1BadGTA

I was wondering what is recommended for tire pressure when the tires are cold (literally). In the summer months, I keep the tires at 40 psi (44 max). I need to add air to them and it's been getting colder here in ND naturally. Tomorrow the temp will hover around the high 40s'. Thanks.

92GTA

iTrader: (11)

Doesn't the side of the tire tell you cold psi Not all tires are the same...

QuickStyle

the sidewall of the tire only tells you the maximum air that the tire will hold. most people confuse the sidewall air pressure rating as what it should be at, that is incorrect. to tell the correct air pressure of any vehicle, you should look in the drivers side door jamb and it will tell you the correct air pressure for that perticular vehicle. with our cars 35 psi is the ideal air pressure. unless you are running some 18" wheels on 35 series tires, then i would recommend 40 psi.

WaOnFiRe

Why in my GTA door it says 30PSI??

DJP87Z28

TThat was for the STOCK tires that were on the car.

WaOnFiRe

And why 30PSI isn't right you think? If the tire is a little softer, won't it gives more traction?

DJP87Z28

Just use any tire pressure that seems right to you. Gave your a good reply about the door sticker and you come back with a dumb question in my opinion. Different size and makes of tires require different pressure.

WaOnFiRe

I have the same size as the original ones, except in another brand. So should I use 30PSI?

DJP87Z28

What do you think...

WaOnFiRe

Hmmm, yes?

Sorry about that, I'm just so stupid... I have a long way to go until I can change the oil on my car myself...

88TPI406GTA

Look at the side of the tire and inflate to about 5 psi under the Max inflate pressure. I have found that when the tire pressure is too low, the steering response sucks and the ride suffers too. If it is too high, you have increased tire wear and a harsh ride...

Example, if the Max inflate pressure is 44 psi, then inflate to 39 psi...


The door sticker ONLY references the stock tire by size and manufacturer. Always go by the directions on the tire itself.

1BadGTA

Brain fart on my part. Didn't occur to me to look on the Mfg label on the door. 30psi it is when cold. Thanks again.

QuickStyle

that is just , in my profession in working with tires for about 5 years, i would say i am correct. for example, many 1500 silverados have load range E tires on them which is 80 psi max, so you are saying i should inflate the tire to 75 psi... that is just rediculus, with that much pressure there would be no traction on the road and would easily loose control of the vehicle. the only reason the door jamb says 30 psi is because it is a sports car, and will handle really well at that pressure, and just because the manufacture specifiys that psi doesnt mean that is the ideal pressure you want, it all depends on what you want from your car. the lower the pressure in the tires equals better traction, and harder steering, too low of pressure will make the tires wear really bad on the outside edges, and higher pressure will give less traction and easier steering, but can also cause the tires to wear really bad in the center of the tires, like i said it depends on what you want, i personally run 35psi in the fronts for easy steering and also good grip to the road and 30psi in the back for better traction and have yet to see any premature wear on the tires. so to sum this up, any where from 30 to 35 psi is best.

88TPI406GTA

No one is talking about a load range E tire for your Silverado here. Since this is a Thirdgen site and we are talking about Thirdgens, my post is accurate. Just out of curiousity, do you inflate those tires to 30-35 psi?

There has never been any proof posted about the manufacturer intent on the door sticker, other than to apply to the EXACT stock tire that came on the car. So if you have manufacturer documentation, post it now.

So because a Thirdgen is a sports car, then any tire you install should be automatically inflated to 30 psi? Right....

What kind of tires are you running on your car? What is the max tire pressure on the sidewall of those tires? Is it 35 psi? Or 44 psi?

Newer tire designs tend to run higher pressure for less rolling resistance. If you run 30 psi on a tire designed to have 44 psi max, it will handle like crap as it would be underinflated. So again, it depends on what THE TIRE STATES on the sidewall.

Lastly, in general, I don't have a high opinion of tire jockeys because the majority of them that I have dealt with also quote the door sticker pressure without looking at the tire/application.

todd200

Document ID# 872616
2002 Saturn SL2/SC2
Tire Inflation Description
Inflation Pressure

For tire pressure and maximum tire load rating specifications, refer to the tire loading information sticker located on the driver's door opening, below the door latch.

The metric unit for tire inflation pressure is the kilopascal (kPa), although inflation pressures are usually given in both kPa and psi. To convert between kPa and psi, use the following conversion formula:

1 psi = 6.9 kPa

Important

Tire valve caps must always be installed onto the tire valve to keep dirt and moisture out of valve.

Maintaining correct tire inflation pressure is essential to proper vehicle performance. The specified inflation pressure is carefully calculated to provide satisfactory ride, stability, precise steering, proper tire wear, and resistance to road damage.

Tire inflation pressure should be inspected when the tires are cold. Cold tires are defined as tires on a vehicle that have not been driven for at least 3 hours, or more than 1 mile.

As a vehicle is driven, the tires heat up. It is normal for tire inflation pressure to increase by at least 28 kPa (4 psi), when tires heat up. Therefore, on a vehicle with warm tires, never attempt to correct tire pressure by letting air out of the tire; wait until the tire cools down to check and adjust tire pressure. Letting air out of a warm tire reduces the cold inflation pressure.
Incorrect Tire Inflation Pressure

Incorrect tire inflation pressure can lead to the following symptoms:

* Over-Inflation Hard ride
* Tire bruising or carcass damage
* Rapid tread wear at center of tire

* Under-Inflation Tire squeal on turns
* High steering effort
* Rapid tread wear on tire edges
* Tire bruises or bead rupture
* Tire cord breakage
* High tire temperatures
* Degraded handling
* Reduced fuel economy

* Unequal-Inflation Pressure On Same Axle Uneven braking
* Steering lead or pull
* Degraded handling
* Swerve on acceleration

Document ID# 872616

Manufactures always suggest replacing tires with the same type, size, and load rating as OE. With non-OE tires the only truely accurate way I know of to get the correct tire pressure is to drive the car how you drive and measure the temp of the tire in the center and both edges with an infrared temp gun. When the temp matches across the face of the tire, that is the correct pressure for that tire and your driving style. BTW, my sidewall says 44psi max, I run 30psi cold for daily and strip use, 32-33psi for spirited backroad fun.

88TPI406GTA

Todd200, while the time you spent to type that in is impressive...most of it doesn't apply.

The heat gun is a good idea, but how about just testing different pressures?

What happens when you run 40 psi cold on your Saturn? Since that isn't a "Sports Car", maybe you shouldn't run the 30 psi.

todd200

Ummm... 30 psi would be for my IROC. Sorry I didn't make that clear. I'm the Lead Tech at a Saturn dealership.

Oh, I cut and pasted but thanks!

todd200

Some people aren't sure where to set their tire pressures. The one thing that is certain is that the maximum inflation pressure on the sidewall is not the right one to use. The vehicle manufacturer's recommendation is always a good starting point. It will be somewhere in the car. This used to be a sticker in the driver's door jamb, but more and more it's located on the back of the gas filler door. If that fails, the information should be in the owner's manual. Sometimes, there will be a range specified, or two different recommendations, depending on load. Anywhere between these numbers should be safe.

Changing the tire size or going to a plus-size fitment will change the required inflation pressure somewhat. Within the range of optional OE tire sizes, the vehicle manufacturer's recommendations should be followed. For sizes outside the range, the tire manufacturer should be able to help. Yokohama, for instance, includes pressure recommendations for stock and plus-sizes, by vehicle, in its annual Fitment Guide, which your tire dealer should have a copy of. Typically, these are 0-3 psi higher for a Plus-one or Plus-two fitment. Also listed are maximum load ratings at maximum inflation pressure for each size of each tire Yokohama makes.

If the recommendations you find leave you with a range and you want to know more specifically, you can experiment. Air, after all, is free. A change of 2-3 psi can completely change a vehicle. An underinflated tire will ride smoothly but feel sluggish, have mushy turn-in and go around corners with high slip angles or just not much grip at all. An overinflated tire will feel harsh on impact and over smaller bumps, and while responding crisply, will lack grip when pushed hard. To an experienced person, these characteristics are obvious even from the passenger seat. Try the minimum and maximum of your target range, and maybe slightly outside it, and decide what you like.

In the event that you aren't able to find a recommendation for your car, or the tires on your car are so different from those that were originally fitted from the manufacturer as to be incomparable, we received the following rule of thumb from Oscar Pereda, an engineer for BFGoodrich. He calls it a "realistic starting point," saying it has never been just right, but is a good place to start. The rule is:

(Vehicle Weight in lb/100) + 2 psi at heavier end + 2 psi all around if suspension and alignment are stock.

Example: Stock 911, 3,000 lb.
(3000/100) = 30 psi
Add 2 psi all around = 32 psi
Add 2 psi to heavy end = 34 psi at rear
With modified suspension, the result is 30 psi front, 32 psi rear.

"There is no 'golden' tire pressure," Oscar said. The optimal setting depends on the individual driver and his preferences. For those inclined to find the ultimate setup for track use, Oscar provided additional instructions. First, get a skidpad, and plan to be dizzy. Take your dramamine. Drive in a circle, first one direction, then the other. Measure and record tire temperature distributions with a probe-type pyrometer that actually penetrates the rubber, not the "aim and click" infrared type. You want bulk temperature, not surface temperature, because the surface cools rapidly while the inner temperature is more stable. When measuring tire temperatures, if center is hotter or cooler than shoulders, there is too much or too little pressure, respectively.

Adjust pressures in 2-psi increments and record all adjustments. Adjust pressures by differences. If you start at 30 psi, and want to take out 2 psi, but the tires have heated up and are at 33 psi, set them at 31 psi rather than 28. The sum of all the changes made will be very close to the change from your initial cold setting. To check this, leave the tires alone at the end of the day, let them cool, and check the pressures in the morning. If at any point during the day you "reset" your pressures to some arbitrary starting place, you are suddenly lost, and all the work you have done that day is gone.

QuickStyle

Tire jockey?? it just so happens that i work for the number one tire company in the U.S. and i am not a "tire jockey"... you should not go off of what the tires says, all the tire is telling you is that it is the maximum pressure for that specific tire. most passenger tires are rated at 35 or 44 psi maximum. but that does not nessisarily mean that is the pressure it should be at, you should not post this information here, you are just confusing everybody even more. RMA standards insist that the tire pressure to be set at manufactures specs listed in the door jamb, and the pressure should stay the same no matter what size the tire is unless you get into really low series tires like 40 and 35 series, but even at that, you should only up it 5 pounds or so. and it all depends on the weight of the car also, you want the correct amount of pressure to match the weight of the vehicle to keep the tread as paralell to the road as possible, like i said before i have had alot of experience in tires, and i am correct. its like this.... if you wanted to know the correct pressure setting for a particular vehicle where do you go? do you really think that a cashier at a fast food joint would know this question.....no. that is why you go to a tire technician at a tire shop. how many professional years experience have you had with tires?

QuickStyle

that is also true, but is only a reference point.
"There is no 'golden' tire pressure"