A comment and question for the group...
We were on a trip to the Pacific Northwest (Oregon / Washington) a few years ago. This was pre-Clarity, and we had a rental car.
One of the first things we noticed (it was quite dramatic) was that the road surfaces were significantly coarser than we are used to here in Maryland. It was remarkable how much road noise resulted from this. These roads were in good condition, it just seemed like there was a substantial difference in the composition of the asphalt that was used there (larger aggregate, or similar).
I could imagine that this would result in much more tire wear than what I am used to here.
Has anyone else noticed large differences in road surfaces across different regions of the country? I don't know where
@ClarityBill lives, but perhaps there could be a contributing factor like this. Of course that wouldn't explain uneven wear, but it certainly could accelerate wear.