Originally Posted by DavidNJ

I find the whole think dubious. This is a picture of a 225/40 Hoosier R7 to a 255/40-17 RC-1. Hoosier says its tire is 9.6, Maxxis says theirs is 10.5, yet the Hoosiers are wider. I'm guessing one of them isn't being accurate in their specs. Maybe its the Hoosier. Otherwise, why is Sickdayracing using 225 R7s when the 245 would fit the TT5 rules (rules: 266mm, spec: 262mm)?

I found this review of the RC-1 on a Miata (Maxxis RC-1 - Race & Track Driving (formerly Win HPDE) ) that implies that it may like a lot of negative camber.



This is the Hoosier 245/40-17 on a 9.5" rim:

Have drivers done back-to-back tests on rim width? It would be interesting to see a driver doing consistent lap times due back-to-back runs. The change should have a small effect on sidewall stiffness and a slight change in OD. Tread width, molded into the tire, shouldn't change. More sidewall stiffness could be a detriment, depending on shocks tuning and the rest of the setup. 1/2 inch of rim width, especially within manufacturer's specs, seems unlikely to make a huge difference.

Originally Posted by Bullwings

^ any particular reason you went with the smaller 17x9 TC105N for your scrub/practice set of wheels as opposed to a second set of 17x9.5 SA72Rs?

Originally Posted by Sickdayracing

Got a good price on them used. I occasionally drive the car on the street to cars and coffee and they look better also. 9.5 would've been better but I am not winning anything RC1s (my practice tire) so not a big deal.

Originally Posted by anorexicpoodle

Are you driving from/to on hoosiers (R's not A's right)?

If so how does that affect heat cycles and tire life?

Originally Posted by freq

Agreed on the Volk comment, and not just for looks.