Either a tail light or a separate light shall be so constructed and placed as to illuminate with a white light the rear registration plate, when such registration plate is required, and render it legible from a distance of fifty feet to the rear. Any tail light, together with any separate light for illuminating the rear registration plate, shall be so wired as to be lighted whenever the headlights or auxiliary driving lights are lighted, except where separate lighting systems are provided for trailers for the purpose of illuminating such registration plate.
R.C. § 4513.05