Tongue weight that is too low causes sway. Too high overloads the rear axle. The target band is 10 to 15 percent of loaded trailer weight for a conventional trailer.
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With too little weight on the ball the trailer can pivot more freely around the hitch, so small steering inputs or passing trucks start an oscillation that builds.
Yes. The tongue weight presses down on the hitch and is carried by the vehicle, so it consumes payload capacity along with passengers and cargo.
A dedicated tongue weight scale under the coupler is the direct way. A bathroom scale with a lever and a known pivot ratio also works. Measure with the trailer level and the coupler at towing height, because angle changes the reading.
Method last reviewed 2026-07-29. Figures are guidance, not a substitute for the ratings printed on your own equipment.