Trailer Safety Checklist and Tips You Need to Know

Updated: Mar. 01, 2023

Hauling trailers can be dangerous, but for many people in the trades it is a daily necessity. Get a trailer safety checklist and tips here.

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Creating a pre-trip checklist | Construction Pro Tips

Create a Pre-Trip Checklist

You owe it to the other drivers you will be sharing the road with to make sure your trailer is road-worthy every time you take it out. Check the following items before taking to the streets:

  • The ball and the coupler are compatible sizes.
  • Chains, wiring harness and breakaway cable are all connected.
  • Ball mount pin is in place.
  • Locking lever is down and pin installed.
  • Ball is fastened securely to the ball mount.
  • Tongue jack is raised.
  • Tires are properly inflated and lug nuts are tight.
  • Lights are all working.
  • Ramps and/or gates are in place and secure.
  • Load is fastened and secure.
  • Brakes are working.
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Greasing Bearings With High-Temperature Grease | Construction Pro Tips

Grease the Bearings

Over time, bearing grease breaks down and loses its ability to lubricate and dissipate heat. Many manufacturers recommend repacking wheel bearings in grease every year or 10,000 miles, whichever comes first. Under-maintained bearings can overheat, eventually causing them to seize, start on fire, or separate completely so the wheel falls off while you are driving.

Bearing caps with a built-in grease fitting seem convenient but can be a bad idea. Adding grease through the cap can permanently damage the rear seal. Plus, this method fills the axle/spindle area, which should remain dry, with grease. Removing the old grease and cleaning the bearing are vital components of repacking bearings, and both are often neglected when people rely on these caps.

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Inserting a Wire Lock Pin | Construction Pro Tips

Always Pin the Coupler

If poor bearing maintenance is the most common cause of trailer breakdowns, the second most common cause is the trailer’s coupler coming loose from the ball mount. Make sure that you are not hooking up a trailer to an undersize ball.

A loose locking lever is another common cause of losing a trailer. As the trailer bounces down the road, the locking lever can wriggle up into the unlocked position. A pin will keep that from happening. Wire lock pins like the one shown here costs just a few dollars online, so there’s no excuse for not using one.

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Leveling the trailer hitch and ball mount | Construction Pro Tips

A Trailer Should Ride Level When Loaded

Trailers are designed to ride level. A trailer that is out of level just will not pull as smoothly or as safely. Also, hauling a tandem axle trailer unevenly will cause more wear and tear on one set of tires and suspension than on the other.

The “drop” of the ball mount determines how high or low the tongue of the trailer will ride. Here’s a good way to estimate the amount of drop your ball mount needs:

  1. Measure up from level ground to the top of the receiver
  2. Measure up from the ground to the bottom of the coupler on the trailer
  3. Subtract the first measurement from the second.

But that will only get you close. The problem with this method is that it doesn’t take into account the tongue weight of your particular trailer, or the stiffness of your truck’s rear suspension. The only true way to get your trailer to ride level is to hook it up to your truck, fully loaded and using a ball mount you think has the proper drop. If the trailer is level, great; if not, adjust accordingly.

Next, check out our guide to mobile marketing and how to use truck and trailer decals. 

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Two couplers, one of which is rusted out | Construction Pro Tips

Inspect Your Coupler

The friction from the coupler pressing down and twisting on the ball will wear down the coupler, causing the metal to thin out over time. Inspect the coupler periodically and if you find even one hairline crack, replace it immediately. Some couplers are bolted on, but some need to be cut off and the new one welded on. Greasing the ball might reduce the wear a little bit, but it’s not worth the mess. If you’re shopping for a trailer and you know you’re going to put tons of miles on it, buy one with a cast tongue rather than stamped metal; they are thicker and last longer.

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Holding a hook next to a trailer hitch | Construction Pro Tips

Cross the Safety Chains

Crossing safety chains creates a cradle that the coupler can fall into, and it will reduce the distance the trailer will swing side to side if it uncouples. Crossing chains also keeps them up a little

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Testing a trailer's emergency brake | Construction Pro Tips

Test Your Emergency Brake

Most states require electric brakes on large trailers, and many require a backup emergency braking system that activates if the trailer is separated from the tow vehicle. The most common type of emergency braking system consists of a cable attached to a key, which fits into a breakaway switch that’s powered by a dedicated battery. The other end of the cable is attached to the truck. In case of separation, the key would be pulled out of the breakaway switch, which would send an electric charge, provided by the battery, to activate the brakes.

Checking the emergency brake system is simple enough. Hook up the trailer, pull the key from the switch, and pull the trailer forward. The wheels shouldn’t roll if the system is working properly. If the brakes don’t engage, you could have a bad switch or faulty wiring, but a dead battery is the usual culprit. Breakaway batteries receive a charge every time you hook up your wiring harness, but they should still be replaced every couple of years.

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Three different sizes of trailer hitches | Construction Pro Tips

Use the Proper Size Ball Mount

Not all ball mounts are created equal. Make sure the ball mount you’re using can handle the weight of your trailer and its load. Exact specs can vary, but here are some common ones:

  • 1-1/4 x 1-1/4-inch solid steel—1,000 to 3,500 pounds.
  • 2 x 2-inches tube steel—up to 7,000 pounds.
  • 2 x 2-inches solid steel—up to 16,000 pounds.
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Trailer tires kicking up dust on a gravel road | Construction Pro Tips

Only Use Trailer Tires

Installing car or truck tires on a trailer is a bad idea. Trailer tires (ST for “Special Trailer”) and light truck tires (LT) or other passenger vehicle tires are not built the same. The sidewalls on truck tires have more flex, which improves traction and makes for a more comfortable ride. The sidewalls on trailer tires are stiffer. Stiffer sidewalls increase the amount of weight a tire can handle and reduce the risk that a trailer will sway.

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Jacking up the back of a trailer | Construction Pro Tips

Keep a Good Jack on Hand

Storing a spare trailer tire on board is a no-brainer, but what about the jack? Some trucks have jacks that may not be able to handle a loaded trailer, or they may have a strange configuration that might not work safely on a trailer. Try out your truck jack on your trailer; if it doesn’t work, buy a dedicated trailer jack. The one shown above is a combination jack and jack stand made by Powerbuilt.

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Different sizes of ball shanks | Construction Pro Tips

Use the Proper Size Ball Shank

The proper size of the ball is not the only thing to consider when buying a ball for your trailer; the size of the ball shank is crucial. The size of the shank determines how much weight the ball can handle. Shank capacities vary, but here are some common specs:

  • 3/4-inch shank—up to 3,500 pounds.
  • 1-inch shank—up to 7,500 pounds.
  • 1-1/4-inch shank—more than 7,500 pounds.
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A graphic showing proper placement of objects in a trailer | Construction Pro Tips

Double-Check the Load

Tongue weight is the force that the tongue of the trailer exerts on the back of the truck. Proper tongue weight should be 10 to 15 percent of the combined weight of the trailer and its load. So a 2,000-pound trailer with a 3,000-pound load should have a tongue weight of 500 to 750 pounds. The proper way to load a trailer is to keep the bulk of the load over the trailer tires, with a little more weight toward the front.

Too much tongue weight is hard on the truck’s suspension and takes weight off the front tires. This makes the truck unwieldy on curves and reduces stopping distance. Too little tongue weight will cause the trailer to sway back and forth and possibly fishtail out of control.

Unless you have a super-fancy ball mount that has a built-in scale, you’ll have to judge the tongue weight by how much the back of your truck drops down when the trailer is attached. The next time you have a few buddies over, have them climb onto the bumper of your truck. Measure and take note of how much the rear of the truck drops with the added weight.

Even loads that have been properly secured with the appropriate chains or straps can come loose after getting jostled on a bouncy trailer. It’s a good idea to stop after driving a short distance to inspect the load to make sure it’s still secure. And then every time you make a stop, for gas or whatever, check it again. You can’t be too careful.