Weights
 

Question about weights and how to accurately understand them.

I had went to a CAT scale and had my truck and trailer weighed. The CAT scales show 3 weights from 3 different scales. They are Steer axle, Drive axle, and Trailer axle. And also lists the total Gross weight.

My truck only with 2 adults was weighed and these were the results. With the truck front axle on first scale (Steer) it showed 3360 and the truck rear axle on the second scale (Drive) it showed 2680 and Gross of 6040.

Then I hooked up my trailer and weighed again with 2 adults these were the results. With the truck front axle on first scale (Steer) it showed 3020 and the truck rear axle on the second scale (Drive) it showed 3120 and the trailer single axle on the third scale (Trailer) 3100 and the Gross of 9240.

The trailer weight is acceptable for the tow rating on my truck so I am not worried about that part. The question, is there a way to determine from these weights what the TW is on the TV? Thanks in advance for any responses.

From the second set of weights: 3020 + 3120 = 6140 (GVW of TV with trailer). Take the GVW of the TV without the trailer and subtract it from this: 6140 - 6040 = 100 (trailer hitch weight)

Also, compute the trailer weight: 9240 - 6040 = 3200 (trailer weight)

A few things to consider:

1- You usually want the hitch weight to be 10-15% of the trailer weight. This makes the rig more stable when being towed. In your case that would work out to 320 Lb. minimum. Your weight 0f 140 Lb. looks awful low. Was the trailer level when hitched or was it tilted back? If tilted back, this may result in the low hitch weight. If it was level, or tilted forward, you may want to fill the propane tanks and the fresh water tank to get a bit more hitch weight. Keep in mind that this will increase the trailer weight and Gross Combined Weight a bit.

2- Are you using a weight distributing (WD) hitch? Your numbers show a 340 Lb. reduction in weight on the steer axle with the trailer hitched. This can lead to instability, understeer, etc. A WD hitch that is adjusted properly will level the TV and put more weight on the front axle.

Thanks for reply Raul. I am trying to understand how you came up with the 140lb though? I had already figured out the trailer weight: 9240 - 6040 = 3200 (trailer weight) and your calculation for the hitch weight makes sense as long as that is the correct way to calculate, not saying it isn't though, just not sure is why I am asking. Only reason is that without the trailer the rear axle weighed 2680 and with the trailer it shows rear axle weighs 3120 which is 440lb difference.

The trailer was setup at the dealer and it looks level to me, no WD hitch just sway control. Initial tow of trailer it seems fine and took out on the highway and no noticeable issues. The trailer was weighed dry since it is new to me, but it did have (2) 20lb propane tanks full on tongue, did not have the fresh water tank filled either which is on the front side of the trailer axle so that would add TW also if filled. I will add the majority of my gear to the front area also of the trailer. Thanks again. Trying to make sure I have the weight calculation figured out correctly.

Sorry, I was typing too fast. The hitch weight is 100 Lb, not 140 Lb.

When you calculate the hitch weight you don't use the weight over the rear axle only. You use the effect of the trailer on the sum of both axles. In your case the rear axle weight went up by 440 Lb. with the trailer attached, but the weight on the front axle went down by 340 Lb. Thus, you have a 100 Lb. total difference and that's the hitch weight. Think of it this way, if a TV by itself weighs a total of x Lb. and a TV with a trailer attached weighs a total of y Lb, the hitch weight of the trailer is y-x.

I think some thing is wrong, never heard of a single axle Hi-Lo with a 100 lb tongue weight. Anyone that has weighed only the tongue weight of a single axle has found it to be on the heavy side. One forum member even had the axle moved forward to reduce the tongue weight.

interesting
 

Some interesting stuff here. I'll review this again later. I always thought that you had a goal of about 200 pounds as a tongue weight.

Later Tim

Tongue weight should be at least 10-11% of trailer weight. Otherwise sway comes into play, which you don't want.

sway
 

I believe that sway is only wanted on a dance floor..

Later Tim and crew

I was that forum member! Had over 600# tongue weight with a 17 ft trailer.

But, something is certainly wrong. With no WD hitch, and a trailer attached, the weight on the rear TV axle increased by 440#. The front axle weight decreased by 340#. That effect was due to the force exerted by the trailer tongue. There's no way, in my opinion, that a 100# force can do this. I think the trailer tongue weight is much higher.

Now, I agree with Raul's calculations, but something's wrong, and I think it's the weights reported for the scale. If you DO have only 100# at the tongue, TooLow, you should be able to easily lift it by hand if the trailer is disconnected from the TV. (Most people can lift 100#).

I hate to say it, but I think you need to weigh things again, or put the trailer on the scale so that the axle is on one scale and the tongue support is on another so that you can weigh those two values by themselves.

It's also possible the scale needs calibration, or the person taking the readings misread things. A truck scale can probably easily give you a value within +-5# of the actual weight.

- Jack

You may want to check this out. Determining Trailer Tongue Weight | etrailer.com

Try using a bathroom scale for tongue weight.

tongue weight
 

RichR
Thanks for that nice link in on that tongue weight info. Nice scale that Joe Martin's folks at sherline make.

Later Tim

weights
 

What were you weighing?

Lincow

I have a Sherline scale. It IS nice! Kind of expensive, but to me, it was worth it. I tried the bathroom scale method, and in spite of constructing the thing very accurately, could not really get an accurate measurement. Possibly, the scale I used was too cheap.

- Jack