Tire size?
Thread Starter
Cruising
Joined: May 2009
Posts: 10
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Tire size?
I want to buy a set of Kuhmo XS tires for street/autocross for my C5 w/ ZO6 wheels. They come in 315/30/18 for the rear and 275/40/17 for the front. Is a 30 in the rear too low profile? I have read that it should be a 35 so you can maintain the .8" or .9" or so stagger higher in the rear so as not to affect the ABS. I don't have active handling so that is not affected. The rears would actually be .22" diameter shorter than the fronts. Will that affect my ABS and Traction control since they will be my street tires too? Thanks
Race Director
Joined: Oct 2002
Posts: 16,477
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From: Gone
CI 6-7-8-9-10 Veteran
St. Jude Donor '03
Yes, it will definitely screw up your traction control.
The profile number is not an absolute, it is a percentage measure of the tire's sidewall compared to it's width. A 255/40/17 would work fine on the front with that size rear tire (for example)..the profile number is the same, but the narrower 255 will be short enough to compliment the 315/30 rears.
When searching, focus on overall tire height (diameter), not so much about the profile number. Keep the rear tires slightly taller than the front, and you'll be fine.
The profile number is not an absolute, it is a percentage measure of the tire's sidewall compared to it's width. A 255/40/17 would work fine on the front with that size rear tire (for example)..the profile number is the same, but the narrower 255 will be short enough to compliment the 315/30 rears.
When searching, focus on overall tire height (diameter), not so much about the profile number. Keep the rear tires slightly taller than the front, and you'll be fine.
Tech Contributor
Joined: Oct 1999
Posts: 40,995
Likes: 9,759
From: Charlotte, NC (formerly Endicott, NY)
You will trigger the TC with that tire ratio. TC will not even let you coast in nuetral with the rear tire being smaller than the front it will apply the rear brakes to try and slow down the rear tires.
Bill
Bill
