18 inch receiver height
What ball mount do you need from a 18 inch receiver to a 17 inch coupler?
A ball mount exists to put the ball at the height that makes the trailer frame level when it is 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 two things, both on level ground and both with the tow vehicle loaded the way you will actually tow it. A is the ground to the top inside edge of the receiver opening, here 18 inches. B is the ground to the bottom of the coupler with the trailer frame level, here 17 inches. The difference is what the mount has to make up.
Here the receiver sits 1 inches above the coupler, so you need a drop mount. That is a common, easily stocked size.
On this page
The measurement
The working
Published standardA = ground to top inside edge of the receiver opening = 18 in B = ground to bottom of the coupler with the trailer frame LEVEL = 17 in drop needed = A - B = 18 - 17 = 1 in positive means DROP, negative means RISE
Measure with the tow vehicle loaded as it will tow, including passengers and anything in the bed, because a loaded truck sits lower than an empty one and that difference is frequently an inch or more.
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. Aim to be within one inch of level.
Rule of thumb Widely taught towing convention rather than a published specification. It is a good starting point and it is not a rating.
| Trailer attitude | What happens to the load | Consequence |
|---|---|---|
| Level, within 1 inch | Both trailer axles share the load as designed, tongue weight is what you loaded for | This is the target |
| Nose high | Load shifts rearward onto the back axle, tongue weight FALLS | This is the sway condition. Fix it. |
| 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. Level is the target; slightly nose down is safer than slightly nose up if you have to choose.
Which stocked drop gets you closest?
Mounts are sold in whole and half inch steps, so the exact figure usually is not available. Read down for what each stocked drop produces from a 18 inch receiver.
From a 18 inch receiver, a 1 inch drop puts the ball at about 17 inches, which is closest to the 17 inch coupler height.
Published standard A published, traceable figure: a standards body, a federal regulation or a manufacturer specification states it.
| Mount drop | Resulting ball height | Trailer attitude |
|---|---|---|
| No drop | 18 in ball height | Within 1 inch of level |
| 1 in | 17 in ball height | Within 1 inch of level |
| 2 in | 16 in ball height | Within 1 inch of level |
| 2.5 in | 15.5 in ball height | 1.5 in nose low |
| 3 in | 15 in ball height | 2 in nose low |
| 4 in | 14 in ball height | 3 in nose low |
| 5 in | 13 in ball height | 4 in nose low |
| 6 in | 12 in ball height | 5 in nose low |
| 7 in | 11 in ball height | 6 in nose low |
| 8 in | 10 in ball height | 7 in nose low |
| 9 in | 9 in ball height | 8 in nose low |
| 10 in | 8 in ball height | 9 in nose low |
| 12 in | 6 in ball height | 11 in nose low |
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, but check the maker diagram if you are within half an inch of a decision.
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 is not going to change.
An adjustable mount earns its price in three situations. If you tow more than one trailer with different coupler heights. If you tow with more than one vehicle. Or if your truck's ride height changes, which it does with air bags, with a lift, and with a heavy bed load.
The trade with adjustables is that they are heavier, they 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's ball nut.
Mounts that reach a 1 inch drop
Chosen against the numbers on this page rather than from a general list, so the recommendation cannot contradict the arithmetic above. Every rating quoted is the manufacturer figure, and the rating on the part you receive is what governs.
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.
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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.
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Draw-Tite Titan Tri-Ball Trailer Hitch Ball Mount
$78.34All three common ball sizes on one fixed head. Rotate to the one you need rather than carrying spares.
Best for: A truck that tows a mix of small trailers.
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Reese Towpower Tri-Ball Trailer Hitch Ball Mount
$62.99The lower priced Reese tri-ball, same idea and the same three sizes.
Best for: Occasional towing of several different trailers.
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Reese Towpower Ball Mount, 2 inch receiver, 2 inch drop, 6,000 lb
$42.99 Published ratingsA plain fixed ball mount with the ball included, rated at 6,000 lb. When the drop you need is 2 inches, this is the correct purchase and everything else on this page is over-buying.
Best for: A known, fixed combination that tows level with a 2 inch drop.
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CURT 45036 Loaded Ball Mount, 7,500 lb, 2 inch drop
$31.99Ball mount and ball supplied assembled and torqued, rated to 7,500 lb, which removes the most commonly skipped step on a new hitch: torquing the ball nut.
Best for: Somebody who does not own a torque wrench big enough for a ball nut.
Check price on AmazonHow we chose
We did not test this hardware in person and we never claim to. Picks are researched from manufacturer specification sheets, published towing standards, and the recurring themes in verified owner reviews. Every pick is matched to a real gross trailer weight rating, a real tongue or pin weight rating, a real receiver size or a real load index rather than to a price bracket, and it is placed in the tier where its published capability actually belongs. We rejected the unbranded flood that dominates the search results in several of these categories, because a weight distribution hitch, a brake controller, a trailer tire and a set of safety chains are all parts whose failure puts a loose trailer on a public road. Where a figure is towing convention rather than a published standard we label it that way, and where a manufacturer does not publish a figure we leave it out instead of estimating it.
Frequently asked questions
What drop do I need from a 18 inch receiver to a 17 inch coupler?
You need a 1 inch drop. Ball mounts are stocked in whole and half inch steps, so the practical choice is between 1 and 1 inches. Being within one inch of level is the goal, and if you have to miss, missing slightly nose down is safer than nose up.
How do I measure receiver height correctly?
On level ground, with the vehicle loaded the way 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?
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. Nose low shifts load forward, raising tongue weight and loading the front trailer axle and the tow vehicle rear, which is a stable problem rather than a self-amplifying one.
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: a ball fitted to the underside of an inverted platform is not how the part was designed to carry load.
Does a weight distribution hitch change the drop I need?
Yes. A weight distribution head sits on its own shank rather than on a conventional ball mount, and those shanks come 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 shank rather than a ball mount.
How close to level is close enough?
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.
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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.