Originally Posted by Mike Magee
If dangerous sway occurs, applying trailer brakes only is the best procedure.
In terms of prevention, the number one thing is to make sure at least 10% of the trailer's total weight rests on the hitch. For a 2500 lb trailer, that's 250+ lbs. Number two thing, if desired, would be some sort of sway control device. Friction bars are helpful, but a WD hitch with built-in sway control is better. I liked using the Andersen No-Sway hitch in the past because it is light
and clean. With my Hauley I don't use anything, but I make sure hitch weight is adequate, and it hasn't even hinted at a sway in thousands of miles. And boy did I have the side gusts, coming home through Wyoming this month.
As Mike has indicated applying brakes to the trailer ONLY is always your best option. Applying brakes to the vehicle can/will make the situation worse.
Having an anti sway bar is an added safety item but it should not be something you rely on to fix a sway issue &/or from actually stopping the trailer from doing a big wag. Personally do not attach one to my trailer until I had done some test runs with my set up to make sure it is as solid as I can get it without the anti sway bar on it.
How much tongue weight you need to obtain a solid tow in all travel conditions are going to change greatly between various tow vehicle and trailer combos. No two set ups are the same.
For example I pulled my 16' Scamp
with a small cross over SUV that was very solid at highway speeds and high cross winds & big truck passing with only around 10% of its totally loaded trailer weight on the tongue. Same trailer in the same state on a different larger tow vehicle required closer to 15% of the total weight on the tongue before it would stop doing little wiggles at highway speeds with light
side winds or trucks passing.
That later combo was also the one and only time in thousands of miles of travel in the past 10 years that I had to use the lever on the brake controller to stop a sway situation that was going south fast!
I do have to take full ownership for the above situation though. I stopped to fill up the water tanks as I was getting close to where we would be camping. Having spent a lot of time working on getting that set up as stable as I could I was well aware that it did not take a lot of changes in the stowage of the trailer to change how it felt, particularly with a side wind. As I started off down a narrow pass at posted speed limit and there was some wind and the trailer started to do a BIG wag.
Once I got it straightened using the brake controller lever I pulled over fast for two reasons #1 to let my heart rate recover and #2 to start searching for heavy items in the back of the tow vehicle to put on the floor of the trailer ahead of the axle
to compensate for the weight of the water at the rear of the trailer had taken off the tongue.
Moral of the above is to always keep in mind when pulling a light trailer it does not take much to change the % of weight on the tongue - empty propane
tanks &/or full water tanks may be all it takes to tip the scale in the wrong direction.
Another issue is when the trailer is too heavy on the hitch for the tow vehicle weight is transferred off the front wheels of the tow vehicle. This can result in loosed braking traction and steering control on the front axle
of the tow vehicle, which is also very dangerous. This is where the use of a WDH is helpful BUT it is also possible to create an equally as dangerous tow set up using a WDH that is over rated for your trailer. An example of a not so good WDH hitch st up would be putting one that is rated for 800 or 1000lbs on a trailer that only has a loaded tongue weight of 400lbs or less, this can/will result in a not so good redistribution of weight
One thing is for sure one needs to weigh the trailers axle as well as tongue in a loaded state in order to even start figuring out what you need to do to set it up correct to achieve a nice solid safe tow.