Originally Posted by
NOS88
Knobby tires are really designed to grab hold of the surface for traction. I'm not sure of the kind of gravel you'll be on, but for the bike paths around my area with gravel the knobby tires are really needed.
Maybe it is a regional difference, but I find knobbies make more difference in wet dirt, clay and mud where there is something there to grab. In gravel or sand I am looking more for floatation and width for stability.