When a Load Requires Permitting vs When It Is Legal

Dec. 11, 2025, 4:48 p.m.
Washington State has strict rules on vehicle dimensions and weight. Whether you need a trucking permit depends entirely on whether your vehicle exceeds the legal limits established by WSDOT. This guide breaks down when no permit is needed and when a load must be permitted.
Permitting in Washington State

When a Load Is LEGAL (No Permit Required)

Your load is considered legal if it stays within Washington’s standard size and weight limits:

 Legal Dimensions (No Permit Needed)

  • Width: up to 8 ft. 6 in. (102 inches)

  • Height: up to 14 ft.

  • Single Vehicle Length: up to 40 ft.

  • Truck + Trailer Combination: up to 75 ft. (varies by configuration)

 Legal Weight Limits

  • Gross vehicle weight: up to 80,000 lbs.

  • Single axle: up to 20,000 lbs.

  • Tandem axle: up to 34,000 lbs.

  • Must comply with Federal Bridge Formula.

If your vehicle stays within these limits, you can operate without any OS/OW permit in Washington.

When a Load REQUIRES a Permit

You will need a Washington oversize/overweight permit when:

1. The Load Is Over Legal Dimensions

Examples that require permitting:

  • Width greater than 8′6″

  • Height greater than 14′

  • Length greater than 75 ft. (depending on combination)

  • Any load that protrudes beyond legal overhang limits

Common loads needing permits:

  • Excavators, dozers, backhoes

  • Prefabricated structures

  • Industrial tanks or machinery

  • Manufactured/mobile homes

  • Agricultural equipment wider than 8’6″

2. The Load Exceeds Legal Weight Limits

You need a permit if:

  • Gross weight is over 80,000 lbs

  • Any axle exceeds legal weight on its axle group

  • You exceed Bridge Formula compliance

Examples:

  • Heavy construction equipment

  • Transformers

  • Large concrete or steel loads

  • Heavy-haul cranes

3. The Load Is Non-Divisible

Washington only permits non-divisible loads to exceed legal limits.
A load is non-divisible if:

 It cannot be reduced in weight or size without:

  • Damaging the load

  • Compromising its function

  • Requiring more than 8 hours of disassembly

Examples of non-divisible loads:

  • Wind turbine blades

  • Large machinery

  • Prefabricated concrete beams

  • Oversized tanks

  • Mobile homes

Divisible loads (gravel, pallets, lumber bundles, scrap, etc.) cannot be overweight unless covered under specific special-use permits.

4. You Are Transporting Mobile or Manufactured Homes

Mobile homes require special OS/OW permits due to:

  • Extra width

  • Escort requirements

  • Routing controls

  • Structure fragility

5. You Are Operating Specialized Equipment

Certain vehicles always require permits due to inherent oversize/overweight dimensions:

  • Cranes

  • Well-drilling rigs

  • Specialized forestry trucks

  • Certain logging equipment

Penalties for Operating Without a Permit

If you operate an oversize or overweight load in Washington without the proper permit, you may face:

  • Costly fines

  • Immediate out-of-service order

  • Weight station delays

  • Mandatory re-routing or offloading

Washington State Patrol & WSDOT enforce these rules aggressively, especially around ports and mountain corridors.

Quick Comparison

Situation Permit Needed?
Load within legal size & weight  No
Load over 8’6″ wide  Yes
Load over 14’ tall  Yes
Load over 80,000 lbs GVW  Yes
Divisible load overweight  No (usually prohibited)
Transporting a mobile home  Yes
Oversize construction equipment  Yes
Specialized crane transport  Yes

Source:

https://wsdot.wa.gov/travel/commercial-vehicles/commercial-vehicle-permits