The Master Lock 389DAT leads this comparison for coupling locks. A receiver hitch pin and a wheel clamp do different jobs, so the right alternative depends on which part of your setup you want to lock. These eight picks cover all three types.
The comparison uses listing specifications and ratings. We have not tested resistance to attack, and no recommendation here is a promise that a lock prevents theft.
Best overall: Master Lock 389DAT
Best overall: the Master Lock 389DAT, because its listing covers three coupling sizes and describes a mechanism that resists picking and prying.
The listing says it fits virtually all couplers in three sizes, converted to about 47.6, 50.8 and 58.7 mm. It describes a bright red finish, resistance to rust and corrosion, and simple installation and removal. It holds 4.7 stars from 16,627 ratings, the largest count here.
It suits someone choosing a lock for a compatible trailer coupling. The honest catch: the listing gives three nominal coupler sizes, so match your coupling model and shape as well as its size before buying.
Best second coupler lock: Master Lock 379ATPY
Best second coupler lock: the Master Lock 379ATPY, because the listing says it fits couplers of 48, 51 and most 59 mm and resists picking and prying.
The listing describes a mechanism that resists picking and prying, and zinc construction to resist rust and corrosion. Its coupler sizes are rounded in the listing to 48, 51 and most 59 mm. It holds 4.6 stars from 5,885 ratings.
It suits someone who wants another coupling lock to compare with the 389DAT. The honest catch: the largest size is qualified as fitting most 59 mm couplers, and the listing describes the body as zinc.
Best hitch pin lock: Rhino USA Locking Hitch Pin
Best hitch pin lock: the Rhino USA Locking Hitch Pin, because it is listed for Class III and IV receivers with a weatherproof slide cap.
The title's pin diameter converts to about 15.9 mm. The bullets specify Class III and IV receivers of about 50.8 by 50.8 mm, solid forged steel and a weatherproof slide cap against dirt and mud. It holds 4.6 stars from 8,916 ratings.
It suits a Class III or IV receiver of about 50.8 mm square with a pin hole matching its approximately 15.9 mm pin. The honest catch: this is a receiver pin, so it does not replace a lock on the trailer coupling. The title says stainless, while the bullets say solid forged steel.
Best for standard 50 mm couplings: Maypole MP953 Universal Hitchlock
Best for standard 50 mm couplings: the Maypole MP953 Universal Hitchlock, because it lists that fit and a case hardened 12 mm steel bar.
The listing says it fits most standard 50 mm couplings and comes with two keys. The product details identify model MP953 and a weight of 500 g. It holds 4.5 stars from 1,936 ratings.
It suits buyers whose coupling is explicitly marked 50 mm. The honest catch: the listing says most standard 50 mm couplings, so check the exact head before you buy.
Best for ALKO couplings: Maypole Alko Hitch Lock
Best for ALKO couplings: the Maypole Alko Hitch Lock, because its listing names the ALKO AKS3004, AKS3504, AK130 and AK160 heads and says the lock covers the trailer hitch fixing screws.
The listing describes a Stronghold hitchlock for ALKO hitches with what it calls a European patented high security locking system, covering the trailer hitch fixing screws as a clearly visible deterrent. It names the ALKO AKS3504, AKS3004, AK130, AK160, AKS1300 and AKS2004 heads. The product details identify model SH5412 and list a hitchlock, barrel and three keys in the box. It holds 4.7 stars from 779 ratings, the same average as the 389DAT from far fewer buyers.
It suits a caravan owner with one of the ALKO heads the listing names. The honest catch: match your exact ALKO head to that list before buying, and it costs more than twice the Master Lock 389DAT.
Best wheel clamp: FullStop Nemesis Ultra
Best wheel clamp: the FullStop Nemesis Ultra, because it is listed as a caravan wheel clamp and has the highest average rating here.
The listing calls it a Purpleline Nemesis Ultra caravan wheel clamp. Product details state key unlocking and a weight of 3 kg. It holds 4.8 stars from 580 ratings, a smaller count than every other pick here.
It suits a caravan owner who wants the highest rated wheel clamp here. The honest catch: the listing gives very few details and does not say which wheel or tyre widths it fits, so check that with the brand first, and it costs several times the Cartman.
Best budget wheel lock: Cartman Trailer Wheel Lock
Best budget wheel lock: the Cartman Trailer Wheel Lock, because it offers an adjustable tyre width range at the lowest price among these picks.
The listing specifies high strength steel plate, a soft coated surface, a copper lock cylinder and a waterproof cover. Its tyre width range converts to about 177.8 to 279.4 mm. The finish is yellow and red, and it holds 4.4 stars from 1,372 ratings.
It suits a buyer choosing a wheel lock on a smaller budget. The honest catch: the title says six alike keys, while the bullets say three keys. Confirm the contents, and compare the stated width with your tyre.
Best bright coupling lock: Hyfive Tow Ball Hitch Lock
Best bright coupling lock: the Hyfive Tow Ball Hitch Lock, because the listing describes a bright yellow body and six variable locking positions.
The listing names most pressed steel and cast 50 mm couplings. It describes a cast steel body, hardened 12 mm steel bar, integrated cylinder lock and two keys. It holds 4.4 stars from 1,527 ratings.
It suits someone who wants a yellow coupling lock with adjustable positions. The honest catch: the stated fit is for most pressed steel and cast 50 mm couplings, and its average rating is lower than both Master Lock coupling picks.
How to choose a trailer lock
Choose the fitting you want to lock
The Master Lock, Maypole and Hyfive picks address the trailer coupling. The Rhino USA addresses the tow vehicle's receiver, while FullStop and Cartman address a wheel. Start with that distinction before comparing ratings. For the tow vehicle's steering wheel, our steering wheel lock guide covers that separate fitting.
Compare the listed specifications
The table uses each listing's own figures, with inch sizes converted to millimetres. Where a listing gives no size, the cell says so, and a missing size is not a sign that the lock fits everything.
Trailer lock specifications side by side| Pick | Type | Listed fit | Construction or feature |
|---|
| Master Lock 389DAT | Coupling | Virtually all about 47.6, 50.8 and 58.7 mm couplers | Bright red finish |
|---|
| Master Lock 379ATPY | Coupling | 48, 51 and most 59 mm couplers, listing rounding | Zinc body |
|---|
| Rhino USA | Receiver pin | About 15.9 mm pin; about 50.8 mm square receiver, Class III and IV | Weatherproof slide cap |
|---|
| Maypole MP953 | Coupling | Most standard 50 mm couplings | Case hardened 12 mm steel bar |
|---|
| Maypole Alko | Coupling | ALKO AKS3504, AKS3004, AK130, AK160, AKS1300 and AKS2004 heads | Model SH5412; covers the hitch fixing screws; three keys |
|---|
| FullStop Nemesis Ultra | Wheel clamp | Listing does not say | Key unlocking; 3 kg |
|---|
| Cartman | Wheel lock | Tyre width about 177.8 to 279.4 mm | Steel plate; soft coated surface |
|---|
| Hyfive | Coupling | Most pressed steel and cast 50 mm couplings | Cast steel body; hardened 12 mm bar |
|---|
Match the stated size and shape
The Hyfive listing calls 50 mm couplings the standard for most trailers, and the Maypole MP953 is listed for the same size. The Master Lock 389DAT gives its sizes in inches, and the middle one converts to about 50.8 mm; the 379ATPY listing rounds that same size to 51 mm. A coupling head also has a shape, so match the lock to your coupling model, not only to the nearest millimetre figure.
Separate construction from performance claims
The 379ATPY listing specifies zinc, the MP953 a case hardened 12 mm steel bar, the Hyfive a cast steel body with a hardened 12 mm bar, and the Rhino USA bullets solid forged steel. These material descriptions do not rank resistance to attack. The Maypole Alko listing says VbV / SCM MP03 approved; we have not tested any of these locks.
Check the model and key count
The 379ATPY, MP953 and Hyfive each list two keys, and the Maypole Alko product details list a hitchlock, barrel and three keys. Cartman's title says six alike keys and its bullets say three, so check what the exact option includes before you buy. Whatever the shop, compare by the model number and the listed fit, not by the words trailer lock alone.
Choose for a caravan or boat trailer
A caravan or boat trailer label does not answer the fit question. FullStop names caravans but its listing gives no wheel fit range; Hyfive names coupling materials and a 50 mm size. Choose using those details. For other equipment on the same trip, our tyre inflator guide compares corded and cordless options.
Frequently asked questions
What is the best trailer lock in Australia?
The Master Lock 389DAT is our overall choice for a compatible coupling. Its listing describes three fit sizes, a bright red finish and a mechanism that resists picking and prying. Choose the type first: the Rhino USA pin addresses a receiver hitch, while the FullStop Nemesis Ultra is a wheel clamp.
What is the best trailer hitch lock in Australia?
For the trailer coupling, start with the Master Lock 389DAT or the Maypole MP953 for most standard 50 mm couplings. For a tow vehicle receiver, the Rhino USA is the relevant pick. Its listed pin diameter converts to about 15.9 mm, with a receiver opening of about 50.8 mm square.
What is the best trailer wheel lock in Australia?
The FullStop Nemesis Ultra is our wheel clamp pick, listed for caravans, but its wheel fit range is not stated. The Cartman Trailer Wheel Lock is the budget choice with a listed tyre width range of about 177.8 to 279.4 mm. Confirm wheel fit before choosing between them.
Which trailer lock should I choose for a caravan?
Match the caravan's coupling first. The Maypole Alko Hitch Lock is the pick for the ALKO AKS3004, AKS3504, AK130 and AK160 heads its listing names, while the Maypole MP953 lists most standard 50 mm couplings. For a wheel clamp, the FullStop Nemesis Ultra is listed for caravans, but its listing gives no wheel fit range.
What is the best boat trailer lock in Australia?
Choose by coupling fit rather than the boat label. The Maypole MP953 lists most standard 50 mm couplings, and the Hyfive names most pressed steel and cast 50 mm couplings. The Master Lock 389DAT listing says it resists rust and corrosion, but gives no specific saltwater exposure rating.
Is a trailer coupling lock the same as a hitch pin lock?
No. The Master Lock 389DAT is a lock for the trailer coupling. The Rhino USA Locking Hitch Pin is listed as a tow receiver lock for Class III and IV hitches of about 50.8 mm square, with a pin diameter of about 15.9 mm. Match the lock to the fitting and dimensions.
Which trailer lock has the best reviews?
The Master Lock 389DAT has the most ratings here, 4.7 stars from 16,627, and the FullStop Nemesis Ultra the highest average, 4.8 from 580. The Rhino USA hitch pin lock has 4.6 stars from 8,916 ratings. These are Amazon listing averages, so use them with the fit details, not instead of them.
Is a Kovix trailer lock included in this comparison?
Kovix was not among the trailer lock listings we compared on Amazon Australia, so this page makes no call on it. For a coupling lock, compare the Master Lock 389DAT and the Maypole MP953 by their listed fit sizes. For a wheel lock, the FullStop Nemesis Ultra and the Cartman Trailer Wheel Lock are the picks here.
Do I need both a coupling lock and a wheel clamp?
They lock different parts. A coupling lock such as the Master Lock 389DAT or the Maypole MP953 covers the coupling, and a wheel clamp such as the FullStop Nemesis Ultra or the Cartman locks a wheel. No listing here claims to do both jobs, so one of each covers both parts of a parked caravan or trailer.
