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:
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
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
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.
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 | |
|---|---|
| 2 Stop/brake lights | These 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 lights | These functions are frequently combined into a single side marker light. |
| 2 Front side marker reflectors | |
Exceptions
| Required Lights | |
|---|---|
| 2 Stop/brake lights | These 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 lights | These functions are frequently combined into a single side marker light. |
| 2 Front side marker reflectors | |
| 2 Rear clearance lights | Front and rear clearance lights can be combined on boat trailers. |
| 2 Front clearance lights | |
| Rear identification lights | ID lights are often grouped into a single light bar. |
Exceptions
| Required Lights | |
|---|---|
| 2 Stop/brake lights | These 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 lights | These functions are frequently combined into a single side marker light. |
| 2 Front side marker reflectors | |
| 2 Rear clearance lights | Front and rear clearance lights can be combined on boat trailers. |
| 2 Front clearance lights | |
| Rear identification lights | ID lights are often grouped into a single light bar. |
Exceptions
Trailers 80" or Wider and over 10,000 lbs GVWR must have the following markings, which can consist of reflectors or reflective tape
| 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 | |
|---|---|
| 2 Stop/brake lights | These 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 lights | These functions are frequently combined into a single side marker light. |
| 2 Front side marker reflectors | |
| Rear identification lights | ID lights are often grouped into a single light bar. |
| 2 Intermediate side marker lights | These 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 lights | Front and rear clearance lights can be combined on boat trailers. |
| 2 Front clearance lights | |
Exceptions
Trailers 80" or Wider and over 10,000 lbs GVWR must have the following markings, which can consist of reflectors or reflective tape.
| 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.
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 * |
| 15" - 72" above the ground |
| Brake lights * |
| 15" - 72" above the ground |
| Rear turn signals |
| 15" - 83" above the ground |
| Rear reflectors * |
| 15" - 60" above the ground |
| License plate light |
| Varies based on position of license plate |
| Rear side marker lights |
| 15" or more above the ground (On trailers 80" or wider, no more than 60" above the ground) |
| Rear side reflectors |
| 15" - 60" above the ground |
| Front side marker lights |
| 15" or higher above the ground |
| Front side reflectors |
| 15" - 60" above the ground |
| Intermediate side marker lights |
| 15" or higher above the ground |
| Intermediate side reflectors |
| 15" - 60" above the ground |
| Rear clearance lights |
| N/A |
| Rear identification lights |
| N/A |
| Front clearance lights |
| 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 |
| N/A |
| A strip of alternating red and white tape (or reflectors) marks the rear bumper bar |
| N/A |
| A strip of alternating red and white tape (or reflectors) marks the rear lower body |
| 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 |
|
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 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
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 lights | Red | T |
| Stop/brake lights | Red | S |
| Rear turn signals | Red or amber (yellow) | I |
| Rear reflectors | Red | A |
| License plate light | White | L |
| Rear side marker lights | Red | P2, PC, P3, or PC2 |
| Rear side reflectors | Red | A |
| Front side marker lights | Amber (yellow) | P2, PC, P3, or PC2 |
| Front side reflectors | Amber (yellow) | A |
| Intermediate side marker lights | Amber (yellow) | P2 or P3 |
| Intermediate side reflectors | Amber (yellow) | A |
| Rear clearance lights | Red | P2, PC, P3, or PC2 |
| Rear ID lights | Red | P2 or P3 |
| Front clearance lights | Amber (yellow) | P2, PC, P3, or PC2 |
| Rear upper body markers | White | |
| Bumper bar markers | Alternating red and white | |
| Rear lower body markers | Alternating red and white | |
| Side markers | Alternating red and white |
What is the difference between lights that have a "C" in the code (PC and PC2) and those that don't (P2 and P3)?
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.
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
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
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.
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.
I am currently building a 53’ chassis and plan to bolt on a box structure to it. My question is if i need clearance lights? 53’ length, wider than 80 in, and gwvr is over 4500 kg.
With a box of this size, you will definitely need clearance lights. There is a section in this article that lay out what exactly you'll need. I've linked to it here.
Helpful Links
faq-trailer-lighting-info-and-regulations.aspx#trailermore80more10000less30
what is the requirement on a 48 foot spread axle trailer between the spread does it half to be red and does the amber light half to stop in front of the axle then red
You're talking about the intermediate side marker lights, correct? If that's the case it looks like you want to place the side marker lights about halfway on the side of your trailer.
@JonG it has lights all the way down to the red light what I want to know is in between the spread axle it suppose to be red or amber
@WilliamR Should be amber.
The following is listed for a 80+ width, less than 30' long and less than 10,000 lb trailer Required Lights 2 Stop/brake lights These 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 Question: Does the stipulation of 2 tail lights and 2 turn signals mean; 2 per side or 2 in total meaning one per side?
If it would be 2 total, so 1 per side.
Rear Clearance Lights Separate from Other Lights Listed above; 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. Question; Can the same be said about the front side marker light? Can the one mounted on the fender be the only yellow light on the side of a 12' long trailer?
From what I'm seeing in the article you'll need 4 side clearance lights - 2 for the front and 2 for the back. I don't think you'd want to install the front clearance lights on your fender because they would be less visible. I do recommend checking with your local DMV or state trooper location though to make sure everything is just how it needs to be.
I am in the process of lengthening my open car trailer. There is now a 95” wide by 83” long sleeper on the front. My question is what I need to put on the rear of the box, number of lights and color. Any help getting this figured out will be appreciated. Trailer is 300” total length. Thanks,
You'll want to check out the charts in this article starting with the section (Required Lights for Trailers 80" or Wider, Less Than 30' Long, and with a GVWR of 10,000 lbs or Less) and then the section after that if your trailer has a GVWR greater than 10,000 lbs. The charts for those 2 sections have the number of lights, reflectors, and locations that you'll need to have. If you're still unsure then you can check with your local DMV or highway patrol to verify you're good to go.
I have a small (4x8), tilt trailer that I'm installing lights on. The back of the trailer tapers down to 3/4" thick leaving nowhere to mount rear facing t,b,t lights. The fenders are wider than the deck but are 2.5' from the back of the trailer. Can I mount my t,b,t lights on the back of the fenders? Also, do I have to mount rear, side facing, lights between said t,b,t lights and the back of the trailer? I'd appreciate help with these questions asap so I can finish mounting these lights tonight before I use it tomorrow. Thank you for your time.
While it is okay to mount clearance lights on the fenders, you'll need to have the tail and brake lights mounted on the outer parts of the trailer that are furthest back so that others on the road can tell the size of the trailer during the night.
on a Bargman LED Double Tail Light which light needs to be the outermost light stop/turn or the red reflex?
You want the running, or tail, lights to be on the outermost side.
I tow a small sailboat on a trailer, less than 80" wide and less than 30' long, but the boat overhangs the rear of the trailer by 3 or 4 feet, and the mast extends another 6 feet or so past the back of the boat. Am I required to have sidemarker lights on the end of the mast?
If it's something that's overhanging off the back of the trailer then I'm not sure if a flag would be needed or if that calls for extra lights. I'd check with your local DoT or highway patrol to get their input and make sure you're following local and state laws.
I have a 40ft flatbed gooseneck that I'm updating. It has a full 102" deck. Is there DOT restrictions on maximum number of tail/brake/turn lights? Instead of the 3 brake/turn/tail on each side (6 total), I am wanting to upgrade to a total of 10 LEDs. It would go in this order, (3) Tail/Turn, (2) Tail/Brake, (1) Reverse, space, (3) identification lights, space, (1) reverse light, (2) Tail/Brake, (3) Tail/Turn. Basically, I would be adding 4 extra LEDs in the rear. I am also aware and know how to separate the wiring from brake to turn signals using relays. I just need to know if there is DOT restrictions. Most trailers only have 2 to 3 lights on each side. Thank you
From my understanding you have to at least have the required amount of lights on your trailer - if you wanted to add more than that you should be fine as long as they are in the standard areas on your trailer. You will want to double check with your local DMV or state highway patrol to make sure that any additional lights are placed in the correct locations and that you are cleared to do this.
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
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.
Helpful Links
@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.
@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.
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?
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.
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?
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.
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?
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.
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,
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.
Helpful Links
dept-pg-accessories_and_parts-sf-license_plates_and_frames-pt-mounting_brackets.aspx
@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.
@Bruce That works too!
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.
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
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.
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.
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.
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