How does a WD Hitch affect tongue weight?

[Steven L]

I'll get to my reasons for asking in the first place later in the replies, if this post receives any, but here goes...

Anyone out there have any reality-based data on what if any effect a correctly installed and properly set up WD hitch has on the tongue weight which is being applied to (and counts against the payload capacity) of their tow vehicle?

As I understand it, a certain percentage of that raw payload is being redistributed off (primarily) the rear "drive" axle of the tow vehicle in two directions. Some portion of the distributed weight shifts forward to the front "steer" axle of the tow vehicle, and the remaining portion being distributed shifts rearward to the towed trailer's axle(s), correct?

If my understanding there is correct, does it then follow that:

If the tongue weight is at the recommended ratio of 10% - 15% of the loaded trailer weight PRIOR to engaging whatever the WD method the hitch uses, that recommended ratios lessens AFTER the hitch WD method is engaged?

What I'm getting at here is that (on paper at least) utilizing a WD hitch could possibly cause your tongue weight to drop below 10% of loaded trailer weight, and thusly create the dangerous scenario of sway or loss of control said WD hitch is designed to prevent?

Or am I just overthinking this?

 

[Gary RV_Wizard]

I'll get to my reasons for asking in the first place later in the replies, if this post receives any, but here goes...

Anyone out there have any reality-based data on what if any effect a correctly installed and properly set up WD hitch has on the tongue weight which is being applied to (and counts against the payload capacity) of their tow vehicle?

As I understand it, a certain percentage of that raw payload is being redistributed off (primarily) the rear "drive" axle of the tow vehicle in two directions. Some portion of the distributed weight shifts forward to the front "steer" axle of the tow vehicle, and the remaining portion being distributed shifts rearward to the towed trailer's axle(s), correct?

If my understanding there is correct, does it then follow that:

If the tongue weight is at the recommended ratio of 10% - 15% of the loaded trailer weight PRIOR to engaging whatever the WD method the hitch uses, that recommended ratios lessens AFTER the hitch WD method is engaged?

What I'm getting at here is that (on paper at least) utilizing a WD hitch could possibly cause your tongue weight to drop below 10% of loaded trailer weight, and thusly create the dangerous scenario of sway or loss of control said WD hitch is designed to prevent?

Or am I just overthinking this?

Your understanding of WD is correct but not the conclusion about the change in recommended tongue weight. So yes, you are over-thinking.

The subtlety is that the WD doesn't change the trailer tongue weight at all. You measure the tongue weight before you place it on the hitch and it is what it is. Instead, WD alters how that tongue weight is carried on the tow vehicle, basically moving it around so it is less of a burden on the rear axle and suspension.

 

[Ex-Calif]

Gary, as usual, is 100% correct.

I will add that the weight of the WD hitch is truck/tow vehicle payload.

In theory the WD hitch also reduces weight on the rear axle but it is definitely not worth noodling over because once you are set up and you weigh - the weights will be the weights and you'll have an idea how much (if any) capacity you have left in the towing vehicle.

 

[Tulecreeper]

Gary is correct. I guess to put it a bit simplistically, the WDH pushes up on the back of your truck, shifting some of the weight forward. The hitch weight remains the same, but a little of the responsibility for holding it up has been shifted forward to the front wheels.

 

[Onyrlef]

I'll get to my reasons for asking in the first place later in the replies, if this post receives any, but here goes...

Anyone out there have any reality-based data on what if any effect a correctly installed and properly set up WD hitch has on the tongue weight which is being applied to (and counts against the payload capacity) of their tow vehicle?

As I understand it, a certain percentage of that raw payload is being redistributed off (primarily) the rear "drive" axle of the tow vehicle in two directions. Some portion of the distributed weight shifts forward to the front "steer" axle of the tow vehicle, and the remaining portion being distributed shifts rearward to the towed trailer's axle(s), correct?

If my understanding there is correct, does it then follow that:

If the tongue weight is at the recommended ratio of 10% - 15% of the loaded trailer weight PRIOR to engaging whatever the WD method the hitch uses, that recommended ratios lessens AFTER the hitch WD method is engaged?

What I'm getting at here is that (on paper at least) utilizing a WD hitch could possibly cause your tongue weight to drop below 10% of loaded trailer weight, and thusly create the dangerous scenario of sway or loss of control said WD hitch is designed to prevent?

Or am I just overthinking this?

Doesn’t require any theorizing or armchair engineering at all. Simply take your truck and trailer to a Cat Scale. Weigh it without the WDH engaged and then with, if the weight of the truck hasn’t changed ( GVW) then tongue weight hasn’t changed. Because as long as the trailer is hooked to the truck the only thing that can materially affect the trucks GVW in that configuration is tongue weight. It’s really that simple.

 

[Onyrlef]

I'll get to my reasons for asking in the first place later in the replies, if this post receives any, but here goes...

Anyone out there have any reality-based data on what if any effect a correctly installed and properly set up WD hitch has on the tongue weight which is being applied to (and counts against the payload capacity) of their tow vehicle?

As I understand it, a certain percentage of that raw payload is being redistributed off (primarily) the rear "drive" axle of the tow vehicle in two directions. Some portion of the distributed weight shifts forward to the front "steer" axle of the tow vehicle, and the remaining portion being distributed shifts rearward to the towed trailer's axle(s), correct?

If my understanding there is correct, does it then follow that:

If the tongue weight is at the recommended ratio of 10% - 15% of the loaded trailer weight PRIOR to engaging whatever the WD method the hitch uses, that recommended ratios lessens AFTER the hitch WD method is engaged?

What I'm getting at here is that (on paper at least) utilizing a WD hitch could possibly cause your tongue weight to drop below 10% of loaded trailer weight, and thusly create the dangerous scenario of sway or loss of control said WD hitch is designed to prevent?

Or am I just overthinking this?

It is, the WDH works by means of momentary torque and moving the virtual leverage point on the towed vehicle rearward. When the leverage point moves forward some ~15% of the affective TW is transferred to the axle of the trailer and ~30% is transferred to the front axle of the towing vehicle. If you for example have a class III hitch with a 500 lb TW rating, that rating goes up by half again if you engage a WDH. If your hitch is in real terms capable of only a 500 lb TW without the WDH it’s still only capable of 500 lbs with the WDH engaged. You can now load 750 lbs on it because 250 won’t be there when the WDH is engaged.

 

[Tulecreeper]

The purpose of a weight-distribution hitch is to restore weight to the front axle that was transferred to the rear axle of your tow vehicle when you set the trailer tongue on the hitch. In doing so, it also transfers some of the hitch weight to the axles of your trailer.

This can be a difficult concept to grasp – but a weight-distribution hitch doesn’t reduce the tongue weight of your camper! It applies a moment (torque) at the connection to reduce the hitch weight seen by your truck.

You can't cheat the system. If your tow vehicle is rated for 1,000 lbs hitch weight with a weight-distribution hitch, you can’t sneak in some extra pounds by subtracting the transferred weight.

The Big 7 Misconceptions About Weight Distribution Hitches - Ask the RV Engineer

If you’ve read my article on the hidden danger of a weight-distribution hitch, you might be wondering what else you thought you knew that isn’t true! I’m a big fan of weight-distribution hitches. If you’re towing with a half-ton truck, I’m 99.5 percent positive you either need or could benefit...

askthervengineer.com

 

[Steven L]

Thank you for all of the replies. My reason for asking lies in the amount of weight being placed on my F150 which I will need to count as payload which then decreases the remaining amount of GVW I have available as rated by Ford.

For some reason my brain was pondering the possibility that since SOME of that tongue weight is being distributed away from the tow vehicle and on to the towed trailer, that would mean whatever portion of that weight is being transferred off MUST no longer count as payload on the truck.

As my truck now with only myself, my wife, our two dogs, the WD hitch head itself, a full tank of go-go juice & a few items in the cab and bed weigh in at 6430# at my nearby CAT scale. With a GVWR of 7200# as read from the DOT sticker Ford placed on the driver's door panel, that would leave me 770# of available payload which I'm budgeting as tongue weight only, and to be a bit safe I'll be rounding that down to 750#.

So I've been restricting my search for a travel trailer t only those models that I can reasonably assume will yield no more than 725# of hitch weight once I'm loaded up and cargo in the trailer is distributed to hit just over a 10% mark given the GTW. That would be a GTW of a touch over 7250#.

The bugaboo which was pestering me in estimating all of this was that percentage of approximately 15% of hitch weight "payload" which gets sent to the trailer's axle(s) once the WD hitch is performing it's intended task.

15% of 725# transferred off the truck was reading to me as a tongue weight AFTER engaging the WD side of the hitch changing to an "Actual" tongue weight going down the road as now closer to 616#... the upshot then being that I've now messed up my calculated 10% tongue ratio at rest nearer to 8.5% in actual practice when moving.

But somehow I must be wrong here... and 15% of that load pressing down on the tow vehicle really isn't being transferred off the rear axle and on to the trailer.

Correct?

 

[Steven L]

The purpose of a weight-distribution hitch is to restore weight to the front axle that was transferred to the rear axle of your tow vehicle when you set the trailer tongue on the hitch. In doing so, it also transfers some of the hitch weight to the axles of your trailer.

This can be a difficult concept to grasp – but a weight-distribution hitch doesn’t reduce the tongue weight of your camper! It applies a moment (torque) at the connection to reduce the hitch weight seen by your truck.

You can't cheat the system. If your tow vehicle is rated for 1,000 lbs hitch weight with a weight-distribution hitch, you can’t sneak in some extra pounds by subtracting the transferred weight.

The Big 7 Misconceptions About Weight Distribution Hitches - Ask the RV Engineer

If you’ve read my article on the hidden danger of a weight-distribution hitch, you might be wondering what else you thought you knew that isn’t true! I’m a big fan of weight-distribution hitches. If you’re towing with a half-ton truck, I’m 99.5 percent positive you either need or could benefit...

askthervengineer.com

This part I'm understanding better now, but my issue is virtually the same as I've seen and read about from countless others... I will never need concern myself about blowing past the Hitch Weight rating of my Class-IV receiver (in my case that being 1050# with a WD hitch).

Rather, I will be limited by maxing out my F150's GVWR of 7200# long before my receiver sees #1050 since (in my specific case) I only have 750# of payload available to use, which will be taken up PURELY by the tongue weight of the trailer I'm hooking up to it.

Does that make my dilemma clearer now?

 

[Steven L]

To repeat for emphasis, I've no concern at all that I'll overload my hitch receiver... my ony concern is overloading my truck's GVWR with a hitch weight greater than 750#>

The fly in the ointment appears to be finding a method or equation which will mathmatically calculate an accurate tongue weight, prior to settling on a travel trailer which I can confindently load to a certain weight, and know I'll not exceed my GVWR and compromise the handling of or damage my truck.

One thing I know for certain in that can of worms is I no longer trust ANY manufacturer's published hitch weight values at their published trailer weights. I picked up a tongue scale I know to be accurate within +/- 25# which I'll be using to verify manufacturer numbers when I'm on a dealer lot.

I've read enough comments on those published numbers ALWAYS being light comapred to the actual weights.

EVERY... DAMN... TIME!

 

[Contributor]

For some reason my brain was pondering the possibility that since SOME of that tongue weight is being distributed away from the tow vehicle and on to the towed trailer, that would mean whatever portion of that weight is being transferred off MUST no longer count as payload on the truck.

This is true. The weight that gets moved from the hitch of the tow vehicle does end up on the trailer axles. This definitely reduces the weight on the tow vehicle even though the sum of all of the distributed weight remains the same - thus tongue weight is not reduced. just that less of the tongue weigh is on the tow vehicle.

 

[Tulecreeper]

Here is a way to measure tongue weight using a bathroom scale. It's amazingly accurate.

 

[Steven L]

This is true. The weight that gets moved from the hitch of the tow vehicle does end up on the trailer axles. This definitely reduces the weight on the tow vehicle even though the sum of all of the distributed weight remains the same - thus tongue weight is not reduced. just that less of the tongue weigh is on the tow vehicle.

This is exactly what I was questioning in my initial post, reading the title again just now caused me to realize I phrased my point poorly.

So am I correct then to assume that since some portion of the tongue weight "payload" is no longer being brought to bear on my tow vehicle, I am able to add some of that weight back to the truck with added cargo in the trailer, and by doing so I would also gain the needed weight to get back to or over my "10% of GTW" ratio on the tongue itself?

 

[Onyrlef]

This is exactly what I was questioning in my initial post, reading the title again just now caused me to realize I phrased my point poorly.

So am I correct then to assume that since some portion of the tongue weight "payload" is no longer being brought to bear on my tow vehicle, I am able to add some of that weight back to the truck with added cargo in the trailer, and by doing so I would also gain the needed weight to get back to or over my "10% of GTW" ratio on the tongue itself?

All the quoting other people and arm chair engineering are moot. If you've already got the trailer, truck and wdh, go weigh it, with and w/o the wdh engaged. if your truck weighs less with the wdh engaged then there's less tongue weight bearing down on the hitch ball, ie., your tongue weighs less, if there's no difference then your tongue weight hasn't changed, it's not magic, it's physics.

 

[Contributor]

The amount of weight moved to the trailer axles is not much. I don't remember the percentage but it's not enough to make much difference. most of the weight that gets moved goes to the front axle of the tow vehicle. Where it helps is, staying within the TV rear axle rating, not necessarily the TV GVWR.

 

[Onyrlef]

The amount of weight moved to the trailer axles is not much. I don't remember the percentage but it's not enough to make much difference. most of the weight that gets moved goes to the front axle of the tow vehicle. Where it helps is, staying within the TV rear axle rating, not necessarily the TV GVWR.

~15% to the trailer axle, ~30% to the tow vehicle front axle.

 

[Contributor]

~15% to the trailer axle, ~30% to the tow vehicle front axle.

sounds about right, I was thinking maybe a little less than 15%, but sounds about right. So for 700 lb tongue weight, about 100 lbs get moved to the trailer axles.

 

[Ray-IN]

Yes a WDH adds weight to the trailer axles, and both axles of the tow vehicle.
This without a doubt the best, most complete explanation of how to properly set-up a WDH I've ever seen or read.

Also, this WDH calculator is fun to play around with: Trailer Towing Calculator: Weight Distribution Hitch

 

[Onyrlef]

sounds about right, I was thinking maybe a little less than 15%, but sounds about right. So for 700 lb tongue weight, about 100 lbs get moved to the trailer axles.

Yes and a couple hundred to the TV front axle. That's why a receiver hitch lists two allowable tongue weights, the upper weight, that is w/wdh, is >~50% higher than the lower weight w/o wdh. IOW's if the unhitched tongue weight is ~735 lbs, you can with a wdh hitch to a classIII 500 lb. TW hitch.

 

[Steven L]

The amount of weight moved to the trailer axles is not much. I don't remember the percentage but it's not enough to make much difference. most of the weight that gets moved goes to the front axle of the tow vehicle. Where it helps is, staying within the TV rear axle rating, not necessarily the TV GVWR.

sounds about right, I was thinking maybe a little less than 15%, but sounds about right. So for 700 lb tongue weight, about 100 lbs get moved to the trailer axles.

For my particular case being able to subtract around a hundred pounds of hitch weight from what I'm accounting for as payload in my towing vehicle is actually rather a large difference... seeing as how at a strategically loaded trailer with it's tongue bearing 10% of it's GTW translates into another 1000# of weight available to be added to the "towed" side of the equation, so to speak.

Even though I will likely make use of that 100# which has been freed up to load a few more items in the bed of my truck when towing.