Calculating Trailer Tongue Weight quickly on the road

To calculate trailer tongue weight is pretty easy if you have the right pieces of information.

You just need;

  1. The weight of the tow vehicle alone.

  2. The weight of the tow vehicle with the trailer attached.

One of the easiest ways to determine tongue weight is to weigh the tow vehicle then weigh the tow vehicle with the trailer attached and do a little math but there are some other options depending on your situation.

trailer hitched

4 Ways to Calculate Trailer Tongue Weight quickly on the road.

1.  Spend the money and get a tongue weight scale.

This is the easiest way out and will pay for itself.  These are nifty devices that really should be at each marketing vehicle fabrication facility.  Unfortunately in our experience they are not.  The con’s of these devices are the added cost, they must be stored properly, and lugging around something that you only need once or twice per project (hopefully).  However to be fair they are remarkably small and light weight, possibly fitting in a glove compartment or center console.  We found one for around $125.  So at $11 per trip to the scale it will pay for itself after the 12th weigh. (and that doesn’t include re-weighs!)

We chose this scale from Sherline ( 5000lbs Trailer Tongue Weight Scale ).  It seems to be most affordable and looks the exact same as the Reese and others.  It has a weight capacity that exceeds anything you will tow on a bumper hitch and could probably handle some some smaller goosenecks.  If you have a stock 1 ton truck you should not have a bumper pull trailer that exceeds around 2000 pounds in tongue weight.  If you do look into an aftermarket HD hitch.  Also, as the truck wars go on the stock hitch capacity will likely increase past 2000 pounds and already has in some cases.

2.  Just Estimate… at your own peril.

A bumper pull trailer should deliver 5%-10% of its total weight to the tongue or hitch.  So it you have a trailer with a GVWR of 10,000 pounds and assuming you don’t over load it, the tongue should be receiving 500-1000 pounds of the weight at a maximum right?

(Goosenecks should deliver 15-20% of their total weight to the bed hitch.)

The answer can be a little less clear.  There are 2 assumptions being made here that are more significant in the custom trailer world than in other applications.

  1.  Relying on proper weight distribution. If you go to a well known trailer manufacture and purchase a generic cargo trailer you can bet money the weight distribution will be inside of the ranges mentioned above, unless you load it wrong (see item #2). However, in the marketing world a lot of custom trailers are built as one off’s. That’s often the point right, to create a unique brand experience using a unique platform? Due to bad estimations or more likely just innocent changes in scope during the build process these custom trailers can be nose heavy or nose light both of which are not good.
  2. Overloading,  more often the culprit, means the tow vehicle or trailer exceeds its GVWR, and legally it would be considered overweight. It can also be overloaded due to poor weight distribution. Take a look at the the trailers listed on this website for example. In many the generator and the storage are in the nose of the trailer. So on launch day as the team loads up samples, collateral, and sand bags into the nose there is a potential to overloaded the tongue. The trailer may not exceed GVWR but it will exceed the max tongue weight of the hitch components. You are only as strong as the weakest link and the weakest leak on a bumper pull is typically the hitch components.

Tongue weight calculator

3. Calculate the tongue weight and drive safely.

As soon as we pick up a trailer we head to a scale to make sure we are under the GVWR of each asset and under GCWR of the combination.  We also check the tongue weight. It costs $10-15 and takes 10-15 minutes. Usually a scale is within 10-20 miles of a pickup and if you are pulling a trailer for the first time you should be getting out to check the trailer and the interior load anyway.

If the hookup doesn’t pass a visual inspection at the pick up there is no need to head to the scale, adjust the load prior to departure.

To save time you should scale the tow vehicle before you pickup the trailer.  Hitting a scale prior to picking up the trailer at the fabricator will save having to detach later.  This only works if the truck is already packed.  If you scale the truck and then load up the truck bed with samples, supplies, or luggage you will have to re weigh.  The truck needs to be basically the same each weigh.

If you are not able to weigh the truck prior to picking up the trailer simply weigh the combination (truck and trailer), then drop the trailer and ask for a re-weigh for just the truck.

Either way you do it once you have these 2 pieces of information you can calculate tongue weight.  And if you need to calculate tongue down the road you only need to scale the combination since you already have the tongue weight.

If you need help on how to use a scale Cat has instructions for most combinations including pickup truck and trailer.  They have videos too.

As shown in the diagram shows the truck needs to have the front or steer axle on the pad #1 and the rear or drive axles on the pad #2.  For this method of tongue weight the trailer doesn’t really matter.  So to calculate the tongue weight for this method you add the pad #1 and #2 numbers with the trailer attached and subtract them from the weigh ticket for just the truck.  The difference is the tongue weight.

Cat Scale: how to scale a truck

So to calculate the tongue weight for this method you add the pad #1 and #2 numbers with the trailer attached and subtract them from the weigh ticket for just the truck. The difference is the tongue weight.

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4. Detaching on the scale to weigh the tongue jack.

This is probably  first choice for calculating tongue weight for many drivers.  It removes most of the chances for error above and is pretty straight forward.  The reason it’s not our first choice is because you have to detach on the scale each time you want to check the weight.  By using the method in #3 above, as long as the truck pack doesn’t change, you can check the tongue weight for the rest of the tour by simply driving the combination across the scales and using the prior truck weight for the calculation.   You don’t have to detach.

To detach and get the tongue weight the key is to isolate the tone jack.  This can be done a couple ways.  Using Cat’s diagram to the right you can see the tongue jack is over pad #2.  If you drop the trailer there you just need to pull the pickup forward so that there are no truck axles on remaining on pad #2.  Or just pull totally off the scale.  Once you pull the truck forward ask for a weigh.  The tongue weight will be on the “drive axle” line of the weight ticket.

Another downside to this method is while you detach pull forward then re attach the line behind you for the scale may be growing longer.   Additionally, if you find you are overweight on tongue weight you may need to re-adjust they trailer pack.  So you have to do the whole detach thing again and again if you need to check the weight.  Using option #3 above allows you to simply drive through the scales and get a pretty accurate tongue weight. This just seems simpler.

Everybody’s requirements are different.  For some it might be worth toting a scale around.  For others detaching maybe preferred due to constantly changing truck payload.  The only wrong answer is not insuring you have a proper connection.  Have a better way to check tongue weight quickly? Let us know!