Deeper 33mm knobs for increased traction in deep mud speed and max traction all in one details use cyclocross size 622700quot width 33mm weight 340 gr tpi 300 bead aramid carcass super poly bar 2 6 psi 28 87 challenge open tubular hand made open tubular differ from traditional clinchers for the construction the tyre is produced just like a tubular and uses the same materials and production process instead of being sewed with an inner tube inside at the end of the process beads are made