Not for anything wrong, but to get some non-knobbies on it. I've been riding my FCR3 lately, but it just doesn't have the "hardrock" feel to it under my large self. Plus, when riding with the Mrs. and her Giant Boulder SE with 1.5s on it I still have to slow down so she can keep up, and she's much more fit than I am.
Ended up putting some Specialized Hemisphere's 1.95s on cheap ($14 a tire and since I Bought the bike recently installation is free). I was thinking Nimbus 1.5s but decided I liked the larger tire under me.
I'll use the FCR for my AM rides and my Hardrock with the new tread for the rides with my wife.