There a several 3-series out there rule limited to 7" wide wheels. The heaviest of them weigh 3225.
I can not suggest their wheels because they all race on stock brakes.
Also none of them make the same power levels as they are NA.
So with a conservative go foot; 7" wide wheels would provide and adaquate, but not optimal, section width. Something to consider if you want to open up your options.
http://www.edgeracing.com/2005/BMW/330Ci/wheels/17/
@ $109 and 18lbs are pretty much a steal compared to the BBS.