Kevin,
You said a positive outset would push the wheel and tire further "out" than the factory position. I thought, for example, that the series 4 with +5mm offset would bring the tire in away from the fender. The XPS Rib is wider but the positive offset brings the tire edge in. The problem would be the room on the inside of the fender well to handle the wider tire and positive offset.
I may be all wet on this but I have a 50% chance I am right.
Barry
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