xDrive wheel sizes

x_M240i · 04-04-2024, 12:27 PM

Hello, planning on getting a set of 19 inch wheels for my M240i xDrive.
Current setup is:
225/40/R18 - 7.5J front
245/35/R18 - 8J rear
I'm thinking about running 225/35 R19 front and 245/30 R19 rear but I'm kinda worried about the transfer case because the smallest width I find is 8J.

Question is, will it be okay if I run 8J and 8.5J with the specified tyre sizes?
Thanks

Kernel Kurtz · 04-04-2024, 01:16 PM

It is not so much the wheel width as the rolling distance front vs rear.

Conventional wisdom say you should keep the circumference of the front and back tires within 1% of each other, but the factory 225 front/245 rear setup actually works out to 1.2%, so it would be reasonable to assume that is safe. I don't think I would exceed that though.

There are calculators online that can help you work out these numbers, but note that different brands of tire may vary slightly from the general result these tools will give.

You may get more exacting advice by posting in the wheel and tire subforum. Cheers.

04-04-2024, 12:27 PM	#1
x_M240i Registered 0 Rep 1 Posts Drives: BMW F22 M240i xDrive Join Date: Apr 2024 Location: Romania iTrader: (0)	xDrive wheel sizes Hello, planning on getting a set of 19 inch wheels for my M240i xDrive. Current setup is: 225/40/R18 - 7.5J front 245/35/R18 - 8J rear I'm thinking about running 225/35 R19 front and 245/30 R19 rear but I'm kinda worried about the transfer case because the smallest width I find is 8J. Question is, will it be okay if I run 8J and 8.5J with the specified tyre sizes? Thanks
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04-04-2024, 01:16 PM	#2
Kernel Kurtz Major 347 Rep 1,016 Posts Drives: 2020 M240i xDrive Join Date: Sep 2007 Location: Winnipeg, Canada iTrader: (0)	It is not so much the wheel width as the rolling distance front vs rear. Conventional wisdom say you should keep the circumference of the front and back tires within 1% of each other, but the factory 225 front/245 rear setup actually works out to 1.2%, so it would be reasonable to assume that is safe. I don't think I would exceed that though. There are calculators online that can help you work out these numbers, but note that different brands of tire may vary slightly from the general result these tools will give. You may get more exacting advice by posting in the wheel and tire subforum. Cheers.
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