Towing Setup & Capacity
The Best Trailer Hitch Locks
Locks are deterrents, not vaults. Here is which theft each one prevents and the cheapest one that matters most.
By Mike M. ·
How this page is funded: we earn a commission if you buy through our links, at no extra cost to you. It never changes which product we rank first. Prices come from Amazon and are read automatically — each one shows the date it was read. Full disclosure.
Quick picks
Scored on security (35%), fit range (25%), weather resistance (20%), usability (10%) and price (10%). No lock here is defeat-proof; all of them are deterrents.
| # | Product | Best for | Score | Price |
|---|---|---|---|---|
| 1 |  Master Lock Coupler Lock and Receiver Lock Set, 3895DAT Two locks keyed alike: one through the receiver, one through the coupler latch. Buying a matched pair is the difference between locking up and carrying two keys you will lose. Top pick | Locking the coupler and the receiver on one key | 7.0/ 10 | |
| 2 |  Trimax UMAX100 Universal Coupler Lock A universal coupler lock covering 1-7/8 in through 2-5/16 in, which solves the real problem with coupler locks: most of them only fit one size. Fits any coupler | A coupler lock that fits whatever coupler you own | 8.0/ 10 | $71.53View on Amazon
|
| 3 |  Reese Towpower Hitch and Coupler Combo Lock Set, 7014700 A combo set that fits both receiver sizes and both common pin diameters, which is the set to buy if you are not certain what your truck has. | Covering 1-1/4 in and 2 in receivers plus the coupler | 7.4/ 10 | |
| 4 |  CURT Barbell Hitch Lock, 5/8 in, 23518 A 5/8 in locking pin for a 2 in receiver. Cheap, and it stops the single most casual theft on the list: somebody pulling the clip and walking off with your ball mount. Cheapest fix that matters | Replacing the pin and clip on a ball mount you leave in | 6.8/ 10 | |
| 5 |  Universal Trailer Wheel Lock Clamp A bright wheel clamp. Its value is that a thief sees it from the road and keeps driving; it is a deterrent, not a vault, and the color is doing most of the work. Most visible | A visible deterrent on a trailer stored off-site | 6.5/ 10 | $29.99View on Amazon
|
Tap any row to jump to the full write-up. Prices come from Amazon and are read automatically — see each product below for the date.
The short answer
Understand what these products are before you buy one. Every lock in this price class is a deterrent. A determined thief with an angle grinder defeats all of them, and nobody sells a trailer lock that stops that. What locks do is make your trailer a worse target than the unlocked one three sites over, and that is genuinely most of what theft prevention is.
The four theft points
| Theft point | What goes missing | Lock |
|---|---|---|
| Receiver pin and clip | Your ball mount, from a parking lot | Locking receiver pin |
| Coupler latch, unhitched | The whole trailer, towed away | Coupler lock |
| Coupler latch, hitched | Nothing — it is on your truck | Coupler lock (optional) |
| Wheels | The whole trailer, after the coupler is defeated | Wheel clamp |
The first row is the one almost everybody leaves open, and it is the cheapest to close. An adjustable ball mount with a dual ball is a meaningful amount of money sitting in a receiver held in by a clip. A locking pin is a few dollars.
Coupler locks: fit is the whole problem
A coupler lock fills or blocks the coupler so it cannot be dropped onto a ball. There are two families.
Latch locks pin the coupler’s own latch mechanism closed. Small, cheap, and they only fit the couplers they were designed for — coupler latch geometry varies by manufacturer and a lock that fits a Bulldog may not fit an Atwood.
Universal couplers locks are a shaped steel body that fills the coupler socket and locks in place, typically covering 1-7/8 in through 2-5/16 in. They fit anything, which is their entire point, and they are bulkier and heavier because of it.
If you know your coupler and the lock is listed as compatible, a latch lock is neater. If you are not sure, or you expect to change trailers, buy universal.
The common mistake
Receiver pin locks: get the diameter right
Two sizes, and they are not interchangeable. A 2 in receiver takes a 5/8 in pin. A 1-1/4 in receiver takes a 1/2 in pin. Buying the wrong one is the most common mistake here, and a combo set that includes both covers you if you are unsure.
Barbell-style locks — a shaped head on each end rather than a padlock hasp — are harder to lever than a hasp-style pin and barely cost more. The receiver sizes page has the full table if you are not sure what you have.
Weather is the real enemy
A trailer lock lives outside, in the weather, often in road salt. The lock cylinder is the first thing to fail, and a seized lock on a trailer you need to move is its own kind of problem.
Two habits fix most of it: a shot of dry lubricant in the cylinder a couple of times a season, and a rubber cover or a plastic cap over the keyway when it is not in use. Both cost nothing and both roughly double how long a cheap lock stays usable.
Wheel clamps: the visible deterrent
A wheel clamp is the most visible thing you can put on a trailer, and visibility is doing most of the work. A bright yellow or red clamp says “this one is going to take time” from fifty feet away.
Security-wise it is not a vault — bolt cutters beat clamps in this price class — and it is bulky to store. For a trailer parked at home or in a storage lot for weeks at a time, it is worth it. For weekend camping it is usually more than you need.
The verdict
Buy a locking receiver pin today — it is the cheapest security on this site and it closes the most-left-open theft point. Add a coupler lock sized to your coupler for a trailer parked unhitched. Buy the keyed-alike set if you want both on one key, or the combo set if you are unsure what receiver and pin size your truck has. Add a wheel clamp only if the trailer is stored somewhere you cannot see it.
What to remember
- Every lock in this class is a deterrent, not a vault. The aim is to be a worse target than the trailer next door.
- The locking receiver pin is the cheapest fix and closes the most-ignored theft point.
- Check your coupler size and brand before buying a coupler lock — fit is the usual failure.
- 2 in receivers take a 5/8 in pin; 1-1/4 in receivers take 1/2 in.
- Lubricate the cylinder and cap the keyway, or the lock seizes after a wet winter.
The picks in full
Master Lock Coupler Lock and Receiver Lock Set, 3895DAT
Master Lock · Best for locking the coupler and the receiver on one key
Two locks keyed alike: one through the receiver, one through the coupler latch. Buying a matched pair is the difference between locking up and carrying two keys you will lose.
Key specifications
- Includes
- Coupler lock and receiver lock
- Keying
- Keyed alike
- Use
- Coupler latch and 2 in receiver
- Pack
- 1 pack
How it scored
- Security (35%)7
- Fit range (25%)7
- Weather resistance (20%)6
- Everyday usability (10%)8
- Price for capability (10%)8
Weighted average of the figures above. We did not test this product — see how we pick.
What it does well
- One key for both locks
- Covers the two theft points people actually leave open
- Established lock maker with available replacement keys
What it is bad at
- Not a defeat-proof lock — it is a deterrent, like every hitch lock
- Needs lubricating or it seizes after a wet winter
- Coupler lock fit varies by coupler brand; check yours
Price as of October 5, 2026. #ad How this is funded
Trimax UMAX100 Universal Coupler Lock
Trimax · Best for a coupler lock that fits whatever coupler you own
A universal coupler lock covering 1-7/8 in through 2-5/16 in, which solves the real problem with coupler locks: most of them only fit one size.
Key specifications
- Fits couplers
- 1-7/8 in to 2-5/16 in
- Type
- Universal coupler lock
- Body
- Hardened steel
- Use
- Parked trailer, unhitched
How it scored
- Security (35%)8
- Fit range (25%)10
- Weather resistance (20%)7
- Everyday usability (10%)6
- Price for capability (10%)7
Weighted average of the figures above. We did not test this product — see how we pick.
What it does well
- One lock covers every common coupler size
- Solid, heavy body that resists a casual attack
- Survives a trailer upgrade
What it is bad at
- Bulky and heavy to carry in the truck
- Universal fit means it is not snug on every coupler
- Pricier than a size-specific lock
Reese Towpower Hitch and Coupler Combo Lock Set, 7014700
Reese Towpower · Best for covering 1-1/4 in and 2 in receivers plus the coupler
A combo set that fits both receiver sizes and both common pin diameters, which is the set to buy if you are not certain what your truck has.
Key specifications
- Fits receivers
- 1-1/4 in and 2 in square
- Pin diameters
- 1/2 in and 5/8 in
- Includes
- Hitch lock and coupler lock
- Keying
- Combo set
How it scored
- Security (35%)7
- Fit range (25%)9
- Weather resistance (20%)6
- Everyday usability (10%)7
- Price for capability (10%)8
Weighted average of the figures above. We did not test this product — see how we pick.
What it does well
- Fits whichever receiver and pin size your truck turns out to have
- Two theft points covered in one purchase
- Long-established towing brand
What it is bad at
- Bulkier than a single correct-size lock
- Deterrent-grade security, not high security
- Needs regular lubrication
Price as of October 5, 2026. #ad How this is funded
CURT Barbell Hitch Lock, 5/8 in, 23518
CURT · Best for replacing the pin and clip on a ball mount you leave in
A 5/8 in locking pin for a 2 in receiver. Cheap, and it stops the single most casual theft on the list: somebody pulling the clip and walking off with your ball mount.
Key specifications
- Pin diameter
- 5/8 in
- Fits
- 2 in receivers
- Type
- Barbell style
- Finish
- Black
Capacity figures read from CURT hitch lock specifications, October 2026.
How it scored
- Security (35%)6
- Fit range (25%)7
- Weather resistance (20%)5
- Everyday usability (10%)9
- Price for capability (10%)10
Weighted average of the figures above. We did not test this product — see how we pick.
What it does well
- The cheapest security upgrade on the whole site
- Barbell shape is harder to lever than a padlock-style pin
- Fits the 2 in receiver on most half-ton trucks
What it is bad at
- 5/8 in only — a 1-1/4 in receiver needs a 1/2 in pin
- The lock cylinder is the first thing to corrode
- Protects the mount, not the trailer
Price as of October 5, 2026. #ad How this is funded
Universal Trailer Wheel Lock Clamp
Tevlaphee · Best for a visible deterrent on a trailer stored off-site
A bright wheel clamp. Its value is that a thief sees it from the road and keeps driving; it is a deterrent, not a vault, and the color is doing most of the work.
Key specifications
- Type
- Wheel clamp
- Fit
- Universal, cars through trailers
- Keys
- 3 included
- Finish
- High-visibility
How it scored
- Security (35%)5
- Fit range (25%)8
- Weather resistance (20%)6
- Everyday usability (10%)7
- Price for capability (10%)8
Weighted average of the figures above. We did not test this product — see how we pick.
What it does well
- Highly visible, which is most of the point
- Universal fit across wheel sizes
- Cheap relative to what it protects
What it is bad at
- Bolt cutters beat it, as they beat every clamp in this price class
- Bulky to store in a trailer pass-through
- No published security rating
Common questions
Yes, for a trailer parked unhitched — it stops someone backing up and towing it away, which is the common theft. It will not stop power tools, but most trailer theft is opportunistic.
5/8 in. A 1-1/4 in receiver takes 1/2 in. They are not interchangeable, and the wrong diameter is the usual ordering mistake.
Not necessary while hitched — the trailer is attached to your vehicle. Some owners do it as a second barrier against the latch being released. It has no safety function and does not replace the latch pin or safety chains.
Sources
- CURT published towing product specifications — read October 2026
- SAE J2807 — tow-vehicle gross combination weight rating procedure — read October 2026
- SAE J684 — trailer couplings, hitches and safety chains — read October 2026
- 49 CFR 393.70 — coupling devices and towing methods — read October 2026