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Old 11-22-2011, 11:42 AM   #1
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Max tire size on 18x7.5 rim?

Looking at running a 245/35/18 R6 on a stock 18x7.5 rim.

Hoosier recommends a rim width size range of 8.0-9.5.

I have seen quite a few boards where other makes routinely run larger than recommended tires on stock rims with no claimed ill effects either on the track, drag, or AX....

I dont want to prematurely wear R6s unevenly on too small a rim...Should I just do 225/40/18s on the front?


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Old 11-22-2011, 12:06 PM   #2
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I think you will be fine, though I have no first hand knowledge on your application. I doubt you'd want to give up front grip on the AX course by going down to 225's.
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Old 11-22-2011, 03:19 PM   #3
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245 is quite a wide tire for a wheel as narrow as 7.5 inches . 225 would seem more appropriate .
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Old 11-22-2011, 04:33 PM   #4
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Using smaller than recommended wheel sizes usually results in uneven tire temps so you probably won't get the most out of those 245s. Will they perform better than 225s on the front?? I don't know. On my car the fastest big track setup is 225/255 while the fastest AX setup is 245 square. I run 245 tires on 8.5 rims.

YMMV
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Old 11-23-2011, 07:08 AM   #5
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That's interesting, normally the wider the better for track duty, within reason, at least on production-based cars. Any change to the cornering balance can be solved with an adjustable antiroll bar(s).
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Old 11-23-2011, 09:42 AM   #6
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7.5 with a 245 Hoosier should be fine. I ran a few sets on 7.5 wheel. IF the wheels are turbo twist, for some reason they are more difficult to mount with the wider tires. FYI, all the Caymans running in SCCA AS run 285 hoosier on the front 8 wheel. You can also run a 285 on 9or10 rear.
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