For MA residents, check the last line:
Is defined as: “A portable, collapsible or separate two-wheel tow dolly limited only to the purpose of transporting or towing a registered vehicle.”
A Dealer may tow a vehicle on a two-wheel tow-dolly if the towed-vehicle displays a “Dealer” plate but the towing-vehicle cannot display a “Dealer” plate or a “passenger plate” but should display a “commercial plate.”
A Repairer displaying “commercial plates” on the towing-vehicle can tow a vehicle on a two-wheel tow-dolly but the towed-vehicle must be properly registered or have the “Repair” plate displayed on the towed-vehicle. A Repairer displaying “Repair” plates on the towing-vehicle can tow a vehicle on a two-wheel tow-dolly without plates on the towed-vehicle if the towing-vehicle is properly registered, displays the valid repair plate, maintains insurance which also provides coverage for the motor vehicle being towed on the dolly and displays a valid compliance decal.
A Transporter can tow a vehicle on a two-wheeled tow-dolly if the vehicle being towed displays the “Transporter” plate. The towing-vehicle must be properly registered (not a passenger registration).
An Owner-Contractor generally will have vehicles that will be too large for towing on a two-wheeled tow-dolly but if the registrant does have one that safely fits it needs to display the O/C plate and the towing-vehicle must also display the O/C plate.
Tow dollies themselves are exempt from registration requirements.