I've been riding x23 Zaffiro's since May of 08. Some 4000 miles later, I'm about to replace them with another low cost, lightweight trainer tire from Panaracer. I've gone through 2 rear to one front with the Zaffiros. For the price and durability, they've been just great. Currently, the flat wear pattern on the rear is at 3/8 of an inch, or 9.5 mm. Almost a slick for a road bike tire!