We took the tread design of the Fast Trak a step further by manipulating each knob with FE Analysis. Paired with extensive rider feedback & design experience the result is a tyre with less rolling resistance & more traction all in a lightweight package. Adaptive Tread technology for Competitive XC riders. Casing: 60 TPI for 15% enhanced cut resistance over S-Works model Bead: foldable Butyl wrapped bead = 2 Bliss Ready Compound: 60a> 27.5&34; x 2.0; psi 35-65