I'm giving you what I've found to be optimal, so far. First, lowering the car will increase static negative camber about 1/4 degree. That puts the rears at negative 1 degree, which is where I'm at now. Negative 1 degree is not enough for the fronts if you drive hard. I'm at 1 3/4, and I haven't checked it out with my Hoosiers yet. For autocross, you really need to set the front toe out about 1/8 to 1/4 for the track, leave it at zero (be sure to set back to zero for the street becasue toe out eats the inside of tires something fierce). I also leave my rear toe at zero for both track and autox.
Also, BFG does not have a set of tires left that will work on the Z06. They do have the correct size for the rear of a Z06, but not the front, at least according to tire track. I checked today, and there was no combination that would give tire diameters that are compatible with the Z06 (front tires were either larger in diameter than the 295 rears, or about two inches smaller which is too much smaller. Race tires for the 06 are going to be a problem for a while.
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John Von Loh
Black on Black and Red Z06
Also, BFG does not have a set of tires left that will work on the Z06. They do have the correct size for the rear of a Z06, but not the front, at least according to tire track. I checked today, and there was no combination that would give tire diameters that are compatible with the Z06 (front tires were either larger in diameter than the 295 rears, or about two inches smaller which is too much smaller. Race tires for the 06 are going to be a problem for a while.
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John Von Loh

Black on Black and Red Z06