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      02-03-2013, 10:49 AM   #1
jaconley
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Square wheel/tire setup

Guys, I need your suggestions on what size wheel and tire combination to get for a square setup for autocross. I have a 2007 M Coupe with stock suspension, and have no plans for lowering the car.

Currently I am running the stock 18" wheels (8" ET42 front, 9" ET30 rear) with 245/40 fronts and 275/35 rears.

Besides the benefit of haveing a square setup for autocross, I'm also looking forward to being able to rotate tires front to back to even out wear.

Thanks for your help.
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      02-04-2013, 07:58 AM   #2
schwank
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Hi,
Last year I bought a Set of 4 O.Z. Racing Ultraleggera 18x9 +40mm offset, with 265/35 all the way around from a guy with a stock z4M Roadster. He used them to Autocross. I asked him a few questions, heres what he had to say.

"I ran 12mm spacers in the rear. The car was stock.
Lots of rubber left on the Dunlops, the R1's (slicks) are half gone. The wear dimples are still there though.

I ran 3 different tire brands with a 265 width without issue.
It is right at the limit. I never heard any rubbing, but when I changed tires I could see minor contact marks.
Square Setup: I went to a square setup to reduce tire cost as I was going through fronts faster than the rears. I co-drove the car with my wife so I'll blame that on her. She liked to 'plow' into corners!
This way I could rotate the tires front to back to even the wear better.
It will reduce understeer and increase oversteer. You can enter the corner faster, but have to be a little more patient with the throttle on the way out.
My experience is with autox not track."

By the way, My car is Lowered on KWV3 and the 265's would not fit up front so I have not run a square setup
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      02-04-2013, 08:54 AM   #3
Kgolf31
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Consensus is 18x9.5 ET 35 with a lot of camber up front. You'll need to run a spacer in the rear to avoid rubbing

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      02-04-2013, 08:24 PM   #4
jaconley
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After talking to APEX, I have two options for a square setup (with stock struts and no lowering):

1) 18" x 9.5" ET35 with 265/35 tires. Will also need camber plates with about -2.5 degrees camber. Additional 12mm spacers are needed to push the back tires out for aesthetic purposes.

2) 18" x 9" ET42 with 245/40 tires. Additional 20mm spacers are needed to push the back tires out for aesthetic purposes.

Option 2 doesn't really put any more rubber on the road verses stock tires (225/45 front and 255/40 rear), and less than what I have today (245/40 front and 275/35 rear). So, it looks like I'll be investing in a set of camber plates.
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      02-05-2013, 12:00 PM   #5
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Seems to me like you could just get another set of stock wheels and make a set all the way around that's the same. Seems like the best to me might be to run the rear wheels all arond with a spacer in the rear?
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      02-05-2013, 11:58 PM   #6
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Quote:
Originally Posted by jaconley View Post
After talking to APEX, I have two options for a square setup (with stock struts and no lowering):

1) 18" x 9.5" ET35 with 265/35 tires. Will also need camber plates with about -2.5 degrees camber. Additional 12mm spacers are needed to push the back tires out for aesthetic purposes.

2) 18" x 9" ET42 with 245/40 tires. Additional 20mm spacers are needed to push the back tires out for aesthetic purposes.

Option 2 doesn't really put any more rubber on the road verses stock tires (225/45 front and 255/40 rear), and less than what I have today (245/40 front and 275/35 rear). So, it looks like I'll be investing in a set of camber plates.
I have number one and I don't think you can fit a 12mm spacer in the rear without any rubbing. Maybe?
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      02-06-2013, 09:17 PM   #7
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Quote:
Originally Posted by seank View Post
I have number one and I don't think you can fit a 12mm spacer in the rear without any rubbing. Maybe?
I'm running a modified #1 - I have 18" x 9.5" ET35 with 245/40 tires. Running Vorshlag camber plates with about -2.5 degrees camber. I put 15mm spacers to push the back tires out for aesthetic purposes. Car is very balanced and looks great. Also had AST coilovers installed and dropped car -1.5 inches. No rubbing at all with my setup. I am running APEX wheels and Hankook RS-3 tires.

Prior to these changes, I was running 245/40 on stock fronts and 265/35 on stock rears. I can tell you running 245/40 on the 9.5inch rims is putting more rubber on the road than the 265s or stock 255s in my opinion. As my car is a daily driver, I decided to go with the 245s since I had problems with the 265s wandering on roads, not been disappointed. BUT, I believe the 265s will work with this set up and would look awesome. Period.

That's my input at least.

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