I had a Nevegal 2.2 on a ZTR Flow kicking around, I wanted to see if it would fit. I threw it on and it had clearance on both sides. I would not have ridden it though. Currently running a Bontrager 29.1 2.2" and there are scuff marks on the heli-tape that I put on the chainstays. I think an Ardent 2.25 would be fine.