The Rex 2100-A Tire Durometer / Hardness Meter RX-2100-A, ASTM D-2240 is a precision instrument that allows racers to quickly and accurately make checks of tire hardness. Unlike other racing durometers (which are just relative hardness gauges), the RX-2100 is calibrated to the ASTM D-2240 standard for durometer hardness and is traceable to N.I.S.T. Thus, the RX-2100 allows comparison with the factory tire specifications.
