Tongue weight: physics help and options?

[Peds109]

Cross posting from the Ridgeline Owners forum from Honda. Thanks all!

Apologies if this sounds like another “can I tow this?” thread... if you’re willing to read through, the heart of this has to do with tongue weight and understanding the physics and options to consider. But first, the background:

2017 RTL-E with AWD so the traditional 5000/500 tow capacity and hitch rating.

Looking to buy a TrailManor camper. For those unfamiliar, it is a hard shell pop up... or a folding hard side travel trailer, depending how you look at it. Really unique rig. They market themselves as having the best of both worlds and being lighter and better to tow than even most canvas pop ups.

Part of their rationale for their claim of being the most comfortable rig to tow is that it not only has a lower profile than a travel trailer... but the axle is further back than most. This puts more weight on the hitch which reduces sway. Sounds good... except if you have a limited hitch rating.

The model I’m considering is 2800lbs dry and would probably end up at 3500lbs or less when loaded (shorter trips and not carrying fresh/gray will keep weight down). This leaves a remaining 1500lbs for people, cargo, and more. I’m very confident in all the payload, total weight, combined weight, axle ratings, etc. What concerns me is tongue weight.

The TrailManors structurally put higher weights on the hitch because of axle placement. If the 10-15% range, they’re on the higher end. 15% on a 3500 loaded trailer surpasses the 500lb hitch weight before adding a battery or propane tank (much less 2!). And because of the folding nature of the trailer coupled with the axle placement, moving your cargo to or past the axle isn’t much of an option. So I have a few questions I’m hoping people smarter than me can answer:

1 - any general input on this? Has a limited tongue rating hindered anyone else in a Ridgeline even in a lighter RV?

2 - will a WDH help? I know Honda discourages them (their reasoning has been debated) so I’d prefer to avoid, but I’m not certain of their physics. They just ‘distribute’ weight from the rear axle of the TV to the front axle of the TV and the axle of the trailer, right? They don’t actually distribute the downward force on the hitch do they?

3 - if I had excess payload available, would there be benefit in not loading the RV and loading the front of the bed instead? If I reduce the weight of the trailer, hitch weight would come down... but I’d be putting weight on the rear axle of the TV. Is that a better alternative?

Lastly, I’m really trying to do this by the book. I’m looking to stay within payload, total capacity, hitch rating, axle rating, ideally without a WDH, and with margin if possible. I’ll have to eventually hit the scales to get there... but I’m looking for insight on the hitch rating mostly. I appreciate people’s “feel” of their RL... but I’m looking for numbers here, not gut comfort.

Thanks all!
Joe

[commodor47]

Joe,

Some years ago I ran across an excellent explanation of the physics related to a weight distributing hitch. It is a post on Good Sam RV.net.

https://www.rv.net/forum/index.cfm/f...d/14265335.cfm

I hope this will help answer some of your questions.

Dick

[Bill]

Originally Posted by Peds109

Looking to buy a TrailManor camper. ... What concerns me is tongue weight. ... - will a WDH help? ... They just ‘distribute’ weight from the rear axle of the TV to the front axle of the TV and the axle of the trailer, right? They don’t actually distribute the downward force on the hitch do they?

I think I disagree with this conclusion.Think of it this way. The total weight of the tow vehicle and trailer is fixed. Before you crank up a WDH, each axle (TV front axle, TV rear axle, and TM axle) presses down on the ground with some specific force, and they add up to the total weight of the rig. Now if you add a WDH, the total weight doesn't change, but if the TV front axle and TM axle press down on the ground with more weight, then the TV rear axle must press down on the ground with less weight. And part of the TV rear axle weight comes from the hitch. Since nothing else changes, the load on the hitch must reduce.

There is an analogy that is sometimes helpful. It is less rigorous, and a lot simpler than the Good Sam explanation. It goes like this. Suppose that you stand behind a lightweight wheelbarrow that is filled with 175 pounds of gravel. As you stand there (and neglecting the weight of the wheelbarrow itself), let's say the wheel of the wheelbarrow presses down on the ground with a force of 100 pounds, and the legs of the wheelbarrow press down on the ground with a force of 75 pounds. And your feet press down on the ground with the force of your own weight, say 185 pounds. The total weight pressing on the ground is 360 pounds.

Now suppose you lean forward, grasp the handles of the wheelbarrow, and lift with a force of 20 pounds. The ground is still supporting the total 360 pounds, but now it is distributed differently. Specifically, the legs of the wheelbarrow are now supporting only 55 pounds, rather than the initial 75 pounds - the other 20 pounds have been transferred (distributed) to the wheel of the wheelbarrow, and your own feet.

In this analogy, the wheel of the wheelbarrow is akin to the front axle of the tow vehicle. The legs of the wheelbarrow are akin to the rear axle of the tow vehicle. And your feet are akin to the trailer axle. In particular, the weight on the wheelbarrow legs includes the hitch weight, which is reduced by the action of your hands (the lift provided by the WDH).

This analogy works for me, but it doesn't work for everyone. If you can derive benefit from it, I'm pleased.

Bill

By the way, someone is sure to point out that a WDH weighs 50 pounds, so it cancels out its own benefit. It is true that a WDH is heavy, but if it provides 200 or 300 pounds of lift, it is still of benefit. Remember, the whole idea of a WDH is to take load off the tow vehicle's rear axle, and put it elsewhere.

[Larryjb]

Bill has a very good answer for your questions.

I know you wanted to avoid the discussion of how the WDH affects the Ridgeline, but I think you need to consider how the physics of the WDH is going to affect the unique frame of the Ridgeline.

The WDH, as Bill explains, lifts the truck up like you lift the wheelbarrow up. As he said, you are not changing the total weight, just moving more weight to the front. In a traditional body on frame the WDH lifts up the hitch, which is bolted to the frame. As a result, the frame is lifted up at the rear, placing a little more weight onto the front wheels. Because the body is bolted to the frame through body mounts, any twisting of the frame does not add any undue stresses on the the frame/body connections because they are allowed to flex just a little.

In the Ridgeline frame, which is completely welded to the body, any twisting of the frame will put stresses on the weld joints between the frame and body. Just how much of these stresses can this frame/body system take? I don't know, but the welding does not allow any flex between the frame and body.

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I read some discussion about WDH and the Ridgeline, and some of it suggests Honda doesn't want added weight place on the front axle. But keep this in mind. If you hook up a trailer to the back of your truck, that's like standing on the handles of the wheelbarrow. What does that do to the front wheel of the wheelbarrow? It transfers the weight of the front axle to the legs of the wheelbarrow! You now have potentially reduced steering and braking control of the front axle. Using a WDH should not add significant weight to the front axle but, rather, restore the weight to the front axle.

This is one reason why unibody construction has a lower towing rating than full frame vehicles. The 2020 Explorer improved its towing capacity by going back to RWD, but it's towing capacity is still less than that of my 2008 Explorer in part due to its unibody structure.

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My conclusion is that I don't have a conclusion. I don't own a Ridgeline, but you are right to ask those who have a Ridgeline about towing. If some of them have used WDH, find out how much weight they redistribute. Perhaps you can still use a WDH, but don't equalize all the weight and leave your rig slightly tongue heavy.

Do keep in mind the axle rating of your Ridgeline. You didn't mention that. I actually overloaded the rear axle of my Tahoe with my 2720, yet was still 2000 lbs under the total weight limit. That's when I knew I needed a WDH.

Sorry, this was longer winded than I thought I was going to write!

[Larryjb]

Talk to this guy:


from https://www.ridgelineownersclub.com/...-photos.12327/ post #4

[Peds109]

Bill & Larry - much appreciate the thoughtful responses to a towing newbie and prospective owner. I am confident I can make all the numbers (including axle rating) work... and I’m inclined to go without WDH and assess after that. I’ve got a line on a local 06 2720 that will be available in the spring. I’m sincerely hoping it works out... but I’m trying to be as diligent as possible prior.

Thanks again.

[Shane826]

If the seller is local, see if they would be willing to meet up with you at a truck stop with a CAT scale. You could hitch up and weigh each axle to see where you stand and make a real world decision whether the actual weight of the camper will work for you.

[Bill]

Originally Posted by Larryjb

Talk to this guy:
Attachment 18759

from https://www.ridgelineownersclub.com/...-photos.12327/ post #4

Larry -

Good find. Not only is there the photo of a Ridgeline connected to a TM in the photo sequence, but the photo clearly shows a WDH. Beyond that, there are several photos of a Ridgeline towing an Airstream. You can be sure that the Airstream is a lot heaver than a TM, and the hitch weight is higher - and sure enough, the photos clearly shows a WDH.

Bill

[Larryjb]

Even with the WDH, you can still see some squat in the Ridgeline. Either that is because of the added weight of the ATV in the back, or the owner is being conversative with the WDH adjustment.

[lisasTM]

We are borrowing a friends trailmanor and planning to tow with 2019 Highlander XLE. We have installed Redarc brake controller and tough tow WDH. BUT, we are still a bit worried about damaging new Highlander by towing TrailManor with too much tongue weight.
We decided to measure the tongue weight using the methods suggested at Curt. https://www.curtmfg.com/trailer-part...ers/learn-more

First set of measurements using scale at local dump:
highlander w/o trailmanor attached 4940 lbs (2 highlander axles on scale)
highlander WITH trailmanor attached 5500 lbs (2 highlander axles on scale)
----------------------------------------------------------------
tongue weight 5500 - 4940 = 560 lbs

Then we removed 2 propane tanks (30lbs x 2 = 60lbs)
from the tip of the tongue and repeated measurement at local dump
highlander WITH trailmanor attached 5380 lbs (2 highlander axles on scale)
---------------------------------------------------------------------------------
new tongue weight is 5360 - 4940 = 420 lbs.

QUESTION IS: how is it possible to remove 60lbs and change tongue weight by 140 lbs = 560-420 ??
(might have taken bike out of car that would account for 30 lbs)
we also did the other method that CURT suggests with a bathroom scale and got pretty much the same result ??

Can anyone explain why ?? What the heck ?

total rig weight including us was 8460 on dump scale
TM only was 3520 on dump scale