Washington Trailer Laws & Regulations

In Washington, there are a variety of trailer laws and regulations that must be followed. Failing to do so can result in fines or other penalties. In this post, we will provide an overview of some of the most important trailer laws and regulations in Washington.

Do all trailers need to be registered in Washington State?

All trailers, no matter the size, require registration. If you buy a completed homemade trailer, then you must show us a notarized bill of sale/gift/trade from the person who sold it to you. This document should include all original parts documentation.

Any driver that wants to operate a motor vehicle, trailer, or semitrailer not equipped with fenders adequate for minimizing the spray or splash of water or mud from the roadway must have their car fit with devices. These devices should be as wide as the tires behind which they are mounted and extend downward at least halfway to the center of the axle.

But how many trailers can you pull in Washington state? A motor carrier is the only exception to allow for pulling more than one trailer at a time, and even then, the combined length cannot exceed 61 feet.

Washington Trailer Laws & Regulations


Nobody is allowed to occupy any trailer during transport down a public highway, with the exception of somebody occupying a proper position for steering if it's being steered from the rear.

Vehicles pulling trailers are not allowed in the left lane of highways with three or more lanes, except when getting ready to turn left.


The total length is 75 feet, the trailer length is 53 feet, the width 8 1/2 feet and height 14 feet. The rearview mirror can extend 5 inches, safety appurtenances such as clearance lights and door latch 4 inches while an awning can extend 6 inches.


All vehicles, including trailer brake systems and pole trailers, must have service brakes that can control the movement of the vehicle, as well as stop and hold it under all conditions—including inclement weather and different grades. Every trailer and pole trailer needs brakes on the wheels, unless it's Gross Weight is less than 3,000 lbs. That being said, if the weight of the vehicle including the trailers does not exceed 40% of towing vehicle's total weight when connected to the trailer, then an exception can be made.

Hitches and Signals

All vehicles towing a trailer must use safety chains.

The drawbar or other connection between vehicles must be strong enough to hold the weight of the towed vehicle on any grade where it is operated. The trailer should not whip, weave, oscillate, or fail to follow the course of the towing vehicle.

All vehicles must have turn signals and reflectors.


Every car needs to have mirrors on both the driver and passenger sides. These mirrors should allow the driver to see at least 200 feet behind them while driving.


You need to have a tail light, brake light, and license plate light.

Speed Limits

Similar to what was posted for trucks.

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