I have 15x10" centerlines on 275/60/15 on my regal. The backspace on the wheels are around a 5", and i use a 1/4" spacer. no rubbing, but my black trim around the wheel wells was removed. I really want to go back to my 8" wheels with the 275/60/15 tire. (just seems to fit better). 10's look killer though!!!! hope this helps some on your decisions. i would post pics, but not sure how to do it yet. (I agree that the 4" BS will stick out from the wheel wells too much with the 10")