I had a blow out at 700 miles (chronicled
here) and didn't have any more issues over the next 15k miles. Part of that, I think, was being hyper vigilant and avoiding all potholes and road irregularities as much as possible. I did hit a few big pot holes I didn't see and thankfully the tires and wheels held up. I had wanted the 20s originally when I ordered my GT, but it would have been a months long wait to get the car, so I went with the 21s. I finally decided to pull the trigger and go back to the 20s for the looks and higher sidewall tires. Getting the Michelins rather than the Pirellis was an added bonus.