Originally Posted by Lamplight

I have a bike with the 50mm and another with the 60mm, I didn't know there was a 55mm as well. Between the 50 and 60 there is plenty difference. The 50mm look downright puny if one has been riding the larger tire for a while. Overall I think I've come to prefer the 50mm size, as it seems like it's just easier to keep the bike moving for some reason. I don't pretend to understand all the aspects of rolling resisistance, but when I'm riding the 2.35" tires it seems to be harder to keep the bike moving even with 50 or so pounds in the tires. The larger tires are fun, though, as it feels like you can run over just about anything in your way.