When Are Lights Required on a Trailer?

Parts
Trailer Knowledge

Trailer lights are required any time your trailer is on public roads, especially between sunset and sunrise, in low-visibility conditions, or when your trailer blocks the taillights or signals of your tow vehicle. Federal and state laws mandate that trailers must have functioning lights to ensure safety and visibility at all times.

At TrailersPlus, we’re your trusted resource for navigating trailer regulations, staying DOT-compliant, and ensuring every haul is a safe one.

Why Trailer Lights Are Required

Trailer lights do more than light up the road. They signal your presence, direction, and actions to surrounding drivers. Lights are required:

Between sunset and sunrise
In poor visibility conditions (fog, rain, snow, tunnels)
Whenever braking, turning, or changing lanes
On trailers that block the tow vehicle’s lights
On trailers over certain size or weight thresholds

Towing without functioning trailer lights can result in fines, failed inspections, or worse—serious collisions.

Brake Lights, Turn Signals & Tail Lamps: Always Required

These are the most critical trailer lighting components—and the ones most often inspected by law enforcement:

Tail Lamps: Illuminate with your headlights to create a consistent red glow at the rear of the trailer.
Brake Lights: Shine brighter than tail lamps when you slow or stop, helping prevent rear-end accidents.
Turn Signals: Must flash in sync with your tow vehicle to signal lane changes and turns.

All three are required by federal law, even in daylight, especially if your trailer obstructs your vehicle’s rear lights.

Lighting Requirements for Larger Trailers

Trailers that are longer than 30 feet or wider than 80 inches must include additional lighting features to remain compliant:

Amber front-side marker lights
Red rear-side marker lights
Reflective tape or DOT-approved reflectors along the side

These lights ensure your trailer remains visible from all angles—even in low visibility or if an active light fails.

License Plate Lamp

A white license plate light is required after dark. It ensures your plate remains clearly visible to law enforcement and other drivers. Though small, this light plays a key role in maintaining legal compliance.

Trust TrailersPlus for Lighting Knowledge and Compliance Support

Understanding when trailer lights are required—and which ones are needed for your specific trailer type—isn’t always straightforward. That’s where TrailersPlus comes in.

With over 80 locations nationwide, we can help you find the right trailer for your needs while keep you compliant and safe on the road. Our local service centers are staffed by trained technicians who provide timely, compliant repairs, part upgrades, and trailer maintenance. Whether you need help replacing a faulty light, upgrading your lighting system, or choosing a model that meets state DOT requirements, our team is here to help.

Get Expert Help With Trailer Lighting Today

Don’t leave your next haul to chance. Visit your local TrailersPlus to speak with our knowledgeable team, explore DOT-compliant lighting kits, or schedule a lighting check. We'll make sure your trailer meets all legal requirements before you hit the road.