The Challenge Strada Bianca Clincher tire is designed for bumpy, rough roads. Not only is it one of the toughest tires in Challenge's lineup, it's also one of the smoothest riding, which, for a manufacturer that's known for its smooth riding tires, is saying a lot. The Strada Bianca's casing is its handmade, puncture resistant, lightweight SuperPoly material. With its 260 threads per inch TPI, you'' immediately notice the supple ride. On top of the casing, Challenge added a belt of corespun polyester, made by twisting fibers around a central filament core, creating one yarn from multiple strands. The material is 40 to 50% stronger than typically spun materials, while retaining or even reducing overall weight. This is the PPS Puncture Protection System layer, and it's specifically made from the tightly woven polyester material to preserve the casing's supple feel. Challenge then added another PPS layer for additional puncture protection. The tread pattern the Paris Roubaix Herringbone is among Challenge's most versatile. The tread is hand glued onto the already inflated carcass. This means that the tread isn't under tension when you inflate your tires, resulting in lower rolling resistance, added grip, and increased comfort.