A pivoting exterior rearview mirror assembly comprises a mirror housing, a base, a support frame, a pivot assembly, and associated elements comprised primarily of a plastic or polymeric material. The pivot assembly is provided with a pivot reinforcement made of a relatively high-strength material, such as steel. The base is provided with a cantilever reinforcement made of a relatively high-strength material, such as steel. The reinforcing steel increases the load carrying capability of the plastic and reduces the potential material failure of unreinforced plastic.