California Code, Insurance Code - INS § 383.6

(a) Trailers, house trailers, mobilehomes, campers and all other wheeled vehicles or nonwheeled structures so made as to be capable of being moved as a compatible portion thereof, or trailed behind, any motor vehicle as that term is defined in the Vehicle Code, whether in immobile position or not.

(b) Motorcycles, motorbikes and motor scooters, except powered bicycles not manufactured for inclusion of a motor.

All present or future rules or regulations promulgated by the commissioner pursuant to Section 383.5 shall be applicable to motor vehicles as defined in this section.