Question, purely for intellectual curiosity... hitch weight vs UVW towing.

[Juany118]

I know this is getting into the weeds, and this is a question purely out of intellectual curiosity. Is tongue/hitch weight subtracted from UVW, for the purposes of towing calculation. Let me give an example.

A hypothetical 5000 lbs UVW trailer has a tongue weight of 500 lbs. Since the 500 lbs is applied to the vehicle's payload capacity does this mean you are *technically* only using 4500 lbs of your vehicle's towing capacity?

I know I tend to over think stuff and this question has had me scratching my head for a bit.

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[Davidjc]

I know this is getting into the weeds, and this is a question purely out of intellectual curiosity. Is tongue/hitch weight subtracted from UVW, for the purposes of towing calculation. Let me give an example.

A hypothetical 5000 lbs UVW trailer has a tongue weight of 500 lbs. Since the 500 lbs is applied to the vehicle's payload capacity does this mean you are *technically* only using 4500 lbs of your vehicle's towing capacity?

I know I tend to over think stuff and this question has had me scratching my head for a bit.

No. The 500 lb hitch weight will take away from your cargo capacity (the amount of weight your truck can Carry). The 5000 lb trailer weight will be taken from your truck towing capacity *the weight your truck can Pull.) You will usually run out of cargo capacity before towing capacity,but not always. You're asking good questions.

 

[Big Blue]

I know this is getting into the weeds, and this is a question purely out of intellectual curiosity. Is tongue/hitch weight subtracted from UVW, for the purposes of towing calculation. Let me give an example.

A hypothetical 5000 lbs UVW trailer has a tongue weight of 500 lbs. Since the 500 lbs is applied to the vehicle's payload capacity does this mean you are *technically* only using 4500 lbs of your vehicle's towing capacity?

I know I tend to over think stuff and this question has had me scratching my head for a bit.

Boy, did you ask a interesting question! The quick answer is No! The tongue weight is not subtracted from the trailer weight when looking at towing capacity. And yes it is also added to the payload weight on the tow vehicle when looking at the payload rating of the tow vehicle.

Now the fun party and there will probably be some who will disagree with some of what I am about to say.

UVW (unloaded vehicle weight) is really not a useful term for what you are talking about. You need to deal with loaded vehicle weight or gross vehicle weight of the trailer (GVW). Which is different from the GVWR of the trailer, that is a maximum weight your trailer is rated for, don't exceed it. Here's the controversial part. The towing capacity of your vehicle is really a performance type rating and is given as a maximum number for your vehicle model. The numbers that you need to be concerned about are the GVWR of your to vehicle and the GVWR of the trailer along the the GCVWR (gross combined vehicle weight rating) of your tow vehicle. Other weight rating to be concerned with are the axle weight ratings for the tow vehicle and the trailer. Tongue weight should be between 10 and 15 percent of your trailers GVW.

Now the only time these numbers come a big concerns is if you are planning on towing close to the maximum numbers for your tow vehicle. It is also good to know your axle weights to help with setting up your weight distribution hitch, if you are using one.

 

[Juany118]

Boy, did you ask a interesting question! The quick answer is No! The tongue weight is not subtracted from the trailer weight when looking at towing capacity. And yes it is also added to the payload weight on the tow vehicle when looking at the payload rating of the tow vehicle.

Now the fun party and there will probably be some who will disagree with some of what I am about to say.

UVW (unloaded vehicle weight) is really not a useful term for what you are talking about. You need to deal with loaded vehicle weight or gross vehicle weight of the trailer (GVW). Which is different from the GVWR of the trailer, that is a maximum weight your trailer is rated for, don't exceed it. Here's the controversial part. The towing capacity of your vehicle is really a performance type rating and is given as a maximum number for your vehicle model. The numbers that you need to be concerned about are the GVWR of your to vehicle and the GVWR of the trailer along the the GCVWR (gross combined vehicle weight rating) of your tow vehicle. Other weight rating to be concerned with are the axle weight ratings for the tow vehicle and the trailer. Tongue weight should be between 10 and 15 percent of your trailers GVW.

Now the only time these numbers come a big concerns is if you are planning on towing close to the maximum numbers for your tow vehicle. It is also good to know your axle weights to help with setting up your weight distribution hitch, if you are using one.

It was actually interesting because a representative of the Pennsylvania Department of Transportation, who is responsible for regulations related to commercial towing said that "technically" my premise is correct, when it comes to the weighing process at a scale.

As you say though they also weigh GVCW. So in my hypothetical, trailer only, the GVCW of my set up would be ~9400 lbs (curb weight + trailer weight) but the trailer weight alone, while hitched, would be 4500 lbs at the trailer axel because 500 lbs is being born by the rear axle of the tow vehicle.

I didn't ask PennDOT directly by the way. I posted this question on a Facebook group as well and someone else responded.

 

[Juany118]

No. The 500 lb hitch weight will take away from your cargo capacity (the amount of weight your truck can Carry). The 5000 lb trailer weight will be taken from your truck towing capacity *the weight your truck can Pull.) You will usually run out of cargo capacity before towing capacity,but not always. You're asking good questions.

That's all understood. Now PennDOT answered my question but let me be more clear regardless.

A trailer just standing there weighs 5000 lbs dry *if* I was to hitch it to a truck 500 lbs of that 5000 would be hitch weight. That hitch weight is calculated as part of the vehicle's payload, in the case of my Ranger, almost 1600 lbs. So does that mean my Truck now has 1100 lbs of payload capacity remaining and is effectively only using 4500 lbs of its towing capacity.

As I said in my other response, both contribute to reaching the 12,500 lbs GCVW of the vehicle. This is more about me understanding things so I can make a proper spreadsheet for safer loading/towing.

 

[Big Blue]

It was actually interesting because a representative of the Pennsylvania Department of Transportation, who is responsible for regulations related to commercial towing said that "technically" my premise is correct, when it comes to the weighing process at a scale.

As you say though they also weigh GVCW. So in my hypothetical, trailer only, the GVCW of my set up would be ~9400 lbs (curb weight + trailer weight) but the trailer weight alone, while hitched, would be 4500 lbs at the trailer axel because 500 lbs is being born by the rear axle of the tow vehicle.

I didn't ask PennDOT directly by the way. I posted this question on a Facebook group as well and someone else responded.

The point is you are still towing 5000 lbs, it is just that the trailer AXLE weight is only 4500 lbs. At the scales the only thing they can read is the axle weights. And the main rating they are concerned about is the GCVW for your tow vehicle. Again the advertised towing capacity is really just a performance number and not an actual legal rating they can charge you for. As long as you are under the listed GCVWR for your tow vehicle you are good to go. The axle weight rating are where you risk damage to components if you exceed them, bearings, axles, Wheels and tires. That is the benefit of WDHs to take some of the weight off the rear axle and distribute it to the front (steering) wheels and to the trailer axle(s). On commercial vehicles they also have enforceable axle weight limits.

 

[Big Blue]

As I said in my other response, both contribute to reaching the 12,500 lbs GCVW of the vehicle. This is more about me understanding things so I can make a proper spreadsheet for safer loading/towing.

One last small point, well maybe not so small, the 12,500 lb GCVWR for the Ranger is for a 4x4 crew cab. If you have a 4x2 or a super cab it is less. Also you and all passengers are considered payload along with any weighty mods you have made.

As I said an interesting question. One with many nuances when hauling/towing near anyone of you vehicles weight ratings.

 

[Juany118]

One last small point, well maybe not so small, the 12,500 lb GCVWR for the Ranger is for a 4x4 crew cab. If you have a 4x2 or a super cab it is less. Also you and all passengers are considered payload along with any weighty mods you have made.

As I said an interesting question. One with many nuances when hauling/towing near anyone of you vehicles weight ratings.

Your point regarding tow rating and payload, as it relates to GCVW is well taken.

For context my Ranger is the 4x4 Supercrew, not 4x2, and with my current spread sheet I include passengers, dogs, etc into the payload calculation. Currently I have no concerns with towing. My current trailer maxes out at 5500 GVWR. This exercise was more about gaining a better understanding of how the vehicle and trailer interact with one another, if in the future I start looking at trailers that start approaching 7000 GVWR. The closer we get to max ratings, the better I want to understand how everything integrates.

Thank you for all of the input!

 

[WOADKIL]

Simple physics: you are asking about two different directional vector forces that are not necessarily linked. One is gravitational pointing to the center of the Earth (load). The other is inertial that is in the direction of motion (towing).

Discuss...

 

[Juany118]

Simple physics: you are asking about two different directional vector forces that are not necessarily linked. One is gravitational pointing to the center of the Earth (load). The other is inertial that is in the direction of motion (towing).

Discuss...

But as was pointed out the GCVW is what goes to the inertial portion of the equation. The reason for my experiment was, largely, to confirm that fact. Look at it this way

A Maxed out Ranger 4x4, with the 2.3 Ecoboost, has a GCVW of 12,500 lbs. Now hitch weight obviously goes to payload, want to be safe regarding suspension and handling etc. The reason I asked the question was to see whether or not you counted the hitch weight once (as payload) or twice (as payload and as part of the towed unit). It appears the answer is once, not twice.

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