Morris9

I plan on auto-xing my 2003 Convetible, 6spd, Z51 with new Pilot Super Sports for the first time in A/Stock and wonder what pressure I should start at. I run 30psi for normal driving. I had to go with 245-40-17 frt. and 285-35-18 rear as that was the closest to stock size Michelin makes for a C5. I am just doing this for the fun, not a dedicated auto-xer yet just don't want to roll my tires off the wheels

froggy47

I have no experience with those but I would go 36f/34r and mark the tires with white shoe polish to see clearly how far over they roll.

Add/subtract to control handling over/under steer and also to control roll over.

Gordy M

Stock tires for autocrossing come in many flavors, some are hard sidewall, some have medium sidewall and some are soft. I know individuals who are rather competitive and run all the flavors and all their pressures are a little different. I run the Hankook RS3 and start at 30/28 cold and by the third run the tires really come in. If I am at an event with back to back runs, I start with 1 lb less. My hot pressures are usually around 34/35 front and 30/31 rear. Remember, by the time you pit, get your tire gauge and check your pressures have cooled off from the exit temps. As most will tell you a tire temp reading is the best.

When I first started out, I did the shoe polish system and was pretty close to the edges. While doing this I had a good time running events and soon became somewhat competitive. When you serious on auto crossing, however, the rule book and what you can do, alignment, corner weighting, rake, shocks etc will greatly effect the amount of tire pressure to use.

Morris9

Thanks, I think I will add a couple pounds to the fronts and leave the rear at 30psi to start with shoe polish on. I think I saw a BMW running PSS at the last event and will ask what he is running for tire pressures. He was one of the faster drivers at that event.

Dynamite76

For what it is worth, I have been old to target 43 psi hot for a 20 to 30 minute track session. Lower pressures may get you better grip coming out of corners while higher pressures will be more responsive into and through the corners. Best thing to do is check hot pressures after a run and adjust them up or down and see what you like. It really depends on the tire and a lot on the camber settings.