I test drove an X this weekend with the 22s. It looks to me that there is a little more rubber/sidewall (and therefore, protection) around the 22s on the X compared to that of the 21s on the S. I had very bad experiences with the 21s on my old S up here in New England. The 21s make the S look incredible, but I believe the 22s on the X make an even bigger difference appearance wise. Anyone have any thoughts on whether the 22s are as prone to damage as the 21s?