E6X Looking for the correct offset

Mar 31, 2018
Hey y'all... I need help!

My desire is to run 20/30/295 or 20/30/305’s in the rear on my E60 535. Because of this desired size, the rim width has to be 10.5in or 11in. With a rim that wide, the offset must be perfect to avoid rubbing of the fender or any other contact points...

And there lies my problem... while I recall seeing (on forums) multiple E90/E60’s running 295 and even a few running 305 running flush (no rub), I am having a hell of a problem establishing the correct offset for a 20/10in or 20/11in

I'm thinking I could calculate the correct offset based on the popular opinion on forums that a 20/9in rims "should" have a +30 offset but I'm not even sure I'm doing that correctly so here is a scenario

20/9in rim with +30 offset sits flush/no rub & I want to know what the offset would be on a 20/10 inch rim that also sits flush/no rub (i.e. just adding backspacing)

If offset/ET is measuring the distance from the center of a wheel to its mounting face in MM and we know that 1in = 25.4mm is it proper to add 12.7mm (25.4mm/2 because we are looking at a new center) to the offset of the 20/9in rim and come to the conclusion that a 20/10in rim should have a 42.7mm offset? Did I do that right? Would that rim 20/10 et42.7 even fit?

Any help is appreciated. Thanks again
May 9, 2017
Rhode Island
A 9" wheel is wide for the front 20x9 wheel with a +20 offset will work. With factory suspension, the width becomes an issue, it starts to hit things, and can't be classified as the he same as the m5. There are a few who,are running 305/35r20 on the rear with 10" wheels, a little scrap,,so th and 295 is more feasible. You can find more sizes and offsets for m5 than the standard e60, the only you'll have to compensate for the front offset tho.
Mar 31, 2018
@CaStylin, did you figure this out and get them mounted?
People have given me offsets that should work but no one has confirmed the math on here on in other places that I raised the question. That said, I put custom wheels on hold since I've greatly overspent my budget on my home renovation

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