Hi Sidney..answers...(m) (archive)

Offset is simply the distance from the inside
wall of the hub of the wheel to the wheel centerline. For the E-32 and E-34, 20mm offset
situates the wheel relatively equidistance to
the fender lip and for the front suspension to
the strut..technically for a 7 inch wheel, it's 11mm to the strut and 15mm to the fender. By choosing a wheel and/or tire wider
than 7 inches, say 8 inches, you are now closer to
the fender lip and strut by 1/2". If you are running an 8 inch wheel, I would try to stay
at or around 20 mm offset and won't run much if
any wider than 235mm tire width. Richard Mui's
car for example runs an 8.5mm rim width, with
235mm tire width with 13mm offset all around. This combo with 25mm offset would rub on the front struts and "may" just clear on the rear's.
As to your question about 10mm offset and 30mm
offset..you had it reversed...here is why. If
the inside hub wall of the wheel is 10mm versus
20mm (E-32 spec) from the centerline of the wheel
then the wheel is sticking outboard closer to the
fender by 10mm compared to a stock E-32 20mm offset wheel.
There are many wheels to choose from..each with
tradeoffs. If you are looking for a 16" wheel,
have a quick look at the amazing low mileage 1991 750il now on E-bay. That car has been retrofitted
with rare 16" 3-piece BBS wheels..car is beautiful...though it could use a bit of lowering
in the front..he..he. Other thing is..this owner
may not know it but the tires he/she is running
are shorter than production tire diameter i.e. should be 55 series with 225 width/16 inch
wheel to match tire diameter of a stock E-32.
Last point is, although many times endorsed by
some pretty knowledgeable car people, BMW does not
recommend rotating tires. I know that sounds like
heresy, but the noteable example of this is all
the cars BMW sells with staggered wheel/tire combinations..can't rotate them. I generally
rotate mine but BMW does not endorse this practice.
Hope this helps,
George
90 735il/145k

For some time now I have been looking to upgrade/replace my existing 15" basketweave/cross-spoke OEM wheels with newer style 15" wheels. I have not had much luck. So I am now looking at 16" wheels. I am not curerently interested in anything bigger that 16". Also want all 4 to be the same size so that I can rotate them.
Will a 16x8 with 25mm offset fit my 91 750iL?
What size tires could I put on the 16x8s with 25mm offset?
I am not sure how the offset number works.
Comparatively speaking does it make sense to say
10mm offset = more wheel towards center of car
and
30mm offset = more wheel away from center of car
Is this correct or do I have it backwards?

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