Just looking at the wear , I would say that you have to much air in the tire. Being that it only wore in the center, but maybe you only drive most of the time on the highway and don't make many turns. I had someone tell me last month that they got real bad wear on a tire when they mounted the wrong size compared to stock. Now, I don't understand how a tire one size different would wear different more. But, the tire company gave him this story. Now if this is true or not I don't know.