A wheel fairing and preferably a set of wheel fairings for reducing aerodynamic drag caused by the left-side and right side wheel sets of a rear wheel assembly supporting a trailer body at its rear end. The fairing body includes a tapered aerodynamic surface with a substantially U-shaped cross-section that tapers from a second end to a first end, and a base surface at the second end with a substantially same dimensional profile as one of the left-side or right-side wheel sets. Fasteners or other mounting devices secure each fairing body to an underside of the trailer body either upstream (as a nose fairing) or downstream (as a tail fairing) of the rear wheel assembly so that the second end is adjacent to an exposed rolling surface of the left-side or right side wheel set.