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Trailer Tech for Towing Your Trail Rig

Posted in How To: Tech Qa on April 18, 2018
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Photographers: Fred WilliamsCameron Hotchkiss

Trailer kings and queens, untie! Or is it unite? It really should be strap down.

For years and years we resisted the temptation to use a trailer to drag our off-road rigs to the trail and back. After all, the journey to the trailhead and back home is part of the adventure. Still, there’s something to be said for towing your trail rig. The trailer allows you to try things off-road that you wouldn’t try if you had to road-drive the rig back home. Also, those unbalanced tires that are trail tough but a nightmare at about 40 mph or above are no longer a concern. Same goes for that bent tie rod that shouldn’t be on the road at speed but still gets the job done in the rocks and mud. We could keep going, but we’re sure you get the point.

Still, jumping into the trailer game blind is not a good idea. What do you know about trailer tires, trailer brakes, hitch ratings, tongues, and load securing straps? Did you know that the type of hitch on your truck may not meet the maximum towing capacity for that very truck? Towing even a lightweight trail rig on a trailer means moving and securing a lot of weight. You need to learn which tools are necessary, what ratings to pay attention to, and what to check periodically. That’s why we’re here. Let our experiences, successes, and failures be your teacher when it comes to trailering your rig to the trail, across the country, or to its final resting spot at the metal recycler (please don’t do that).

Hitch Ratings

Understanding hitch ratings isn’t easy. With five classes of hitches, investigating what you can tug with your hitch on your truck isn’t exactly straightforward. Researching hitch class ratings turns up wishy-washy words like usually and often, even on the websites of well-known hitch manufacturers.

For the purposes of this story we are going to keep it brief and stick to a few rules of thumb. The real tow rating answers to your questions come from the vehicle manufacturers, and by that we mean the answer is in your owner’s manual in the glovebox. From there the type of hitch your vehicle has determines if that rating can be met. For example, you could have a 1-ton truck with no hitch, so although the truck is rated to tow 10,000 to 30,000 pounds, physically (and legally) it can’t tow the smallest trailer ever invented. A good rule of thumb is to make sure your hitch can carry more than your truck is rated for by the manufacturer, and then dial it back to whatever the manual says is safe. Overdo it and cause a wreck and you can be in serious trouble even with what you thought was the proper insurance coverage.

Here are the general ratings for Class III through Class V hitches. Anything under a Class III shouldn’t be used to tow a trailer that can hold another vehicle, so for the purposes of this story we are going to ignore Class I and Class II hitches.

The Class III hitch is probably the most common hitch you’ll bump into when towing a vehicle trailer. Here a steel cradle with a 2-inch square receiver is bolted to the frame of the truck or SUV. With a max gross weight rating of 6,000 pounds and 600 pounds of tongue weight this should cover most trail rigs and trailers out there. The sticker reminds us that just because the hitch can tow 6,000 pounds does not mean the vehicle can handle that load. That is specific to the vehicle. If you want to tow more than 6,000 pounds and your truck or SUV is rated to do so, look to weight-distributing (WD) hitches, or Class IV, and V hitches up to 17,000 pounds gross weight and 1,700 pounds of tongue weight. More than that and you’ll need to look into a gooseneck or fifth-wheel hitch.

Class III: Usually has a 2-inch square receiver on a frame-mounted hitch. Can tow up to 6,000 pounds Gross Trailer Weight (GTW) with 600 pounds of tongue weight if the vehicle and components they are attached to are rated for that weight. For example, a combined weight of 3,500 pounds of load and 2,500 pounds of trailer. Or 4,000 pounds of load and 2,000 pounds of trailer. You get the idea. With a weight-distributing hitch a Class III hitch can carry 10,000 pounds GTW with 1,000 more of tongue weight if the vehicle and components they are attached to are rated for that weight.

Class IV: Usually has a 2-inch square receiver on a frame-mounted hitch. Class IV can tow up to 10,000 pounds GTW with 1,000 pounds of tongue weight if the vehicle and components they are attached to are rated for that weight. With a weight-distributing hitch, a Class III hitch can carry 14,000 pounds GTW with 1,400 of tongue if the vehicle and components they are attached to are rated for that weight.

Class V: Usually has a 2 1/2-inch square receiver on a frame-mounted hitch. Class V can tow up to 12,000 pounds GTW with 1,200 pounds of tongue weight if the vehicle and components they are attached to are rated for that weight. With a weight-distributing hitch a Class III hitch can carry 17,000 pounds GTW with 1,700 of tongue weight if the vehicle and components they are attached to are rated for that weight. Anything over that and you’re talking about fifth-wheel or gooseneck trailers and hitches to get the job done.

Receiver hitches come in different styles so you can keep the trailer level. Drop-hitch receivers come in many different drop heights and can be used as shown for lifted vehicles or flipped for use on stock or lowered vehicles, or very tall trailers.
A weight-distributing (WD) hitch spring loads the connection between tow vehicle and trailer. This helps equalize the load between both axles on the trailer and both axles on the tow vehicle (rather than only the axle closest to the hitch). A WD hitch increases the tongue weight you can have and overall load of the trailer with torsion bars and preloaded latches that require a special tool to load (shown). WD hitches are also helpful when your tow rig’s nose points to the sky when the trailer is attached, or if your trailer causes swaying going down the road.

Hitch Balls

Two or three parameters of a hitch ball determine how much weight it’s rated to hold and pull. The first should be obvious and is the ball size used (commonly 1 7/8, 2, and 2 5/16 inches). The next parameter is shank size, which ranges from 3/4- to 1 1/4 inches. The last parameter is material and construction of the ball, which can affect the load rating. Clearly, the larger the ball the harder the material, and the larger the shank the higher the possible load. But two balls the same size can have different load ratings because of differences in material or manufacturing. Load ratings for different balls will be stamped into the ball itself. The torque specification for tightening the nut on the different shank sizes is also different, but generally: 150 lb-ft for 3/4-inch; 250 lb-ft for 1-inch; 450 lb-ft for 1 1/4-inch.

The ball size and load rating is stamped, machined, or cast into the ball as shown. Hitch balls and tongues must match in size, whether 1 7/8, 2, or 2 5/16 inches.
This ball has a built-in rise once again to help keep the trailer level with the tow rig. Trailer hitch balls should be periodically greased and inspected for wear. If the ball (or tongue) wears enough, these two parts can pop apart. That’s very bad.

Trailer Tongue

The front end of a trailer has the coupling device attached to it. Usually called a tongue, an A-frame, or trailer coupler, there are a few different designs out there. Some are cast steel and some are made of stamped steel, and all are specific to a trailer ball size. By that we mean the tongue size must match the trailer ball size or bad things can happen. Ball size and construction dictate their load capacity, which will be stamped or cast into the tongue housing. How the tongue attaches to the trailer varies, but the general parts of a trailer tongue are the ball socket and latching mechanism. Tongues are wear parts that need to be periodically adjusted and replaced or rebuilt. Some tongues can be locked with a padlock, and all should be secured with a pin or bolt while in tow. Some tongues also hold a hydraulic actuator for surge brakes and/or an emergency brake actuator that is connected to the truck with a cable. If the cable pulls tight (because the hitch has come apart) the trailer brakes are actuated.

Here is the tongue on the trailer we use a lot. This is a cast steel hitch has a pin style coupler. The front of the tongue has a hinge on it and a spring loaded coupler. When open the hinge is open and the tongue can go over the hitch ball when closed the hinged coupler is closed and a steel collar slides forward over the coupler. The collar is held in place with a pin. Other tongues have a trigger latch, a wrap-around yoke latch or a thumb latch.

Trailer Chains

Trailer chains are there in case the ball and tongue, or receiver and hitch, somehow become disconnected while driving down the road. Chains hook onto part of the hitch. Often the hooks on the chains or the loops on the hitch or bumper are not properly rated to hold the trailer to the tow rig. That’s dumb since this is a backup that you really don’t want failing. The chains should form an “X” under the trailers tongue so if things come apart the chains will act like a hammock under the tongue.

Crossing the chains under the tongue of the trailer creates a hammock that can grab the tongue of the trailer if the hitch comes apart.


This should be obvious, but trailer lights help other drivers know how long and wide your trailer is, illuminate the license plate, and let other drivers know when you are slowing or stopped. Two stop/brake lights, two tail lights, two turn signal lights, two rear reflectors, one license-plate light, two rear side marker lights, two rear side reflectors, two front side marker lights, two front side reflectors, two rear clearance lights, two front clearance lights, and three lights in a row as a trailer identification bar. That’s what’s required for a trailer wider than 80 inches and less than 30 feet long with a GVW under 10,000 pounds. Phew! If your trailer is longer or rated for more weight, the number of lights just goes up from there.

We like LED lights for their compact size, brightness, and durability.

DOT regulations require lights on any trailer over 80 inches wide, with clearance lights at the widest points and three lights in a row as a trailer identification bar. This is similar to the lighting required on a wide truck like a dualie or Ford’s Raptor. A license plate light is also a must, as are several reflectors that are often integrated into the lenses of the brake lights.


When carrying extra weight, it’s important to increase your braking power with trailer brakes. There are two general types of trailer brakes: hydraulic surge and electric. Surge brakes are controlled via a trailer tongue-mounted mechanism that applies the trailer’s brakes hydraulically when the tow vehicle slows. Surge brakes can work well when set up properly, but unlike electromagnetically controlled brakes, they cannot be applied without slowing the vehicle. Also, they can engage when you’re backing up a hill unless a mechanical stop (or a more elaborate electrically operated stop operated by the vehicle’s backup lights) impedes the tongue from depressing and engaging the trailer brake master cylinder.

Electromagnetic trailer brakes use electric power from the tow vehicle to slow the trailer either when the tow vehicle’s brakes are applied or when the driver uses the brake controller to apply only the trailer brakes. This is especially helpful if a trailer starts to sway when you’re going down a steep hill, a time when slowing the tow vehicle may make the situation worse.

There are two types of electromagnetic brake controllers: inertia based and time based. Inertia-based brake controllers use an accelerometer to sense what the tow vehicle is doing and translate that to the trailer brakes. These are generally a bit smoother when stopping. Time-based controllers apply the trailer brakes based on gains set by the driver and are less precise than inertia-based controllers.

Pretty much every trailer brake we’ve ever seen has been a drum, and periodically the drums need to be adjusted to work well. Adjustment is done through the drum backing plate with a spoon or a screwdriver. Turn the star wheel until the brakes drag slightly, and then back off a notch or two.

Surge brakes use a tongue mounted hydraulic system that applies the trailer brakes when the tow vehicle slows.
Our tow rig has been around for a while and so has our brake controller, but it still works…most of the time. It is about time to update it, and lots of controllers and wiring harnesses are now available. There is loads of information and tons of trailer related parts at

Trailer Tires

The tires on your trailer are its interface with the road and are just as important as the tires on your vehicle. You want trailer tires to provide lateral traction and also traction when stopping. As with the tires on your rig, picking the correct tires for what you’re doing will make or break your trip. While there are special trailer-specific tires, we’ve had pretty good luck with high-load-rated tires intended for midsize pickup trucks. Whatever you run, it’s important that your tires are all similar diameters and have a high load rating.

Often overlooked is checking trailer tire pressure. We like to keep the maximum recommended pressure printed on the sidewall.

Some folks swear by trailer-only tires. After a stint of exploding trailer tires (a lot of our towing occurs in the 110-degree Southwest), we’ve had better luck with these light truck tires. They are rated for 2,183 pounds per tire, and we keep all four aired up to the max pressure of 50 psi.


Just like your trail rig’s front (and maybe rear) axles, the axles on your trailer have wheel bearings, and these bearings live no easy life. They are constantly under heavy loads and spun down the road at highway speeds, and they literally fight each other going around a turn on a dual-axle trailer. Consider, too, the lack of maintenance and the occasional hard hit on a curb, a pothole, or rocks, and you can be sure those bearings (and tires) have lived a tough life.

Every time we head out on the road for a long trip with our trailer we like to jack up each wheel and check out the bearings. This includes seeing how they spin and how much play there is in the bearings. If we have to, we replace, repack, or tighten the wheel bearings and almost always add grease. Different axles have different ways to grease and access the bearings. Some have caps, some have greasable fittings. The greasable fittings do make keeping on top of maintenance easier, but hey, if you’ve never repacked a bearing there’s no time like the present to learn.

Before every major trip we jack up each trailer tire, check the bearings for excessive play, and tighten if necessary. We also pop the caps of the hubs and check the grease, adding it when possible. On the trip, whenever we stop for fuel or food, the first thing we do is go back and put our fingers on the hub. A warm hub is fine. Hot to the touch is OK too. But if you can’t leave your fingers on the hub, you can be sure something’s wrong. You want to catch these problems early before a bearing seizes or the trailer axle’s spindle gets damaged. If that happens, most of the time you have to cut the old spindle off and replace it with a new one or replace the whole axle—not something easily done on the side of a highway, although some spindles do bolt on.
Trailer axles have different weight ratings that reflect how much weight they can hold. Since most trailers that will haul a 4x4 have two axles, take the axle weight rating and double it to get an idea of what the trailer can hold. Most four-lug axles are good for 1,500-2,000 pounds; five-lug, 3,500; six-lug, 5,000; and eight-lug single-wheel, 8,000. Dualie axles are usually good to 10,000-12,000 pounds, and wet (oil-bath hubs) go up from there.

Tie-Down Points

If you don’t safely secure your load to your trailer you won’t make it far down the road and you’ll end up in lots of trouble. Most of how you secure your load is tied (pun intended) to how your trailer is built. The best method to secure a vehicle on a trailer is to use straps attached to the axles (or A-arms for independently suspended rigs) of the rig and then from there to secure anchors on the trailer. Attaching straps to the chassis of the towed vehicle may seem like a good idea, but when the trailer hits a bump and the suspension compresses, the straps will loosen and could fall off. Anchors welded to the chassis of the trailer are the best places to attach the other end of the straps. The trailer we use most often has anchors welded to the chassis and metal deck of the trailer. Alternatively, the stake pockets of the trailer make for great anchors, although not all straps work well with stake pockets. Our straps come from Mac’s Custom Tie Downs, 800.666.1586,

Our trailer straps from Mac’s Custom Tie Downs have been in service for years yet aren’t showing any major signs of wear. Our trailer is a steel deck trailer with these collapsing tie-downs welded to the deck and chassis. Always check and retighten the vehicle straps after you’ve driven a few miles down the road and things have had a chance to settle.
The direct hook ratchet straps with chain extensions from Mac’s Custom Tie Downs are perfect for strapping down a rig (or two) to the stake pockets of a trailer. They allow the strap to be attached around a steel corner without damaging the fabric material of the strap.

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