Originally Posted by Maelstrom
wasn't this asked yesterday? You might want to look at yesterdays posts, the answer is in there.
I believe it has to do with the fact that the rear is just accelerating you, who cares about tire width on the back. You can save the weight by running a smaller tire with no drawbacks. I personally like the way a small tire feels on the rear, feels more 'precise' but I ride the mtb like its a 20" so it might just be me-