Bridgestone 120/80-19 (63M) X40R MX Hard Terrain Tyre RearBridgestone 120 80 19 (63M) X40R MX Hard Terrain Tyre Rear Bridgestone X40 Intermediate Hard Terrain Front TireBridgestone certainly has the legacy of making great tires, so when they finally come out with a brand new tire it's a big deal. Called the X40 Hard, the design shares virtually nothing with past efforts. Featuring advanced designs like cooling fins on the rear tire and large convex "Castle Block" knobs, the X40 can grip and corner in