Tongue Weight Part 2 CAT Scales

Appears you were not in the truck for the combo weighing.

My method is

1) Weigh the entire rig on the three pads of the scale: truck steer axle - truck drive axle - trailer axles

2) Weigh the trailer hooked up to the truck with the two trailer axles on separate pads and the truck not on the scale

3) Drop the trailer and weigh the truck alone.

Last week it was
#1 - Whole Rig Weight
Steer - 3,600 lbs
Drive - 6,040
Trailer - 8,870
Total = 18,420

#2 - Trailer on truck pads
Steer - 4,740
Drive - 4,080
Total = 8,820

#3 - Truck only
Steer - 3,935
Drive - 4,340
Total = 8,275

When I dropped the trailer - the weight on the rear axle of the truck is 1,700 lbs lighter, however the weight on the front axle of the truck is 335 lbs heavier. This tells me the tongue puts 1,365 lbs on the truck.

(The rig was front heavy for the 80 mile trip. I had a near full tank of water, and had not dumped a nearly full black water tank.) (There is always a slight weight difference between the weight of both trailer axles on the same pad and the two trailer axles on separate pads of about 30-50 lbs which I guess is variance in the truck being dead level or not level when it is not on the scales.)

I calculate the total trailer weight as the difference between the total weight of the total rig, minus the total weight of the truck alone - 10,145 lbs.

An 'alternate' tongue weight figure would be to take the total weight and subtract the trailer axle weight - which gives the same 1,365 figure.

What do you mean by TT Weight Steer axle on your top line? Is that the weight of the TT on the first pad (sitting on the jack) and the Drive axle is the weight on the second pad?? If so, 840 lbs would be the actual tongue weight of the trailer.

When you say without sway bars do you really mean without weight distribution bars? or are those weights with the WD bars hooked up but no separate sway bar? If your truck drive axle, without trailer, is 2780, and your drive axle, with trailer connected, without WD bars is 3740, then your additional weight, as it relates to the truck would be 960, (3740-2780) would it not? This would likely/could be due to the tongue weight of 840, plus the weight of the WD hitch. 840 is 15 percent of the total weight. WD hitches are somewhere in neighborhood of 100 additional lbs, which may account for the majority of the difference between 960 and 840.

Not sure if Im reading it right.

Mike

If I'm understanding your numbers properly, you have about a 180-200 pound discrepancy between your separate weights and your combined weight (with the combined being the lower weight). Possibly you ended up weighing yourself twice in the separate weighings. You also have three ways of figuring the tongue weight; however, since the numbers from the various weighings don't all add up the same, there are some significant variations in the results.

For the trailer alone numbers, I can only assume the "steer axle" weight is the tongue weight (on the tongue jack), and the "drive axle" weight is the weight on the trailer wheels. That would put the tongue weight at about 15%, which seems reasonable. This has the advantage of directly measuring the tongue weight without computation.

Subtracting the trailer axle weight in the combined weighing from the known total trailer weight in the second weighing gives a tongue weight of 640 pounds, or about 12%.

Computing from the truck weight (2920 + 3740 - 6190) gives a tongue weight of 470 pounds, or about 9%. This differs from the 12% because of the 200 pound discrepancy in total weight between the first two weighings and the third one. These differ from the trailer alone because of this discrepancy and perhaps also because of a weight distributing hitch (if you're use one).