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

[prosports1977]

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]

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]

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.

[73stingray]

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]

Originally Posted by xeroinfinity

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.

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]

Originally Posted by '97ventureowner

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.

[doctorhrdware]

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.

[73stingray]

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-_-]

Originally Posted by xeroinfinity

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.

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

['97ventureowner]

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/con...TOKEN=63821049

[Gir-_-]

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.

['97ventureowner]

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 .

[doctorhrdware]

Gir that was going to be my next question. I wonder if the tire retailers would have that type of information.

['97ventureowner]

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.

[xeroinfinity]

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.