Track Wheels, 16, 17 or 18"?
 

For autocross events, has anyone played with different rim sizes? I run 18" on the street, but was curious on others opinions. For autocross events, is there any big differnce between a 16,17 or 18" rim assuming the same diameter tire? I know that lower profile on a 18" would be tighter, but then the 16" with a 55 might give better roll. Thoughts?

Rim size will govern a bit of what width wheel/tires you're trying to use. I think people use 17s to go with a square setup of 255s but that may also require swaybar changes to keep understeer in check. A square setup has the ability to rotate all 4 evenly. Also, not all tires are available in all rim size and width combinations.

I looked into this over the winter to possibly make some changes. I decided to stay with 18s because it is the best compromise for me with the car's setup and classification.

17's are the way to go.

Lots of tire choices and you will save $$$ over 18's

Also for early year cars it not recommended to use 18's

Square setup is what some people use, but the vast majority are staggered
In 17's 255/40-17 rear and 225/45-17 front is a good setup for both AX and track

Most run 17s for AX/DE/TT because the tire size/width is just right for the 986 car balance and there are a ton of good tire choices available. I run 18s on my 987.2 and they do allow a bit wider tire but they cost 30% more. If I were running a 986 again it would be on 17s for certain.

I like the idea of using a balanced setup, it would possibly save a few to be able to rotate... 18" is probably out, rims are expensive in that size and what would I actually gain? 5mm? Besides, a smaller rotation on the rim with that same size profile tire would be a faster RPM on the tire anyway right?