RCW 46.37.535: Motorcycles, motor-driven cycles, or mopeds—Helmet requirements when rented.

It is unlawful for any person to rent out motorcycles, motor-driven cycles, or mopeds unless the person also has on hand for rent helmets of a type conforming to rules adopted by the state patrol. It shall be unlawful for any person to rent a motorcycle, motor-driven cycle, or moped unless the person has in his or her possession a helmet of a type approved by the state patrol, regardless of from whom the helmet is obtained.