10-27-2017, 12:57 PM | #1 |
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Autocross wheel/tire sizes tested?
I’ve been placing well at Autocross this year in the M2 on stock size RE71Rs. For next year I’m considering moving to an 18” wheel and wider tires. (The lighter wheel is better as it has a lower unsprung mass). I have to stick with stock width to stay in street classification so that means 18x9 front and 18x10 rear.
My question is what is the max width tire anyone has put on these wheels without rubbing. I can adjust the offset somewhat and stay within the rules. I used wheel-size.com to look up the numbers but i’d Love some confirmation from someone who has tested fit. For the fronts it looks like I could get to 265/35 easily and maybe 275/30 I’m thinking 285/35 rear. |
10-28-2017, 12:08 AM | #2 |
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You might want to check out the dedicated track/autox subforum.
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10-28-2017, 07:41 AM | #3 | |
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10-29-2017, 10:01 PM | #4 |
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To remain in B-street class I can’t do any suspension mods other than front sway bar. So I’m looking at the widest on the stock suspension. I can go down an inch on the wheels and adjust the offsets by up to +/- 7mm. Any tire size that fits the rim is allowable.
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10-29-2017, 10:04 PM | #5 | |
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The B-street thread has useful insights, though inconclusive so far. |
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10-30-2017, 02:33 AM | #6 | |
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Can you put adjustable camber plates? |
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10-30-2017, 10:13 PM | #7 |
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I have those cheap Tire Rack wheels, square 18x9.5 (33??) I run 275/35/18. I do have camber but I think a member in Arizona runs 265's square and is stock.
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10-31-2017, 04:52 PM | #8 |
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Thanks, alas SCCA doesn’t allow a change in wheel width to be strict stock B Street. But I can see putting 265 on the front 9” and keeping 265 also on the 10” would yield a square setup. That said, I really feel the car needs more rubber on the rear to fully manage the bursts of power needed on technical courses. I’m thinking more like 285/35 x 18 on the 10” rears if I can find the right (I.e light enough and correct width) 18” rims somewhere. Also, how did you manage camber adjustment without camber plates?
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10-31-2017, 04:57 PM | #9 |
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11-01-2017, 02:16 PM | #10 |
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If your not allowed to have camber plates I wouldn't run an upgraded front bar if your not sure. My 265/285 setup tends to push a little bit unless I trailbrake hard. I put my front bar to soft after a few sessions and it helped. If I didn't have a rear bar with it, I'm thinking it would've been strange even with camber plates. I don't think I'm ruining enough camber though since I'm running staggered tires and sways. If I stay staggered I'm dropping down to a 275 on the rear, adding a little more rake and camber on the drivers side front.
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autocross, autox, solo, tires |
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