The nighttime equipment rule measures from the rear of the bed or body. The 15-foot maximum is measured from the center of the last axle; the daylight flag subsection says beyond the vehicle's rear.
More than 4 ft beyond the rear: red or fluorescent-orange flags at least 18 in square must mark the load extremities.
At 4 ft or more beyond the bed or body: two rear red lamps, two rear reflectors indicating maximum width and one red lamp on each side indicating maximum overhang. More than 4 ft also triggers the flag provision.
No part of the permanent structure or load may extend more than 15 ft beyond the center of the last axle, subject to the specialized-equipment exception stated in RCW 46.44.034.
The boundary wording matters
Washington says “more than four feet” for flags but “four feet or more” for the specified nighttime equipment. Exactly 4 ft reaches the nighttime threshold but not the rear-flag threshold.
A visibility marker does not by itself make a setup legal. Maximum projection, total length, securement and exceptions remain separate checks.
Checks the calculator cannot finish for you
- Measure from the center of the last axle for the 15-foot maximum.
- Confirm whether the specialized-equipment exception applies.
- Confirm total length, securement, vehicle limits, permit needs and route restrictions.
STATE PRESELECTED
Measure the actual setup, then review the rule result.
The calculator keeps unsupported cargo length separate from the legal projection named by the state rule.
Open with Washington selected →OFFICIAL SOURCES
Rule information was last checked on Aug 16, 2026. Official pages and current law control if this summary differs.
Washington RCW 46.37.140 · lamps, reflectors and flags ↗Washington RCW 46.44.034 · maximum protrusions ↗