I've seen that style wheel on there, not sure how wide the rims are, but the sport package rims on the x5 has 275s and 315s front and rear...so if the wheels are wide enough (9.5 and 10.5) then you should be able to use those sizes.

Is this the rim you're talking about: http://www.xoutpost.com/x5-e70-forum/...ghlight=wheels