Dangers of Improper Tongue Weight

Safe towing requires a certain amount of downward pressure on the hitch ball, called tongue weight, to ensure that the trailer will tow straight and remain stable. Do you know what happens when you tow with improper tongue weight? There are two main categories of catastrophes: those caused by not enough tongue weight, and those caused by too much.

What you do not have enough tongue weight the following can happen, as shown in the video:

#1 – Trailer sway: ‘fishtailing’ or side-to-side movement
If you hook up your trailer with less than 10% of your GTW (Gross Trailer Weight) situated on the tongue of your trailer you will have:

-too little tongue weight
-too much of your load situated behind the axle of your trailer
-an unlevel tow set-up that “peaks” at the hitch connection
-conditions in which trailer sway will most likely occur

Why is trailer sway so dangerous? Let us explain…

#2 – Loss of steering control
The swaying side-to-side movement of a trailer can escalate very quickly, especially when you’re traveling fast. Enough momentum caused by the sway-force of your trailer can completely, and swiftly, overturn your truck in a matter of seconds.

Although this video does not demonstrate the effects of too much tongue weight, it does show you what can happen if you have too little tongue weight. This video demonstrates just how vital it is to keep your tongue weight within 10-15% of your GTW (Gross Trailer Weight).

If you want to know more about what happens with too much tongue weight, check out this blog article on our website for more information:

[mafosa]

Everyone who buys a trailer. should be required to watch this video!

[richardhenry]

I have known this for a long, long time. When I first got an old trailer, the axle was dead centered. But I knew how to pack it. but one time I knew it wasn't right. When I was driving down I95 it started to sway. People panic when this happens, slow down, brake it. not jam it. You slow it down just fast enough to stop this issue. Experience goes a long way. After I got home from my trip, I made PLANS to change this issue, I moved the axle 6"inches back. Never had the problem since. I have seen a lot of stupid out there when it comes to people with trailers, that don't have a (Thank you for showing this )

[eldridge]

The moral of this video is, don't put your beer cooler in the back of the boat. It could land in someone else's vehicle and you don't want to give someone else free beer. ;-)

[tralwil]

Swaying all over the road!! WATCHED the video, readjusted my load and smooth sailings. Thank you

[markkowaleski]

Absolutely brilliant. As a retired NASA aerospace engineer, I can tell you this is perfection. And no math!

[lexstockton]

I’ve been in a vehicle (Chevy El Camino) with too much tongue weight. Pretty much like the demo except on a steep downhill the front tires got light and the driver showed me he could turn the wheel and not much happened. I’m very happy it was a straight down hill road. I’d never seen the driver (my father) scared in a car, he had driven about everything short of a tank at that point and was pretty hard to upset. We had no trouble rearranging the load afterwards, that kind of fear is very motivating. Be smart, get your loading right before your experience this particular thrill.

[jonbradley]

Just compelling. Well done! Nice edit.
I have learned quite a bit more seeing the model interact in the physical simulation.
I look foreword to more of your teams work.
Consider placing a box fan in front of the model in motion and "threadding" up the surfaces with attached stringlets. Very visually appealing.. Seeing weight distribution combined with a visual of air, moving over the surface. Laminar and flow separation interactions will be fun to set up and film, and add layers of understanding of how these forces interact.
Everyone can relate to toys, let them be science toys for fun learning.

[eldridge]

In all seriousness Weigh Safe, as someone else in these comments pointed out, you should do a video without the music. Nobody wants to watch videos with music in the background or other noises. If people want to listed to music, they can do that on their own. People are here to try to learn something about towing and not have to listen to some music. Anyway, also, you should put out the video with them explaining things. Although this video is fairly self explanatory with the text in the video, some people just like to hear how it's explained from a human's mouth.

[itmagic]

Super great test, and very, very important! Just purchased your truck hitch with built in scale to safely carry a 5-7000lb tractor on a new 20 ft trailer I just purchased. Thank you for the fantastic lesson and informative information!

[davidbower]

Never saw it like that. Makes perfect sense.

[MrBowser]

Great illustration! Now get back to work! I have a back ordered heavy that I can’t wait to install 😁

[mebeingU]

Couldn’t you have deleted the drama filled music and used a narrator to explain the process and weight changes instead?

[sef]

Notice how safe the boat tows when you keep your beer cooler in the bow of the boat. ;-) Seriously this video is an example of what will happen when towing an improperly loaded trailer.

[justinwhitmer]

Thanks for the knowledge and your time to make this video.

[Mato]

In europe a ave. car/SUV has a tongue weight between 75-100kg. Small caravans to mid-caravans are already at 1200-1600kg GTW. So we will never ever get the 10-15% 😳😳😳

[reubenjanzen-martin]

Have you done a similar test that varies the distance between the hitch point and the tow vehicle back axle? That would be nice to see in a scale model demonstration. I'm looking for a new tow vehicle and wondering how much impact that variable has on stability.

[fredm]

What would results be for trailering with a bicycle? Parameters:
1) 70lb electric bicycle
2) capable of 28mph (class 3) with a
3) 150-200lb rider,
4) pulling a trailer rated at 100lbs loaded with 50lbs.

Differences in parameters & conditions from the Youtube experiment:
1) tongue weight is fully on the bicycles rear axle, and therefore
2) the tongues vertical pivot point is not creating a lever effect to the towing vehicles' (the bike) rear axle, and
3) with the bike, there is one fewer vertical pivot point to consider ... which makes towing loads on a trailer much less prone to issues demonstrated with the car towing loads ... although similar forces are still in play here but are somewhat dampened.
4) with typical & common speeds, both ave and top speeds are significantly slower than those used in the car use case in this Youtube

So the above use case is real. I installed a beefy mid drive motor on my bike, bought a beefy 30lb additional spare battery to lug around in the trailer, with the trailer loaded with an additional 30lbs worth of gear, bringing total weight to 70lbs. I have gone downhill confidently with this going as fast as 37mph with no sway, no noticable vertical pivoting issues w the tongue, and no control issues when recovering from quick maneuvers around pot holes, debris, rocks, sewer covers, uneven road repair humps.

The battery is secured to one side of the rear trailer with bugee cords ... the battery itself is secured within of a marine battery case. Center of gravity with the additional 30lbs of gear looks like it is in quadrant IV of center of gravity for trailer alone, perhaps 10% to the right of center, and 30% below center.

Could load imbalance be not as severe in this use case as the car be perhaps due to lighter weights, fewer vertical pivot forces, and slower speeds. I would like to see real life demonstration of these forces in action using their test lab environment on a bike & bike trailer!

Ive run over a pothole at 30mph with the lighter side of the trailer and felt a horizontal sideways force on the rear wheel for a long moment ... perhaps 1-2 seconds, triggering my spidey senses into alert mode (aka *panic*) for the next 15 seconds warning me of pending doom ... but am here to tell you nothing came of it. Same for running over a big rock at similar 'high speed' (about 28mph) about the size of an egg under the heavy side of the trailer ... with spidey sense going off for a few moments, followed by about 1-2 seconds of horizontal force on rear wheel, and 15 seconds of feelings of dread ... but again, with no trauma to report. Both of these experiences are certainly more sensitive and therefore dangerous if experienced in wet or icy conditions.

So there you have it. Maybe all these variables are simply not able to produce enough amplitude to provide any similar catastrophic effect as with a car+trailer going at 35 or 55 mph. But I think seeing these forces in play would be worthwhile and super fascinating to see in these guys' workshop. Particularly to see where any inflection points can be observed in range of data inputs (varying center of gravity and at varying speeds)

[Sabumnim]

Good test but there is one issue not accounted for and that is that the car is on a fixed point, . Try this again but tether the car with rope at at least as long as the car.
I agree with 7.5 to 15% on the ball but 15% and above may not be as good as putting most of the weight over the trailer axles with the 10% on the ball.

[jonathanjuarez]

Can you guys do a video pulling dobles, that can be helpful too, thanks for this video

[rogerbannon]

It’s easy to do when you know the weight of a boat or 4x4, I want to know how people know the weight when moving boxes and furniture that you might not have weight specs for. Getting ready to do a tow of all my totes and maybe a rocking chair or two along with odds and ends, free up some space in my little apartment. Nervous as hell about getting the weight distributed correctly, I live in the UP of Michigan and no weigh scales anywhere nearby.