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'm not interested in being in a particular class, just my time vs. others. I don't care about classification rules.

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


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.

 

I would suggest splitting the middle...

Maybe go with 15*7 front, with a 15*8 rear... Watch the offsets to prevent rubbing issues.

I'd probably go 205/50 on front and 225/50 on the back... Pretty decent contact patch, and since NA's don't have an abundance of torque, the reduced unsprung weight (if you wheel-shop wisely...) will definitely help accelerating out of corners.

With a relative lack of torque, it's possible to over-tire the car... You need a little wheelspin at the start to keep the engine from bogging, and you can actually use a slight lack of grip from a not-so-wide tire to help the car rotate thru tight turns.

For wheels, you can pick up pretty cheap, light wheels from Kosei, Rota and a couple others.

Hopefully I haven't sent you down the wrong road... This is just some stuff I figured out on my 88 GTU before I blew it up...

Good luck, and have fun!!!

 

If you're only concern is outright laptime your choice is simple. Get the widest wheels with the widest rubber that will fit. Wider tires will outrun narrower tires everytime.

 

check out diamond racing wheels. they are cheap so you can buy a couple of sets and see what you like. and they are descently light. i'm autoxing with 13x7's on my fb with some STICKY tires and i have no complaints. they are kinda old school style, i haven't seen any on a FC but i have seen numerous on fb's and they look great if you get the right style.

www.diamondracingwheels.com/