A statistical model for steady-state sliding wear of the metal counterpart in metal-composite systems has been extended to include composite reinforcement size and size distribution. It has been shown that the wear rate of the metal counterpart under conditions where MMC wear is characterized by plastic deformation (microplowing) is controlled by the ratio between the mean of particulate radius squared and the square mean particulate radius, E(r 2 )/E(r) 2 , a descriptor of the particulate size and distribution. Under these instances, e.g. for 4, 10 and 13 μm particulate discontinuously reinforced aluminum (DRA)/17-4 PH tribosystems, the modified statistical model permits accurate prediction of the wear performance of the unreinforced counterpart. However, when MMC wear involves reinforcement cracking and delamination, the model overestimates the wear rate of the counterpart, i.e. in the 29 μm Al-SiC p /17-4 PH tribosystems.