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      05-28-2010, 08:43 PM   #14

Drives: TheArtist formerly known as M3
Join Date: Apr 2008

iTrader: (0)

Originally Posted by TrackRat View Post
The max tire pressure listed on the sidewall is for DOT purposes for a fully loaded vehicle running down the hwy. It's typically 50 psi or higher on hi-perf radial pass car tires. This pressure rating has nothing to do with the operating pressure that the tire can use. You should use the pressure that gives the best performance which is typically 5-8 psi higher cold than the car maker suggests for street use but it varies and that is why a tire pyrometer is so valuable. Each tire, driver, track and vehicle are different so you adjust the tire for the best performance. If you're starting with 33 psi cold and getting to 45 psi you're probably over driving/heating the tires.

FWIW - Many FWD appliactions run well above 55 psi pressures hot without any issues. As Hoosier and BFG state, this is much better than running under inflated tires and damaging them.

Excessive heat from under-inflation or abuse can cause serious tire failures as seen in the link below.
I usually start at 40psi front 36psi rear,anything less than 35psi hot I get serious front tires rollover then again autocross is a bit more extreme than road racing.hahaha
I wouldn't start off at 30-31psi for such a heavy car...