saleenssc

I just installed 4 new tires on my 98 LS400 (factory size 225/60/16) According to the little PSI sticker above the glovebox it says 29 PSI & 32 PSI (fully loaded). For the last 60k miles or so on my last set of tires i set front and rear PSI to 30 PSI. I got great tread life and no issues with uneven tread wear. However in the cold winter months when the temps drop into the 20's and 30's the tires look under inflated. Im curious as to what others are setting there PSI to in the winter and summer months. DO i need to add more PSI in the cold winter months to compensate for the drop in temps ?

Thanks

brybo86

PSI drops by 1 for every 10 degrees F in change.
so if you filled them to 30 PSI and it was 90F outside...
​​​it is now 30F your tires will be roughly at 24 PSI

so yes you need to add air when temps drop and recheck pressures

Legender

What he said^^^^most people are not aware that temperature affects tire pressures.

phohunned

When I first put on my winter tires I had the psi set to 34psi was a little bouncy at first .....but now they look under inflated.
Mind you here in Toronto it gets to below freezing temp quite often.

Summertime I have them at 30psi, feels great to me at this setting.

Sin1UZFE

I run them at 35

Bylan

Like others said, temperature will have a big affect on the tire pressure. Check it every few months at the least. I run about 35psi all around on my 97 because i prefer a little more feedback, and I drive my car hard enough that I know I won't get 40k+ miles out of my tires.

Legender

If you start at 35 PSI, after being on the road they will be much higher. I know I can see 3-5 PSI increase after driving about 5-10 miles. And if you drive hard, it could be even higher. So you may be starting at 35PSI but when you get finished driving it's probably closer to 40PSI.

deanshark

Oh yea, that's why in a NASCAR race they start with the tires at about 8-10 PSI. Just imagine how high it gets after driving 190 MPH for 100 miles or so sliding in the corners. Much fun.

400fanboy

When I take sports cars into the canyons, there is a very objective difference to when the tires are cold to when they are up to operating temperature.

If I take a summer tire on a sports car, I would guess there is a 30-50% difference in grip from when they are stone cold (60f) compared to full operating temperature of 100f+. I've locked up the brakes at highway speeds on accident because the tires were stone cold, while I can surpass that braking by a LOT when they are properly warmed up.

Most tires are designed to have a "optimal range" where they grip the best. Winter tires do well when it gets cold while race slicks need to be VERY warm to offer any grip at all.

If you drive your car hard for extended sessions, the tires will heat and the air pressure in them will actually rise as well because of this temperature\pressure relationship.