Washington OSOW permits

Updated: Sep 2

Permits valid for three days. Must have a permit prior to entering the state. Washington permits can no longer be purchased at POEs.

Washington permitting system: https://secure3.wsdot.wa.gov/commercialvehicle/permits/public/login.aspx

Contact phone number: 1-360-704-6340


One-half hour before sunrise to one-half hour after sunset, including Saturdays and Sundays. In addition, vehicle/loads not exceeding 12' wide, 14'6" high and 105' long, including legal overhangs, may run at night with proper lighting defined by Federal Regulations 49 CFR 393.11.


Monday through Friday time/width curfew restrictions for the vicinities of Seattle-Everett, Tacoma, Olympia, Vancouver, and Kelso are listed on the Commuter Curfew Hours sheet which accompanies permits. A validation number for permission to use city routes in Seattle and Tacoma can be obtained by the Sammons Permits Department. No travel on major holidays, and possibly on the day before or after. Check with the Sammons Permit Office.


Width: 8'6"

Height: 14'

Length: 53' semi-trailer (a 56' trailer and load permit is available for legal loads)

Overhang: 3' front, 15' rear from the center last axle to end of the load.

Weight: 80,000 Gross or more, depending on a number of axles and their spacings Steer – 600 lbs. per inch of width (13,200 for 11" steers) Single – 20,000 Tandem – 34,000 Tridem – 42,000 (with at least 8' of axle spacing)

Divisible Loads Exceeding 80,000:

You can exceed 80,000 gross without a permit on state highways and on Interstate highways as long as you are legal on all axle/group weights and you are licensed for at least the amount of your gross weight.


Width: 16' (14' on 2-lane highways)

Height: 16'

Length: 125' trailer and load

Weight: 99,000* (5 axles) 114,700* (6 axles) 130,000* (7 axles) *Depending on axle spacings Steer Axle – 600 pounds per inch of tire width (13,200 pounds maximum with 11 inch tires) Single – 22,000 Tandem – 43,000 Tridem – Depends on spacings (4'2" spacings get about 54,080 pounds; 4'6" spacings get about 58,500 pounds, etc.) Loads exceeding these dimensions or exceeding 200,000 pounds are considered as Super Loads. Note on Height Clearances: Washington state oversize permits do not guarantee height clearances on permitted routes.


On Multiple Lane Highways:

Width: Over 14' – 1 escort; over 16' – case by case basis

Height: Over 14'6" – 1 escort

Length: Trailer length including load over 125' – 1 escort

Overhang: Center the last axle to end of the load exceeds 1/3 of the total trailer and load length – 1 escort

On 2-Lane Highways:

Width: Over 11' – 2 escorts; over 16' – case by case basis

Height: Over 14'6" – 1 escort.

Length: Trailer length including load over 105' – 1 escort.

Overhang: rear overhang exceeds 1/3 of the total trailer and load length – 1 escort.


All lift axles must be on the ground if exceeding legal axle weights. Overweight single piece loads must be reduced when possible. Loads created by means of welding, bolting, or tying will be considered to be reducible.


"Oversize Load" signs are required for all oversized loads at the front of the tractor at a height of 5' from ground level (or as high as practicable on the vehicle or load if it can not accommodate the 5' height), and at the rear of the vehicle at a height of 5' to 7' from ground level (or as high as practicable on the vehicle or load if it can not accommodate the 5' to 7' height). Signs are not needed for overweight only loads. Flags must be displayed on all four corners of all over width loads, and at the extreme ends of all protrusions, projections, or overhangs.

When night movement is allowed, loads projecting beyond the sides of the vehicle must have amber lights visible from the front and side at the outermost extremities. The rearmost edge of the projecting load must be marked with a red lamp visible from the rear and side.

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