In the world of travel trailers, the open road beckons with adventure and excitement, but for those who tow, a top topic demands our attention: travel trailer sway. Today, join us as we look into the causes, prevention, and safety measures to tackle this common challenge. Understanding trailer sway is crucial whether you’re a seasoned traveller or just starting your journey. It all begins with proper weight distribution—balancing the load and ensuring even weight on both sides of your trailer is the foundation of a smooth ride.
Now, before we begin, let me say that we have done extensive research, towed our trailer thousands of miles over the years, and have had no incidents.
Let’s start by talking about the side-to-side weight of your trailer. How you load your trailer in terms of side-to-side weight can affect stability and cause you to exceed your weight limits. Let’s take a look at this using our trailer as an example. Our trailer has a slide on the driver’s side, including the kitchen and a few recliners. Also on the driver’s side is the hot water tank, which holds 6 gallons of water—approximately 50 extra pounds on the driver’s side. All these things combined tell me that my trailer will weigh heavier on the driver’s side than the passenger’s before it is packed. I consider this as I pack my trailer, trying to keep some of the heavier items on the passenger side of the trailer.
Now, let’s talk about the front-to-back weights. From here on, our discussion will be about bumper-pulled trailers because that’s our experience. Bumper-pulled trailers’ hitch weight, also known as tongue weight, should be between 10 and 15% of the trailer’s total weight while hitched. We’ll discuss how you can figure that out later in the video. The hitch weight is the weight the trailer places on the tow vehicle. Since the hitch weight will add weight to your tow vehicle, this will be an issue with the payload on your tow vehicle. An easy solution to the payload problem is simply buying a bigger truck.
Now, let’s look at how you pack your camper and how it can affect hitch weight. Think of an RV like a lever, where the wheels act as the fulcrum. The hitch weight will be determined by the trailer’s weight where it attaches to the truck. In my simulation, I placed a 1 kg mass near the fulcrum (or the wheels) to simulate the trailer’s weight before loading. I’m using a force meter to measure the hitch weight. I use a smaller mass to simulate the load I place in the trailer. Notice how the hitch weight changes as I slide the load mass towards the fulcrum or the trailer wheels. This lighter hitch weight does help solve some payload problems for the tow vehicle.
I’ve even seen on social media and some online forums where people suggest packing the back of the trailer to lighten the hitch weight. If your hitch weight drops below 10% of the weight of your trailer, you could have a precarious situation on your hands, contributing to trailer sway. Can you put bikes, a generator, or a canoe on the back of your trailer? Sure, but you’d better be certain of your weight.
Looking at how the engineers have designed your trailer, you may notice the wheels are slightly back from the centre. This increases hitch weight. You’ll also see that the battery and propane tanks are near the hitch, which increases the hitch weight. You also see that the pass-through and under-bed storage are placed near the front of the trailer. This encourages packing that will not make your hitchweight too light for a stable ride.
Let’s look at a simple experiment we did with a model of our truck and trailer on our treadmill in the basement; I found some simple weights around the house, which included some batteries and a plumb bob. When I placed these weights near the front of the trailer and tried to induce sway, I noticed how stable the trailer was. When I placed the weights behind the wheels of the trailer and induced sway, I saw it started to get out of control. I did a secondary experiment with the weights near the back of the trailer but cut the speed by more than half and noticed how much more stable it is. So, speed certainly plays a role as well.
Now, let’s discuss how we can determine if our hitch weight for our trailer is between 10 and 15% of the total weight of our trailer. The simplest way to do this is at a CAT scale. Before we begin, I want to inform you that CAT scales have limitations. If so, the scales must be accurate within 1% of the scale’s capacity to be legally certified. That means if the scale can weigh up to 200,000 lb, there could be an error of up to 200 lb. I have put my truck and trailer on a CAT scale and then reweighed it and seen as much as a 60 or 70 lb difference, and this is without removing anything or adding anything to the truck or trailer. Also, the CAT scale can only give you your axle weights; it cannot tell you the weight of any tyre. But a CAT scale weight is better than no weight.
Now, I’m careful with my packing and don’t typically use the CAT scale to determine hitch weight. Now, if you’re uncertain because you’ve strapped a generator to the bumper of your trailer, you could follow the simple steps to determine your hitch weight at the CAT scale. The first thing I did was weigh just my truck. This meant I needed to find a place to park my trailer. Remember to be courteous to the truck drivers; there were plenty of open spots, and we probably had our trailer there for no more than 5 minutes. Next, weigh the truck with the trailer attached. The first weighing just the car cost $13, and the second weighing just $4. I did the second weight without the weight distribution system connected.
We can see here that the truck’s weight was 5,800 lb. The second weighing shows the truck and trailer’s combined weight is 11,520 lb. Subtract the truck weight from this combined weight, and you will find the weight of your trailer. Calculate 10% and 15% of this weight to find the range that your hitch weight should be in. Now subtract the trailer axle weight from your second and calculated trailer weights. This will be your hitch weight. This should show you whether you need to change how you have packed your trailer.
If you pack your trailer carefully, will you still get sway? Yeah, you sure can. Let’s talk about other things to reduce sway and what you can do if you have sway while driving. But first, let’s talk briefly about how your trailer is hooked up. If your trailer is not sitting level and the hitch is too high or too low, this can throw off all the weights, and all bets are off. A trailer distribution hitch with an anti-sway system is essential. We use the Equalizer weight distribution hitch. It has two bars that use friction to reduce sway.
Finally, we’ll emphasize the importance of safe driving practices—from maintaining the right speed to staying alert. Your journey should be as enjoyable as your destination. From time to time, sway will occur, whether it’s from a passing truck, a crosswind, or just differences in the surface of the road. The question is: What do you do when it happens? I’ll share what I’ve done and give you my opinion on why this works.
When a force is applied to the side of the trailer, it begins to sway and will have a net velocity more significant than the truck as its path is more extended. When you notice the trailer swaying, apply pressure to the brake controller without braking the car. Braking forces the trailer to slow down, matching the truck’s speed. Since speed is simply distance over time, the distance the trailer travels has to match the distance the car travels in the same amount of time. So, the trailer will stop swaying and come in line with the vehicle. Time is of the essence because it only takes a few seconds before the trailer gets out of control. The faster you tow, the quicker things happen, and the less time you have to react.
So, fellow travellers, whether exploring the rugged wilderness or relaxing by the shore, understanding and managing trailer sway is your key to a worry-free adventure. Buckle up, hit the road, and let’s work on this journey together.