What is a Weight Distribution Hitch And When to Use It

If you haven’t done it yourself, you have certainly seen it. A vehicle pulling a trailer that is noticeably sagging at the hitch. Valley Auburn Buick GMC  and the Valley RV Supercenter are here to tell you that this not only looks bad but is unsafe. If the rear is being forced down, weight is being removed from the front. This reduces traction on your steering tires, and makes your front brakes – usually your strongest brakes – less effective. At the same time, the rear axle is being overloaded, creating possible heat issues and putting a burden on your rear brakes. Overall, the vehicle is significantly less stable, and pulling a trailer is definitely the worst time for that. 

One might just assume that this is caused by pulling a trailer over the vehicle’s maximum towing capacity, but that may not be the case at all. Remember, there are two important weights to consider regarding trailers. Besides the trailer weight is the tongue weight, which is the actual amount of the trailer weight at the trailer hitch. Most trailers towed with a ball hitch should have a tongue weight that’s 10-15% of the total trailer weight. Less than 10% can cause sway and stability issues, while more than 15% can potentially overload the tow vehicle’s rear axle and lighten the front. 

A proper camping trailer was likely designed with a tongue weight in this range. If nothing else, those trailers will be able to give you their tongue weight. It is entirely different when working with trailers with variable contents such as cargo, vehicles, or even livestock, where both the weight and distribution vary. The solution for this, at least on a pickup like the GMC Sierra 1500, is a weight distribution hitch.

What is a Weight Distribution Hitch?

Alex Dykes of Alex on Autos describes weight distribution hitches as “poorly understood, absolutely essential, and seldom used”. They are designed to distribute the tongue weight evenly to the tow vehicle’s front and rear axles as well as to the trailer axle(s), enabling the hitch connection to be parallel with the road. The industry term for this is Front Axle Load Restoration (FALR), and the idea is to return 50-100% of the weight lost from the front axle.

Weight Distribution Hitches accomplish FALR by the use of a more complex and adjustable hitch and, most importantly, spring bars. The spring bars mount to the trailer hitch on each side of the ball and to each side of the trailer’s A-frame at about 23 to 35 inches from the coupler. Chains are often involved in mounting the spring bars to the trailer frame. What the spring bars do is effectively reduce the vertical pivoting at the hitch ball. Almost like a splint, they force a parallel connection between the tow vehicle and trailer. In turn, they distribute and enact a load on both the tow vehicle and trailer frames. For the tow vehicle, this forces weight back on the front axle. The spring bars are essentially torsion bars that enable turning and allow a significantly reduced level of vertical articulation to account for uneven surfaces. 

Caveats and Considerations

It is important to note that weight distribution hitches are supposed to be used within a vehicle’s maximum towing capacity. They do not increase that capacity. Also, keep in mind that a model equipped with rear air springs may level the vehicle but still not return the weight to the front.

Weight distribution hitches do require more setup than a conventional hitch. There are multiple settings regarding hitch height and spring bar mounting to consider, and they should be done when both the tow vehicle and trailer are level. If your trailer doesn’t change much, again, like a camping trailer, you can pretty much set it and forget it. But if the trailer load changes, it will need to be set again. 

Because the spring bars increase the load on the vehicle frame, they should only be used on “truck-based” body-on-frame vehicles. In the case of GMC, that includes all the pickup trucks and the Yukon and Yukon XL SUVs. “Car-based” models with unitized body frames, such as the GMC Acadia, Terrain, and all Buick SUVs, should not use weight distribution hitches as the frame loading can cause body integrity issues. Most trailers with surge brakes are also not compatible with at least chain-style weight distribution hitches. 

When to Use a Weight Distribution Hitch? 

The heavier a trailer is in relation to the weight of the tow vehicle, the greater its effect on the tow vehicle. As a general rule of thumb, you should consider using a weight-distribution hitch when the trailer weighs 50% or more than the tow vehicle. This would apply to Sierra HD vehicles as well.

A GMC Sierra 1500’s weight can range from about 4,440 to 5,780 pounds, so the rule of thumb would recommend a weight distribution hitch for a trailer weighing about 6,600 to 8,600 pounds, depending on your model. But that assumes a tongue weight of 10 to 15% of the trailer weight. If you anticipate a front-heavy trailer, a lower weight threshold should be considered.

Most weight distribution hitches cost between $250 to $500. That is certainly more than a conventional hitch but probably a fraction of what you are towing and certainly a fraction of what you are towing it with, both of which will be better protected by more table towing. And as mentioned, they take more time and effort to set up. But if you are towing something fairly heavy, they are the way to do it correctly. Talk to our parts and service department, we can order and install the correct weight distribution hitch for your vehicle, be it when you purchase new, or after the fact. If you have any specific questions about towing with your GMC truck, ask one of our professionals at Valley Buick GMC or the Valley RV Supercenter.