spare donut size?

GrimJaw · 12-03-2023, 01:15 PM

I have a donut that is 17 inches would it be the worst thing if I ever used it if my wheels are 18s?

zoro2001 · 12-04-2023, 09:37 PM

Just a guess.
As long as you don't have x-drive and it doesn't hit your brake I would say yes.

Hopefully someone can confirm this.

GrimJaw · 12-10-2023, 09:59 AM

I have xdrive 😔

Kernel Kurtz · 12-10-2023, 04:20 PM

You can use an online calculator to find the circumference of the spare based on wheel and tire size and compare it to the others. Conventional wisdom says for xDrive you should keep it within 1%, but the factory staggered setup is more like 1.2% and apparently that is fine long term. I'd try to keep it in that range but exceeding it by a little bit is probably fine so long as you are not driving far.

M3SQRD · 12-15-2023, 06:01 AM

It’s not a problem at all to run a donut spare. However, if you have AWD, then as long as the spare tire’s diameter/revs per mile is < 1% difference in rolling diameter/revs per mile. One thing I’ve nowith three different BMW x-drive is it likes to have the rear tire to be slightly taller than the front (still < 1% difference still applies).

12-03-2023, 01:15 PM	#1
GrimJaw First Lieutenant 106 Rep 344 Posts Drives: 2015 M235i Join Date: Dec 2017 Location: MD iTrader: (1)	spare donut size? I have a donut that is 17 inches would it be the worst thing if I ever used it if my wheels are 18s?
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12-04-2023, 09:37 PM	#2
zoro2001 Enlisted Member 23 Rep 43 Posts Drives: 2014 M235i Join Date: Nov 2021 Location: WI iTrader: (0) Garage List 1998 SLK 230 [0.00] 2014 BMW 235i [0.00]	Just a guess. As long as you don't have x-drive and it doesn't hit your brake I would say yes. Hopefully someone can confirm this.
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12-10-2023, 09:59 AM	#3
GrimJaw First Lieutenant 106 Rep 344 Posts Drives: 2015 M235i Join Date: Dec 2017 Location: MD iTrader: (1)	I have xdrive 😔
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12-10-2023, 04:20 PM	#4
Kernel Kurtz Major 345 Rep 1,014 Posts Drives: 2020 M240i xDrive Join Date: Sep 2007 Location: Winnipeg, Canada iTrader: (0)	You can use an online calculator to find the circumference of the spare based on wheel and tire size and compare it to the others. Conventional wisdom says for xDrive you should keep it within 1%, but the factory staggered setup is more like 1.2% and apparently that is fine long term. I'd try to keep it in that range but exceeding it by a little bit is probably fine so long as you are not driving far.
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12-15-2023, 06:01 AM	#5
M3SQRD Major General 2161 Rep 5,543 Posts Drives: E92 M3,G20 330ix,F22 240iX,F82 Join Date: Jun 2009 Location: Mid-Atlantic iTrader: (11)	It’s not a problem at all to run a donut spare. However, if you have AWD, then as long as the spare tire’s diameter/revs per mile is < 1% difference in rolling diameter/revs per mile. One thing I’ve nowith three different BMW x-drive is it likes to have the rear tire to be slightly taller than the front (still < 1% difference still applies).
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