A wheel assembly includes a rigid wheel and an airless tire. The wheel includes a cylindrical rim portion that is parallel with an axis of rotation of the wheel and includes a transversely flat outer surface corresponding to at least eighty percent of the total width of the rim portion. The tire is mounted on the rim portion of the wheel and includes a cylindrical tire body presenting a transversely flat inner surface that engages the outer surface of the wheel. A plurality of traction lugs are spaced circumferentially around the tire and extend radially outwardly from the tire body. A plurality of drive lugs are spaced circumferentially around the tire, extend radially inwardly from the tire body and engage corresponding receptacles on the rim portion of the wheel.