Interesting back to back testing Greg. I do currently run a smaller size on the rear primarily because my fronts are corded faster than they heat cycle out while the narrower rears last 2-3 times as long. Of course I also used to like the balance with the narrower rears but with changes I made to the front last year I seem to find myself a little short of rear grip so it may be time to move back to wider rears. If my wear rate wasn't so high on the front I would see the advantage of only dealing with a single tire size.