E89 shares the same fitment as E46 M3 and Z4M. I am running 19x10 and I feel that is is wide enough for our cars. There's no point in running too wide because you don't want to stretch your tires too much and rub over big bumps.
What are the specs of your wheels? You may be able to run them if the offset is right. Check the center bore as well. You may need center rings to fit them properly.