Now, correct me if I'm wrong, but isn’t one of the main reasons that the Saleen wheel's are so desirable is that they’re so light. The problem with the weight as already mentioned is with the tire, not the wheel. That and most 15" Welds are no more than 7" in the front....if not 4.5” skinny's. As where the 18's are what.....9"....10"-wide? That's a lot of drag and rolling resistance to overcome compared to a narrower wheel.