Challenge Grifo Pro Tires 28" x 33c Tubular Folding Handmade 300TPI Super Poly casing, Natural Rubber compound, PPS anti-puncture belt, 415g, 23-90PSI, Black/Tan A great All-Around tire, GRIFO is Challenge's best selling tread-a perennial World Championship winner Handmade with 300TPI Superpoly casing glued to natural rubber tread for supple ride with great traction Seamless Latex Inner tube with a removable core reduces weight while improving ride PPS belted Puncture Protection System keeps you rolling