Trailer Lighting Requirements

Light on PWD trailer lit up

When you're out on the road pulling your trailer, you want to be as safe as possible. One important component of towing safety is visibility - making sure other drivers can see your trailer. And lighting plays a big role in visibility. So, whether you're replacing a single light bulb or lens cover, or you're adding a complete set of lights to a homemade trailer, you want to get the right part for the job.


You also want to get lights that comply with the US government's lighting requirements for trailers. Based on standards developed by the Society of Automotive Engineers (SAE), the National Highway and Traffic Safety Administration (NHTSA) has developed requirements for vehicle lights. The set of regulations that applies to vehicle lighting is known as FMVSS 108, and it includes lighting requirements for trailers. These regulations define how many lights a trailer must have, where the lights should be located, what performance standards the lights must meet, and how manufacturers must label lighting components.


Note: The information contained in this article is based on the US government's regulations pertaining to vehicle trailer lighting. These regulations can be found under Title 49, Part 571, Section 108 of the Code of Federal Regulations. This section covers lamps, reflective devices, and associated equipment related to motor vehicles. To see these regulations and to get the most up-to-date information, visit the US government's Electronic Code of Federal Regulations.


This article will help you answer the following questions:





Determine Which Lights Your Trailer Needs

All trailers are required to have stop lights, tail lights, turn signals, and reflectors. Trailers that are 80" wide or wider, or that are 30' long or longer need additional lights and reflectors. A trailer that is 80" wide or wider and has a Gross Vehicle Weight Rating (GVWR) over 10,000 lbs requires conspicuity treatments. These treatments consist of strips of reflective tape or rows of individual reflectors that create an alternating pattern of red and white along the sides and rear of a trailer to make it easier to see.


To determine which lights a trailer needs, you need to know the trailer's overall length and width and whether the trailer's GVWR is greater than 10,000 lbs. If you don't know the dimensions of your trailer, you'll have to measure it. To find your trailer's GVWR, look for a sticker located somewhere on the trailer.


Measuring the Length of a Trailer

Diagram showing where to measure the length of a trailer

To find a trailer's length, measure from the rearmost point on your trailer to the point of the trailer closest to the vehicle. Be sure to include the coupler or any overhang in this measurement.


Measuring the Width of a Trailer

Diagram showing where to measure the width of a trailer

To find the width, measure at the trailer's widest point. This measurement must include any overhang or protruding fenders.


Locate Trailer GVWR

To find a trailer's GVWR, look on the trailer's tongue or frame for a label like the one seen below.

Image of trailer label showing GVWR

Once you know your trailer's length, width, and GVWR, you can use the following list to find the specific lights for your trailer.





Required Lights for Trailers Less Than 80" Wide and Less Than 30' Long

Diagram with minimum required trailer lights

Required Lights
2 Stop/brake lightsThese functions are frequently found together in combination tail lights.
2 Tail lights
2 Turn signals
2 Rear reflectors
1 License plate light
2 Rear side marker lights
2 Rear side reflectors
2 Front side marker lightsThese functions are frequently combined into a single side marker light.
2 Front side marker reflectors

Exceptions





Required Lights for Trailers 80" or Wider, Less Than 30' Long, and with a GVWR of 10,000 lbs or Less

Diagram of trailer over 80 inches wide illustrating required
lights

Required Lights
2 Stop/brake lightsThese functions are frequently found together in combination tail lights.
2 Tail lights
2 Turn signals
2 Rear reflectors
1 License plate light
2 Rear side marker lights
2 Rear side reflectors
2 Front side marker lightsThese functions are frequently combined into a single side marker light.
2 Front side marker reflectors
2 Rear clearance lightsFront and rear clearance lights can be combined on boat trailers.
2 Front clearance lights
Rear identification lightsID lights are often grouped into a single light bar.

Exceptions





Required Lights for Trailers 80" or Wider, Less Than 30' Long, and with a GVWR Greater Than 10,000 lbs

Diagram of trailer over 80 inches wide and greater than 10,000 lbs GVWR and less than 30feet long


Required Lights
2 Stop/brake lightsThese functions are frequently found together in combination tail lights.
2 Tail lights
2 Turn signals
2 Rear reflectors
1 License plate light
2 Rear side marker lights
2 Rear side reflectors
2 Front side marker lightsThese functions are frequently combined into a single side marker light.
2 Front side marker reflectors
2 Rear clearance lightsFront and rear clearance lights can be combined on boat trailers.
2 Front clearance lights
Rear identification lightsID lights are often grouped into a single light bar.

Exceptions


Required Conspicuity Treatments for Trailers 80" or Wider, Less Than 30' Long, and with a GVWR Greater Than 10,000 lbs

Trailers 80" or Wider and over 10,000 lbs GVWR must have the following markings, which can consist of reflectors or reflective tape


Diagram of trailer over 80 inches wide and greater than 10,000 lbs GVWR illustrating required conspicuity treatments


Required Conspicuity Treatments
2 Pairs of rear upper body markings
1 Continuous bumper bar marking
1 Continuous rear lower body marking
2 Continuous side markings

Note: If conspicuity treatment would be placed at a location where a reflector would otherwise be required, the reflector may be omitted.





Required Lights for Trailers 30' or Longer (Regardless of Width or GVWR)

Diagram of trailer over 80 inches wide and greater than 10,000 lbs GVWR illustrating required lights and reflectors


Required Lights
2 Stop/brake lightsThese functions are frequently found together in combination tail lights.
2 Tail lights
2 Turn signals
2 Rear reflectors
1 License plate light
2 Rear side marker lights
2 Rear side reflectors
2 Front side marker lightsThese functions are frequently combined into a single side marker light.
2 Front side marker reflectors
Rear identification lightsID lights are often grouped into a single light bar.
2 Intermediate side marker lightsThese functions are frequently combined into a single side marker light.
2 Intermediate side marker reflectors

Additional Lights for Trailers 80" or Wider
2 Rear clearance lightsFront and rear clearance lights can be combined on boat trailers.
2 Front clearance lights

Exceptions


Required Conspicuity Treatments for Trailers 80" or Wider, 30' or Longer, and with a GVWR Greater Than 10,000 lbs

Trailers 80" or Wider and over 10,000 lbs GVWR must have the following markings, which can consist of reflectors or reflective tape.


Diagram of trailer over 80 inches wide and greater than 10,000 lbs GVWR illustrating required conspicuity treatments

Required Conspicuity Treatments
2 Pairs of rear upper body markings
1 Continuous bumper bar marking
1 Continuous rear lower body marking
2 Continuous side markings

Note: If conspicuity treatment would be placed at a location where a reflector would otherwise be required, the reflector may be omitted.





Where to Mount Trailer Lights, Reflectors, and Conspicuity Treatments

US regulations specify where lighting must be installed on trailers. The following list gives general rules that apply to all trailer lighting. And the following table shows rules that apply to specific types of lights.


Proper Mounting Locations of Trailer Lighting

Light Location Position
Tail lights *
  • Rear of trailer
  • Same height above the ground
  • Same distance from the trailer's vertical centerline
  • As far apart as possible
15" - 72" above the ground
Brake lights *
  • Rear of trailer
  • Same height above the ground
  • Same distance from the trailer's vertical centerline
  • As far apart as possible
15" - 72" above the ground
Rear turn signals
  • Rear of trailer
  • Same height above the ground
  • Same distance from the trailer's vertical centerline
  • As far apart as possible
15" - 83" above the ground
Rear reflectors *
  • Rear of trailer
  • Same height above the ground
  • Same distance from the trailer's vertical centerline
  • As far apart as possible
15" - 60" above the ground
License plate light
  • Rear of trailer
  • Above or to the side of license plate
Varies based on position of license plate
Rear side marker lights
  • One on each side of trailer
  • As far toward the rear of the trailer as possible
15" or more above the ground (On trailers 80" or wider, no more than 60" above the ground)
Rear side reflectors
  • One on each side of trailer
  • As far toward rear of trailer as possible
15" - 60" above the ground
Front side marker lights
  • One on each side of trailer
  • As far toward the front as possible
  • Not on trailer tongue
15" or higher above the ground
Front side reflectors
  • One on each side of trailer
  • As far toward the front as possible
  • Not on trailer tongue
15" - 60" above the ground
Intermediate side marker lights
  • One on each side of trailer
  • Halfway - or as close to halfway as possible - between the front and rear side reflectors
15" or higher above the ground
Intermediate side reflectors
  • One on each side of trailer as close to halfway between the front and rear side reflectors as possible
15" - 60" above the ground
Rear clearance lights
  • Rear of trailer
    • May be located farther forward if necessary
  • Same height above the ground
  • Same distance from trailer's vertical centerline
  • As high as possible on trailer
    • Can be lowered if identification lights are at the top or if header extends less than 1" above doors
N/A
Rear identification lights
  • Rear of trailer
  • Same height above the ground
  • Spaced 6" to 12" apart
  • As high as possible on trailer
    • Can be lowered if header extends less than 1" above door
N/A
Front clearance lights
  • Front of trailer
    • May be located farther rearward if necessary
  • Same height above the ground
  • Same distance from the trailer's vertical centerline
  • As high as possible on trailer
N/A

* If only 1 light is used on a trailer less than 30" wide, it should be as close to the vertical centerline as possible.


Rules That Apply to Trailer Lights and Reflectors


Proper Mounting Locations of Conspicuity Treatments

Conspicuity Treatment Location Position
A pair of white reflective strips at each upper corner marks the rear upper body
  • Each pair consists of a horizontal and a vertical strip
  • Each strip must be 12" long
  • The strips must be mounted as close as possible to the upper and outer edges
  • Treatment can be mounted on the rear-facing surface of a bulkhead on an otherwise flat trailer
  • Treatment can be omitted on container chassis or platform trailers without bulkheads
N/A
A strip of alternating red and white tape (or reflectors) marks the rear bumper bar
  • Mounts along rear bumper or underride protection device
  • Runs the full width of bumper bar
N/A
A strip of alternating red and white tape (or reflectors) marks the rear lower body
  • Runs along full width of lower portion of body
  • Extends horizontally, as far as possible to each end
15" to 60" above the ground
(height measured at horizontal centerline of strip when trailer is at curb weight)
A strip of tape (or reflectors) marks the sides of the trailer
  • Running along both sides of the trailer, as evenly spaced as possible
  • Covering at least 1/2 of trailer's length
  • Extending horizontally between the front and rear of the trailer as far as possible
15" to 60" above the ground
(height measured at horizontal centerline of strip when trailer is at curb weight)

Code Markings Required on Conspicuity Tape and Reflectors

Reflective marking tape must be marked with codes "DOT-C2", "DOT-C3", or "DOT-C4" on each white or red segment and at least once every 12" on all-white tape. Reflectors to be used in place of tape must be marked "DOT-C".


Rules That Apply to Conspicuity Treatments

US regulations call for conspicuity treatments to be added to trailers that are 80" or wider and that have a GVWR greater than 10,000 lbs. Conspicuity treatments consist of reflectors, reflective sheeting (tape), or a combination of both.


Apply to a Flat Surface


Proximity of Conspicuity Tape to Lights


Splitting Marking Tape to Clear Rivets or Other Obstructions


Red and White Marking Tape


Reflectors Used in Place of Tape





Trailer Lighting Standards

Trailer lighting must meet performance standards that are specified by US regulations. These regulations spell out what colors lighting devices must be, how they must be tested, how they must perform, and how they should be labeled. The following list and table show what information is typically included on lights, reflectors, and reflective tape. This information is usually molded into the cover of a light or reflector, and it is printed on the reflective tape.


Information Indicated on Lights, Reflectors, and Reflective Tape


SAE Codes on Trailer Light Lens

Trailer light cover and exploded view showing details of SAE codes

The SAE codes on the lens of the light pictured above indicate that this light can perform more than 1 function. Many trailer lights are designed to do this. Based on the SAE codes on this light, it performs the following functions.


Trailer Lighting and Conspicuity Tape Codes

Function Color Code
Tail lightsRedT
Stop/brake lightsRedS
Rear turn signalsRed or amber (yellow)I
Rear reflectorsRedA
License plate lightWhiteL
Rear side marker lightsRedP2, PC, P3, or PC2
Rear side reflectorsRedA
Front side marker lightsAmber (yellow)P2, PC, P3, or PC2
Front side reflectorsAmber (yellow)A
Intermediate side marker lightsAmber (yellow)P2 or P3
Intermediate side reflectorsAmber (yellow)A
Rear clearance lightsRedP2, PC, P3, or PC2
Rear ID lightsRedP2 or P3
Front clearance lightsAmber (yellow)P2, PC, P3, or PC2
Rear upper body markersWhite
Bumper bar markersAlternating red and white
Rear lower body markersAlternating red and white
Side markersAlternating red and white





Common Questions About Trailer Lighting


What is the difference between lights that have a "C" in the code (PC and PC2) and those that don't (P2 and P3)?

Diagram to illustrate 45 degree light spread of P2- and P3-rated lights

The light beam emitted from a P2 or P3 light spreads out 45 degrees to each side of its centerline for a total of 90 degrees of coverage. This beam pattern can be seen straight on, but it cannot be seen clearly from the side of the trailer. When mounted square to the front, sides, or back of a trailer, this kind of light provides adequate visibility.



Diagram to illustrate 90 degree light spread of PC-rated lights

The light beam emitted from a PC light spreads out 90 degrees to either side of its centerline for a total of 180 degrees of coverage. This beam pattern can be clearly seen when you are standing directly in front of the light, as well as when you are standing on either side of the light. This wide angle beam allows the light to perform not only as a front clearance light, for example, but also as a side marker light.



To perform its combined functions, a PC light must be properly mounted. Some lights are designed to be mounted at a 45-degree angle between the front and side or between the side and back of a trailer. You must mount these lights on a part of the trailer that provides this 45-degree angle. Other PC lights emit light through 2 lenses, 1 that faces toward the front or back of the trailer and the other that faces toward the side. These lights must be mounted square to the back or front of the trailer and at the outer edge so that the light will also be visible from the side of the trailer.


What does it mean when a trailer light is for trailers wider than 80"?

Trailers that are 80" (6' 8") or wider at the widest point require front and rear clearance lights and rear identification lights in addition to basic trailer lights. The clearance lights indicate the width of the trailer when it is viewed from the front and the back. To properly indicate the width of the back of a trailer, 1 rear clearance light is required at each side on the back of the trailer at the trailer's widest point. Both of these clearance lights should be at the same height and as high as possible unless identification lights are mounted at the top, in which case the clearance lights can be mounted lower. A light that functions as a rear clearance light can be designated as a light for 80" wide trailers, whether the light is combined with other functions or it is intended only as a clearance light.


Rear Clearance Lights Combined with Other Lights

Trailer over 80" wide that can use combination
lights made for trailers 80" wide or wider

If the bed of the trailer extends out past the wheels, then the back of the trailer would most likely be its widest point. In this case, you can use combination lights that are designed for trailers wider than 80" and that have the clearance lights built in. These lights would be mounted at the widest point of the trailer at the rear.


These combination lights are most commonly found on flat bed utility trailers. Rear clearance lights must be mounted low on these trailers because there is no place above the frame on which to mount the lights.



Rear Clearance Lights Separate from Other Lights

Trailer over 80" wide that wouldn't use
combination lights made for trailers 80" wide or wider

If the trailer's wheels extend out at the sides beyond the bed of the trailer, then the fenders most likely create the trailer's widest point. In this case, you can use standard combination stop lights, tail lights, and turn signal lights just for those functions and mount separate lights on the fenders to mark the rear clearance.


You would not use a combination light made for trailers greater than 80" for this application, even though the trailer is wider than 80". The rear clearance lights, though, could be designated for trailers that are 80" wide.


Tall trailer over 80" wide that wouldn't use
combination lights made for trailers 80" wide or wider

You wouldn't use combination lights that include rear clearance lights on a tall trailer either. The rear clearance lights on a tall trailer are mounted high on its body - away from the tail lights.




What's the Difference between Non-Submersible, Submersible, and Waterproof Lights?

Trailer lights differ in their ability to resist or tolerate water entry. Trailers that may be submerged, like boat trailers, should be equipped with lights that can handle being in water.


Non-submersible lights are not designed to be submerged. The lens may have a seal or gasket to help keep water out, but that may not be enough to guarantee that water won't get into the light assembly.


Submersible lights are designed to avoid damage if they are submerged. To improve the ability of a light to resist water damage, manufacturers use 1 of 2 methods.


Back of trailer light housing to show water drain hole





Questions and Comments about this Article

Andyr

I have five rear marker lights along the top edge of my fifth wheel. Regulations only require two reflectors. I removed the center light and used that wire as a power source for a rear view camera. I always travel with my lights on when I tow so it works pretty well. I was told by a NY state inspection station that any light that came from the factory MUST be retained. I cannot find any reference to such a regulation on the NYS DMV web site. All I find are the same light charts included in this article. Can anyone shed any light on this? Thanks 101864

Reply from Jon G.

The lighting on 5th wheel trailers should be up-to-date as far as how many lights you need along the top at the back. It is true that you should not replace a rear light with a camera - that's actually why the Furrion Vision S kit has a camera option that allows you to actually replace a 3rd brake light (see linked answer page). We got our information from the US government's Electronic Code of Federal Regulations so that might be what your inspection station was referring to. 75126

Reply from Andyr

@JonG I cant find any regulation that requires ANY lights, only reflectors. And those require only two. My reduction from five to four exceeds the requirements. The as shipped trailer exceeded the requirements. Not sure why anyone would think it must remain in a state that exceeds requirements. Your statement about not removing the light for a camera is not apropos to my question. 75129

Reply from Jon G.

@AndyR I was replying to your comment about "I removed the center light and used that wire as a power source for a rear view camera." If I were you I'd reach out to that same NY state inspection station and ask where their statement comes from so you have a direct source from your state government to refer to. 75131

Gbs

What regulation (e.g., DOT) requires the lights described in the "Required Lights for Trailers Less Than 80" Wide and Less Than 30' Long" section? 99115

Reply from Jon G.

Per the note at the start of this article - These regulations can be found under Title 49, Part 571, Section 108 of the Code of Federal Regulations. 73702

Drew

I pull a very small truck behind my motorhome. I've installed additional red brake lights on the truck,which are red and amber. The amber lights are turn signals without brake applied but do light when brake is applied. Is this illegal? 97367

Reply from Jon G.

Pretty sure that would get the attention of a highway patrol officer. You need to separate out those functions really. If you install the Vehicle to Vehicle Tail Light Converter # 118158 this will split those circuits so that your amber lights will only activate when your turn signals are used. 72742

Brad H.

Two Questions.. Can you have several side marking lights on a large boat trailer, similar to the semi trailers that have several side marking lights along their sides? Can you tow with LED lights under the trailer that cast light on the trailer tires so that you can see them in your mirrors and know you don't have a tire coming apart? 97219

Reply from Jon G.

You can add more clearance lights on the sides of your trailer, and I'd imagine that you can have lights shining on your tires as long as they aren't too bright but that's something you'll need to run by your local highway patrol to get their take on it. 72741

Bruce

I need help finding a trailer license bracket. I mounted one on my old tilt trailer. The bracket mounted to the back of the standard square trailer taillight, and then extended up and to the left to keep the license plate up and from getting crushed when tilting the trailer. The bracket also had a license light at the top, 78381

Reply from Chris R.

We do have a large selection of trailer license plate brackets, which I've linked below, but I'm not sure if we have exactly what you're describing. One of the more popular models is a hanging unit like the CE Smith # CE26053A , which does mount behind the tail light. 63664

Reply from Bruce

@ChrisR thank you for the help. I am looking for one that puts the plate above the tail lamp and has a separate illumination light. Now I am designing it in CAD, and will have a 1/8 in ABS plastic prototype tomorrow. 63669

Reply from Chris R.

@Bruce That works too! 63874

E V.

Hello, In your video, review-optronics-led-trailer-light-tll36rk, you put a ground wire on the frame. Why do you use the "cheap" non sealed common crimp connectors? If you are going to use these types of connectors, why don't you coat them with "liquid electrical tape" or at the very lease a dielectric grease to keep the crimped area from corroding in 5 years? They are not sealed so they WILL corrode in time especially if salt is on the roads in winter! I did see you use a heat gun on the butt connectors however I feel the below is better. Why not use this self sealing solder ring? On your installation of the clearance (sidemarker<) light, you should use a grommet to avoid the wire chafing and shorting out. Thank you for your videos and website, they are very informative. 76485

Jonathan L.

I have an old army surplus M100 trailer built in 1953. It is 56 wide and 6 feet long. It has stop - tail - turn signal lights on each side and also has 2 red reflectors on the black and one red reflector on each side toward the back. Do I need to add clearance lights? I would rather not drill holes in the frame if I dont have to 70545

Reply from Chris R.

The basic signal lights already installed on your M100 trailer is all that it needs based on its size. There's no need to mount additional side clearance lights so you're good to go. 57566

Phillip

I recently purchased a 1984 Zieman, flatbed, utility trailer, for hauling my quads on. The trailer is more than 80 wide, less than 30 long and less than 10klb GVWR.The trailer does not have any fender mounted lights, front side marker lights or rear triple red light bar, as it came from the factory like that, back in 1984.How can I find out what the actual lighting requirements were at time of manufacture? Trailer mfg has no record. So that I have the information in case Im stopped when south of the border CA.Theres no place to mount front side marker lights U-shaped frame rail only has 1/2 flat between the U points, whereas the narrowest marker light I can find is 1 wide, without putting them on the tongue. Which is not allowed, per current regs. Theres no way to add the three red lights on the tail, for the same frame rail reason as above. And I have no intention, at this time, of mounting fender lights on it. 68828

Reply from Jason S.

Trailer manufacturers don't keep good records and you may need to adjust or adapt to meet your state requirements. I recommend reaching out to your local DMV for requirements to determine if you need to upgrade or if they grandfather your trailer in based on its age and use. 56815



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