The best explanation I've heard (and makes sense) was explained earlier. By running max pressure and a light load on each tire the weight is all carried on the center of the tire and not spread out across the tread. That lets the outer edges scuff more. I know I have been running 95-100 lbs cold pressure for over 3 years and don't have an issue. I'll probably drop back to around 90 if I ever get a chance to weigh each individual tire and adjust appropriately.