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Nov. 2, 2009 6:24 p.m. iceracer HalfDork

Tires for an autocross. Worn to 2-3/32 tread mounted on 5.5" wheel or brand new mounted on a 7" wheel. The 7" wheel widens the track as well. I'm just curious what others think. I know the theory about tread squirm. I'm more curious what the difference in wheel widths would make. Both makes are rated the same as far as performance.
Nov. 2, 2009 6:48 p.m. maroon92 UberDork

the width of the contact patch should more than make up for the tread squirm.
Nov. 2, 2009 6:51 p.m. Gimp Dork

How are they rated? Tread wear rating and speed rating is arbitrary. Compounds can vary even if these numbers match. What makes/models of tire are we talking here?
Nov. 2, 2009 9:10 p.m. irish44j Reader

depends on the tire in question....
Nov. 2, 2009 9:38 p.m. alstevens New Reader

Don't forget to consider unsprung weight
Nov. 3, 2009 9:40 a.m. iceracer HalfDork

Both tires are rated UHP. I didn't mention brands because it is not relevent. The Tire Rack tested and compared both and they are very close. My curiosity is will the worn tire offset the difference in wheel widths and offsets.
I probably will go with the worn tires.
Nov. 3, 2009 10:15 a.m. oldsaw HalfDork

In this case, size really does matter.

And the tire size is?
Nov. 4, 2009 9:25 a.m. iceracer HalfDork

Both are the same size. 205/55x15
Nov. 4, 2009 9:32 a.m. Gearheadotaku Reader

7'' is wide for a 205 tire, I'd rather see 6". 215 or 225 would fit 7" better.

If we are talking about the same tire, I'd go with the fresh rubber. Being streched over the wider rim may help with the squirm.
Nov. 4, 2009 9:51 a.m. amg_rx7 Reader

Gearheadotaku wrote:

7'' is wide for a 205 tire, I'd rather see 6". 215 or 225 would fit 7" better.

If we are talking about the same tire, I'd go with the fresh rubber. Being streched over the wider rim may help with the squirm.

Huh? 205 is excellent for a 7" wide wheel.

8" is better for a 225-245 width tire.
Nov. 4, 2009 10:26 a.m. pinchvalve UltraDork

This posts assumes that the worn tread has the same advantages as a shaved tread, but is that true? Does wear on the sidewalls, heat cycling, impacts, etc. make a worn tire worse than a new tire?
Nov. 4, 2009 12:32 p.m. procainestart Dork

I'd rather have a brand new tire than a well-worn tire any day unless the wear you describe is actually from shaving, not use.

To reiterate what amg_rx7 said: a 7-inch rim works great with a 205 tire. A 5.5-inch rim will not support the sidewall as well.
Nov. 4, 2009 12:40 p.m. griffin729 Reader

The '98-'01 Impreza RS came stock with 7" rims and 205/55 r16 tires. I'd imagine 7" and a section width of 205 should work fine.
Nov. 4, 2009 1:40 p.m. Gearheadotaku Reader

Well, my Grand Am had 205/55/16 on 6" from the factory, they fit perfect. My 88 Fiero Formula I had 6" fronts w 205/50/15 and 7" rear 225/50/15. the fit was perfect. No bulging over the rim, or strecting to fit.
Nov. 4, 2009 6:53 p.m. iceracer HalfDork

The "worn" tires are just that. 3+yrs and 28000 miles. If I felt like changing tires ,which I don't, I would try both. Maybe in the spring when I run on a go-kart track,I will try both.