Originally Posted by badger1

Yes, it's not clear at all to me -- and won't be til I get mine -- that the 'X' frame and the other current carbon Sirrus frames have the same tire clearance.

From the photo above from markjenn, the 'X' frame certainly has adequate clearance for its 38s; whether that would be true for the other carbon Sirrus frames, only one way to know for sure, absent confirmation from Specialized: measure and/or try it and see. Dealers should be able to help on this.