Hi Everyone. I put Michelin Pilot Sport 4S' on my Cayman this spring and have loved them for about 12,000 km. I recently took a road trip to PEI in Canada and hit a hard thing on the road which blew out the sidewall on the left rear. It took two days to get a new tire from Montreal but all is good now. My question is: Should I worry about the difference in the tire circumference between the old and new rear tires? A friend has suggested to me that this could be hard on the rear differential. I haven't a clue about this.