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.
Tongue weight by the numbers
| Loaded trailer weight | 10% (minimum) | 12.5% (sweet spot) | 15% (maximum) |
|---|---|---|---|
| 3,000 lbs | 300 lbs | 375 lbs | 450 lbs |
| 5,000 lbs | 500 lbs | 625 lbs | 750 lbs |
| 7,000 lbs | 700 lbs | 875 lbs | 1,050 lbs |
| 9,000 lbs | 900 lbs | 1,125 lbs | 1,350 lbs |
| 12,000 lbs | 1,200 lbs | 1,500 lbs | 1,800 lbs |
Most owners guess their tongue weight, and most guess low. The brochure "dry tongue weight" is measured before the battery, propane, and your gear go in, and it routinely lands 100 lbs or more under the real number. Measure it; do not estimate it from the sales sheet.
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.
If sway starts while you are driving: ease off the accelerator, hold the wheel straight, and do not brake the truck hard, which can make the swing worse. If you have a brake controller, squeeze its manual lever to apply the trailer brakes only. That drags the trailer back in line behind you. Let speed bleed off gradually, pull over somewhere safe, and fix the load before you drive on. A sway-control bar damps minor wiggle; it does not cure a badly loaded trailer.
Too much tongue weight: the payload problem
Above 15%, the tongue overloads the truck's rear axle, lightens the front axle (worse steering feel and longer braking distances), and devours payload. Every extra tongue pound is a pound you cannot spend on passengers or cargo. A weight-distribution hitch shifts some of that weight back onto the front axle and the trailer axles, but the tongue weight still counts against payload in full.
How to measure it
- Tongue scale (about $120–$180): set it under the coupler with the trailer level and the wheels chocked. It reads tongue weight directly and is the most accurate home method.
- Bathroom scale + lever: rest the coupler on a pipe laid across two supports, with a bathroom scale under one end. If the coupler sits one quarter of the way along the beam, the scale reads one quarter of the tongue weight. A scale reading of 220 lbs means 880 lbs of tongue weight. A 300 lb scale on a 4:1 lever reads up to about 1,200 lbs.
- CAT scale, two passes: weigh the truck alone, then weigh truck and trailer hitched. The increase in the truck's combined axle weights is your tongue weight. You also get per-axle numbers, which makes this the gold standard. A pass costs roughly $15.
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; on many campers the tank sits ahead of the axles and adds tongue weight fast.
- Too heavy? Shift cargo behind the trailer axles. Move the spare, tools, or gear rearward. Remember that batteries and propane sit ahead of the axles on most travel trailers: two batteries plus two full 20 lb propane tanks add roughly 150–200 lbs, nearly all of it on the tongue.
- Worst spot of all: a cargo carrier or bike rack hung on the trailer's rear bumper. Weight back there subtracts tongue weight with leverage working against you, and it is a leading cause of mystery sway.
- Re-weigh after every change. Small moves make big percentage swings.
Mistakes that throw it off
- Trusting the dry tongue weight. It excludes the battery, propane, options, and everything you load. Real tongue weight is often 10% or more above the brochure figure.
- Loading the rear because it fits. Rear kitchens, rear bunks, and rear storage bays invite you to stack heavy items exactly where they hurt most.
- Assuming a weight-distribution hitch changes the target. It redistributes weight between axles. The 10–15% coupler target stays the same.
- Weighing once, then changing the load. Full versus empty water tanks and a weekend of gear can swing tongue weight by 100 lbs or more. Weigh the way you actually travel.
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.