Best Trailer Lock

What Is The Best Trailer Lock?

For those in a hurry and just want a quick answer, the best trailer lock is the AMPLock U-BRP2516. Each key is unique and the design is superior to universal fits.

My Dad and I often use a trailer to tow our vehicles long distances. It’s a quick and convenient way to transport a project car across town or to car shows. When we get to the event we’ll usually unhook the trailer so we can drive our main vehicle around. Unfortunately that leaves the trailer vulnerable and anyone could hook up to it and drive off.

Trailer owners often overlook a high quality lock to prevent theft. While you may not consider that someone would want to steal your trailer, you would be surprised. But you have options to prevent this.

You’ll need a lock that fits your hitch, is tamper resistant, and is easy to install and remove. Here are a few tips and reviews to help you find the best trailer lock for your trailer.

What To Look for In A Trailer Lock

Design Types

You will find that there are two main trailer lock designs. The most popular is the universal lock and the hitch pin. It can adapt to many trailer hitches because of its range of coupler options and varying sizes. It features a metal ball and a bridge that keeps the lock securely in place. The tongue lock will fit into couplers that range in size from 1-7/8-inches to 2-5/16-inches.

Another type is deadbolt locks. These fit into the holes found inside the couplers. You will need to know the exact size of the coupler for it to work correctly. The benefit of a deadbolt lock is the tighter fit that you get in comparison to the universal lock. The tighter fit makes it harder to tamper with.

One more popular option is the Krok Lock. It’s made of hard plastic and will fit easily onto the trailer hitch. This type of lock is bolted on and prevents the thief from unbolting it when it’s locked. This is an easy and quick lock to install. It requires drilling two holes and a bolt to assemble it to the hitch.


The hitch on your trailer is similar to an RV and is categorized by class. They start from a Class I and go to a Class V. Not all locks will support all five classes. A trailer lock will use either a 5/8 inch or ½-inch pin, and you will need to make sure that the lock you buy matches your hitch.

For instance, Class II hitches will usually need a lock with a ½-inch pin. Locks that work on Class III, IV, or V hitches will require ⅝-inch pins. You can’t use it if you choose a lock with the wrong pin size.

Class I and Class II hitches need a 1-¼ inch trailer lock. Class III and higher need at least a 2 inch lock. Not following guidelines may cause you to buy a lock that won’t work with your hitch.


The material type determines the level of quality. Hardened and high quality steel are more durable and tougher than other materials. This will help prevent someone from tampering or trying to cut a lock. If a thief sees these materials they may think twice before attempting to drive off with your trailer.

Aluminum is lighter in weight and not as strong as steel. If you consider an aluminum material, try to research and see what the manufacturer has done to increase the strength.


Your climate can also have a long term effect on the lifespan. If you leave a lock outside in the elements like snow, salt, rain, and water, it can rust or corrode over time. Enough corrosion will cause them to seize and become unusable. Look for a durable design and research how others have held up over time.

One feature to prevent corrosion is a waterproof cap over the keyhole. This is helpful in cold climates since to prevent water from entering and freezing.

Look for a product that is designed to resist corrosion and water damage. Some products may be designed better than others and will have a longer lifespan.

A Caution About Keys

Manufacturers will often use the same key on all locks. It’s cheaper and less complicated than keying all locks differently. This is a problem because a thief can buy the same lock and have access to the same key.

One solution is to look for a lock with a unique design or is keyed differently than other models.

This will help make sure your lock can’t be opened as easily.

REESE Towpower

This is a hoop style, heavy-duty universal coupler lock. It is adjustable and features a heavy-duty steel lock bar and an aluminum body. Equipped with 11 locking positions, this lock is easy to install and comes with a ratchet design that fits 2-5/16 inch, 2 inch, and 1-7/8 inch couplers.

The coupler hitch features a heavy-duty steel bar that is durable without being too heavy. It can resist drill outs, picking, prying, and is bright yellow in color. It also comes with two receivers with one that works with a class I & II hitch and the other with a class III or above hitch.

Featuring three different lock options, you get a lot of versatility out of one lock. The REESE Towpower Coupler Lock is very affordable and is highly visible as a deterrent..


  • The lock bar is hardened steel and will resist cutting.
  • It comes with two keys so you will have a backup.
  • It’s easy to install and remove. This is a good feature for small utility trailers.


  • The frame body is aluminum, not steel. It can be broken open easier than a steel body.
  • A numeric code option would be better than a key lock
  • Some users mentioned it didn’t fit their trailer. Measure and double check the fit before buying.

Master Lock Universal

This is another universal size option. It uses a hardened steel plate instead of a lock bar to prevent access.

It’s bright red to discourage and future thieves. It fits 2-5/16 inch, 2 inch, and 1-7/8 inch couplers. The lock bar has more moving parts where the Master Lock is just the key and the adjustable ball. The plate will prevent thieves from accessing or prying it open.

Some users mention this style lock is easier to install in cold weather compared to the lock bar style. Master Lock built it from forged steel to be weather resistant avoiding corrosion and rust.

This is an affordable option if you are looking for a basic deterrent from the casual thief that is hard to remove without the key.


  • This is a very affordable option without sacrificing quality.
  • The movement of the keyed lock is smooth and easy to open.
  • Its bright red color to deter theft.


  • A few users mention the lock cylinder won’t turn after a few winter seasons.
  • Some users can open the lock with other Master Lock keys.

Trimax UMAX100

This is another universal option with a lock bar.

The Trimax UMAX100 is made from solid, hardened steel. It weights six pounds and is easy to install and remove. This universal sized lock will fit 2-5/16 inch, 2 inch, and 1-7/8-inch couplers.

One great feature is the key cover. It slides open and closed to prevent dust, water, and dirt from entering. This means it should last longer if left in the weather elements. The key is a circular seven pin kety. It’s not the normal key with a tumbler lock. That’s great because thieves will have fewer key options to open it up.

The one negative I see is the nylon plastic housing. The housing may absorb a few small blows from a hammer but it will eventually fail if impacted with a larger object.

This lock is an option to prevent people from tampering with your trailer. But it will not stop a determined thief.


  • The lock door will prevent dirt buildup to keep the lock functioning longer than other designs.
  • The key is designed differently to prevent others keys from opening it.
  • It’s easy to install and remove.


  • The housing is made of nylon plastic. This is easier to destroy and open compared to hardened steel.
  • Some users complain of the lock jamming over time and being unable to open it.

Blaylock TL-33

The Blaylock TL-33 is another lock bar universal option.

It fits 2-5/16 inch and 2 inch couplers. Blaylock makes this in the United States out of high-grade aircraft aluminum. It’s very heavy, thick, and will resist most attempts to destroy it.

One thing to know is this doesn’t come with a lock. Some may see this as a negative because that means you need to also buy a lock. I see it as a positive. It’s a plus because can choose your own high quality lock. I recommend a shackle or tamper resistant disc lock. You won’t have the issue of other keys opening your lock.

The steel locking rod will resist corrosion and rust for a longer lifespan. It also has three different hole positions that let you choose the best option for your hitch.

Some people mention it didn’t fit their trailer. Blaylock makes a few sizes so research what you need and choose the correct one.


  • This option doesn’t come with a built in lock which means you don’t have shared keys. You can purchase a higher quality lock.
  • It can adapt to many trailer hitches because of the three-hole options.
  • It’s solid, sturdy, and very thick to deter most thieves.


  • The aluminum construction can be easy to damage with a hammer blow. It won’t stop all thieves, but it’s a deterrent.
  • The aluminum cast is very rough. There are imperfections from the cast and from grinding spots.

AMPLock U-BRP2516

This is going to be your high quality option with tighter security. It’s a more expensive option than the others.

This one is not a universal fit. It fits only 2-5/16 inch couplers but there are other sizes available. This will fit tighter to your coupler compared to a universal lock. That means less space for a thief to work with. AMPlock has a patent on their high security locking mechanism. It’s unique because thieves can’t easily access the cylinder lock.

The whole unit is 12 pounds. I like the design because of the included ball joint. You insert the ball joint in to the trailer coupler and the lock goes around the joint. This is a very secure way to prevent access and tampering. The cylinder lock rotates which prevents someone from drilling in to it.

What I like the most outside of the design is that keys are unique. AMPLock uses a cylinder key that has millions of combinations and will be different for every customer. You can even order new keys with the same code if you need an extra.

It’s made of heavy-duty stainless steel and ducted cast iron. The AMPLock can absorb blunt force impact, resist liquid nitrogen, and torch cuts. It’s corrosion resistant and will last longer than others.

It’s made in Canada using American materials.


  • This is the highest quality lock and offers the highest level of security over all the options.
  • It’s designed to prevent the use of drills, metal saws, and even torches.
  • Some users mention it would be quicker to cut the trailer tongue off than remove this lock. It’s very robust.


  • It only fits a 2 5/16 inch coupler lock. However they do have other options.
  • It can be difficult to remove because of how tight it is. This is a negative when removing it but it’s also a positive because it’s tamper proof.


When I look to protect my trailer I’ve got to consider not only the cost of the trailer but the cost of the cargo inside the trailer. Everyone has a different budget, circumstances, and different uses for a trailer.

If you’ve got a commercial trailer and have valuable contents, the AMPLock U-BRP2516 is the best option. Yes, it is more expensive. But this is a time where you want a higher quality product. It’s made from high quality materials, has unique keys, and has a superior design.

If you’re on a budget and don’t have a lot of expensive contents, I recommend the Master Lock. It’s strong enough and colorful enough to deter most attempts. It won’t stop someone who is determined but it’s a great deterrent.

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