What is NOT included in Class M vehicles?

Class M vehicles specifically refer to motorcycles and certain types of motorized two- or three-wheeled vehicles that require a motorcycle endorsement to operate. This classification encompasses standard motorcycles and three-wheeled vehicles such as trikes or scooters.

The distinction lies in the definition of what constitutes a Class M vehicle, which does not cover trailers, regardless of size or braking system. Trailers, including those over 20 feet in length equipped with air brakes, fall under different classifications related to vehicle towing and are not considered part of the Class M vehicle category. Therefore, trailers do not require a motorcycle endorsement and are not included in Class M regulations.

This understanding clarifies why the selection relating to trailers with air brakes is the correct answer, as it lies outside the scope of Class M vehicles.