E60 tire size

I recently puchased an 04 525i and would like to know if anyone can tell me how large I can go on tires without fender modification. I will be running 19x8's in the front and 19x10's in the rear. I have 245/35's and 275/30's on order, however If I can go larger, I will as long as it alleviates the problem of the unsightly gap between the fenderwell. I do not intend on lowering the vehicle because I do not want to lose the integrity of the stock ride. Suggestions?