The specialized big roller 20x28 tyre the big roller tire gives younger riders advantages that adult size bikes are getting wider tires along with a new tread design allows for maximum traction and stability in many riding conditions this leads to more fun and better confidence specialized big roller 20x28 tyre features casing 60tpi bead wire compound 60a 20 x 28 max ride 25psi max install 35psi approximate weight 670g 24 x 28 max ride 25psi max install 35p