Axle, Weight, and Dimension Limits in Washington

Jan. 21, 2026, 8:39 p.m.
Understanding axle, weight, and dimension limits in Washington State is essential for trucking companies, owner-operators, and heavy haul carriers. Operating outside legal limits without the proper permits can lead to fines, delays, and out-of-service orders. This guide explains Washington’s standard limits and when permits are required.
Axle, Weight, and Dimension Limits in Washington

1. Legal Size Limits in Washington (Without Permits)

If your vehicle stays within these limits, no oversize permit is required:

Width

  • 8 feet 6 inches (8'6") max

Height

  • 14 feet max (most routes)

  • Some local roads or bridges may have lower clearances

Length

  • Single vehicle: 40 feet

  • Truck + trailer: 75 feet

  • Semitrailer: 53 feet

  • Doubles (twin trailers): 61 feet combined

Anything exceeding these dimensions requires an oversize permit from WSDOT.

2. Legal Weight Limits in Washington

Washington follows federal weight standards with some state-specific rules.

Maximum Gross Weight (Without Permit)

  • 80,000 lbs total GVW

Axle Weight Limits

Axle Type Max Weight
Single axle 20,000 lbs
Tandem axle 34,000 lbs
Tridem axle 42,500 lbs (varies by spacing)

Washington also enforces the Federal Bridge Formula, which limits weight based on axle spacing.

3. When You Need a Permit in Washington

You need an oversize/overweight permit if any of the following apply:

  • Width over 8'6"

  • Height over 14'

  • Length over legal limits

  • Weight over:

    • 20,000 lbs on a single axle

    • 34,000 lbs on tandem

    • 80,000 lbs gross

Permits are issued by:

  • WSDOT (Washington State DOT) for state highways

  • Local cities/counties for local roads

4. Washington Oversize / Overweight Permit Types

Single-Trip Permit

For one-time moves of oversize or overweight loads.

Annual (Continuous) Permit

For frequent moves within defined limits.

Superload Permit

Required for extremely large loads (usually over):

  • 200,000 lbs

  • 16 ft wide

  • 17 ft tall

  • 125 ft long

Superloads require route studies and engineering approval.

5. Seasonal & Road Restrictions

Washington applies seasonal weight restrictions, especially:

  • In spring (frost laws)

  • On rural or mountain roads

  • On certain bridges

These restrictions can temporarily lower axle limits.

6. Escort / Pilot Vehicle Requirements

Escort vehicles are required when loads exceed:

Dimension Escort Required
Width over 12 ft 1 pilot car
Width over 14 ft 2 pilot cars
Height over 16 ft Height pole
Length over 105 ft Escort
Superloads State patrol

7. Penalties for Violating Limits

Operating outside legal limits without permits can result in:

  • Fines per pound over limit

  • Vehicle placed out of service

  • Load reconfiguration or unloading

  • Permit suspension

8. Quick Summary Table

Category Legal Limit (No Permit)
Width 8'6"
Height 14'
Length (combo) 75 ft
Single axle 20,000 lbs
Tandem axle 34,000 lbs
Gross weight 80,000 lbs

Final Tip

If your load is even slightly over Washington’s legal axle, weight, or dimension limits, always secure a permit before entering the state. Washington is known for strict enforcement, especially on I-5, I-90, and port corridors.

 

Axle, Weight, and Dimension Limits in Washington