Serfas Krest Folding Mtb Tire (Black, 26" X 2.1") Our dual density Technology uses multiple rubber compounds used to improve feel and durability Harder rubber compounds give you improved rolling resistance and improved longevity, while softer compounds on the outer tire improve grip Will help to reduce your risk of flats through the use of thin weave nylon layers between the tire casing and tread layer Folding Bead reduces weight and improves performance Intergrated Flat Protection System Tightly spaced lug pattern for constant traction Fast and predictable Cross Country and All Mountain Tire Max PSI = 65