I don't have an RX-8, but I plan on autocrossing my NA 89 RX-7 this up coming season. I am looking for opinions as to which of 2 tire and wheel choices would be most beneficial. I already have the wheels and would prefer not to buy another set. I'm not interested in being in a particular class, just my times vs. my friends' times. I don't care about classification rules. Assuming same tire model and constant driver skill, which of the following setups would be better?

Choice 1 : Stock 15*6 (16 lbs) with 225/50/15
Advantages: Lower gearing due to smaller diameter
Reduced tire weight
Disadvantages: Narrow wheel means less control of contact patch shape


Choice 2 : SSR 17*7.5 (14 lbs) with 225/45/17
Advantages: Larger overall contact patch
Less wheel weight
Wider wheel
Shorter sidewall
Disadvantages: Taller gearing
Higher tire weight

I think the reduced weight and lower gearing of the 15" combo is my best bet despite the narrow wheel. Tips? Advice? Thanks in advance.

 

autox is funny, usually the wider tire will be faster, even if it weighs more. the taller gearer is more of a factor, but id try for a 245 or so with a 7" rim. since you are changing the rim width, you are out of stock class and maybe can use camber plates to get better geometry.

in any case, a 6" rim is a challenge.

james