stock tires Good Year RT or some other cheapo'.

Every tire is a little different. I use GY Assurance and if I ran 30psi it would ruin my tires. Typicaly I have 40psi cold, not even sure what the max is.
If you have to much it'll ride rougher, not enough and you can damage a rim/tire if you hit a chuck hole. :2cents:

IIRC in most owners manuals it says to follow car manufacturer's recommendations found on the sticker on your vehicle in regards to proper tire pressure. Mainly because the tire manufacturer has no idea in advance what vehicles their tires will be installed on.

xeroinfinity
02-10-2009, 07:05 PM
IIRC in most owners manuals it says to follow car manufacturer's recommendations found on the sticker on your vehicle in regards to proper tire pressure. Mainly because the tire manufacturer has no idea in advance what vehicles their tires will be installed on.

But they do have a good idea what the Max pressure should be before it explodes. So as long as youre under that I dont see any problems.
Ive usualy followed the tire recommendations as GM(or any other manuf.) has no idea what tire one would install on the car and tires do very from model to model and season to season.
:2cents: :2cents:

doctorhrdware
02-10-2009, 07:38 PM
So if the tires max load pressure is 44 LBS then would it be ok to inflate the tire to 40 LBS. Or would that be considered under inflated. :2cents:

73stingray
02-10-2009, 08:10 PM
40psi would be overinflated if anything. The tire manufacturers do know the burst pressure, and the max pressure should be below that just for a safety factor. As said earlier, the tire manufacturers have no idea how much weight you're going to be putting on their tires. If a car weighs 3,000 lbs (rough curb weight of a grand am) it has to get all that weight to the ground. At 30 psi that means you will have 100 square inches of rubber on the ground, or 25 square inches per tire..no more, no less. The higher the tire pressure, the smaller your contact patch will be. And the lower pressure the larger the contact patch, but if you go to low then the tire will flex a lot more and overheat. The recommended pressure on the door plate is a good compromise between handling and tire wear and unless you're planning on doing any autocrossing or towing than it's probably a good number to use.
Sorry for all the math, but hopefully that's at least some food for thought.

Gir-_-
02-10-2009, 10:24 PM
You are suposed to add what it says on the tire.
The door sticker is for the stock tires Good Year RT or some other cheapo'.

Every tire is a little different. I use GY Assurance and if I ran 30psi it would ruin my tires. Typicaly I have 40psi cold, not even sure what the max is.
If you have to much it'll ride rougher, not enough and you can damage a rim/tire if you hit a chuck hole. :2cents:


I 2nd this statement, if your max is 44psi then setting your tires at 40psi is just fine. For driving in the summer you want to use caution as your tires heat up from driving, like said.. too much (they could go boom). Less and youll eat them out on the sides and also ruin your gas mileage!

During the winter is a good time to check the pressure, possibly set the pressure a few psi below 40psi if you have 'winter' weather including ice/snow.... Anywhere from 35-40psi would be good for the tire.

I've followed that method and my tires have had even wear through 3 years of use and abuse :evillol:

:2cents:

'97ventureowner
02-11-2009, 01:12 AM
One of the garages I worked at in the early '90s had a tire shop. I remember a tire manufacturer rep was in the shop one day and he mentioned that the Rubber Manufacturers Association had some good publications on the care and maintenance of tires that we could get to display in our waiting area. I went to their site and they have a downloadable publication for free on the care of your tires. In that publication is the following quote:
"PRESSURE
It’s important to have the proper inflation pressure in
your tires, as under inflation can lead to
tire failure. The “right amount” of
inflation for your tires is specified by
the vehicle manufacturer and is shown
on either the vehicle door edge, door
post, glove box door or fuel door. It is
also listed in the owner’s manual.
The link to the site where you can download and read the entire publication is here:
https://www.rma.org/publications/consumer_tire_information/index.cfm?PublicationID=11173&CFID=23536477&CFTOKEN=63821049

Gir-_-
02-11-2009, 10:47 AM
but what if you have different tires/rims, size and max pressure? If.. lets just say the max is 44psi, and you set them at 40psi, Great gas mileage, even wear all around with tire rotations when needed. You're doing the already needed amount if it calls for just 35psi from factory to hold the specific weight front/rear.

I know what you're saying with specs recommended from the factory. But what are those specs for, the factory tires that came with the car? I know I dont know...
What would a guy who has rigged his pickup truck bed into a capable RV towing truck and needs bigger/stronger tires on the rear with a max of 65psi. I'm sure if 40psi was the factory spec... it wouldn't cover it. Thats my example.

But, at this point... for prosports1977 ... It's up to the user to decide what works for them. :iceslolan

'97ventureowner
02-11-2009, 11:11 AM
Gir-_- That's a good point, and I wonder if that association I linked to in my last post has any info on that? Back in the early '90s there wasn't as much customization relating to bigger, different rims/tires for vehicles, so info about that really wasn't needed at that time. But that part of the industry has really grown in the last decade and info pertaining to proper care and maintenance of the different tires should be made available. Especially if the industry wants to have happy customers :grinyes:.

doctorhrdware
02-11-2009, 01:25 PM
Gir that was going to be my next question. I wonder if the tire retailers would have that type of information.

'97ventureowner
02-11-2009, 02:02 PM
There has to be something out there. If I had more time I'd do a little research . One would think the manufacturers of these larger tires and/or rims would have some specs or info on proper inflation rates. Or even the RV manufacturers, trailer manuf. or anything that would cause the need for a different setup. Originally i believe certain vehicles had the info on the sticker because those cars were 'tuned' (for lack of a better term.) to use certain tires/rims to work with the suspension of the vehicle and other aspects such as weight distribution, handling, etc. :dunno:

xeroinfinity
02-11-2009, 07:53 PM
I just think of the sticker on the door as a recommendation as to how much air.

Its just been in the last few years that Ive not seen a minum. tire pressures markerd on tires. Some still do show it, some dont.

But for the GA 35-40 PSI is a good spot IMO. And most tires will handle more then the Max ratingbefore it blows.
I had 65psi in one of the SE tires, good year, it was riding a little rough. :lol:

outerfire
02-13-2009, 10:34 PM
You are suposed to add what it says on the tire.

...


??????

The following may be somewhat helpful.

"Keep your tires properly inflated and you could improve gas mileage by more than $1.50 every time you fill your tank. The recommended tire pressure for your vehicle is located on a sticker inside your driver-side door or noted in your owner's manual."

Source: http://www.goodyeartires.com/kyt/tireTips/ (http://http://www.goodyeartires.com/kyt/tireTips/)

Now to qualify things. I've been known to make adjustments every now and then and tend to sometimes run things a little higher than the sticker. I also don't see what different tire sizes have to do with anything. Might be a minimal difference at best

doctorhrdware
02-13-2009, 10:50 PM
But the problem with that is, if you do not have the same OEM tires. So if the new tires require different pressure that what the sticker calls for. You are saying to still inflate the tires to what the sticker says to. Even though it could be less or more than what the new tires call for? That would be a big mistake. I bought new tires for the wife's truck the and the sticker for the old tires called for 50 PSI and the new tires call for 44 PSI max pressure on the side wall, so what you are saying still inflate the tires to 50 PSI.

73stingray
02-14-2009, 04:00 AM
But the problem with that is, if you do not have the same OEM tires. So if the new tires require different pressure that what the sticker calls for. You are saying to still inflate the tires to what the sticker says to. Even though it could be less or more than what the new tires call for? That would be a big mistake. I bought new tires for the wife's truck the and the sticker for the old tires called for 50 PSI and the new tires call for 44 PSI max pressure on the side wall, so what you are saying still inflate the tires to 50 PSI.

Sounds to me like you got the wrong tires for the truck. Heavier vehicles or vehicles towing things are going to need more air in the tires. This thread seems to have turned into a lot of "this is the way I've always done it" and not so much reasoning behind anything. The only reason an aftermarket tire would need a pressure different than the door sticker is if it was designed to have a different contact patch. Typically the more rubber on the ground the better though.

doctorhrdware
02-14-2009, 01:04 PM
The truck had the optional P265 larger sized tire, and the standard tire which is P245 so they are not the wrong tires for the truck. I was on a tire retailers site and found out that the P265 was an option, since we are not doing that much hauling so went with the standard tire. So you are telling me that the tire retailer is wrong, and GM is also wrong. I was just on Midwest Tires web site and that site lists both tires for the Sliverado. So I beg to differ. I bought BF Goodrich tires for the truck.

xeroinfinity
02-15-2009, 02:53 PM
I sell or repair 30-40 tires a month, I always look at the sticker on the door if its there. But usualy go with the tires manufactures recommendations. If you change rim sizes or run different tires the spec calls for you'll need to make adjustments for that. :2cents:

doctorhrdware
04-12-2009, 08:41 PM
I found this info on Discount Tires web site

The Benefits of Correct Air Pressure
Experts agree that keeping the correct air pressure in your tires is as important as giving your engine a tune-up. In fact, the economic benefits may be even greater. With the right amount of air pressure, your tires wear longer, save fuel, enhance handling, and prevent accidents. Failure to maintain the correct air pressure can result in poor gas mileage, reduce tire life, affect vehicle handling, and cause vehicle overloading. If you consider these factors, then the need to routinely check your tire pressure is even clearer.

Check Air Pressure Routinely.
Because tires do so much without appearing to need attention, it's easy to forget about them. However, tires do lose pressure each day, through the process of permeation. In cool weather, a tire will typically lose one or two pounds of air per month. In warm weather, it's common for tires to lose air at an even higher rate. Tires are also often subjected to flexing and impacts that can diminish air pressure as well. So it's important to realize that refilling your tires is as important as refilling your gas tank. In fact, associating the need to refill your tires with the need for refilling your fuel supply can also be a useful reminder. Check the air pressure in your tires every other time you stop to fill up at the gas station. That interval will allow you to check your tire pressure consistently enough to maintain recommended air pressure. Another good time to check air pressure is when the tires are rotated. Many vehicles have different tire pressures on the front and rear axle, so remember to have this adjustment made. Also remember to have the pressure in your spare tire checked. The space-saver type spare requires a much higher air pressure level than other tires, and is virtually useless (due to overloading) at lower air pressure levels.
Where To Find Air Pressure Information
The correct air pressure may be found in the vehicle owner's manual or on the tire placard (attached to the vehicle door edge, doorpost, glove box door or fuel door). The placard tells you the maximum vehicle load, the cold tire pressures and the tire size recommended by the vehicle manufacturer. If you have trouble, visit your local Discount Tire or America's Tire location (http://dt.know-where.com/DiscountTire/) for assistance.
Another valuable resource is tire load/inflation tables. Your local Discount Tire/America's Tire should have a copy. Not only will this document tell you the correct tire pressure for stock sizes, but it will provide the information on optional plus sizes as well. A good example would be the findings on a Honda Civic with the stock size 185/65R-14. The recommended air pressure is 28 psi. Plus one size is 195/55R-15 with a recommended air pressure of 32 psi. Plus two size is 205/45R-16 with a recommended air pressure of 36 psi. Note how the air pressure increases with plus sizing to meet the load carrying capacity for the car.
Other Factors Change Air Pressure
In addition to routine air checks, other circumstances necessitate a visit to the air pump. Seasonal changes or altitude changes create a rise or drop in air pressure (for every 10 degrees change in temperature, tire air pressure changes 1 psi). Perhaps the most overlooked factor is vehicle loading for trucks and RVs. Since these vehicles can be configured and loaded in many ways, actual tire loads should be used to determine the proper inflation pressure. This is best determined by weighing the vehicle. Keep in mind that vehicle loading can change from trip to trip.
Sometimes a small nail, screw or other object will puncture a tire and then act as an inefficient plug. Air pressure drops slowly over a matter of hours or days, undetected by the driver. Your best defense in this circumstance is to be alert to the symptoms of this. Be aware of any pulling or vibration that seems unnatural. Listen for any ticking sounds, which will be especially audible at slow, parking lot speeds. If you detect this, get off the road and inspect the tires on the side of your vehicle where the pull, vibration or unusual sound is occurring. A bulging sidewall and/or excessively hot tire indicates a slow leak. Put on your spare tire and have your tire dealer repair the punctured unit. Ask the repair technician if any sidewall damage has occurred (a powdery residue inside the tire indicates this condition). If sidewall damage has occurred, you will need to have the tire replaced.
How To Check Air Pressure
Properly checking tire pressure requires an accurate air gauge. Many people believe that they can check air pressure just by looking at the tire and judging the sidewall appearance. Also, many people use air meters at service stations, which can be grossly inaccurate due to exposure or abuse. Invest in a quality air gauge. For trucks and RVs, use a dual-head inflation gauge that is calibrated up to 120 psi at 2 psi increments.
When checking your vehicle's tire pressure, make sure the tires are "cold". Cold air pressure means that the vehicle has not yet been driven one mile. Remember that driving on a tire increases its temperature and air pressure. If you must drive more than one mile for air, check and record the air pressure in all your tires before you leave. Once at the tire dealer, measure each tire's inflation again and then note the difference. Inflate the tires with low pressure to a level that is equal to the recommended cold pressure plus the difference at the higher temperature.
http://www.discounttire.com/images/kotspacer.gifhttp://www.discounttire.com/images/airPressure.gifhttp://www.discounttire.com/images/kotspacer.gifIn this example, add 3 psi in the right rear tire to match the other rear tire's warm reading. When the tire returns to cold pressure, it should end up at the recommended pressure.
Finally, after completing the pressure check, make sure that the valves and extensions are equipped with valve caps to keep out dirt and moisture. Remember to replace the valve assembly when you replace the tire. It's your best assurance against a sudden or consistent loss of air pressure.
Environmental Impact
How can routine air pressure maintenance impact our environment? Consider that fewer tires per year would end up in the landfills and scrap heaps that trouble our ecology. How many tires are we talking about? We estimate that most drivers lose from 10% to as much as 50% of tire tread life due to underinflation. That's a significant statistic. Now consider the extra fuel we burn to push cars along on soft, underinflated tires. Tires do require extra energy to roll if they are underinflated. While the statistics vary widely and can be somewhat inconclusive, the implications are staggering. Maintaining tire pressure may seem like a low priority in our busy daily routines, but it adds up to big environmental consequences. We must all take action to do the right thing. Want to know more about better tire wear? See our articles on Balancing (http://www.discounttire.com/dtcs/infoTireBalancing.dos), Tire Rotation (http://www.discounttire.com/dtcs/infoTireRotation.dos), and Alignment (http://www.discounttire.com/dtcs/infoAlignment.dos).

Gman2007
04-12-2009, 10:16 PM
I have always inflated my tires whether on my 94 or 96 to 32PSI, complete even wear, always gets around 35MPG and usually exceeds the manufactures tire life, never had a tire last less than 60,000 miles, but thats me.

Airjer_
04-12-2009, 11:15 PM
If its a stock wheel and a stock tire or replacement tire of the same size than the tire pressure is set to the vehicle spec not what the tire says. It odes not matter if its the original tire or a replacement tire of a different brand it gets set to the vehicles spec. If there is any question you can go to any tire manufacturers website and read the same thing over and over and over and over and over.

Throw in TPMS technology and if there over inflated the light will be on and if there underinflated the light will be on. So what are you going to do drive around with the light all the time because you think the tire pressure should be higher. Now you just defeated a system that has every intention of making your commute safer because you think you know more about how much air should be in your tires than the people that engineered the vehicle you drive?

DO yourself a favor and visit the tire manufacturers website. If there is any doubt after that than your mind will never change.

mhr430
06-25-2011, 12:17 AM
The pressure listed on the driver side door/pillar is a good recommendation. It is true that neither car nor tire manufacturers know what tire/car combination the end user will have therefore they work together, after a fashion, to come up with the recommended pressure listed on the tire and on the cars label. Unless you are planning to put a truck tire on your car or a car tire on your truck you'll probably have a tire with an appropriate weight rating and thus the recommended pressures will be close to just right for you. If you're still worried you can 'fine tune' the air pressure by driving until your tires are warmed up and taking three temperature readings on each tire on the tread surface. The temp.readings should be taken on the outside edges of the tread and in the center of the, ... wait now we're making things complicated. Suffice it to say that after 'fine tuning' the tire pressure using this method, you'll find that the recommendations made by the manufacturers will be within a couple psi of what you will end up with.

Now I know you're wondering why I didn't finish giving instructions on how to use tire temp to fine tune the tire pressure. Because you need to know more about tires than that they are round and need air. You also need to know the relationships between caster, camber and toe-in affect tire alignment and vehicle handling among other things. If you are serious about learning these things you can but the bottom line is that the manufacturers may not know your tire/car combination but they do know what they're talking about when they make their pressure recommendations and because the car manufacturer knows how much the car weighs they are the ones who make the most accurate recommendation.

SierraK1500
08-26-2011, 08:46 PM
No question like that in my eyes is DUMB. You did the right thing by asking.

Dumb is when you let your car go to hell because you didn't ask. Bravo!

I applaud you. Look in your door jamb or glove box lid inside for the correct pressures. Or your owner's manual.

John:):bigthumb:

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