The National Highway Traffic Safety Administration (NHTSA) has developed standards and regulations for lighting on all road-ready trailers. These standards define the number of lights and reflectors a trailer must have, where the lights and reflectors should be located, and which SAE or DOT code the lights must have. These regulations can be found under Title 49, Part 571, Section 108 of the Code of Federal Regulations.

Federal Lighting Requirements and Locations for Trailers

The following information is provided by the National Highway Traffic Safety Administration. For full and up-to-date information, visit www.nhtsa.gov

BASIC EQUIPMENT REQUIRED ON ALL TRAILERS

The following table lists the lights and reflectors required on all trailers regardless of size. These standards apply to utility trailers, RVs, campers, boat trailers, cargo trailers, horse trailers, car haulers, semi trucks, and other towables. As you’ll see, all trailers require tail lights, marker lights, and a license plate light. Many lights combine several functions, such as the typical stop/turn/taillight (sometimes with an integrated reflector).

All lenses are required to have an SAE code. Many lamp lenses have multiple SAE codes, indicating they can perform multiple functions.

• A – Rear reflector
• S – Stop light
• T – Tail light
• I – Turn signal
• P2 – Rear side marker light

Area	Equipment	SAE Lens Code	Functional Purpose	Quantity	Color	Location	Height from the Ground
1	Tail Lamps	(T)	Indicates vehicle presence & width	Minimum 2	Red	On rear- symmetrical-as far apart as practicable	15’’-72’’
1	Stop Lamps	(S)	Indicates braking	Minimum 2	Red	On rear- symmetrical-as far apart as practicable	15’’-72’’
1	Rear Turn Signal Lamps	(I)	Indicates direction of turn	Minimum 2	Red or Yellow	On rear- symmetrical-as far apart as practicable	15’’-83’’
1	Rear Reflex Reflectors	(A)	Indicates vehicle presence & width	Minimum 2	Red	On rear-symmetrical-as far apart as practicable-facing rearward	15’’-60’’
2	License Plate Lamp(s)	(L)	Illuminates license plate	Minimum 1	White	On rear-above or at the sides of license plate	None
3	Rear Side Marker Lamps	(P2, PC* or P3*)	Indicates vehicle presence & width	Minimum 2	Red	Each side at rear – as far back as practicable	15’’-60’’ max
3	Rear Side Reflex Reflectors	(A)	Indicates vehicle presence & width	Minimum 2	Red	Each side at rear – as far back as practicable-facing sideward	15’’-60’’
4a	Front Side Marker Lamps	(P2, PC* or P3, PC2*)	Indicates vehicle presence & width	Minimum 2	Yellow	Each side at front – as far back as practicable	15’’ min
4b	Front Side Reflex Reflectors	(A)	Indicates vehicle presence & width	Minimum 2	Yellow	Each side at front– as far back as practicable-facing sideward	15’’-60’’

ADDITIONAL EQUIPMENT FOR TRAILERS EXCEEDING 80 IN WIDE

These are additional rules and equipment for trailers over 80 inches wide. Generally, this is measured to the widest part of the trailer body or the fenders, whichever is wider. Small appurtenances like assist handles or trim work are usually not counted in the width calculation. These additional lights mark the overall size and height of the trailer.

Area	Equipment	SAE Lens Code	Functional Purpose	Quantity	Color	Location	Height from the Ground
6	Rear Clearance Lamps	(P2, PC* or P3, PC2*)	Show’s vehicles width-MAY NOT be combined with tail lamps	Minimum 2	Red	At widest point-symmetrical-on the rear or near the rear-facing rearward	As high as practical-lower only if ID lamps are at the top
7	Rear Identification Lamps	(P2 or P3)	Indicate presence of wide vehicle	Exactly 3	Red	On the rear-center, facing rearward-horizontally spaced 6’’ to 12’’ apart	As high as practicable
8	Front Clearance Lamps	(P2, PC* or P3, PC2*)	Show vehicle’s width	Minimum 2	Yellow	At widest point-symmetrical-as far forward as practicable-facing forward	As high as practicable

ADDITIONAL EQUIPMENT FOR TRAILERS EXCEEDING 30 FT LONG

Longer trailers over 30 feet in length require intermediate lights and reflectors to better mark their extents. Trailers are normally measured tip-to-tail, from the front of the coupler to the rear bumper. Appurtenances (like window rain guards or latching hardware) are not usually factored in so long as they small, usually less than 3-4″ in prominence.

Area	Equipment	SAE Lens Code	Functional Purpose	Quantity	Color	Location	Height from the Ground
5a	Intermediate Side Marker Lamps	(P2 or P3)	Indicate presence of long vehicle	Minimum 2	Yellow	Each side near center-facing sideward	15’’ min
5b	Intermediate Side Reflex Reflectors	(A)	Indicate presence of long vehicle	Minimum 2	Yellow	Each side near center-facing sideward	15’’-60’’

ADDITIONAL EQUIPMENT FOR TRAILERS EXCEEDING 80 IN WIDTH AND 10,000 LB GVWR

Big n’ Large trailers require additional single and continuous reflectors for highway safety. These are called conspicuity treatments, and they’re usually alternating strips of red and white reflective tape.

Area	Equipment	DOT Code	Quantity	Color	Location	Height from the Ground
9	Rear Upper Body Marking	DOT-C, DOT-C2, DOT-C3, or DOT-C4	Exactly 2 pairs of 300mm long strips	White	On the rear upper corners-facing rearward	At the top
10	Bumper Bar Marking	DOT-C, DOT-C2, DOT-C3, or DOT-C4	Continuous	Red / White	On the rear bumper bar’s horizontal element-full-width-facing rearward	No Requirement
11	Rear Lower Body Marking	DOT-C, DOT-C2, DOT-C3, or DOT-C4	Continuous	Red / White See options	On the rear-full width of the vehicle-facing rearward	As horizontal as practicable and as close as practicable to the range of 375 to 1525 mm from the ground
12	Side Marking	DOT-C, DOT-C2, DOT-C3, or DOT-C4	See Location	Red / White See options below	On rear-symmetrical-as far apart as practicable-facing rearward	As horizontal as practicable and as close as practicable to the range of 375 to 1525 mm from the ground

For more information contact:
Transport Canada: Motor Vehicle Safety Enforcement Branch
National Highway Safety Administration: Office of Safety Performance Standards