Washington Truck Weight and Size Limits
Legal limits for a truck in Washington without a permit: Interstate axle and gross weights, height, width, and semitrailer length, each with its official source.
Washington limits at a glance
| Limit | Washington | Source |
|---|---|---|
| Interstate gross weight | 80,000 lb | FHWA, Compilation of Existing State Truck Size and Weight Limit Laws (Report to Congress, May 2015), Appendices A and B |
| Interstate single axle | 20,000 lb | FHWA, Compilation of Existing State Truck Size and Weight Limit Laws (Report to Congress, May 2015), Appendices A and B |
| Interstate tandem axle | 34,000 lb | FHWA, Compilation of Existing State Truck Size and Weight Limit Laws (Report to Congress, May 2015), Appendices A and B |
| Width (National Network) | 102 in | 23 CFR 658.15, Width (eCFR) |
| Height | 14 ft | RCW 46.44.020 |
| Semitrailer length | 53 ft | RCW 46.44.030(2)(a) |
| Grandfathered semitrailer length | 48 ft | 23 CFR part 658, Appendix B, Grandfathered Semitrailer Lengths (eCFR) |
Interstate weight limits
Federal law sets the Interstate limits at 20,000 lb on a single axle, 34,000 lb on a tandem, and 80,000 lb gross, with the bridge formula on every axle group (23 CFR 658.17). States may keep higher limits they had before the federal limits took effect ("grandfather rights").
FHWA lists 105,500 lb gross as a grandfathered limit on National Network routes (except SR 410 and SR 123 near Mount Rainier).
FHWA on Washington: Washington has a grandfather provision under Federal law ("Grandfathered Weight Provisions 1956") to allow vehicles to operate up to 105,500 lbs. GVW on non-Interstate highways.
Bridge formula check with Washington limits
A 5-axle tractor-trailer is filled in. Change the spacings and weights to match your rig; the limits for single axles, tandems, and gross are Washington's Interstate limits.
Your result
Washington limits off the Interstate
FHWA's summary of Washington law for trucks in regular operation (no permit), including non-Interstate highways. It reflects state law as of October 1, 2012; check the state for later changes.
- Single axle
- 20,000 lbs.
- Tandem axle
- Per State weight table
- Gross weight
- 105,500 lbs. on non-Interstate highways
- Other
- 600 lbs. per inch of tire width
Height, width, and length
- Width: 102 inches. States may not set a width limit of more or less than 102 inches on the National Network (23 CFR 658.15(a)). Permits can allow wider loads.
- Height: 14 ft. There is no federal height limit; each state sets its own.
- Semitrailer length: 53 ft
- Grandfathered semitrailer length: 48 ft. The minimum semitrailer length the state must allow in a tractor-semitrailer combination on the National Network, based on lengths legal in the state on December 1, 1982. Federal law also requires at least 48 ft (23 CFR 658.13(b)(1)).
Over these limits you need a permit. Washington oversize/overweight permits (360-704-6340).
Washington compared with neighboring states
| State | Gross | Single | Tandem | Height | Semitrailer |
|---|---|---|---|---|---|
| Washington | 80,000 lb | 20,000 lb | 34,000 lb | 14 ft | 53 ft |
| Idaho | 80,000 lb | 20,000 lb | 34,000 lb | 14 ft | 48 ft |
| Oregon | 80,000 lb | 20,000 lb | 34,000 lb | 14 ft | Pending |
| Montana | 80,000 lb | 20,000 lb | 34,000 lb | 14 ft | 53 ft |
| California | 80,000 lb | 20,000 lb | 34,000 lb | 14 ft | 48 ft |
Sources
Source: FHWA, Compilation of Existing State Truck Size and Weight Limit Laws (Report to Congress, May 2015), Appendices A and B · Effective Oct 1, 2012 · Last verified Sep 28, 2026
Source: FHWA, Compilation of Existing State Truck Size and Weight Limit Laws (Report to Congress, May 2015), Appendix A: Washington · Effective Oct 1, 2012 · Last verified Sep 28, 2026
Source: 23 CFR 658.15, Width (eCFR) · Last verified Sep 28, 2026
Source: 23 CFR part 658, Appendix B, Grandfathered Semitrailer Lengths (eCFR) · Last verified Sep 28, 2026
Source: RCW 46.44.030(2)(a) · Last verified Sep 28, 2026
Source: RCW 46.44.020 · Last verified Sep 28, 2026
Source: FHWA, Oversize/Overweight Load Permits: State permit contacts · Last verified Sep 28, 2026
Limits change, and cities, counties, and posted bridges can set lower ones. Check with Washington before you run a load near the limits. Page data last verified Sep 28, 2026.