How far can a load hang off the back of a truck in California?
California uses two separate rear measurements. At 4 feet or more behind the taillamps, the load needs the specified daylight flag or nighttime red lights. The general rear-projection maximum is different: the load generally may not extend beyond the last point of support by more than two-thirds of the wheelbase.
For the marker rule, measure from the taillamps to the extreme rear of the load. For the maximum rear projection, measure beyond the last point of support.
At 4 ft or more behind the taillamps: one flag or cloth at least 18 in square for a load 2 ft wide or less; wider loads require two marking the maximum width.
At 4 ft or more behind the taillamps: two red lights, visible at least 500 ft to the sides and rear, in addition to required vehicle lamps.
The rear load generally may not extend beyond the last point of support by more than two-thirds of the wheelbase. Overall-length and special-load provisions can also apply.
The boundary wording matters
California's marker trigger is “four feet or more,” so exactly 4 ft triggers the rule. Do not substitute an open tailgate or bed extender for the taillamp reference point in that marker measurement.
A visibility marker does not by itself make a setup legal. Maximum projection, total length, securement and exceptions remain separate checks.
Example: 5 ft behind the taillamps, 3 ft beyond the support
Suppose the loaded cargo is measured 5 ft behind the taillamps, but only 3 ft beyond the verified last point of support. The marker rule is triggered by the 5 ft measurement. The 3 ft support measurement answers a different question.
For an ordinary vehicle with a measured 144 in wheelbase, two-thirds of wheelbase is 144 × 2 ÷ 3 = 96 in, or 8 ft. A 3 ft projection beyond the last support is within that particular numerical limit. It does not settle overall length, securement or other rules. These are example measurements, not specifications for a named pickup.
| Check | Example measurement | What follows from that measurement |
|---|---|---|
| Marker · from taillamps | 5 ft | Covered flag or darkness-light requirement applies |
| Maximum · from last support | 3 ft, with 144 in wheelbase | Compare with the separately calculated 8 ft limit |
| At the example maximum | 8 ft versus 8 ft 1 in beyond support | 8 ft reaches that limit; 8 ft 1 in exceeds it |
Load width determines whether California needs one flag or two
Under §24604, when the rear marker threshold is reached, a projecting load 2 ft wide or less uses one qualifying flag or cloth. A wider projecting load needs two indicating its maximum width. At a 4 ft rear projection, a 24 in wide load therefore has a different flag count from a 30 in wide load.
The flag or cloth must be solid red or fluorescent orange and at least 18 in square. During darkness the provision requires two red lights at the extreme end, visible at least 500 ft to the sides and rear, in addition to required vehicle lamps. The statute also specifies a bulb rating not exceeding six candlepower; do not infer compliance from a generic red LED listing.
Complete the wheelbase check on the actual vehicle
Use the actual wheelbase applicable to the vehicle carrying the load. Section 35410 states a special semitrailer definition; do not substitute an ordinary-pickup measurement for it. Confirm the applicable vehicle arrangement before calculating.
- Identify and measure the wheelbase required by §35410.
- Identify the last point of support relevant to that provision and measure from it to the cargo endpoint.
- Multiply wheelbase by two-thirds and compare like units. Do not put the taillamp measurement into this comparison.
- Confirm the separate overall-length and cargo provisions. A changed support does not establish that every other rule is satisfied.
Checks the calculator cannot finish for you
- Calculate the two-thirds-of-wheelbase rear limit from the last point of support using the wheelbase definition applicable to the vehicle.
- Confirm overall vehicle/load length, width, securement and route limits.
- Do not treat a material name as a blanket exception. Any special provision must match the exact vehicle or combination, load and route.
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 California selected →California overhang questions
Does exactly 4 ft require a California load flag?
Yes for the covered daylight provision when the projection is measured from the taillamps. The wording is four feet or more. The last-support maximum is a separate check.
Does an extender move the California flag measurement point?
The marker provision names the taillamps. Added support does not relocate them. Whether the installed support is relevant to the separate last-support maximum requires its own verification.
Can I use the 8 ft example as my truck's allowance?
No. It comes from a hypothetical 144 in wheelbase. Use your vehicle's applicable wheelbase and support measurement, then check other limits and exceptions.
OFFICIAL SOURCES
Rule information was last checked on Sep 8, 2026. Official pages and current law control if this summary differs.
California Vehicle Code § 24604 · flags and lights ↗California Vehicle Code § 35410 · rear projection ↗