(a)   Every motor vehicle, trailer, semitrailer, pole trailer or vehicle which is being drawn at the end of a train of vehicles shall be equipped with at least one tail light mounted on the rear which, when lighted, shall emit a red light visible from a distance of 500 feet to the rear, provided that in the case of a train of vehicles only the tail light on the rearmost vehicle need be visible from the distance specified.
   (b)   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 50 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.
(ORC 4513.05)
Penalty - see Sections 307.01 and 307.02