If the tire/rim is 'flipped' to the other side, the same thing happens. The inside bottom rim of the rear wheels are closer to the pavement (on a level road) than the outside bottom of each rear wheel. By the fact that if the wheel is tilted 'top towards the centerline of the car', then the inside sidewall (on a flat road) are slightly more compressed 'inside' of the tire/wheel assembly than on the outside of said tire/rim assembly. If that inside bottom tire wall isn't flexing more than the outside bottom sidewall, then you would expect the 'inside-to-middle' tread to have more wear than the tread from the middle to the outside tread footprint. Again all this is 'given' the balance/load is about equal from either side. Since the tire wear is not an issue, and I have seen a number of the XF rear tire/wheel combinations tilted like they do, I have to conclude both bottom inside walls of the rear tires are compressing more than the bottom outside tire walls. Whew!