Track wheel/tire sizes

[jgiannone]

Trying to go from street tires and wheels to better track set up. My 991 C2S has 20" wheels and 245/35 front tires and 295/30 rears. 8.5"front/11.0" rear widths. I am learning that going to smaller wheels is the way to go. What is the advantage of that? Not sure if it is because of reduced cost or if a smaller wheel with the same tire size produces a bigger contact rubber patch. Or is it because you can put larger tires on smaller wheels? I know that in going to smaller I need to be sure that the wheel fits over calipers. 

If anyone is able to help me with this I would appreciate it. Do you have an opinion of what would be the best set up? Considering going to Toyo R888R tires as opposed to slicks.

Thanks,
Scott Wilkes

Scott, my advice would be to talk to several people who have already done this before you spend a dime. Anytime you change one thing, it changes others, and I wouldn't want to destroy the feel of the car. With that, all the 991 race cars; Cup, R, and RSR run on 18's. And for sure, the availability of sizes and lower prices for tires in 18" is much better than 20". But again, I think you'll have speedometer error, a lower ride height, etc. Not saying anything is bad, just to know what you're getting into.