I bought a 2008 xB, brand new, in May 2008. While it has been meticulously maintained, I'm now considering an upgraded wheel/tire package. I won't be lowering the vehicle, but I would like to push the tires out a bit (not past the fender lines, but right to the edge). How wide of an 18" wheel can I safely add - without danger of any rubbing, and what offset do I need to push the outside wheel edge out a bit, and safely add the widest tire? Any information will be helpful! Thanks!