Trailer Light Regulations According To The DOT

From big rigs and horse trailers to campers and boat trailers, and everything in between, all kinds of trailers need the proper lighting. If not, they do not belong on the road. Trailer light requirements by the DOT (Department of Transportation) are very strict. And they must be adhered to. Before hitting the open road, make sure that your trailer abides by federal and state laws where lighting is concerned.

Requirements for Side Lighting

Denoting length and alerting other drivers to a trailer’s presence, sidelights must, on each side of the vehicle, be placed in the same location. They must be set as far as possible toward the back of the trailer and red in color. They can be as high as 60 inches or as low as 15 inches.

Also as close to the rear of the trailer as can be should be the yellow front side sidelights. These must be at a height exceeding 15 inches.

To notate extended length and alert other drivers to the trailer, intermediate sidelights must be applied to all trailers in excess of 30 feet. These yellow lights must be at least 15 inches high and placed in the middle of each trailer side.

Requirements for Rear Lighting

The following rear lights are needed:

  • United States trailers must have, on the rear, a single white license plate light
  • Red or yellow turn signals (a pair)
  • To indicate a trailer’s width, a pair of red taillights
  • Red brake lights (a pair)

According to the NHTSA, excluding the license plate lamp (which must be mounted precisely to the side or above the license plate), these lights must be lower than 72 inches, higher than 15 inches, asymmetrically placed, and spaced as widely as possible.

Trailers That Are Extra Wide

To indicate the width of a trailer, additional lighting in the rear and front is needed if it is more than 18 inches wide. At the widest point of the trailer, red clearance lights (two) must be placed.

Centered at the trailer’s rear and at the widest point on the trailer, red identification lights (three) must be put at the highest point possible and spread apart at 6 to 12 inches.

At the widest point of the trailer, spaced as widely as possible, and at the highest point possible, front clearance lights must be placed.

But Wait, There’s More

The lights referred to above must be attached, permanently, to the trailer.

The following does not apply to photometrically installed lights (placed at the certified angle):

  • Back and front lights – perpendicular to the centerline of the trailer
  • Side trailer lights – parallel to the centerline of the trailer

Also required by the NHTSA, to further indicate the presence and size of a vehicle, side and rear reflectors must be part of a trailer’s equipment.

At Mickey Genuine Parts, we carry more lighting than one can imagine. We have brake lights, turn signals, interior lights, exterior lights, red lights, yellow lights, LEDs, you name it. And if you need help with installation, we have service centers located throughout the United States. Contact us at Mickey Genuine Parts to see what we can do for you where lighting or any other part or accessory is concerned.

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