Best 5th Wheel King Pin Lock: All You Need To Know

An RV is an investment. After you’ve done the work of researching types of RVs, finding the perfect fifth-wheel trailer for you, and writing that giant check, it is time to enjoy it. Chances are when you’re traveling with your fiver, you don’t just want to stay in the camper the whole time. You can do that at home. Maybe you leave to go hiking, or sight-seeing, or just to the store to get supplies. 

It might seem crazy but RV theft happens surprisingly often. While you are out having fun, anyone with a fifth wheel hitch in their truck can come to hitch up your trailer and drive it off. Few things can spoil your RV trip as much as having your rig stolen.

Thankfully, there are ways to protect your investment and deter those thieves. One of the easiest things to do is to attach a king pin lock whenever you’re not towing, especially if you plan to leave it for a few hours. 

The selection of king pin locks can seem overwhelming. They come in a wide range of shapes, sizes, colors, and prices, all claiming to offer you the best possible protection. They can’t all be the best, right? We’ll help you narrow down the options, evaluate your needs, and choose the best king pin lock for you and your fifth wheel.

What is a King Pin?

The king pin is the part on the front of your fifth-wheel trailer that connects to the hitch for towing. A fifth wheel hitch is mounted in the bed of a truck and the king pin slides into the slot in the hitch to allow you to tow the trailer. King pins are not ball-shaped like a bumper-tow trailer hitch, but rather cylindrical with a wider disc at the end. 

Your king pin is an important moving part that is not easily replaced, so be sure to keep it well-greased and properly maintained. 

Factors to Consider When Choosing a King Pin Lock

There are a number of factors you should consider when choosing from among the many king pin lock options that are available. Prioritizing which factors are most important to you will help you choose the king pin lock that best fits your needs.

Installation Ease and Speed

Let’s be honest, when you’re heading out to have a good time, you want it to be quick and easy to install your king pin lock. By nature, these locks prevent you from towing your fifth wheel while they’re installed, so remember that installation is not a one-time thing. You will need to put it on and take it off every time you use it.

The most secure lock in the whole world will not protect your rig while it’s in a box. If the installation is difficult or is time-consuming, you might be less likely to use it. If it is tricky to install it properly, it may not function as intended if you don’t get it quite right, which leaves your trailer vulnerable to theft. 

Lock Type and Security

If a determined thief has the time and opportunity, there is no lock that makes your rig 100% theft-proof. Just like locks on your house or car, the lock is primarily a deterrent. That being said, there are some locks that are more of a deterrent than others. 

Skilled thieves will be able to recognize different types of locks. They will know which key locks can be easily picked, which padlocks can be easily opened, and other common vulnerabilities. Every lock has a weakness, but since thieves know about them, it’s important that you do too.

Material and Durability

How long can the lock stand up to brute force? Some would-be thieves will focus on picking locks or otherwise removing the king pin lock. Others will skip the finesse and use a tool to beat it repeatedly. Locks are made from different materials and some can endure this kind of abuse a lot longer than others. 

Will your lock weaken with time, leaving you wondering if it can still do the job or forcing you to replace it often? Would you rather buy new locks more frequently or invest more in a lock that will serve you well for years?

Weather Resistance

Your king pin lock will regularly be exposed to the elements, so weather resistance is another important factor to consider. King pin locks are made from different metals, and some metals tolerate moisture much better than others. It is likely that your lock will frequently sit in direct sunlight and it will often endure both extreme temperatures and temperature fluctuations.

Where will you typically park your rig? Are you concerned about extended periods of cold temperatures, or do you usually only use your trailer in the summer? Do you spend most of your time in the deserts of the southwest, where rain and humidity are less of a factor, or will you often park it in the damp and rainy Pacific Northwest? Most RV travelers will want a lock that can stand up to a variety of weather conditions.


Since a king pin lock is primarily a deterrent, visibility matters. If would-be thieves can see from a distance that your rig is protected, they are much more likely to simply leave it alone and look for another target. 

Some locks are small and blend in easily with the king pin itself. You may prefer this type if you find this more attractive. Other locks are much larger and brightly colored. They may be a bit of an eyesore, but they send a clear message: This fifth wheel is hard to steal, so just move on.


While you don’t want to risk your larger investment just to save a few dollars, the prices of king pin locks vary quite a bit. As with most things, choosing a lock will require some compromise between how much you are willing and able to spend versus the quality and longevity of the product you receive. More expensive does not always mean a better product, though, so consider the value carefully. 

Types of King Pin Locks for Fifth Wheels

There are several different types of king pin locks that you can consider:

  • Collar Locks: Collar locks fit around the king pin like a collar. They surround the king pin with one side open and the ends have holes in them to receive a steel bar, which locks the collar in place. 
  • Slide Bolt Locks: Slide bolt locks are shaped like a tube or a pipe and surround the whole king pin. They have a built-in locking mechanism that slides in and locks to secure the tube in place.
  • Conical Locks: Conical locks are wide cones that cover the king pin completely in thick, heavy-duty metal. They are the heaviest and most expensive kind of king pin lock.
  • Sleeve with Padlock: This type of lock uses a simple steel sleeve, similar to a slide bolt lock, but the sleeve is held in place with a separate padlock. 

Best Fifth Wheel King Pin Locks

Best Collar Lock: Curt 23255

Positive Factors: visibility, ease of installation, weather resistance, price
Negative Factors: material and durability, lock type and security

The Curt 23255 is a very popular king pin lock and most users are very satisfied with their choice. This collar lock is not large but the steel pin is wider than the king pin in a way that makes it easily visible that your rig is locked. It is easily installed by putting the collar around the king pin then threading the steel pin through the holes and screwing on the end. It comes with a waterproof dust cap to protect the lock from the elements. With a price tag of less than $50, this is a great buy.

Note that while the locking pin is made of steel, the collar part of the lock is aluminum. The durability and strength of the aluminum has been questioned so this could be a weakness. Some users have reported accidentally driving over it, though, without causing any damage. The key does not turn a specific locking mechanism but rather is used to screw the end of the bar off and on. It is unclear if it would also be possible to do this without the key using something similar such as a screwdriver. 

Note that because this is a rigid collar lock, you should measure your king pin before purchasing to be sure it will fit. The opening has a 2-inch diameter that is designed for the 2-inch king pin found on most fifth wheels.  

CURT 23255 5th Wheel Trailer Lock for 2-Inch King Pin | Amazon

To protect your 5th wheel trailer from theft while it is left unattended, this 5th wheel lock is made with a high-strength steel pin and an aluminum bracket.

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02/18/2024 02:50 pm GMT

Related reads: How to find the best RV wheel locks.

Best Collar Lock (Runner Up): Master Lock 2999DAT

Positive Factors: visibility, weather resistance, price
Negative Factors: ease of installation, material and durability, lock type and security

This lock is the cheapest on the market that’s worth recommending, so if price is your biggest factor, then look no further. The collar on the Master Lock model is powder-coated to protect it from the elements and it is bright red to improve visibility. Similar to the Curt lock, the lock can be covered by a weather-proof cap.

The material and durability questions on this are similar to the Curt model. The cross pin is steel but the collar is not. The swivel-head lock design is functional as a deterrent but hardly theft-proof. The quality of the lock is not important, however, if you are unable to install it. The top complaint regarding this model is that it often fits very tightly or not at all. If it fits tightly, it is difficult to put on and take off. Some users have modified the lock to make it fit better, but this takes a lot of time, tools, and skills. 

If you are not anticipating needing heavy-duty security in a high-risk situation, but just looking for a little extra peace of mind with a small price tag, this lock is an excellent choice. Just be sure to measure very carefully and make sure it will fit your rig.

Master Lock 2999DAT Fifth Wheel/King Pin Coupler Lock | Amazon

5th Wheel King Pin Lock Masterlock Easy-to-use collar locks around your trailer's king pin so that it cannot be hooked up to anyone else's hitch. Powder coated steel is durable and corrosion resistant. 

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Best Slide Bolt Lock: Road Pro RPKPSL-2 Heavy Duty

Positive Factors: material and durability, ease of installation, price
Negative Factors: weather resistance, lock type and security, visibility


The Road Pro RPKPSL-2 Heavy Duty king pin lock is made from heavy-duty steel. It is quick and easy to install: simply slide it over the king pin and engage the lock. This model is available for less than $50 so you get a lot of protection for the money.

While covering the whole king pin is a very secure type of lock, this model is vulnerable in the lock itself. The keyhole has a very simple shape that would be short work for an experienced lock pick, or the lock assembly can simply be drilled out. Because the steel tube hugs the king pin so closely, it doesn’t offer much in the way of visibility. A 12-inch chain hangs from it with a yellow tag warning that the lock is engaged. The primary purpose of the yellow tag is to prevent owners from trying to hitch up with the lock still in place. When it comes to weather resistance, the company claims that having the lock upside-down on the bottom keeps water from getting in, but the primary complaint from users is rust in the lock. Since this makes it nearly impossible to remove the lock and hitch up, it is a significant issue when it happens.

For full-time RVers and those who use their fifth wheel frequently, this lock is an excellent value. If you plan to leave the lock engaged for a longer time, such as in storage, in a humid or rainy environment, this might be one to avoid.

RoadPro RPKPSL-2 Heavy Duty Steel King Pin Lock | Amazon

Constructed of solid steel that covers the entire king pin and locks with a slide bolt, you can depend on it to prevent trailer theft wherever the road may lead you.

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02/18/2024 08:55 am GMT

Best Slide Bolt Lock (Runner Up): Trimax Ultra Tough

Positive Factors: visibility, ease of installation, price, weather resistance
Negative Factors: material and durability, lock type and security

The Trimax works similarly to the Road Pro: it slides over the king pin and locks in place. It is comparable in ease of installation and price. It is coated with epoxy to improve its weather resistance, so it is less likely to rust. One other advantage it has over the Road Pro is its bright yellow color. It can be easily seen from a distance, leaving no doubt that your trailer is locked.

While the Trimax is probably a better deterrent than the Road Pro, if someone decides to try to steal your rig anyway, the Trimax puts up less of a fight. Users commonly report that even accidental impact to the Trimax compromised the security of the lock or broke it completely. 

Trimax TFW55 Ultra Tough 5th Wheel Trailer Lock | Amazon

The spring-loaded lock head makes the Trimax TFW55 simple to install. Insert the key and twist, and the locking pin pops out. This allows the security ring to easily slide over the fifth wheel kingpin catch. Hold the lock over your fifth wheel’s kingpin and insert the key. Push and twist the key to secure the lock in place.

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02/18/2024 05:16 pm GMT

Best Conical Lock: AMPLock U-LPCVR

Positive Factors: visibility, material, and durability, lock type and security, ease of installation, weather resistance
Negative Factors: price

The AMPLock U-LPCVR is clearly an example of getting what you pay for. This is the king of all king pin locks, which makes your fifth wheel virtually impossible to steal. In fact, make sure you keep the key in a safe place or you won’t be towing it anywhere either!

This conical lock is large enough to be easily visible. It is made from a combination of steel and cast iron which makes it virtually impenetrable – and heavy, weighing in at almost 9 lbs! The lock system is complex and difficult to unlock without the original key. With the keys, putting it on and taking it off is a quick and easy process.

The major disadvantage of this lock is that it costs at least 5 times more than other types of locks. Expect to pay between $225-$275 for this one. Compared to the cost of your fifth-wheel trailer, however, it might just be worth it for peace of mind.

AMPLOCK U-LPCVR 5th Wheel Lock for King Pin | Amazon

Materials used by AMPLOCK provide good rust resistance for use in all climates.

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02/18/2024 01:15 pm GMT

Best Conical Lock (Runner Up): Universal Boot Inc.

Positive Factors: visibility, material, and durability, lock type and security, ease of installation, weather resistance
Negative Factors: price

For all of the features of a conical lock with a friendlier price tag, the Universal Boot is a great choice. It is made from carbide steel and features a high-security key system. Its size, shape, and bright yellow color make it highly visible. Among its weather-resistant features is a lock designed to resist freezing. It can be installed and removed quickly and easily.

The Universal Boot weighs a little less than the AMPLock (8 lbs vs. 8.7 lbs) and costs less as well. This model sells for between $125-$150. 

Best Sleeve with Padlock: Ultra-Fab 48-979008 

Positive Factors: ease of installation, visibility, material and durability, weather resistance, price
Negative Factors: lock type and security

This heavy-gauge steel sleeve slides onto the king pin and is then secured with a padlock. It is a very simple design with several advantages. It is very easy to install, and the hanging padlock is easily visible and recognizable as a lock. The sleeve itself is very durable steel that is not highly vulnerable to the weather. Priced between $25 and $40, it is a simple and cost-effective solution.

The Ultra-Fab comes with a padlock but it is a poor quality lock that should be replaced. Many padlocks can be easily cut with simple bolt cutters, so you’ll want to upgrade the lock which adds to the price. The advantage here is that you can choose the lock type that you’re most comfortable with, and if the lock is damaged by weather you can replace it without needing to replace the sleeve.

Ultra-Fab Products 48-979008 5th Wheel Sleeve with Lock | Amazon

Locking feature adds extra security to 5th wheel at campsite or storage. Kingpin lock deters 5th wheel trailer theft.

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02/18/2024 08:46 am GMT

Compare King Pin Locks at a Glance

Lock Name Type Ease of Installation Visibility Material and Durability Weather Resistance Lock Type/ Security Price
Curt 23255 collar Good Fair Fair Good Fair $25-40
Master Lock 2999DAT collar Poor Fair Fair Good  Fair $20-30
Road Pro RPKPSL-2 slide bolt Good Poor Good Poor Fair $25-40
Trimax Ultra Tough slide bolt Good Good Poor Fair Fair $25-40
conical Good Good Excellent Good Good $225- $275
Universal Boot  conical Good Excellent Good Good Good $125- $150
Ultra Fab sleeve with padlock Good Fair Good Good Varies $25-40

Overall Pick: Universal Boot Inc. Steel Conical King Pin Lock

If money is no object, and you want the absolute finest king pin lock on the market, then the AMPLock U-LPCVR is a clear winner. Your fifth wheel is as secure as possible with this lock.

AMPLOCK U-LPCVR 5th Wheel Lock for King Pin | Amazon

Materials used by AMPLOCK provide good rust resistance for use in all climates.

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02/18/2024 01:15 pm GMT

Since money is a factor for the majority of us, however, I find little difference in quality or security between the AMPLock and the Universal Boot that would warrant a $100 price difference. Nothing is 100% theft-proof, but the conical design offers the best possible protection without sacrificing ease of use. The Universal Boot has the fewest compromises on all six of the factors to be considered when selecting a king pin lock. This makes it the best all-around choice.

If the price tag of the Universal Boot is still too steep, and you would prefer to compromise on other factors than price, then the top choice for a budget model is the Curt 23255

Frequently Asked Questions

Q: How does a king pin lock work?

A: There are different types of king pin locks that work slightly differently, but the basic idea is that you lock something onto your king pin that prevents it from fitting into a fifth-wheel hitch. Without removing the lock, the king pin is too large to be connected to the receiver, so the trailer cannot be towed anywhere.

Q: How do I keep my fifth wheel from being stolen?

A: A king pin lock is a great way to protect your fifth wheel from theft. With a king pin lock in place, your rig can’t be hitched up and towed away. Other security precautions include tire boot locks and X-stabilizers that can be locked on the wheels. A king pin stabilizer can also be used together with a king pin lock to provide an increased theft deterrent.

Q: How common is RV theft?

A: RV theft is more common than you might think. The vehicles themselves are very valuable, and they are often filled with other high-end items that are harder to trace. They seem like an easy target because they can simply be driven or towed away. Annual estimates of stolen RVs in the United States vary but the numbers are in the thousands. There are many simple solutions to deter would-be thieves, but if yours is the only one left unprotected it is much more likely to be a target. It doesn’t cost much time or money to protect your investment.

Q: How do you lock a fifth wheel hitch?

A: What you’re actually locking when you secure a fifth wheel is the king pin on the front of the trailer and not the hitch itself (which is in the bed of your truck). There are many different types of locks that you can attach to your king pin that make it impossible to insert the king pin into a hitch and tow the fifth wheel away.

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