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M2 Technical Topics > Track / Autocross / Dragstrip > Can I track my M2C on 20in wheels?

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      07-28-2019, 01:42 PM   #1
Twilson25
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Can I track my M2C on 20in wheels?

What are the downsides of running autocross on 20in wheels with low profile tires?
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      07-29-2019, 03:42 AM   #2
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not big into autox just because, it is terrible on tires and is actually more stress on the car than a regular road course. plus, i prefer being able to pass other cars in my group than being alone surrounded by cones. =)

20" is fine. just expect the tires to get chewed up.
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      07-29-2019, 11:43 AM   #3
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Thanks!
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      08-03-2019, 08:28 PM   #4
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Originally Posted by Twilson25 View Post
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No downsides at all, if you want to test the waters.

If you are doing this regularly, why?

20" rims weigh a ton, cost a bunch, and can only fit low-profile tires.

Track cars run 17" - 18" rims for good reasons - replacements are significantly less expensive and weigh POUNDS less per corner. Also, tires are consumables in this hobby, and 17" tires are a lot less to buy than 20" tires.
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      08-05-2019, 09:41 AM   #5
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Originally Posted by tetsuo111 View Post
No downsides at all, if you want to test the waters.

If you are doing this regularly, why?

20" rims weigh a ton, cost a bunch, and can only fit low-profile tires.

Track cars run 17" - 18" rims for good reasons - replacements are significantly less expensive and weigh POUNDS less per corner. Also, tires are consumables in this hobby, and 17" tires are a lot less to buy than 20" tires.
The wheels might be lighter but the whole package may not make a huge difference. 513M to 437M with tires are only like 1-2 pounds lighter per corner which is miniscule unless your a real trackday hero.

https://f80.bimmerpost.com/forums/sh....php?t=1020511

BTW US M2C can only fit a min of 19" wheels due to the larger brakes.

To the OP, I guess you sold your OEM wheels? I would use those if they are still available.

Edit: Cool touring build, wish they did a factory M3 touring.
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      08-05-2019, 09:54 AM   #6
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Originally Posted by Megator View Post
The wheels might be lighter but the whole package may not make a huge difference. 513M to 437M with tires are only like 1-2 pounds lighter per corner which is miniscule unless your a real trackday hero.

https://f80.bimmerpost.com/forums/sh....php?t=1020511

BTW US M2C can only fit a min of 19" wheels due to the larger brakes.

To the OP, I guess you sold your OEM wheels? I would use those if they are still available.

Edit: Cool touring build, wish they did a factory M3 touring.
Yes, but moving to an aftermarket wheel, like the ARC8 17 x 9 ET:30, drops real rotating mass. Stock BMW rims are around 25 lbs each, while ARC8's in the same size are 16.5 lbs. Remember a traditional tire is typically a pound or so lighter weight compared with its equivalently-sized RFT, and the total rotating mass drops somewhere between 35 - 40 lbs.

And the cost of 17" rubber is in a different universe compared with upsized 20" tires.

While this has a remarkable and noticeable gain in the suspension's ability to maintain contact between the tire and asphalt, I agree that nonetheless it's mostly relevant to regulars at the track.
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      08-06-2019, 05:19 AM   #7
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Quote:
Originally Posted by tetsuo111 View Post
Yes, but moving to an aftermarket wheel, like the ARC8 17 x 9 ET:30, drops real rotating mass. Stock BMW rims are around 25 lbs each, while ARC8's in the same size are 16.5 lbs. Remember a traditional tire is typically a pound or so lighter weight compared with its equivalently-sized RFT, and the total rotating mass drops somewhere between 35 - 40 lbs.

And the cost of 17" rubber is in a different universe compared with upsized 20" tires.

While this has a remarkable and noticeable gain in the suspension's ability to maintain contact between the tire and asphalt, I agree that nonetheless it's mostly relevant to regulars at the track.
Dont disagree with you mate but as I stated the OP cannot go lower than 19s unless he swaps his brakes out (we are in the M2/C forum here, no F87 can fit smaller than 18" wheels on OEM brakes).

Also Ms dont come with RFT tries.

Also Also you need to compare 20" ARCs to 18" or 17" ARCs not really a fair comparison otherwise.

For OPs purposes a 2nd set of OEM 19s should fit the bill nicely as a balance between improved performance and cost if he is serious about Auto Xing repeatedly.

If OP is just starting out in Auto X/trackdays then 20s on any tire are fine for a session or two but will quickly get expensive as you correctly note.
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