The Big Rentals Guide to Towing an Enclosed Trailer in and around Seattle, WA

In the rainiest big city in the country, an enclosed trailer isn't a luxury, it's the obvious choice. The whole reason you rent one here is to keep the weather off your load. But staying dry in Seattle is harder than closing the doors, and the drive comes with a set of Washington rules that catch people off guard.

Load it wrong in the rain and you seal the wet in with your furniture. Drive it wrong and you find out Washington caps your speed and bans your trailer from the left lane. Route it wrong and you're paying by the foot to put it on a ferry. This guide covers the enclosed sizes that fit real Seattle loads, the Washington rules that apply the second you couple up, and the rain, the hills and the crossings that make an enclosed trailer rental in Seattle its own particular job.

Why Seattle Renters Choose Enclosed Trailers

Seattle is wet for a large part of the year, and an enclosed trailer is the only kind that keeps the weather off your load from door to door. Furniture, electronics, tools, instruments, inventory — anything you'd move here needs to arrive dry, and a walled, roofed trailer is the default rather than the upgrade. In a drier metro an open trailer and a tarp might do; on Puget Sound, the box earns its cost every trip. Read more about when an enclosed trailer is worth the extra cost over an open one.

Tech and aerospace drive the next wave of demand. The region runs on Amazon, Microsoft, Boeing and the companies around them, and a workforce that size is always moving — households across the metro, equipment and exhibits to and from campuses and events. An enclosed trailer is what a move rides in when the forecast can't be trusted.

Then there's the gear. Seattle has a deep music scene and a strong maker and outdoor culture, and bands, touring crews and gear-heavy trades all move valuable equipment that has to stay dry and locked. Add a working maritime and construction economy, where tools move in weather that ruins anything left exposed, and the enclosed trailer stays busy year-round. You'll find trailer rentals across the Seattle area from local owners near you.

Washington Towing Laws Every Enclosed Trailer Renter Should Know

When your trailer needs its own brakes

Under RCW 46.37.340, a trailer needs brakes on all wheels once its gross weight reaches 3,000 lb, with a breakaway system that applies them if the trailer separates from the tow vehicle, able to stop within 40 ft from 20 mph. A loaded enclosed trailer clears 3,000 lb easily, so assume you need working brakes and a breakaway, and confirm your tow vehicle's brake controller before you leave. Check the gross vehicle weight rating (GVWR) on the listing before you book. Read more about what GVWR means and how to read it.

You tow slower than the cars around you

This one catches a lot of people. Washington's base highway limit is 60 mph, and where a freeway is posted higher for cars, the lower "trucks" limit applies to vehicles over 10,000 lb and to every vehicle in combination — which means anything towing a trailer (RCW 46.61.400 and 46.61.410). So with an enclosed trailer behind you, you follow the lower posted truck limit, commonly 60, even where the cars around you are doing 70.

The practical read: watch for the truck-limit signs, hold the lower number, and don't let faster traffic push you past it. It's enforced.

Keep your trailer out of the left lane

Under RCW 46.61.100, no vehicle towing a trailer may drive in the left-hand lane of a limited-access freeway with three or more lanes moving in one direction, except when setting up for a left turn or an exit. HOV lanes don't count as the left lane. This is pure Seattle: it applies on I-5 and I-405, the freeways you'll actually be on, and the State Patrol writes tickets for it. Stay right, pass only when you need to, and move back over.

Size, registration and license

Legal width is 8 ft 6 in and legal height is a generous 14 ft, with an oversize permit needed only past 8 ft 6 in wide, 14 ft high or 75 ft long (RCW 46.44). A standard enclosed rental sits well inside all of it. One Washington quirk: the state registers and titles every trailer regardless of weight, so every legitimate rental here has plates and a title — that's the owner's paperwork, not yours. A standard Washington license covers the haul.

Matching an Enclosed Trailer to Your Vehicle and Load

Sizing

Common enclosed sizes run from 5x8 up to 8.5x24. A 5x8 to 6x12 handles small moves, tools and gear or a motorcycle. A 7x14 to 8.5x24 covers full-room and full-house moves, a gear-heavy trade kit or a band's equipment. Interior height is the dimension people forget until a refrigerator or an amp stack won't stand up, so measure the tall things, not just the floor. Read more about choosing the right enclosed trailer size for your load.

Hitch and brake controller

Match the trailer's coupler to your ball size, usually 2 in or 2-5/16 in. If the trailer has electric brakes, your tow vehicle needs a working controller — confirm it before pickup, especially with Seattle's hills in mind.

Balance and the load you can't see

Aim for 10% to 15% of the load weight on the tongue. The enclosed-trailer trap is that the walls hide everything, so it's easy to stack the heavy items against the back doors, close them and build a sway you won't feel until you're at speed on I-5. Load heavy items low and forward of the axles, and strap them so nothing migrates. Read more about how to secure furniture and appliances in an enclosed trailer.

Loading Dry, the Hills and the Ferry

Loading dry in a wet city

The enclosed trailer keeps the rain off once the doors are shut, but you still have to load it in the weather, and that's where a Seattle move goes wrong. Water tracked in on boxes, damp furniture and a wet floor get sealed inside, and a closed trailer that sat loaded and wet for a day or two can come out smelling of mildew.

So load with the rain in mind. Back the trailer up tight to a garage or a covered doorway to keep the gap small, wipe down anything that got rained on before it goes in, keep visibly wet items out, and unload promptly rather than leaving a damp load sealed up. None of it is hard, but all of it is easy to skip when you're moving in the rain and want to be done. Read more about the common mistakes people make when renting an enclosed trailer.

Seattle's hills

Seattle is genuinely steep in places, and a loaded enclosed trailer changes how a hill feels. Pulling away uphill from a stop takes more room and more care, and holding back downhill takes the brakes. Use the parking brake on a hill start so you don't roll back into the trailer's slack, downshift on the descents, and give yourself extra room at hilltop stops. A tall box with weight in it is not something to muscle around a steep intersection.

The ferry crossing

If your route crosses Puget Sound to the islands or the peninsula, a Washington State Ferry may be part of the trip, and ferry fares go by vehicle length. A car plus an enclosed trailer costs more and takes more deck space than a car alone, and on a busy sailing a trailer can affect what fits. Check Washington State Ferries for current fares and reservations before you count on a particular boat, and measure your combined length so you're buying the right ticket rather than sorting it out in the toll line.

The passes, if you're headed east

Going over the Cascades on I-90 or US-2 means real mountain grades and, in winter, traction or chain requirements. Check WSDOT pass conditions before you tow east, and don't take a loaded trailer over a pass in a storm.

Insurance and Damage Protection

What about insurance and damage protection?

Before towing a rented trailer, contact your auto insurance provider to ask whether your policy covers liability and towing-related damage claims.

Eligible rentals booked through Big Rentals also include Basic Rental Protection at checkout. This added protection can help limit your financial responsibility for certain damage or theft events during the rental period.

For full details on how Basic Rental Protection works, including deductibles, exclusions, and renter responsibilities, review our FAQ and platform terms.

Ready To Book?

Get the size right, confirm brakes over 3,000 lb, load with the rain in mind, hold the lower truck limit and stay out of the left lane, and check the ferry if you're crossing the Sound. Do that and an enclosed trailer is the most reliable way to move anything across this metro that can't get wet. When you're ready, browse enclosed trailer rentals in Seattle from local owners near you.

The Short Version

• Enclosed trailers are Seattle's default because they keep the weather off the load — household and tech moves, music and event gear, and trades equipment that can't get wet.
• Washington requires trailer brakes at 3,000 lb gross, with a breakaway (RCW 46.37.340). A loaded enclosed trailer clears that easily.
• You tow slower here: with a trailer you follow the lower posted truck limit, commonly 60 mph, even where cars are doing 70 (RCW 46.61.400 and 46.61.410).
• A trailer can't use the left lane on three-or-more-lane freeways like I-5 and I-405, except to set up a turn or exit (RCW 46.61.100). It's enforced.
• Load dry: back up to a covered doorway, keep wet items out, and unload promptly so a sealed load doesn't mildew.
• Seattle's hills change a loaded haul — use the parking brake on hill starts and downshift on descents.
• If you cross Puget Sound, ferry fares go by length, so a trailer adds to the cost. Check Washington State Ferries first.