Weight Distribution Hitches

A weight distribution hitch is a lever. It takes some of the load pressing down on the back of your tow vehicle and spreads it forward onto the front axle and backward onto the trailer's axles. The visible result is a rig that sits level instead of nose-up; the invisible result is a front axle that still has enough weight on it to steer and brake properly.

Put several hundred pounds of tongue weight on a ball that sits a couple of feet behind the rear axle and you have created a see-saw. The rear axle is the pivot. Load goes down at the back, and the front of the vehicle lifts. Weight comes off the front tires - the ones that steer, and the ones that do most of the braking.

That is why the symptoms of needing a weight distribution hitch are so consistent: steering that feels light and vague, headlights aimed at the trees, a back end that bottoms out over dips, and braking distances that have quietly got longer. None of those is a sway problem, and a friction sway bar will not touch any of them.

• Round bar. The spring bars are round in section and hang below the head. They are compact and clear most trailer A-frames easily, but they sit lower than any other type, which makes them the first thing to touch down on a steep driveway transition.
• Trunnion bar. The bars are square in section and slot into the head horizontally. They give noticeably more ground clearance and generally a higher capacity ceiling, at the cost of needing more room in front of the A-frame.
• Chain tensioned, no spring bars. Systems like Andersen's use chains and a friction cone instead of steel spring bars. Dramatically lighter to lift and store, and the sway resistance keeps working in reverse - but the setup logic is different enough that advice written for spring-bar systems does not transfer.
• With or without integrated sway control. The distinction that matters most. A hitch that only distributes weight does nothing about yaw. One with four-point or cam-based sway control does both jobs with one assembly.

Three things. First, capacity: bars rated for 1,500 lb of tongue weight cost more than bars rated for 600 lb, and the heads that carry them are heavier castings. CURT, for example, publishes its TruTrack 4P at a 10,000 to 15,000 lb gross trailer weight with a 1,000 to 1,500 lb tongue weight range, and the assembly weighs 123.6 lb - that mass is the price.

Second, how the sway control is implemented. Four-point friction, dual-cam and friction-cone systems all cost more than a hitch with no sway function at all. Third, how much of the setup is designed around one person working alone - clamp-on latches and chain-free tensioning cost more than snap-up brackets because they remove the part of the job most people find awkward.

Spring bars are rated for a tongue weight range. You want your actual, measured, loaded tongue weight to land near the middle of that range. Too close to the top and the bar is running at its limit, flexing less than the designer intended. Far below the bottom and the bar is effectively a solid steel rod that transfers almost nothing.

The number you size against includes everything that rides ahead of the trailer's axles when you actually tow: propane bottles, the battery, whatever is in the front storage box, and the hitch hardware itself. The brochure dry tongue weight is not that number. Blue Ox, to take one example, sells SwayPro in discrete tongue weight bands - 350, 550, 750, 1,000, 1,500 and 2,000 lb - which forces the sizing decision to be made before purchase rather than discovered afterwards.

Buying by trailer length or by what the dealer bundled, rather than by measured tongue weight. A 26-foot trailer loaded light at the back and a 26-foot trailer with a generator on the rear bumper need different bars, and no amount of brand loyalty fixes that. Measure the tongue weight, then size the bars, then set the head angle and the washer stack properly - because a correctly sized hitch set up wrong behaves like the wrong hitch.