Stock Z tires, meaning Potenza RE-040's in my car shoul dbe at 35 PSI when the tires are cold.

 

Its was about 40 degrees today and I noticed that my tire pressure was flucuating between 29 and 31 psi all around. When its hot out, I've seen it up to 37psi all around. Is this normal for hot or cold weather?

 

Your tires are underinflated. The Potenza Re-040's loose air pretty fast for some reason. This will lower your gas miledge and wear your tires down faster. these tires have a maximun PSI around 52. Your tires should be 35 PSI when you get in teh car in teh morning.

 

I've always found this statement in general (not meaning you specifically) and that of the manufacturers to be somewhat vague. What is cold?

The rule of thumb is for every 10 +/- ambient degrees the tire will fluctuate by +/- 1 degree. So if you inflate your tires to 35psi and it's 70 degrees ambient then you go out the next morning, it's 40 degrees the tires should read about 32psi.

Are you now supposed to re-inflate up to 35psi which now means that once the ambient temp reaches 70 degrees the tire will now be 38 psi and by running the car the temps will now increase to 40+.

Am I understanding this correctly? How many of you play with the pressures everyday?

 

Damn good question! I don't know the answer for sure, but I imagine that the weather does affect tire pressure. As it gets colder, the air inside the tire creates lower pressure and vice versa in warmer weather. I check my tire pressure about once every two weeks with a hand held tire pressure gauge, and then look at the gauge in my Z everyday. I try to keep my tire pressure at 35 PSI with cold tires not matter what the temperature is.

 

Sorry for bringing up a decade old thread but my question is relevant to the subject. Besides, tire pressures never evolves right?

I understand that with stock z tires and rims, pressure should be 35psi cold all around. What if I have f255/r285 on 19", would the optimal pressure still be the same for daily driving?

Thanks in advance guys, cheers.

 

Should be the same as the factory wheel/tire setup; 35psi is fine.