Originally Posted by
badmother
I guess both how easy they are to put on and how "tall" the whole rim/tyre combo is (and how much is left for fenders) has a lot to do with rims. Same tyre on wide or narrow rim should make a difference. Also I think I read somewhere that they suggest 26" or even 24" wheels for heavy loads on the x-tra.
Take extreme care if using wide tires on narrow rims, especially Schwalbe tires (as they usually are wider than there listed number). Running a wide tire with narrow(er) rims can lead to all kindes of tire problems, including catastrophic failure-like tire roll off, side wall failure, bead popping off etc. All when you would least want something to happen, like on a fast descent.