Have a look at this site to help you assess the details of current wheel and the match provided by the new wheel. Felgen-Katalog - BMW-Treff - der Treffpunkt für alle BMW-Fans und -Fahrer
And then use this one to check the specs on the current rubber and any proposed tire that you might fit in the future Wheel-Tire - WHEELSMASTER
I have found these two sites very handy in my search for the same answer.
Let us know what you end up doing, maybe with some before and after pics.