Well, to complicate your life.
Why not upgrade to 275s all around on 9.5" rear rims? If you need one replacement you're halfway there.
PLUS, you can take the good front wheel and use it as a spare tire!
More that halfway!
Lots of posts on this- do a search if you think it might be appealing.
You can get new BMW rims (forget replicas unless you generally don't ever exceed the speed limit) at
www.bmwwheels.com... last time they were $507 each... bummer, now $557.
http://www.bmwwheels.com/bmwwheels_d...=65&Series=E39
They got fronts too!
A
PS Best bet is to shop for a couple of months and collect two rears- they come up for sale once in a while