Determine tongue weight

[newbury]

Need to know the tow vehicle and the approximate trailer weight or at least type of trailer and what you are hauling. F350 towing a 5x10 single axle utility trailer, doesn't much matter, squat of the truck isn't going to tell you squat. <snip>

In my sig is the trailer I use, an 18' Hudson equipment trailer rated at 12,000 lbs. I haven't loaded it down yet, but when I get to Mississippi I plan on using it to move logs and much heavier tractors.

<snip>two dudes in the bed <snip>

Hey no need to talk about that type of stuff!!

Since the OP didn't tell us much about his tractor or trailer I used the lower end example for us sitting on the tailgate. I have set up the "bathroom scale" measurement and I don't think you really need 2 pipes (which tend to roll) but could use two short lengths of half-round molding or even 1"x1" pieces of wood.

 

[meburdick]

One way you can determine tongue weight is with a Sureline scale.

A second way is to estimate it based on "known quantities"... Open the gate of your truck and stack weight on it. Load it up to specific known amounts (300,400,500,600, etc) and then very carefully measure the distance from the ground to a specific point on the hitch at these different amounts.

When you load the trailer, measure again... Use your "chart" from your known weight quantities to determine what tongue weight you are currently at.

SIDE NOTE: You should NOT be loading your trailer and having it lift the rear of your truck. Get jack stands to put under the rear of the trailer or something to support it. If you have fold-down ramps, those often have "feet" that hang down - block those with some large wooden blocks. Your truck was not designed to be "jacked up" by the hitch as it's putting negative tongue weight on the vehicle of somewhere around 1,000 pounds minimum.

 

[sdkubota]

I believe the 10% tongue weight myth is due to campers and such where shifting the weight is not an option. If you load your tongue weight too high on the towing vehicle, you will risk shifting the center of gravity to far back on said vehicle. If that happens you will have an extremely unstable situation and probably roll into the ditch or worse. Hauling equipment allows you to shift the CG on the trailer and all you need is to make sure the CG is in front of the axles at all times. You can carry the weight where ever you want.

 

[meburdick]

I believe the 10% tongue weight myth is due to campers and such where shifting the weight is not an option. If you load your tongue weight too high on the towing vehicle, you will risk shifting the center of gravity to far back on said vehicle. If that happens you will have an extremely unstable situation and probably roll into the ditch or worse. Hauling equipment allows you to shift the CG on the trailer and all you need is to make sure the CG is in front of the axles at all times. You can carry the weight where ever you want.

"Myth"? Why is it a myth?

You actually NEED tongue weight on the tow vehicle for a variety of reasons, all of which have to do with safety (keeping enough traction under the rear wheels for acceleration and braking, keeping the overall distribution of weight between the tow vehicle and trailer at appropriate proportions, ensuring that the tongue of the trailer will never "lift" the rear of the vehicle, etc). If don't have enough (which could be defined as any value less than 10% of the GTWR, including negative tongue weight), you are not towing with optimum overall safety. The heavier the GTWR, the more downward force on the rear axle you need to ensure you have enough traction on the back of the tow vehicle.

Conversely, if you have too much tongue weight, you could break a rear spring / shock, pull the hitch off of the vehicle and/or bend the frame, cantilever the front of the tow vehicle into the air resulting in too little traction to steer and brake (remember that much more than 50% of your braking comes from the front of any vehicle), and so on.

It's physics and math, not a myth.

 

[schmism]

yep it works.

 

[meburdick]

yep it works.

I would imagine that there's some sort of calculation you have to do that takes into consideration the length of the wooden beam and such... yes? And, how will you be able to leverage that getup to measure "actual" tongue weight with it loaded? I have to do something similar at some point so I can understand what sort of tongue weight I'm getting (mostly because I want to try and get the TW to about 900-1000 lbs and then measure the squat of the truck).

 

[newbury]

yep it works.

Does it actually require a yellow jack on the left and a red jack on the right?
I've only got red jacks.

 

[meburdick]

Does it actually require a yellow jack on the left and a red jack on the right?
I've only got red jacks.

You can use all red, just adjust the math accordingly.

 

[schmism]

I would imagine that there's some sort of calculation you have to do that takes into consideration the length of the wooden beam and such... yes? And, how will you be able to leverage that getup to measure "actual" tongue weight with it loaded?

yes that is why there is a tape measure in on the ground....

1 foot to the jack on the right, 2 feet to the jack on the left. mulitiply the reading on the bathroom scale by 3 to get actual tongue weight. (if you use equal dimentions ie 1 foot right 1 foot right, then you mulitply by 2 but for 800-900lbs tongue weight your bathroom scale doesnt go to 400 lbs so your SOL have to use x3)

as to how to do it loaded. it is loaded (see my tractor in on the trailer in the background)

process for me was...
drive tractor on to trailer with it hooked up to the tow vehical.
place a jack under the rear of the trailer (light pressure on trailer)
block trailer wheels
use tongue jack to raise trailer off of ball
pull tow vehical forward to make room
lower tongue jack till trailer is level (seriously use a builders lvl its important)
lower jack at under rear to the point its showing 1/2" air gap (leave in place for safety)
double check level of trailer
set height of jack stands and 2x4 so that it will carry load at tongue-level-dimention
jack tongue up a few inches, move setup under tongue... lower back down
with trailer wheels blocked i can move the tractor slightly on the trailer to adjust tongue weight reading scale directly.
mark location of tractor on trailer

back tow vehical up, hook up trailer and adjust my WDH so that height of the tongue sits level and i have the right "squat" on the rear of my tow vehical (see setting up a WDH online youtube vids)

this gives me a calibrated setup to measure other loads against.

 

[schmism]

Tongue weight is not some mythical number sprinkled with fairy dust. it is an actual REAL number that needs to be paid attention to. not enough you get trailer sway which can lead to out of control conditions extreamly quickly (see youtube), to much you get porpoising and risk breaking/bending/damageing things that arnt easly fixed on the side of the road.