Hitch hardware
What drop or rise does your ball mount need?
A ball mount exists to put the ball at the height that makes the trailer frame level when hitched. That is not cosmetic. A level trailer puts both axles of a tandem on their designed share of the load and keeps the tongue weight at the percentage you loaded for.
Measure both heights on level ground, with the tow vehicle loaded the way you will actually tow it. A truck with passengers, gear and a hitch sits noticeably lower than an empty one in a driveway, and an inch is the entire tolerance.
Measure, then subtract
You need a 3 inch drop. Stocked in that exact size.
| Figure | Value |
|---|---|
| Difference | 3.0 in |
| What you need | a 3 inch DROP |
| Nearest stocked sizes | 3 in |
| Resulting attitude with that mount | level |
Shown with the example figures above. Change any field to run your own numbers.
The working
Published standardA = ground to TOP INSIDE EDGE of the receiver opening B = ground to BOTTOM of the coupler, trailer frame LEVEL drop needed = A - B positive means DROP, negative means RISE
Measure with the tow vehicle loaded the way you will tow it. A published, traceable figure: a standards body, a federal regulation or a manufacturer specification states it.
Mounts and shanks that reach
Adjustable mounts cover a range, fixed mounts cover one figure. If you tow more than one trailer, or your ride height changes with air bags or a load, the adjustable is worth the extra.
B&W Tow & Stow Adjustable Ball Mount, 2-1/2 inch receiver, tri-ball
$359.00 Published ratingsThree ball sizes on the same adjustable head, which covers a 1-7/8, a 2 and a 2-5/16 inch coupler without carrying loose balls in a toolbox.
Best for: A farm or shop truck that hitches to whatever is in the yard.
Check price on Amazon
B&W Tow & Stow Adjustable Ball Mount, 2-1/2 inch receiver, dual ball
$309.00 Published ratingsAdjustable for height and it stows out of the way when nothing is hitched, which is the single best answer to barking your shin on a ball mount. Two ball sizes on one head, flipped rather than swapped.
Best for: A truck that tows more than one trailer with different coupler sizes.
Check price on Amazon
CURT 45902 Adjustable Dual-Ball Channel Mount, 2-1/2 inch shank, 6 inch drop
$268.74 Published ratingsThe 2-1/2 inch receiver version of the same channel mount, for heavy duty trucks.
Best for: A Class V receiver that needs adjustable height.
Check price on Amazon
Blue Ox BXW4007 1,000 lb Spring Bar Kit
$244.94Replacement or resized spring bars for a SwayPro head, rated at 1,000 lb of tongue weight. Bars are the part that gets sized wrong, and swapping them is cheaper than replacing the hitch.
Best for: A SwayPro owner whose weighed tongue weight turned out different from what they expected.
Check price on Amazon
Rhino USA Adjustable Trailer Hitch, 2 inch receiver, 6 inch drop or rise
$199.90Six inches of adjustment in either direction on a 2 inch receiver, from a maker that backs its towing hardware with a lifetime guarantee.
Best for: One mount that works across a lifted truck and a stock one.
Check price on Amazon
CURT 17132 Weight Distribution Hitch Shank, 2-1/2 inch receiver, 8 inch drop
$197.77The 2-1/2 inch receiver version with a deep 8 inch drop, for heavy duty trucks that sit high.
Best for: A three quarter or one ton truck with a 2-1/2 inch receiver.
Check price on AmazonEvery rating shown is the manufacturer's own published figure. The rating on the part you receive is what governs, and your own door jamb sticker governs everything above it.
On this page
Why level matters more than it looks
A trailer that is not level does not just look wrong. It changes where the load sits, and therefore what the tongue weight actually is.
A trailer towed nose high shifts load rearward and reduces tongue weight, which is the condition that starts sway. Nose low is the safer way to be wrong.
Rule of thumb Widely taught towing convention rather than a published specification. It is a good starting point and it is not a rating.
| Attitude | What happens to the load | Consequence |
|---|---|---|
| Level, within 1 inch | Both trailer axles share the load as designed | This is the target |
| Nose high | Load shifts rearward onto the back axle, tongue weight FALLS | The sway condition. Fix it before driving. |
| Nose low | Load shifts forward onto the front axle and the tongue, tongue weight RISES | Overloads the front trailer axle and the tow vehicle rear |
The one inch tolerance is towing convention rather than a published standard. If you have to miss, missing slightly nose down is safer than nose up.
How to measure both heights
- Park on level ground. Both the tow vehicle and the trailer, on the same flat surface. A sloped driveway invalidates the whole measurement.
- Load the tow vehicle the way you will tow. Passengers, gear, bed load and the hitch itself. A loaded truck can sit an inch or more lower than an empty one, and an inch is the whole tolerance.
- Measure A: ground to the top inside edge of the receiver opening. The top inside face of the square tube, not the bottom and not the outside of the bumper.
- Measure B: ground to the bottom of the coupler. With the trailer FRAME level, not with the jack at whatever height is convenient. Use a level on the trailer frame rail to set it.
- Subtract. A minus B. Positive means you need a drop, negative means you need a rise. Ball mounts are sold in whole and half inch steps, so pick the stocked size nearest the answer.
- Re-measure after anything changes the ride height. Air bags, a lift, new springs, or a heavy permanent bed load all move the receiver height and change the answer.
Stocked drop sizes
Mounts are sold in whole and half inch steps, so the exact figure usually is not available. These are the sizes that actually exist.
Ball mounts are stocked in whole and half inch steps, so the practical choice is usually between the two sizes that bracket your answer.
Published standard A published, traceable figure: a standards body, a federal regulation or a manufacturer specification states it.
| Available drops, inches |
|---|
| no drop, 1, 2, 2.5, 3, 4, 5, 6, 7, 8, 9, 10, 12 |
Drop on a ball mount is measured from the top of the shank to the top of the ball platform, before the ball is fitted. Makers state it that way consistently.
When an adjustable mount is worth it
A fixed mount is cheaper, simpler and has nothing to come loose. It is the right buy when you tow one trailer with one vehicle and the answer will not change.
An adjustable mount earns its price in three situations: you tow more than one trailer with different coupler heights, you tow with more than one vehicle, or your ride height changes, which it does with air bags, with a lift and with a heavy bed load.
The trade is that adjustables are heavier, cost more, and every pinned joint is another thing to check on a walk-around. Check the pins and the torque before every trip, the same as you would a fixed mount ball nut.
Weight distribution hitches use a shank, not a ball mount
If you are fitting a weight distribution hitch, the head sits on its own shank rather than on a conventional ball mount. Those shanks come in their own drop and rise sizes and are frequently reversible, giving a deep drop one way and a large rise the other. Work out the figure exactly the same way, then buy the shank rather than a ball mount.
Frequently asked questions
How do I measure hitch height correctly?
On level ground with the vehicle loaded as you will tow it, measure from the ground to the top inside edge of the receiver opening. Loading matters: passengers, gear and a hitch can drop a truck an inch or more, which is the whole tolerance. Measure the coupler from the ground to its bottom face with the trailer frame level, not with the jack at a convenient height.
Is nose high or nose low worse on a trailer?
Nose high is worse and it is the one to avoid. Nose high shifts load rearward onto the back trailer axle and reduces tongue weight, which is the condition that starts trailer sway and which amplifies rather than damping out. Nose low raises tongue weight and loads the front trailer axle and the tow vehicle rear, which is a stable problem rather than a self-feeding one.
How close to level does a trailer need to be?
Within about one inch is the conventional target, and it is a rule of thumb rather than a published specification. Inside that range both axles of a tandem carry close to their designed share and the tongue weight stays near what you loaded for. Beyond it, re-measure with the tow vehicle loaded before buying a different mount, because the truck height is usually what changed.
Can I flip a drop mount over to get a rise?
Most fixed ball mounts are reversible and give the same figure as a rise when flipped, which is worth checking before buying a second part. Confirm the maker states it is reversible, and confirm the ball ends up on the correct face, because a ball fitted to the underside of an inverted platform is not how the part was designed to carry load.
Where exactly is drop measured from on a ball mount?
From the top of the shank to the top of the ball platform, before the ball is fitted. Manufacturers state it that way consistently, so comparing two mounts on their published drop figures is reliable. If you are within half an inch of a decision, check the maker dimensional diagram rather than assuming, because platform thickness varies a little.
Does a weight distribution hitch change the drop I need?
Yes. A weight distribution head mounts on its own shank rather than on a conventional ball mount, and those shanks are sold in their own drop and rise sizes, frequently reversible to give a deep drop one way and a large rise the other. Work out the figure the same way, then buy the correct shank instead of a ball mount.
Free download
Get the complete tow rig setups emailed to you
Both ladders, conventional travel trailer and fifth wheel, at beginner, intermediate and expert budgets, every item priced and linked with a running total, plus a printable pre-trip weighing worksheet you can fill in at the scale.
One email with the setups. No sequence, no sharing your address, unsubscribe any time.
Researched, not professional advice. This page is compiled from published standards, manufacturer towing guides and product specifications, and owner-review consensus, not hands-on testing. Figures described as a rule of thumb are towing convention rather than published standards, and they are labelled that way wherever they appear. Nothing here overrides your own ratings. Work your payload sum before your tow rating, because payload is the limit that actually binds on most half ton trucks and nearly every SUV. Load a conventional trailer to 10 to 15 percent tongue weight and a fifth wheel to 15 to 25 percent pin weight, and never lighter: a tail heavy trailer is what starts sway. Weigh the rig loaded rather than trusting a brochure dry weight. A weight distribution hitch and a set of air bags both restore ride height and control, and neither one raises a single rating. Trailer brakes are required by state law above a threshold that varies by state, and a breakaway battery that has quietly gone flat is the normal condition of most trailers on the road.