A portable towing system for a motorcycle or similar vehicle, such as a trike, the frame of which can be lowered to ground level to facilitate loading of the motorcycle or similar vehicle by pushing or riding the vehicle onto the frame without risk of the vehicle falling off the sides of a steeply inclined ramp. The towing system may be assembled, raised, lowered, and disassembled by a single person, if desired. The towing system also comprises a cargo box to store the frame when disassembled. The raising and lowering of the frame is effected by a lifting and lowering mechanism connected with the wheel assemblies, and at least three heights of the frame are achieved by rotation of the lifting and lowering mechanism of the wheel assemblies. The cargo box and the frame can use the wheel assemblies interchangeably.