By Russ and Tiña De Maris
New travel trailer users beware. A big boogieman lurking around the next curve could be your undoing. Trailer sway! The National Highway Transportation Safety Administration reports that about 50,000 trailer sway accidents are reported each year. And many of these are preventable.
A bit of sway can ruin your whole day. What causes it? What can result from it? And what can you do to avoid the perils of trailer sway? Read on!
Watch that loading
One major cause of trailer sway is improper loading. Weight in any kind of trailer should be evenly distributed. Put too much weight on the rear of the trailer, the rear of the trailer can turn into the proverbial pendulum. And the trouble is, once that trailer begins to sway, things can get worse in a hurry—jackknifing your tow vehicle, maybe even rolling your whole combination over with disastrous results.
Too much weight forward, you can actually pull the front tires of the tow vehicle away from the roadway, making for out-of-control steering and braking.
Avoid trailer sway issues due to improper loading. Ideally, 10 to 15 percent of your trailer’s gross vehicle weight should be on the trailer hitch. Got a 10,000-pound trailer? Then look to see 1,000 to 1,500 pounds on the hitch.
How do you know if this is the case? Scale your loaded trailer, ideally knowing the weight on each tire, not just on each axle. When you know the weight of the trailer on its axles, and the weight of the tow vehicle while hitched, then you need to unhitch the trailer. Now run the tow vehicle over the scale and weigh it by itself. Subtract the weight of the tow vehicle from your combined weight, then subtract the weight of the trailer tires (combined axle weight). The result is how much weight is resting on your hitch.
Trailer sway when the wind blows
Other causes of trailer sway happen when a big truck passes you. You soon feel that sinking feeling in your gut as your trailer wants to go with that truck. One or two sway bars between your two vehicles and your trailer can knock that problem out.
Sway controls are friction control devices that reduce the amount of sway a trailer makes. They’re not expensive, and the average do-it-yourselfer can install them.
Adjusting a sway control isn’t difficult. In many cases, the “factory” adjusted point will work. But if you find too much sway, or too tight when turning, readjust the sway control tensioner a quarter turn “on” for tighter, or “off” for looser. Road test and repeat the adjustment as needed. One thing about sway controls: Be sure to turn them “OFF” when you hit an area of wet pavement.
More causes of trailer sway
Other causes of trailer sway include tires that are below proper inflation. Check your tires cold every morning before heading out. Too much “foot in the pot,” as Grampa used to say, can also cause dangerous sway. Slow down!
And here’s another time to really slow down—as in, park it and wait. Areas of high winds can really cause control problems. If high winds are forecast, beware. If you start to feel out of control, get off the road and wait it out.
A 2009 study of commercial towing accidents showed that a 35 mph crosswind can exert 3,440 pounds of force on the side of a large rig. You aren’t as big as a semi, but the point is still this: You are bigger than a passenger car, and the wind is bigger than you.
Coming away alive from trailer sway
What should you do if you encounter a case of trailer sway? First, keep your head. A possible inclination is to hit the brakes. Don’t! Get your foot off the accelerator but stay away from the brake pedal—unless you’re going to hit something. Instead, carefully apply the trailer brakes ONLY, by pushing the manual lever on your brake control.
Practice this while parked so you know how to quickly find and apply the control. Stepping on the tow vehicle service brake is far more likely to really mess things up, but slowing the trailer and allowing it to bring your combination back into control may save your bacon.
There are a couple of interesting (terrifying?) clips of travel trailers that got into trouble when trailer sway overcame them. Watch it, and listen to the commentary. Don’t let yourself become a YouTube video. Prepare your rig, and yourself, to avoid the dangers of trailer sway.
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RVDT2752
Speed and tire pressure are major factors.
Pro Pride trailer hitch totally eliminates sway. Pricey but worth every penny.
Agreed! The first year we had our trailer I followed all the advice and would still end up with cramped hands and knotted neck and shoulders at the end of a driving day. Nerve wracking on the highways when trucks would blow by. Even worse on the plains in any kind of cross wind. I bit the bullet and got the Pro Pride. Now I arrive at camp relaxed and loose. It may be pricey, but like Tom said, “Worth every penny!”
People tow these trailers like they stole them. Zero knowledge of safety considerations.
One major problem is people buying their first trailer scrimp on the hitch. They think the one the dealer ‘gives’ them is the best.
They spend 10’s of thousands of dollars for a trailer and then put on an inexpensive hitch.
Also, one problem with the separate friction sway controls is that is needs to be removed when backing up.
When I bought my first trailer, not knowing, the dealer supplied a low end hitch with friction sway control.
I thought some sway was normal.
Then I splurged and bought an Equalizer hitch that matched the trailer specs. Yes. it was around $800, but the difference was like night and day, and no more removing the friction sway device when backing.
Before you jump into buying a mechanical anti-sway device, read the towing section in your tow vehicle’s user manual! Some tow vehicles come with built-in anti-sway. Combine this with a mechanical anti-sway system may give you worse problems if the two systems fight each other.
Our Subaru Ascent is such a vehicle. The manual is pretty specific that the vehicle’s independent wheel and traction control system will deal with sway and mechanical weight-distribution / anti-sway systems should not be used on the factory receiver. We have been towing since 2020 for thousands of miles and I know how well it works.
That said, also know when wind conditions are just too much.
Also, while the purpose has nothing to do with sway, adding SumoSprings (various designs for different trailer types), not only reduced trailer bounce but reduced trailer lean due to side wind. A side effect has been greater sway resistance in crosswind. But again, know when wind conditions are just too much. Slow down or get off the road.
Where/how does one find a scale to weigh trailer and tow vehicle? I live in a semi-rural area which doesn’t have a Love’s or similar truck stop…. Our county does have a dump which requires weighing, but I doubt they would let me take the time to do all this weighing and unhitching and re-hitching.
Hi, Terry. Here’s a link to a recent post from tire expert Roger Marble, which lists several places to get an RV weighed. Here’s a link to another post from Roger regarding weighing an RV. In it is a page from Bridgestone/Firestone which lists some places where you might find scales you can use. Good luck! And have a great day! 😀 –Diane at RVtravel.com
Call the dump and ask, they shouldn’t mind if there is a time they are not busy. Love’s etc. will probably just charge you twice. Moving companies and suspension shops may also have scales. Also check RVSafety.com/weight for events near you or where you will be travelling.
If you put a Hensley Hitch on the trailer, the sway just goes away. No problems at all. Have a hundred thousand miles on my two trailers and never had any sway from either one of them.