Re: wtb wheels - have question/please help (archive)

: I'm looking at some wheels off of a 94 325 for my 87 635. they stck out from the fender a little on the 3 series. does that mean the offset is greater or lower? (i think 325 has a 45mm offset)?????????????????????????

Mickey:

In many cases, the offset will be stamped or embossed on the wheel. On German made wheels it may say "ET:20" for 20mm offset. The 1994 BMW Light Alloy Wheels Catalog lists offsets ranging from 41mm to 47mm depending on the style of wheel, diameter, width, and antisipated tire fitment, so you are probably right at 45mm, give or take.

The offset for the E24 is negative 18 to 22 mm, depending on the wheel diameter. Negative offset means the mounting face is closer to the brake side than the centre line of the wheel. It seems popular replacement for the E24 is 20mm offset in 16" or 17" diameter. My '87 had the 390mm TRX's, which have an offset of 22mm (I think). I replaced with 20 mm offset 16" x 71/2" wheels with no clearance problems. Used the same size wheels on an '87 M6 with no problems as well. These come very close to the original wheel/tire size on the '87 635CSi. Fitted 225/50 R16 tires in both cases.

Personally, I didn't consider three series wheels when shopping due to potential problems with handling and bearing wear; don't know about clearance though, as the increased negative offset should cause them to move away from the strut tower. Also, you can increase the offset with spacers and longer studs, but you cannot decrease it.

Try the tirerack site for an excellent explaination of offset, complete with a diagram. It is under the "wheels/wheels tech" section.
Hope this helps.
Stu

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