bc, I believe the other poster hit it on the head and provided a good resource to check out the offset. I haven't bought a set of rims beyond the stock type in years so I probably wouldn't have been much help there.
As to my tire wear issues, bad shocks caused one problem in the rear, mostly the issues went to worn out tie rods or rubber bushings (I used to track my cars, a lot! That'll make that rubber flex!) or other suspension problems, like bent lower arms (that was back in the day when they were steel).
I race with a couple of guys in Chumpcar and they decided that the chunked out outside edges would be fixed with a whole lot of camber and the alignment was not a problem....yeah, and pigs fly. Numbers on the alignment rack computer didn't even register that high!!! Problem solved.
You did mention that you had rolled the fender edges. I'm sure someone (hmm, Bimmerworks, perhaps?) has inserts that can get the offset back and away from the suspension. But you may have to look at those fender edges again. Good luck, ciao, t