Tow Weight/Tongue Weight - Fiberglass RV


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Old 11-29-2002, 08:59 AM   #1
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Tow Weight/Tongue Weight

My recent attempts to have my trailer weighed leads to concerns as to the accurancy and methods of weighing our trailers. I understand the basics (i.e., tow vehicle capacity, trailer tire limits, weight distribution, tongue weight 10/15%). My question involves methods as to how to weigh and which weights to use.

I called a local RV dealer and asked if they knew somewhere in the area (close) that wouldn't mind helping a 'girl' weigh her travel trailer. Of course, the guy chuckled and said, ''Sure. Any of the stone, rock, concrete companies...'' So, I set out to find one. When I asked, they said that he would be happy to do it, but their scales were not certified. They were calibrated, but not certified. I felt like at this point close would work for now....wrong. My results have me questioning his methods and the weights that I got.

How I set up the TT: With rear A/C, no grey water tank, and a small black water tank, I knew that the tongue weight was going to have to be increased even though I have two 20 lb almost full propanes. I carefully packed the trailer as it would be for camping (except for a few things in the fridge, etc. Other than that it was ready to go. Folding table and 15 gallon tote-along tank in the bathroom, closet filled with folding chairs, leveling blocks, camping essentials, etc.. Keeping in mind the balance and the fact that I had no water on board (but 8 gallons of antifreeze), empty black holding tank, I decided to remove tools from front closet and put in the storage area in front of the wheel well on the street side. Since this is a 16' Casita SD, I have the refrigerator, stove, canned goods, dishes stored on the curb side, I thought I needed the tools for balance on the other side.
My results and the methods used: When I got there they had someone parked on the scale ready to load stone (I had offered to call ahead, etc, but he said not necessary) and he made them move. I feel that he was rushing. He had me pull the tongue over the scale and drive off. He left the tonge jacked up pretty high which, I believe, caused the weight to shift backwards and not reflect a true tongue weight. It weighed in a 160 lbs. I told him that no way that could be correct upon which he said: ''...the scale weighs in 20lb increments so it's probably more like 180. (I weighed it on a bathroom scale when I got home and it was 200 lbs). Next, he weighed the trailer without the vehicle: 2240 lbs. As I was pulling off I stopped and weighed trailer attached to vehicle (with car off of scales) and it was 2060.

Other than finding a better scale and someone to really help me, did I get anything (other than major frustration) out of this? And, if a bathroom scale will accurately weigh a person at that weight, why not a trailer tongue?
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Old 11-29-2002, 09:37 AM   #2
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Quote:
Orginally posted by Suz

Other than finding a better scale and someone to really help me, did I get anything (other than major frustration) out of this? *And, if a bathroom scale will accurately weigh a person at that weight, why not a trailer tongue?
Suz, Suz, Suz,

I think most bathroom scales are inaccurate, simply because they are spring scales. That's why your weight differs when you go to the doctor.

It sounds like the weights were close on the gravel scale:
2060+180=2240.

The gravel scale is probably fairly accurate and the resolution is fair(20 lbs or 1% in your case).

You can find a Certified Automatic Truck (CAT) scale at a nearby truck stop if you want certified weights. Just don't expect any help. The truckers just drive on and push a button then go inside and pick up their weight sheet.

In my opinion (worth what you paid for it) is that you got a useful weighing. Your tongue weight is too low, though; try weight lifting. ;)
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Old 11-29-2002, 10:14 AM   #3
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Trailer/Tongue weight

Thanks a million, Morgan.
Quote:
It sounds like the weights were close on the gravel scale: *2060+180=2240.
In trying to cover all my bases in my explanation to save the 'move this here and there stuff' and the basics I already knew, I did omit the fact that I had noticed the forumla you cited.

Your tongue weight is too low, though, Yes, I know. In fact, I knew before I went that it would be a concern (for the reasons already cited) that is why I packed the way I did before I went. When I actually go out for more than a day or two, I can travel with suitcase/packed clothes in the bathroom; also, once I get a screened room I can put that in there. Aside from that, I don't know what else to do other than go out and purchase a literal twenty pound weight and secure it to the trailer tongue. Guess I could always add a few pounds of water to my black tank and dump when I get there. :o


Last question: Which weight do I go on for the 10%: 2060 or 2240. Better yet...don't answer that one, I don't think I want to know.;)
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Old 11-29-2002, 12:19 PM   #4
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Quote:
Orginally posted by Suz

Last question: *Which weight do I go on for the 10%: *2060 or 2240. *Better yet...don't answer that one, I don't think I want to know.;)
It's 10-15% of total trailer weight, whether or not you want to know. :)

Remember that when you get ready to leave, you'll have fresh water in the tank. That'll shift the weight even more to the rear. You might consider putting a missy box (miscellaneous) in front of the propane bottle(s). Put 50 lbs of stuff in there and you'll probably be ok. Your window AC is the root of your problem. :E :E

You didn't bite on my comment about weight lifting. :weep
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Old 11-29-2002, 01:47 PM   #5
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Morgan

>>You didn't bite on my comment about weight lifting
Might not of bit, but did notice. I used to work out with weights and I kept thinking I oughta get a couple of 20 lb disk weights for barbells and strap them on. Now I just use a couple of ten pound hand held weights which wouldn't do doodly squat. ;)

Of course, you are right about the A/C. I knew that from the get-go. But I do love my comfort.

Thanks for all your help. I'll get this figured out (as we say in Texas)... Regardless...I'm still going camping!:steer
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Old 11-29-2002, 02:05 PM   #6
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One potential problem with a gravel scale is that the owner really doesn't care about actual weight, rather differential weight. An empty truck drives in and gets the Tare weight (which doesn't need to be calibrated, even if it was off 100 lbs, that wouldn't matter), then it fills up and they get the new weight (if the tare was off by 100 lbs, the fill will be off by 100 lbs, with the "error" in the same direction, so it is self cancelling); subtracting the two gets the difference, which is the true weight of the load which is what the gravel guys care about. That's why it really doesn't need to be certified.

Here's how to do it in that case:

Pull the trailer onto the scale so the truck axle is NOT on it, but the tongue jack is over it and the trailer axle is on it. Note the reading; then open the coupler and jack up the tongue until the ball is just free and note the weight -- difference between the weights is the tongue weight, accurate!

The tongue weight computation is 10-12% (a bit high is better than a bit low, esp with back weight being far from trailer axle) of the total weight when the tongue and axle were both on the scale.

A second way to get tongue wt is to pull the truck (both axles) on the scale with the tongue jack over solid ground; take weight, lower jack 'til ball is clear and take another weight; difference is tongue wt.

BTW, your grasp of the mechanics is very good, re: the angle. At flat horizontal, the tongue weight is max. If you lift the tongue up enuf so the trailer is pointing straight up and sitting on its rear bumper, the tongue wt is zero. Had the rock scale been accurate and precise, you would have seen the weight very slowly dropping off as the jack was raised.

As you are climbing and descending mountains, the wt balance changes in a direction that induces sway (lighter tongue) and why a sway control can be a dangerous bandaid. A rig that is somewhat out of balance on flat land, but compensated with a sway control rather than true correction, may go over the edge of steering control just when your brakes and tranny are fighting gravity (edge is a double-edged word here!, puns intended).

The good part is the unlevel trailer going downhill is shifting some of its total weight to the truck, esp the front axle, so the brakes are more effective, skidwise.

Pete and Rats
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Old 11-29-2002, 08:22 PM   #7
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weight

>>"He left the tonge jacked up pretty high which, I believe, caused the weight to shift backwards and not reflect a true tongue weight"

Suz:

I took the tongue weight by resting the jack on a platform hospital scale that's pretty darn accurate. Raising the tongue 8" made about 12lbs difference in the weight, the higher, the lighter. Anyway roughly 1" = 1.5 lbs. :dance

I've weighed my 16' LD on a cat certified scale (twice) and a local sand and gravel scale (calibrated but uncertified). Your overall weight is light compared to my results. I'm over 2,400lbs with no furnace, no awning, 5gals water otherwise 'empty'.:o

==========

>>"Guess I could always add a few pounds of water to my black tank and dump when I get there"........

........We travel with our drinking water in 2 liter and/or gallon containers which ride in the shower area.

==========

Also travel with the water heater empty (that's 50lbs).
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Old 11-29-2002, 08:49 PM   #8
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Don

>>Your overall weight is light compared to my results. I'm over 2,400lbs with no furnace, no awning, 5gals water otherwise 'empty'.
Please remember, Don, that my 16' Casita SD is an '89. There are a lot of differences that most are not aware of. For one thing, the frame that my unit sits on is different than yours. I can't remember exactly when it was changed ('90 or '91 I believe) but that is probably one of the major weight differences. I have no gray water tank and my black water is only 9 gallons. In addition, my tires are ST185R13s instead of 14's Smaller tires, smaller rims, less weight. Because of the weight distribution on that year, the fiberglass unit was mounted a tad forward...just enough so that there isn't quite enough clearance for 14's. When I got new tires, I went from ST175s to ST185s in order to increase the weight limit. Also, the windows are smaller...less glass, less weight. Many subtle differences that would add up to the weight difference you are concerned about.

Thanks to you all for your help.
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