Joined: Dec 2004
Posts: 12,538
Likes: 791
From: Middle of da Mitten
Bikes: Trek 7500, RANS V-Rex, Optima Baron, Velokraft NoCom, M-5 Carbon Highracer, Catrike Speed
The tire size is Shirley (sic) molded onto the sidewall somewhere. It'll read something like "700C x 23" and "23 x 622" which are different designations for the same size. The 23 is the tire width and 700C designates a tire with a bead seat diameter of 622mm.