347.26(6) Warning lamps on tow trucks and service vehicles
(a) Any vehicle which by reason of its use upon a highway creates a vehicular traffic hazard requiring the exercise of unusual care in approaching, overtaking or passing shall be equipped with a flashing or rotating amber lamp of the dome type at the highest practicable point, visible from a distance of 500 feet, or 2 flashing amber lamps, one showing to the front and one showing to the rear, visible from a distance of 500 feet and mounted approximately midway between the extremities of the width of the vehicle and at the highest practicable point. Such amber lamp or lamps shall be lighted when such vehicle is moving a disabled vehicle along or upon a public highway at a speed below the average speed of motor vehicle traffic on such street or highway and may not be lit at other times.
(b) Operators of tow trucks or towing vehicles shall equip each tow truck or towing vehicle with a flashing or rotating red lamp, in addition to flashing type amber lamps. Such lamp shall be placed on the dome of the vehicle at the highest practicable point visible from a distance of 500 feet. This flashing red lamp shall be used only when such vehicle is standing on or near the traveled portion of a highway preparatory to towing or servicing the disabled vehicle.