5spd97

I keep reading discussions concerning the correct tire pressure for our cars and I wanted to add a little input. Tire pressure is not static. As soon as you start driving the tires will heat up independently and the pressures will vary front to rear and corner to corner. That is why manufactuers' state a recommended cold pressure. Cold means when the car has been sitting still long enough that the tire pressures have all stabilized to ambient air temperature. In practice that temp may be 32 or 95 degrees F.

This point recently became very obvious to me after I replaced my TPMS valve stems and I was able to monitor my tire pressure for the first time since I bought the car several years ago. If I adjust the tire pressures equally on a 50 degree morning at 35 psi and take the car for a drive, within a very short distance, maybe a couple of miles, the pressures may be a couple of degrees different around the car with the lowest being 37 or 38 and the highest maybe 40. The next morning they may all be 34.

My point is that there is no definitive answer to the correct initial tire pressure. What works in Cleveland is not the same as in Austin. Keep your pressures uniform when the tires are cold and adjust that pressure to correct uneven tire wear or driving preference.

Legender

I've heard that also and manually measured the same. I think I read somewhere that tire pressure increases/decreases 1 lbs for almost every 10° change in temperature... caused either by driving or air temperature. But don't quote me on that as actual fact but think it's pretty close.

Tom57

It's the temperature of the tires/wheels that's most relevant, the air temp is less so. (Friction of tire meeting pavement generates lots of heat.) Check pressure in morning before car is driven preferably car not having been parked in the sun heating up the tire/wheels.

AlexusAnja

If there is such a variance of say 37 psi one tire and 40 psi on another when tire is hot...doesn't it make more sense to adjust the temp when it's hot to all be even at say 37 psi, since you're driving longer on hot than cold. Doesn't make sense to drive starting cold all 32 psi and then drive for next 50 miles with so much variance. I've never had that big a variance, 2 lbs tops.

5spd97

The variation comes mostly from cornering. For instance a sweeping right hand curve will load up the left side tires with the front left usually heating up more than the others. Left to sit overnight all of the pressures will be pretty equal again although the ambient temperature will determine what that pressure will be. I had 35psi on all four on Monday when the temps were in the 40's, today it was 59 when I left the house and they were all at 37 psi. I made a high speed 600 mile run recently and the right side tires were 1 to 2 psi higher than the lefts. I was heading south in the afternoon in FL and the sun was on my right. I have soft compound, hi-performance tires on that car which probably contributes to tire heat. Coming back at night the pressure was pretty equal although it was still higher than my set pressure. Remember that even going in a straight line, a tire is constantly flexing as it squashes at the road surface, which builds up heat and pressure.

XJSFan

I check my tires on a weekly basis, when cold and hot, and all four are usually the same PSI.

Bocatrip

Living in the blistering heat of Florida, I'm very conscious of how quickly an underinflated tire will absorb heat and of course place excessive wear on the tires. My comfort zone is keeping my tires approximately 1.5-2 lbs over cold recommended pressures. Although there is really no recommended tire pressure for my 17" V rated Primacys, I usually keep them between 35-36lbs.

XJSFan

I also keep my cold tire PSI at 35-36...

BradTank

I set at 35psi cold even though the door tag I think says 32psi.

I'd rather be a little over than a little under, I just don't think you'll get the same life out of the tires with only 32psi, especially since it's going to go down from there as the tire slowly deflates.

Also, I'm not super **** about the air in my tires, but you would be amazed how much variance there is with different air gauges. I bought a higher end Milton gauge for around $10, it shows about 5psi difference with my cheap gauges depending on which one. 5 pounds is a night and day difference.