TrackJunke

I am currently running autox with my stock pirellis on 17's. I was thinking of going up to 18's for street and putting R compound on the 17's. What is the biggest or recommended size for the 17's? What is the biggest or recommended size for 18, I was thinking stock porsche wheels? I am not lowered but maybe in the future. I was thinking of using Kumho ecst 700 as r compound. What do you think or use?

Viken

7" x 17" : 205 (225 will work, though)
8.5" x 17" : 255

7.5" x 18" : 225
9" x 18" : 265