I am going to try to explain a pattern of wear that has me and some local running stores at a loss. Each shoe wears in the general areas that you would expect to find with over-pronation (i.e., inside heal and big toe regions of the shoe). However, the wear is not on the sole. The last four or five pairs of shoes have almost immediately (within 50 miles) begun to wear out on the side/mid-sole of the shoes. The left shoe first. An individual at a local running store described it perfectly when he said it looked like I took a razor blade and just slice the mid-sole over and over. Within 150 miles, the mid-sole no longer has enough material to provide support. One of the stores took a look at my stride but nothing out of the ordinary.