This paper addresses the existence of Persson's theorized adhesion-related, mechanistically distinct rubber friction force-surface deformation hysteresis, or microhysteresis, arising from the sliding interaction of rubber with the microtexture of harder materials. Forty experimentally determined rubber friction data sets obtained by others on macroscopically smooth surfaces and analyzed by the author evidenced the existence of this microhysteretic force, which he theorized to be constant under varying loads. General use of the rubber coefficient of friction as a metric is rendered unreliable by development of this microhysteresis force.