Trailer tongue weight: measure it at the right point

Measure trailer tongue weight with the trailer loaded for travel and the measurement method specified for the equipment. A scale under a tongue jack does not automatically read the same force as a scale at the coupler. Weight-distributed vehicle axle changes are also different from unadjusted tongue load.

The support point changes the reading

Consider a simplified static example: the coupler is 15 feet ahead of the effective axle support and the jack is 12 feet ahead. If the coupler load is 600 pounds, the corresponding jack support force is 600 × 15 ÷ 12 = 750 pounds. Reporting the jack’s 750 pounds as coupler load would be wrong.

Example: same trailer, different support point
Support pointDistance ahead of axle supportStatic support force
Coupler15 ft600 lb
Tongue jack12 ft750 lb

This moment calculation explains the distinction; it is not a universal correction for every suspension or scale. Use a suitable rated tongue scale in its approved position, with the trailer secured and at the prescribed attitude. Do not improvise a heavy-trailer bathroom-scale lever or unstable support stack.

Obtain the actual loaded tongue measurementLoad and secure the trailer as instructedThen: Use the approved scale position or permitted vehicle subtractionThen: Record the load and compare all applicable limitsObtain the actual loaded tongue measurementLoad and secure the trailer as instructedUse the approved scale position or permitted vehicle subtractionRecord the load and compare all applicable limits

A vehicle subtraction needs weight distribution off

Blue Ox’s commercial-scale method compares the loaded vehicle alone with its load when coupled. For unadjusted tongue load, the weight-distribution bars must not be transferring load. Keep passengers, cargo and hardware unchanged and use an approved safe weighing procedure.

For example, 6,800 pounds coupled minus 6,000 pounds alone gives 800 pounds of tongue load. If the complete loaded trailer is 6,400 pounds, that is 12.5 percent. A travel-condition vehicle reading with weight distribution engaged cannot substitute for the coupled untensioned reading.

A percentage is only one requirement

Blue Ox gives 10–15 percent for its conventional-trailer guidance. Follow the actual trailer, vehicle and hitch requirements; do not apply that range to every fifth wheel or specialized trailer. Check tongue limits for the actual receiver operating mode and each component.

Too much vertical load does not justify shifting cargo rearward without checking the resulting distribution. Reduce or relocate cargo only within the trailer’s loading instructions, then remeasure. A weight-distribution hitch cannot make an exceeded trailer, axle or vehicle rating disappear.

Example: 6,400 lb loaded trailerTongue load: 800 lb; Trailer axle support: 5,600 lbExample: 6,400 lb loaded trailerTongue load: 800 lbTrailer axle support: 5,600 lb

For a Blue Ox hitch-selection calculation, cargo behind the tow vehicle’s rear axle may be added to tongue load when selecting equipment. Keep that separate from the trailer’s measured tongue weight. See weigh an RV on travel-ready scale passes and weight-distribution setup for those distinct tasks.