RCW 46.37.186: Fire department sign or plate on private car.

(1) No private vehicle, bearing a sign or plate indicating a fire department connection, shall be driven or operated on any public highway, except when the owner thereof is a bona fide member of a fire department. (2) Any sign or plate indicating fire department connection on a private car of any member of a fire department shall include the name of the municipality or fire department organization to which the owner belongs.