Many an RVer who starts searching online for “RV weight distribution hitches” will be sitting in that same chair three hours later, muttering curse words, browsing comments on RV forums that completely contradict each other, and getting angrier by the click. My aim is to rescue you from that cyber abyss.
If you’re wondering whether a weight-distribution hitch decreases your tongue weight, then the answer is yes/no/depends on how you look at it.
- No, it doesn’t reduce the static tongue weight of your trailer.
- Yes, it reduces the vertical load at the ball-coupler connection.
- … but it significantly increases the clamping force on the trailer ball itself.
- No, it doesn’t allow you to tow more than your truck allows.
- … but your truck probably demands you have one to tow more than 5,000 lbs.
A weight-distribution hitch makes sense once you realize that it’s not a get-out-of-physics-free card. It doesn’t subtract anything from the total weight. All the combined weight of the truck and trailer combination remains the same. The load-leveling hitch just cleverly redistributes that weight to different axles.
How Does a Weight-Distribution Hitch Work, DAMMIT?!
I get your frustration! They’re kind of difficult to wrap your head around.
A weight-distribution hitch is also known as a load-leveling hitch or equalization hitch. This is in comparison to a simple weight-carrying hitch, which is your typical trailer ball on a simple ball mount arm.
Unfortunately, this is one mechanism that is better seen than described. Here’s a pretty good video illustrating how a weight-distribution hitch works:
*Note: It’s an easy-to-understand video, but Alex is not accurate when he says “a weight-distribution hitch doesn’t do anything to the trailer itself.” That is not correct. Weight distribution hitches will add some weight to the trailer axles. I wrote about that in my article on the hidden “danger” of a weight-distribution hitch.
>>> READ MORE: The Hidden Danger of a Weight-Distribution Hitch
If you’re into the physics of how an RV weight distribution hitch reconfigures the vertical loads, then this video is a hidden gem: https://www.youtube.com/watch?v=IEVnjYCR2gw&t=13s
A regular ol’ weight-carrying hitch transfers the tongue weight plus 20-30% onto the rear axle of the tow vehicle. Where does that extra 20-30% come from? It’s stolen from the front axle, which is now raised up in the air. The purpose of a weight-distribution hitch is to not only level the truck-and-trailer combination, but more importantly, to return all (or part) of that extra weight on the rear axle back to the front axle.
Now that you’ve grokked the basics of how a WDH works, let’s tackle the big question: How does a weight-distribution hitch affect the tongue weight?
Does an RV Weight-Distribution Hitch Reduce My Tongue Weight?
Well, that all depends on how you look at it. First of all, there is a semantic difference between tongue weight and hitch weight.
- Tongue weight is the vertical force (due to gravity acting on the center of mass of the trailer) between the trailer tongue jack (or ball coupler) and the ground. It’s usually measured with the trailer leveled and at rest. You can think of this as the static tongue weight. In the US, we usually aim for somewhere between 10-15% of the total loaded weight.
- Theoretically, there is a difference between tongue weight (what our English friends call “nose weight” measured at the wheel/base plate of the tongue jack versus tongue weight at the ball coupler itself because they aren’t in the same location. This difference is so small (especially as the RV gets longer) that we can ignore it.
- Hitch weight is the portion of the trailer’s total weight born by the truck’s hitch. With a simple weight-carrying hitch, the hitch weight is equal to the tongue weight plus the weight of the hitch apparatus itself. When you use a weight-distribution hitch, this number is variable.
A weight-distribution hitch reduces the vertical load at the hitch, yes. But it’s a slight reduction. If you were somehow able to place the hitch on a scale and measure the downward weight when hooked up, then as a weight-distribution hitch was adjusted, that force would be reduced. In fact, in theory, an ideal WDH is capable of decreasing the hitch vertical force to any value, even to a negative number (in which case the rear end of the vehicle would be lifted off the ground). But usually, the final distributed tongue weight will be less than the original tongue weight at rest.
Example: If you have a 5,000-lb trailer with 10% tongue weight, you have 500 lbs on the tongue transferred to the hitch. After adjusting your weight-distribution hitch, the vertical load at the hitch is now, say, 460* lbs.
**This is a sample number only. The decrease at the hitch (and the equivalent increase at the trailer axles) is in part based in part on the length of the RV. The longer the trailer, the less vertical load the hitch will be reduced. But TMI.
… But Does a Weight-Distribution Hitch Increase Stress on My Coupler And Tongue?
Now, here’s where things get weird. In order to accomplish this weight shuffling, all weight-distribution hitches apply a moment, a kind of rotating torque, at the trailer ball. This moment causes several things:
- It reduces the weight gain of the truck’s rear axle (good)
- It reduces the weight loss of the truck’s front axle (good)
- It applies a weight gain to the trailer’s axle[s] (may not be so good)
- It increases the clamping force between the coupler and the ball (usually not an issue)
- It applies a bending force to the trailer tongue (definitely not good)
Those last two points are pretty important. Yes, the vertical load at the hitch is now less than it was; but the ball and the coupler are being sandwiched together under massive pressure. That’s why your WDH has spring arms; they act as levers to apply this torque. That’s how the Weigh-Safe True Tow hitch works; it actually measures and shows you the force you’re directly adding to the ball-coupler connection. It’s thousands of pounds!
This moment also imparts a significant bending force to the tongue of the trailer through the spring arms. The more you “crank” on the WDH, the more you’re stressing the camper’s frame, trying to turn them into origami. For most RVs, this isn’t a structural problem. But if you have an “ultra-light” trailer with a long, light-duty A-frame tongue made of I-beam or C-channel, then beware! I would be particularly cautious if your tongue rails are made of anything 4” tall or shorter.
Make sure your tongue rails are strong enough to deal with the added stress of a weight-distribution hitch. While rare, RV manufacturers have been known to deny claims of frame failure because of the use of weight distribution hitches.
If a WDH Decreases My Tongue Weight, Then Can I Tow A Larger Trailer?
This myth is like a cockroach: It’s nasty, dangerous, and hard to kill. The purpose of a weight-distribution hitch is to restore weight to the front axle that was transferred to the rear axle of your tow vehicle when the trailer’s tongue weight was applied to the truck’s hitch. In doing so, it also levels out your trailer.
This can be a difficult concept to grasp (believe me, I know!) – but a weight-distribution hitch doesn’t reduce the static tongue weight of your camper as it sits on a scale.
If that’s not making any sense, then just understand that you can’t “cheat the system.” If your tow vehicle is rated for 1,000 lbs hitch weight with a weight-distribution hitch, you can’t sneak in some extra pounds by subtracting the transferred weight.
In the words of Inigo Montoya: “Let me explain. No, there is too much. Let me sum up.” Towing capacities are usually based on the static tongue weight of the trailer, not the final distributed hitch weight. Plus, unless you do quite a bit of math, you won’t know the distributed weight anyway, so don’t worry about it.
>>> READ MORE: Let’s Talk Tongue Weight – How Much Is Too Much?
Big Takeaways About Weight-Distribution Hitches
- Yes, weight distribution hitches reduce the vertical load at the hitch, but you don’t need to worry about that. Just use the normal static tongue weight as your basis.
- Yes, weight distribution hitches will increase stress on your trailer ball, coupler, and tongue. You need to make sure your travel trailer tongue can handle the added forces without bending.
- You probably need a WDH if your camper weighs 5,000 lbs or more when loaded.
- Pick a weight-distribution hitch with a weight capacity just above (not below) the maximum loaded weight of your trailer. The closer, the better!