Wheel Math Help
Thread Starter
MBWorld Fanatic!
Joined: Mar 2011
Posts: 2,487
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From: Canada
2023 E63S Wagon
Wheel Math Help
Do I have this right
With a +ET wheel adding X width onto to the rear of the wheel moves the centerline (1/2)X away from the old centerline towards the rear of the wheel, and that also means the new centerline is (1/2)X further away from the old mounting face, so does that mean the new ET of the wheel after adding X to the rear is ET+(1/2)X ?
And
With a +ET wheel if I add a Y spacer the new ET is ET+Y ?
With a +ET wheel adding X width onto to the rear of the wheel moves the centerline (1/2)X away from the old centerline towards the rear of the wheel, and that also means the new centerline is (1/2)X further away from the old mounting face, so does that mean the new ET of the wheel after adding X to the rear is ET+(1/2)X ?
And
With a +ET wheel if I add a Y spacer the new ET is ET+Y ?
MBWorld Fanatic!
Joined: Jul 2013
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From: Toronto, Ont, Canda
go fast grocery getter wagon
In general, the more the wheel is extended out (especially with use of spacers) from the factory specifications and center line, the more stress you are putting onto the suspension components. After all, the wheel and tire probably weigh in around 60+ lbs easily. just my 2 cents.
If you have to do it, i guess you may want to customize the wheel so that the center line is still near factory specifications.
If you have to do it, i guess you may want to customize the wheel so that the center line is still near factory specifications.
Last edited by bobblehead; Jul 28, 2023 at 04:43 PM.
Thread Starter
MBWorld Fanatic!
Joined: Mar 2011
Posts: 2,487
Likes: 1,553
From: Canada
2023 E63S Wagon
I think I screwed up. I think adding a wheel spacer Y moves the mounting face of the wheel closer to the center line which subtracts from ET. So the new ET is ET-Y
If that's right I'll edit the original post
If that's right I'll edit the original post
Member
Joined: May 2013
Posts: 131
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From: New Hampshire
2021 E63S Wagon, 1997 BMW 540i, 2002 BMW Z8
This site is pretty useful for checking factory offset and offset range:
https://www.wheel-size.com/
https://www.wheel-size.com/
Junior Member
Joined: Jul 2023
Posts: 58
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From: Fredericksburg, VA
2003 AMG G55
You appear to have some galvanic corrosion between your aluminum wheels and your steel brake area. It can expand under there to make it close to impossible (It seems) to remove. Penetrating oil over night and some swift kicks to the sidewall will do it. But I doubt I would do all that with just a bottle jack. I'd drop it on some stands.
