Darrell from Jefferson City, Mo. on 4/13/2011 9:15:17 PM:
Full knobbies not needed as Trek says, they would be slow rollers for sure. Have Hutchinson Acrobats 700x37 on the Hybrid, they work well. Have Vittoria Adventure Touring 700x32 on the touring bike, they work even better. Neither of these tires are slicks but are fairly low resistance tires. I furnished the names of the tires for reference to see what they look like, other brands have similar tires.
The Katy is for the most part hard packed, but softer in the center and to the outer edges.