In Reply to: z3 2.8 with M Roadster wheels posted by Rafael on April 03, 1999 at 11:23:43:
change wheels; all the other choices can't be done or will cost more. One of two ideas is to do as previously suggested; buy two more 7.5 x 17 M/Z front wheels and sell the rear ones. Some M/Z racer will want the rear rims because the offset is difficult to duplicate per the Stock class rules.
Sell the M/Z wheels as a set (most likely the quickest way to resolve the whole problem, again some Stock class racer will want to buy them) and get a proper set of 17" wheels. The factory 96+ E36 M3 wheels are dimensionally the same as the Z3 2.8 optional 17" wheels (7.5f/8.5r x 17, 41mm et). There's always the aftermarket too, which are usually stronger, lighter, and cheaper when purchasing new. Call Tire Rack.
Sorry you learned the hard way about the M/Z wheel fitment, it's been discussed on this Board a couple dozen times.