Originally Posted by Cynikal
I have 20's on my road bike and 25's on my fixie. I have a few RR tracks to roll over on my commute so 25's help. I would recomend a fatter tire on the rear because you can lift your front wheel easier than your rear (at least this is the case for me)
I actually run a 25 up front and a 23 on the rear, as I think the front takes most of the abuse (trolley tracks, pavement cracks, and the occasional rear taxi bumper).