Challenge's Criterium is the choice of the pros. Countless victories and podiums have been been won thanks to its supple, core-spun cotton casing. It makes the tires race-day light, fast, and strong. This exceptional tire has a center tread that rolls quickly with a grippy side tread for excellent cornering. There's puncture protection under the tread, too. These tires us latex tubes which are lighter, thinner and more flexible than butyl tubes, increasing your comfort, lowering rolling resistance, and helping to prevent flats.