Trailer Inspection Tips And Checklist For Homemade Trailers

As you are finishing your homemade trailer build, it is easy to get excited about putting the trailer to use. Often the one last hurdle is getting it is all legal for towing – trailer inspection, title, registration, and licensing.

While it is perfectly normal, and usually not a big deal, the idea of having an authority judge your work can be a little nerve-racking. But, when you are prepared, you can treat it like a normal step, and that will help it go smoothly. The goal is to get the trailer legal to tow.

This article is about preparing and presenting your finished trailer so the inspection goes well. The lists and tips below should help you prepare.

What Will The Trailer Inspection Include?

First, to properly prepare, we need to know the things an inspection will include. How to present them is the subject of our Tips For Trailer Inspection section below.

Trailer inspection will include the FMVSS requirements, other standard requirements, and local requirements. Here are some details for these 3 groups of requirements.

Federal Motor Vehicle Safety Standards – FMVSS – Requirements

The most critical safety standard for homemade trailers is FMVSS 108, which dictates the lighting, signaling, and reflective devices. You make sure every component is DOT-compliant and securely mounted.

Basic Equipment Required On All Trailers:

At the rear, trailers need tail lights, stop lights, turn signals – at least 2 of each, mounted symmetrically side to side, as far apart as practical. These must be easily visible to anyone behind the trailer, and be mounted from 15 to 72 inches above the ground.
- Tail lights (often called running lights): Red lights that are on anytime the tow vehicle lights are on.
- Stop lights (often called brake lights): Bright red lights that activate when the brakes are applied.
- Turn signal lights: Amber or red lights indicating a left or right turn. Rear turn signals may mount 15 to 83 inches high.
Side marker lights. While these are more strict for long trailers, every trailer needs at least one red light (near the rear), and one amber light (near the front) of the trailer body – not including the tongue.
- An exception exists for trailers less than 6 ft overall length.
- See below for specific requirements for long and wide trailers.
- If the trailer has fenders that extend to the sides of the main trailer body, many jurisdictions require marker lights (visible from the front, back, and side) for the fenders. Amber visible from the front, red visible from the rear. Check your local laws.
License plate light: A white light illuminating the rear license plate. (Note: License plate lights are always acceptable, but sometimes not required. Check local laws.)
Reflectors: Rear and side reflex reflectors are often required. Some jurisdictions require colors, red on the rear and amber reflectors on the sides. (Note: Many of the rear or side marker lights also have this reflector function built in. Check to see, so you don’t have to buy separate parts.)

Equipment Required Based On Size / Weight:

Trailers 80 inches or wider: Must have amber clearance lights on the front, and red clearance lights on the rear, mounted as high as practical.
- Clearance lights, like side marker lights, are on when the tow vehicle light are on.
- For the front and rear facing ends of the trailer, place one light at each corner as high as practical. On the rear, 3 center lights in a group (identification lamps) are required in the center.
  Note: I do not see an FMVSS requirement for 3 amber front identification lamps on trailers the way they often appear on commercial trucks. I also do not see requirements for a set of 3 red lights both top and bottom on tall trailers like we frequently see. However, adding the 3 lights to the front (amber), and low on the back (red) is not wrong or bad.
Trailers 80 inches or wider with GVWR over 10,000 lb: Usually require a conspicuity system such as DOT-C2 red / white reflective tape. Some exceptions are trailers designed exclusively for living or office use. (See the full requirements for your type of trailer in your jurisdiction.)
Trailers 30 ft or longer: Usually require intermediate amber marker lights and reflectors near the midpoint of each side.
- Marker lights are amber forward of the axles, red behind the axles. While this is true for the front and back of the trailer, for intermediate side markers this may be more of a tradition than a requirement. Amber intermediate lights are in the FMVSS for long trailers.

While there are variations in requirements with different jurisdictions, it is generally smart to include optional lights. It helps with safety when towing at night. These images show typical light locations, but not all are necessary, and it does depend on the size of the trailer and where you are.

Other Standard Trailer Inspection Requirements:

Your homemade trailer also relies on the chassis, axles, and tires for meeting baseline automotive standards. Here are several safety items (beyond the electrical) to also prepare.

Trailer Axles: Most inspections will check the axle capacity to see if it matches the weight rating you declare for your trailer. To make this easy, keep the axle manufacturers sticker (and don’t paint over it).
Tires and Rims: You must use tires rated for the trailer axle weight capacity. (Note: We recommend tires with 15%-ish over the axle weight capacity.)
Brakes: Most states require brakes for trailers above a certain a Gross Vehicle Weight Rating (GVWR) or loaded weight. While it is commonly above 3,000 lbs, the threshold varies. Brakes can be any technology (electric, hydraulic, or other), but must be present, and will often be tested in the inspection. (Note: Surge brake activation is not OK in some places, so check your laws.)
Breakaway Kit: Most jurisdictions now require a breakaway activation for trailers with brakes. Read about the kits in this separate breakaway kit article.
Component Capacities: Inspection will usually check the stated capacity of critical components. Items like the coupler will have a rating which must meet or exceed the trailer GVWR. Other items like trailer safety chains may not have the specification on them, but you should bring paperwork showing the chain rating. Also make sure these items mount securely so they are strong.
Fenders / Mud Flaps: Some places require them, some do not.
Fuel Systems: If your trailer includes a fuel system, like propane tanks, inspection will certainly review those for correct fittings and controls.

These lists are not definitive. They include most of the usual inspection points and requirements, but please check local laws to be sure you have included everything for your specific trailer size and type.

Local Requirements:

In most places homemade trailers are exempt from heavy manufacturer testing, but they must pass a safety and structural inspection to get a VIN and be titled.

Inspections usually have a fee of some nominal amount.
Often, you must provide proof of ownership for materials (like receipts for the axle, steel, and components).
For specific guidance, consult your Department of Motor Vehicles, DMV, for new trailer requirements.

This is a simple list of things that did not fit in the categories above, but are certainly important. While it would be nice if we all had the same rules, there are variations. FMVSS is the minimum, but some locations have additions you need to know. As with everything here, verify with your local laws.

Now we know the things an inspection will include, what is the process?

Process Steps To Expect

To prepare for inspection and licensing, let’s review the normal next steps. The details vary by state, province, and local authority, but the sequence usually goes something like this:

Step 1. Finish the trailer and prepare it for an official trailer inspection. Tips below.
Step 2. Double check requirements for your jurisdiction. – To find the requirements in your area, search with phrases like “[your state] homemade trailer inspection requirements” or “homemade trailer registration in [your county].” Many people call it DOT inspection, but your local authority may call it VIN inspection, title inspection, assigned VIN, or homemade trailer registration.
Step 3. Make an appointment with your local authority for inspection (or some places, simply drive in). Call your local DMV (Department of Motor Vehicles) for information about the process and where to take the trailer in your area.
Step 4. Tow the trailer to the inspection and have it checked. Often, this step ends with a VIN (Vehicle Identification Number), an inspection report, or both. Usually the inspector, or someone in the office, will give you paperwork and info about the next steps for licensing in your jurisdiction.
Step 5. Get the title, license plate, and registration. The exact process varies by location, so check your local DMV or licensing authority.

Now we will look at tips on how to prepare, specifically for the trailer inspection.

Tips For Trailer Inspection

Getting the trailer certified for use (or DOT approved, DMV registered, or whatever you want to call it) can be a little daunting. No one likes having an authority scrutinize their work.

Before trailer inspection, be sure the trailer is complete, clean, wired correctly, legally equipped, tested, painted, and has the required paperwork. Here is a list of helpful tips to make the process go smoothly.

Build it well. Not for inspection, but for you. Build the trailer so it will serve you safely for a long time.
Include all the legally required items. This includes safety chains, lights – brake, stop, signal, side and end markers, etc., breakaway kit, trailer capacity markings or required weight labels, proper ratings for the coupler, axles, jacks, tires, etc., fenders (if required), and a place for the license plate.
Clean up the welds. Good welds matter structurally, of course, but appearance also matters. If an inspector sees rough workmanship, shortcuts, or unfinished details, they may look more closely at everything. That is human nature.
Remove sharp edges or protrusions if they exist. Inspectors will care if something is obviously hazardous.
Test everything before you arrive. Check the lights and wiring, turn signals, brakes, breakaway system, and any other required equipment. Make sure it all works flawlessly. If you are confident, then it will show.
Paint the trailer before inspection. Presenting something that looks nice shows you are serious, and helps the inspection process.
Anchor all the wires. Loose or dangling wires attract bad attention. Anchor them nice and neat, so it shows that you know what you are doing. Also, paint before wiring. As with welds and other visible details, things that look like laziness (painting over the wires) can invite scrutiny.
Make the trailer look complete. For practical purposes, you may wish to add things to the trailer, or change some minor things after inspection, but have the trailer buttoned up for inspection. Things like removable stake pocket sides do not involve the safety items above, so leave them at home.
For tiny houses, we recommend doing the trailer inspection and licensing before you build the house on it. License the chassis first.
Take all the required paperwork. Bring whatever your local authority requires. – In Michigan I had to provide receipts for major parts like the steel and axle to prove that I owned them and recently built the trailer. Some states require a weight slip certifying the weight of the empty trailer. Here is an example from the state of Colorado. Paperwork may seem silly, but just do it.
Take the plans with you in case the inspector wants to see them. The plans, even Certified Plans of some sort, are not actually required. See the article about Certified Plans. (Yes, good plans are important for building a great trailer, but weirdly not for inspection. Don’t worry, our Mechanical Elements trailer plans are fully engineered, and that is what matters. Show them to the inspector if they ask.)
Stay calm and mostly quiet. Answer questions clearly, honestly, and briefly when asked, but refrain from a lot of explanation or small talk. As bad as it sounds, they may be listening for things you disclose to scrutinize, or to disqualify your trailer.

The Point

Trailer inspection is not a game, but presentation does make a difference. You cannot control the inspector, the mood in the office, or how closely they look at the details. What you CAN control is build quality, how the trailer looks, and how well it works. You can also have all the needed papers.

Inspection can be a point of anxiety, because it is where your hard work on the trailer is “approved for highway use”, or rejected for some infraction. Go prepared, then you do not need to worry.

I give the same advice for going to the DMV or licensing office. Bring the required inspection report, receipts, forms, VIN paperwork, and other things. Answer questions clearly, and briefly. They are watching for mistakes, fraud, theft, and missing information, so make their job easy. It makes your visit easier too.

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After you receive the VIN or registration number, use it to protect your trailer. Read the section in the article about Trailer Security, and how to use the VIN as a protection.

If you are still planning your build, start with our engineered trailer plans.

Congratulations on your trailer build! Good luck with the inspection, licensing, and registration. Enjoy your trailer.