C5 Autocross/track day tire& wheel question

Ricestalker · 12-26-2003, 07:47 PM

I'd like to be able to rotate my expensive race rubber so I was thinking of getting four 18s or four 17s instead of two 18s and two 17s like my stock C5 wheels. Is this a mistake? Should I stay with my stock wheel sizes, if not which way should I go? Four 17s or four 18s?

Thanks,
Chet

urtoslo · 12-29-2003, 07:20 AM

Rotating your tires around is a good way to maximize your investment. The only thing stopping you is will they fit (do they rub, will they clear all the chassis components) and what class will you end up in for autoxing.

ZR1 MK · 12-29-2003, 10:29 AM

It depends on your tire choice. What race rubber do you plan to use? Track or autocross? Some tires are only manufactured in 17" size, some only in 18" size. 18s will allow for larger brake upgrades, but are heavier.
Mike

TedDBere · 12-29-2003, 10:57 AM

I've stayed with the 17's and 18's, but I'm in SS class and have to. If you're using Hoosiers you can have them flipped on the rims about halfway through the treads since they are not uni-directional.

Many of the non-SS classes run with 17's all the way around, but your speedometer will need to be reprogrammed, if you care! I've even seen 18's on the front with 17's in the rear, to get bigger front brakes on the car.

Good Luck.

:steering:

DKTZ06 · 12-29-2003, 03:52 PM

Quote:

If you're using Hoosiers you can have them flipped on the rims about halfway through the treads since they are not uni-directional.

Kumhos can also be flipped. The directional stamp on the blackwall is residual from old tire molds .... and by the time you need to flip 'em, there isn't much wet traction tread left anyhow.

Running 315/35 17's all around puts you at less than a 0.5" taller than normal tires. That shouldn't be a big change in the speedo calibration .... at the most, you'd be off by 1-2 mph. However, with this setup, the car will be more inclined to oversteer (not necessarily a bad thing) and the wheel change bumps you to ASP. You'll need a lot more than just wider wheels and rubber to be competitive in ASP! ;)

WRT wheel size, I'd recommend staying with 17's ... better tire size options and a fair bit cheaper than 18's.

[Modified by DKTZ06, 7:57 PM 12/29/2003]