What Size Weight Distribution Hitch Do I Need?

“What size?” is three questions, and every page ranking for it answers one.

You need a hitch load rating — which is not your tongue weight. You need a shank with the right rise or drop — which is a tape-measure job, a separate part number, and a property of your truck rather than your trailer. And your receiver needs a weight-distributing rating of its own, which is a different number from the one on the brochure.

Get the first right and the second wrong and the hitch is correctly rated and tows the trailer nose-high. That is why the ordering mistake is so common: the pages that rank stop after the first number.

The three numbers, and where each comes from

#	The number	How you get it	Who answers it
1	Hitch load — the tongue weight rating to buy	Weigh the rig, then add a third of the rear cargo	Every ranking page, but stopping short of the cargo step
2	Shank rise or drop	Three measurements with the trailer levelled	A separate calculator, or scattered Q&A
3	Receiver’s weight-distributing rating	The sticker on your own receiver	Nobody, on this query

The split is worth naming because it is a split in the work. The first number comes from a scale. The second comes from a tape measure on a level driveway. Doing one does not get you the other, and buying a hitch needs both.

Equal-i-zer, which ranks twice on this search, is honest about it in the only way that counts: it has two calculators. One for hitch size, one for shank size. Neither page mentions the other’s question.

Number one: hitch load, not tongue weight

Start with the tongue weight — 10–15% of the loaded trailer weight, per Equal-i-zer. The towing payload calculator works it out and shows what it costs your tow vehicle, which is a question this page does not repeat.

Then do the step the ranking pages leave out. Equal-i-zer publishes it plainly:

Calculate an approximate hitch load by adding the trailer tongue weight and about 1/3 of the cargo weight that is in the back of your tow vehicle (passengers or gear in back rows of SUV, or gear in pickup bed) … This calculated hitch load is closer to what the minimum tongue weight rating needs to be for the hitch.

Equal-i-zer’s own worked example:

• Trailer tongue weight: 825 lb
• A third of the rear cargo weight: 250 lb
• Calculated hitch load: 1,075 lb

That crosses a model boundary. An 825 lb tongue weight sits comfortably inside a 1,000 lb hitch; a 1,075 lb hitch load does not, and the answer is the 1,200/12,000. A third of the gear in the bed changed which hitch you buy — and not one page ranking for this query mentions the step.

The oversizing problem, which has no number behind it

Every source in this category warns against buying bars rated far above your load. Equal-i-zer’s own phrasing is that “the higher the hitch rating the stiffer the setup is going to be”.

But no manufacturer in our records publishes a minimum tongue weight for any model. Equal-i-zer states a maximum for each of its six; so does Blue Ox; so does Andersen. So the advice is real and the boundary is not published, which leaves “don’t oversize” as a warning you cannot check yourself. Worth knowing before you read it stated with confidence somewhere.

Number two: the shank, which is a different job entirely

This is the half that no page ranking for this query covers, and the demand for it is not subtle — etrailer has at least six separate customer questions asking how to determine shank rise or drop, none of which is the page that ranks here.

The shank is the bar that slides into your receiver and carries the hitch head. It comes in rises and drops because the receiver on your vehicle and the coupler on your trailer are almost never the same height, and the trailer needs to tow level.

Three measurements, and the first thing is to get the trailer level. Equal-i-zer’s instructions:

1. Level the trailer. “Measure to the frame on the front & back of the trailer and use the tongue jack to raise or lower it until the measurements at both ends are the same, and the trailer is sitting parallel to the ground.”
2. Coupler height. “Measure from the ground to the top of the socket where the hitch ball fits into the coupler.”
3. Receiver height. “Measure from the ground directly below the receiver to the inside top of the receiver tube.”
4. Ball height. “Measure from the top of the ball to the flat part of the base where the ball will sit on the hitch head.”

If the receiver sits higher than the coupler you need drop; if the coupler is higher, you need rise. The ball height matters because the ball is mounted on top of the head, so it raises the effective height by its own dimension.

Aim slightly high, not level. Weigh Safe publishes that “generally, the ball height should be 1 to 2 inches above the coupler height” — because coupling up and tensioning the spring bars settles the rear of the tow vehicle. Set it level on the jack and it will tow nose-down.

The same three measurements decide a conventional ball mount, and the ball mount drop calculator runs them for you — including the ball height step, which is the one most estimators skip. It takes the other route on settle, assuming you measured the tow vehicle loaded; use one allowance or the other, never both.

Number three: what your receiver is rated for

A receiver hitch has two ratings, not one — weight carrying and weight distributing — and the second applies only when a weight distribution system is fitted. That is the point of the exercise: fitting the hitch is what unlocks the higher number.

By the conventional class figures:

Class	Weight carrying	Weight distributing
I	2,000 lb / 200 lb	—
II	3,500 lb / 300 lb	—
III	6,000 lb / 600 lb	10,000 lb / 1,000 lb
IV	10,000 lb / 1,000 lb	14,000 lb / 1,400 lb
V	12,000 lb / 1,200 lb	17,000 lb / 1,700 lb

Two cautions on that table. These are the conventional class figures, not your vehicle’s, and the binding number is the one on the sticker attached to your own receiver. And not every hitch in a class is rated for both — a Class III that carries no weight-distributing rating does not acquire one because you bolted a hitch to the trailer.

It is also the reason the answer can be “you already have the capacity”. If your receiver is Class III rated 6,000 lb carrying and 10,000 lb distributing, a 7,000 lb trailer is not a bigger-truck problem. It is a weight-distribution problem, which is a few hundred dollars rather than a few tens of thousands.

Do you need one at all?

Read your own owner’s manual, because they disagree. The “over 5,000 lb” rule gets repeated as though it were universal. Cars.com’s survey of half-ton manuals found:

• Ford F-150 (2022) — over 5,000 lb
• Ram 1500 (2022) — over 5,000 lb
• Nissan Titan / Titan XD (2021) — over 5,000 lb
• Toyota Tundra (2021–22) — over 5,000 lb
• GMC Sierra 1500 / Chevrolet Silverado 1500 (2021) — 7,000 lb and over

Four at 5,000 and one at 7,000 is not a rule of thumb, it is four manufacturers agreeing and one not. A 6,000 lb trailer behind a Silverado sits in the gap.

The other trigger in circulation is the trailer weighing 50% or more of the tow vehicle — and it circulates with two different denominators. Cars.com says “50% or more of the tow vehicle’s weight”; Weigh Safe says “more than 50% of your truck’s GVWR”. Those are not the same number, and GVWR is the larger one, so the two rules trigger at different points. Treat either as a prompt to check the manual rather than as the answer.

Note that the same weight thresholds tend to trigger a second requirement, and that one is more often written into state law than the hitch is: trailer brakes, and therefore a controller in the cab to operate them. Which type you need is its own fork — proportional or time-delay — and the ratio above is exactly the input that decides it, because the heavier the trailer is relative to the tow vehicle, the less a single fixed braking setting can cover.

Where the sizing goes wrong

Buying the rating that matches your tongue weight. It should match your hitch load, which is higher by a third of whatever is in the back.

Buying the hitch and forgetting the shank. They are separate part numbers. A correctly rated hitch on the wrong shank tows nose-high or nose-down.

Measuring the coupler with the trailer on its jack at any old height. Level it first, or every number after that is wrong.

Setting the ball level with the coupler. Aim 1–2 inches high; it settles.

Assuming the class table is your receiver’s rating. Read the sticker.

Sizing up “for safety”. Bars rated far above your load ride harshly — and no maker publishes the minimum that would tell you how far is too far. That gap is common to every hitch we carry, and it is set out in best weight distribution hitches.

Reusing the shank on a new tow vehicle. Re-measure. It is a property of the pairing.

What the three hitches offer to size within

Model	Tongue weight	Gross trailer weight	Sizes available	How the range is stepped	Shank options	Buy
Equal-i-zer 10K	1,000 lb maximum	10,000 lb maximum	400/4,000, 600/6,000, 1,000/10,000, 1,200/12,000, 1,400/14,000 and 1,600/16,000 lb tongue weight / gross trailer weight	10% at every rung	—	Check price(opens in a new tab)
Blue Ox SwayPro 1000	1,000 lb	10,000 lb	350, 550, 750, 1,000, 1,500 and 2,000 lb tongue weight, to a maximum 20,000 lb gross trailer weight across the range	10% at both ends	7-hole, 9-hole and 11-hole	Check price(opens in a new tab)
Andersen No-Sway 10K	1,400 lb	10,000 lb	10,000 lb / 1,400 lb up to 16,000 lb / 1,600 lb	14% at the bottom, 10% at the top	—	Check price(opens in a new tab)

The sizes available column is the one to read here rather than the rating of the model we happen to carry. Equal-i-zer’s six rungs make it the easiest to land on rather than round up to; Andersen’s range starts at 10,000 lb gross, so below that its smallest model is the only option and it out-rates you. The shank options row is mostly empty, which is itself the finding: only Blue Ox publishes its shank choices as part of the product line.

Questions worth answering