Challenge Grifo tires are the standard by which others are judged. A dependable tread that has been ridden to countless victories over the years. Challenge Grifo’s are simply one of the finest tires you can choose. These tires are built on a 300 TPI SuperPoly Casing like the tubulars, giving you the best ride quality possible in a 355 Gram tire. 700x33mm. Don’t forget to add some Quality Tubes to your order.