max wheel width's from what we know
what we know from the e46m3,
can go with 18 or 19, and depending on offset either a 10in (dr. gustave), or a 9.5 (racmonolites, ssrcomp, ccr) is possible up front......
and, in back, for certain a 10in wheel, with offset of 25-26ish, will drop to china without need for a fenderroll with a 275 and rougly 2degrees of camber.
a 10.5 will work, with the proper offset, but rolling and inner fender need to be noticed.
so, if those same wheels, say a 9.5 up front, and a 10with25offset are slapped onto an e90 325-335 sedan/coupe.....the fronts work no problem, its the rears that get dicey, as the 25offset from the 10in, will stickout past the fenderlip with a 275, and with stock suspension will rub if the passengers are in the back, or the dipis big enough...
hopefully, the rear fenderflare on the e92m3 will be the "same or greater" as it is from the e46 to the e46m3.....then we know for sure, pretty much that e46m3 wheels can transfer directly over....
however, perhaps, the flare will be great enough as to allow a 10.5 to fit, with the proper offset.
RAC will hopefully be making wheels for the e92m3, if and when it happens, getting in on the first buy will be great.