# Check Tongue Weight Against the Ten to Fifteen Percent Rule Each Trip > The target is a share of the loaded trailer weight, so it moves every time you repack. How to measure it in a driveway, and what goes wrong on either side. Source: https://ocrv.info/blog/check-tongue-weight-ten-to-fifteen-percent Published 2026-04-03. Category: How-To Guides. About 6 minutes. Conventional trailers want ten to fifteen percent of their loaded weight pressing down on the coupler. Fifth wheels run higher, fifteen to twenty five percent at the pin. Measure with a tongue scale or a lever and bathroom scale, and recalculate whenever the load changes. ## The short answer Ten to fifteen percent of loaded trailer weight belongs on the ball, and a fifth wheel wants considerably more at the pin, fifteen to twenty five percent, because the load sits over the truck axle rather than behind it. The percentage is of what the trailer actually weighs on the day, not the brochure figure. Since the loaded weight climbs every time you pack, the pounds that satisfy the rule climb with it. ## Why is the percentage taken from loaded weight rather than dry? A trailer with a dry weight around 6,000 pounds and a real loaded weight of 7,800 pounds needs roughly 780 to 1,170 pounds on the coupler, not the 600 to 900 that the dry figure suggests. Owners who calculated once against the brochure and never revisited it are usually running light, which is the worse direction of the two. Worse still, the extra 1,800 pounds did not arrive evenly. It came in as a loaded pantry near the front, bikes on a rear rack, and water in a tank that may sit either side of the axles. Two trailers at the same gross weight can differ by four hundred pounds at the coupler purely on where the load went. That is why the number is checked, not assumed. The [travel trailer](/vehicles/campers-and-trailers/travel-trailer) case and the [fifth wheel](/vehicles/campers-and-trailers/fifth-wheel) case are genuinely different problems. A ball coupler hangs its load behind the tow vehicle rear axle, so tongue weight acts on a lever and lifts the front of the truck. A pin box sits ahead of the rear axle inside the bed, so pin weight presses more or less straight down through the suspension. The higher pin percentage is not an inconsistency, it is a consequence of the geometry. ## How do you actually measure it in a driveway? Three approaches work, and they trade cost against precision: - **Lever and bathroom scale.** Lay a stout pipe on a bathroom scale and an identical pipe on a stack of blocks the same height, three feet apart. Bridge them with a length of steel pipe or a doubled 2x4, then lower the trailer jack onto the beam one third of the way from the scale, with the coupler at normal towing height. Multiply the scale reading by three. Keep the beam level and stay under the scale capacity. - **Dedicated tongue scale.** A hydraulic tongue scale slides under the jack foot and reads directly, typically to a couple of thousand pounds. It is the only method most owners will use often enough to catch drift between trips. - **Scale subtraction.** At a truck scale, take the tow vehicle axle readings coupled, then uncouple and read them again. The drop at the rear axle is what the coupler was carrying. Accurate, but it means a trip and a specific stop. Whatever method you use, do it with the trailer level and the tow vehicle on the same plane. A trailer sitting nose high in a sloped Jurupa Valley storage space will read low, and you will chase a number that only exists in that parking spot. ## What goes wrong on each side of the range? Too little is the dangerous end. When the load sits at or behind the axle centerline, the trailer becomes a pendulum with nothing damping it. A truck passing at speed, a crosswind at an overpass, or a lane change starts a yaw that the coupler cannot resist, and each cycle grows instead of shrinking. Light tongue also unloads the tow vehicle rear tires, so the wheels you rely on for traction and braking are the ones you just made lighter. Too much fails in a slower and more expensive way. Every pound at the coupler lands on the tow vehicle rear axle plus a bit more, because the ball hangs behind that axle. The rear springs compress, the front rises, the steering goes light, and headlights point at the trees. Push far enough and the rear GAWR goes over even though the combination is under GCWR. Hardware feels it too. A receiver is not a solid casting, it is a welded tube assembly bolted to frame rails, and a chronically overloaded one develops cracks at the weld toe where the tube meets the side plates. Bumper mounted racks and cargo trays multiply the problem, since a hundred pounds hung two feet behind the receiver loads the mount like far more than a hundred pounds. If you are adding storage back there, the mount should be built for it, which is what a [fabricated rack or bumper](/services/custom-fabrication-and-detailing/custom-bumpers-and-racks) is for. ## How much does moving one heavy item four feet change the number? More than most owners expect, and the arithmetic is simple. Take the distance from the axle centerline to the coupler, call it L. Move a weight W a distance d toward the coupler and tongue weight rises by roughly W times d divided by L. Move it away and tongue weight falls by the same amount. On a trailer with 18 feet from axle centerline to coupler, sliding a 120 pound tool chest from the rear bumper compartment to the front pass through bay is a 12 foot move: 120 times 12 divided by 18, about 80 pounds added at the ball. Two batteries relocated from the A frame to a mid ship tray go the other way. This is also why the same trailer reads differently after a weekend, since a full waste tank behind the axles has quietly subtracted tongue weight while you slept. ## What does the number stamped on the hitch actually limit? A receiver tag carries two pairs of figures. The weight carrying pair covers the trailer weight and tongue weight the receiver handles on its own. The weight distributing pair, always higher, applies only when distribution hardware is in use. Reading the higher number and ignoring the qualifier is a common and consequential mistake. Three separate limits stack on top of that: the ball rating, the ball mount rating, and the tow vehicle manufacturer figure for maximum tongue weight. The lowest one governs the whole setup, and it is often the ball or the mount rather than the receiver. Owners running a Corona to desert route with a heavy trailer and a light mount usually find the mount is the ceiling. ## What to photograph before the rig comes in If you are booking work because something back there is bent, cracked or sagging, take pictures before you unload anything. Shoot the receiver tube where it meets the crossmember, both weld seams at the side plates, the A frame at the coupler collar, and the underside of the frame rails ahead of the axles where a sag will show as a wave in a straight line. Photograph the hitch tag so the ratings are legible. Then photograph the loaded storage bays before you empty them, because how the unit was packed is half of the diagnosis and it disappears the moment you clean it out. Eastvale owners who tow the same weekend loop over and over tend to find one repeatable culprit rather than a general overload. Our [owner guides](/resources/guides) cover the rest of the pre trip walk, and a measured tongue weight written on a card in the tow vehicle beats a remembered one every time. --- OCRV Center. 23281 La Palma Ave, Yorba Linda, CA 92887. (949) 799-3387. info@ocrvcenter.com. Serving Eastvale, California in Riverside County, about 20 miles from the shop. All work is performed in shop at the Yorba Linda facility. No mobile, roadside or on-site service is offered. Scope is body, paint, structural, fiberglass, interior and vehicle systems work. Engine rebuilds, transmission rebuilds, drivetrain work, DOT inspections and emission testing are not performed.