Originally Posted by j rick kirby
for my 03 mach1 w stock sized tires.Doing a HPDE at VIR.
A little thrifty with your setup info aren't you?
Tire pressure may vary due to tire brand, tire model, camber, surface conditions (asphalt, concrete), ambient conditions (wet, dry, warm cold), driving style, course type (predominance of high or low speed corners), etc., etc.
That said, most Mustang drivers find somewhere betweem 30 to 45 psi front and 2-5 psi less in the back will work fairly well.
For HPDE, maybe 40 psi in front to start (2-5 psi more if street tires and/or camber challenged).
Check your pressures after a few laps. They will climb a few psi due to heat buildup. More than a few psi increase means you started low or you are sliding around too much and cooking the tires. Split the difference and try it again. Don't try this too many times if you don't have an air tank or compressor. While you are down there checking tire pressure, check brake pad wear.
Watch the outside edges of your front tires - a combination of street tires, too little camber and too much sliding will kill fronts in very short order. A few extra psi will help, but not
cure this problem.
If you decide to get serious, get a probe-type tire pyrometer and learn how to use it.