For the purposes of § 58-23-8, the term, motor vehicle, means automobiles, motor trucks, motorcycles, and all vehicles propelled by power other than muscular power and designed primarily for travel on the public highway except traction engines, road rollers, farm wagons, freight trailers, house trailers, trailers, vehicles that run only on rails or tracks, and off-road vehicles as defined in § 32-3-1. However, a vehicle not designed for travel on the public highway that is licensed is a motor vehicle for purposes of § 58-23-8. Freight trailers, house trailers, and trailers which are attached to a motor vehicle are part of that motor vehicle.
SDCL 58-23-9