The 10–15% tongue weight rule
Tongue weight is the downward force the trailer's coupler puts on your truck's hitch ball. For a conventional bumper-pull trailer, it should be 10–15% of the trailer's loaded weight. A 7,000 lb camper wants 700–1,050 lbs on the tongue. This single percentage does more for towing stability than almost anything else.
Too little tongue weight: the sway problem
Below 10%, the trailer's center of gravity sits too far back, and the trailer starts to wag — the tail wagging the dog. Once sway starts at highway speed it can escalate faster than you can react. If your rig feels squirrely, light tongue weight is the first suspect, not the truck.
Too much tongue weight: the payload problem
Above 15%, the tongue overloads the truck's rear axle, lightens the front axle (worse steering and braking), and devours payload — every extra tongue pound is a pound you can't spend on passengers or cargo.
How to measure it
- Tongue scale (~$150): set it under the coupler with the trailer level. Most accurate.
- Bathroom scale + lever: for lighter trailers, a 4:1 lever setup with lumber works.
- CAT scale, two passes: weigh truck+trailer hitched, then truck alone; the math gives you tongue weight. Also gives you axle weights — the gold standard.
How to fix it
- Too light? Move heavy cargo forward of the trailer axles — ahead of the wheels, not behind. Fill the front fresh-water tank if the trailer has one.
- Too heavy? Shift cargo behind the trailer axles. Move the spare, batteries, or gear rearward.
- Re-weigh after every change. Small moves make big percentage swings.
Does the rule apply to fifth wheels?
Fifth-wheel and gooseneck trailers use pin weight instead, and the target is higher: 15–25% of trailer weight, carried in the truck bed. The physics differ because the pivot sits over the rear axle. Our calculator uses the 10–15% rule for conventional trailers.