Real world tongue weight numbers- step inside!

Lzerarc · 01-04-2019, 07:57 PM

Forums and Youtube can be fantastic sources of information...its up to the reader to determine if its factual or not. Forums and youtube is also a great place for bad advice or added confusion. The question that seams pretty consistent is how tongue weight is figured and how weights within the trailer effect that. I had the same questions for my own TT as I determine needing to purchase a heavier truck or not. I decided to order a tongue weight scale and do testing of my own to see not only the exact weights of my TT, but also how shifting weight within the trailer helps or hurts it.

I have the luxury of being able to test 2 Rockwoods. Mine is a 2905ws and my mothers is a 2506s. (see pictures below of family shot!)

There is always confusion of what is included in the TW as listed on the publications. FR has always indicated that the TW listed includes the (2) 30 lb tanks (empty) and no battery. Many people have argued this. I think the results of my scale test might surprise people. It certainly did me.

First off, the 2905ws:
Posted empty weight is 6,975 lbs on my door sticker. Published TW is 834 lbs. There was about 300 lbs loaded in the trailer. Most of that was in front of the axles, specifically in the front storage pass through and kitchen area. The rear of the TT has about 60 lbs worth of lawn chairs and random things.
Total weight of the tested rig is right around 7,275. When traveling, food would be added to the pantry and fridge, which sits over the axles. I would not expect much TW change, due to the experiment you will see.

I ordered a Sherline 2000 lb scale off of Amazon.

Lzerarc · 01-04-2019, 08:03 PM

So here is the result for the first camper....

(I will add both 30lb tanks are mostly full)

As you can see, it is about 850 lbs. Again, advertised TW is 834. I lowered it, rest it and did it multiple times. Each were right around 850 lbs. This works out to be right around 12% of the trailer weight.

Lzerarc · 01-04-2019, 08:16 PM

I then decided to see how adding additional weight effected the loading. I used myself as the added weight. I weight about 225 lbs. I placed my phone on the tongue and recorded the scale while I went inside the trailer. I first stood in the front bedroom. As you can see in the video it increased to about 1000 lbs TW. So about 67% of my weight was added to the tongue in the bedroom. I then walked to the back and stood in the bunkhouse. You can see all of the weight shifted and reduce the TW to just below 850 lbs, probably about 825 lbs.
This information is useful when knowing how to load the trailer. It tells me I can add quite a bit of weight to the middle and rear when loading and still keep my TW at 12% -ish and not adding additional to the truck.

Here is the video of the scale reading.

https://youtu.be/dHY63yJCc2M

Lzerarc · 01-05-2019, 01:57 AM

Images arent working above. Here they are:

Mch5jdm · 01-05-2019, 07:11 AM

This is very interesting. Does the grass absorb some weight? Maybe test on concrete?

Lzerarc · 01-05-2019, 08:09 AM

Good thought but the ground is frozen currently.

woo10-210 · 01-05-2019, 09:57 AM

Quote:

Originally Posted by Mch5jdm

This is very interesting. Does the grass absorb some weight? Maybe test on concrete?

Makes no difference whether you're on a hard surface or soft surface. As long as the force isn't accelerating or decelerating, the weights will be the same.

lbrjet · 01-05-2019, 11:45 AM

I watched your video and the lowest reading is about 880 lbs.

Boomerweps · 01-05-2019, 11:48 AM

I plan to do similar this year. But I'm too CHEAP to buy that scale

Just bought a new bathroom scale and will use the old one with a lever setup for tongue weights. Got to be extra careful. It appears they no longer make those all metal spring scales. They are all digital with GLASS tops. I'll have to use a plywood sheet for a base on the scaling rig.

babock · 01-05-2019, 12:05 PM

I have a Sherline scale as well. My tongue weight is at 780# with full water tank. Advertised tongue weight is 635#.

Sherline scale is an awesome tool. Very inexpensive for the value and ease of it.

Weighing on grass will give you the exact measurement as doing it on concrete. Like the previous poster said, if it's not accelerating or decelerating, it will be the same. High school physics!

babock · 01-05-2019, 12:14 PM

Quote:

Originally Posted by Boomerweps

I plan to do similar this year. But I'm too CHEAP to buy that scale

They are only around $135!

JohnD10 · 01-05-2019, 12:28 PM

Why not just do it right and take it to a certified scale and get the whole thing weighed the right way.

Those are numbers that you can believe...

Bathroom scales...yeah...right!

babock · 01-05-2019, 01:03 PM

Quote:

Originally Posted by JohnD10

Why not just do it right and take it to a certified scale and get the whole thing weighed the right way.

Why go to a CAT scale when if all you want to do is weigh the tongue after loading or doing a modification? LOL

Lzerarc · 01-05-2019, 01:36 PM

The whole point of it, and I realize it's somewhat trailer specific, was to find out how accurate the "rules of thumb" quick math is. And my results say: not that accurate.

Many people on here have you believe the advertised TWs can be upwards of hundreds of pounds off from your loaded rating. My testing shows I can load the trailer with over 500 lbs and it only increases the TW by about 50lbs over the posted amount in publications.

I am going to reach out locally and test other friends TT to see how it ranges from brand to brand. I especially want to test a Grand Design since the rumor is they are the worse at posting low ratings. (Goes along with their r40 rv roof!)

larry2c · 01-05-2019, 01:48 PM

I recently went to the local CAT scales and did the 3 weights needed to calculate TW (trailer hooked up with WDH engaged, then WDH disengaged with bars in truck be, then just the loaded truck). I then used a calculator I found that lets you plug in the weights and calculates the TW. Because the scales were moderately busy I didn't position the truck/trailer where I could get just the tongue on a pad. The calculation showed 840# which was 13.6% of the loaded trailer weight.

It would be really interesting to take this calculated weight and compare it to a true tongue weight. Anybody done that? BTW, I have used the bathroom scale method and think it is probably fairly accurate as long as your distance/positioning of the scale and the fulcrum are accurate.

dfreeman · 01-05-2019, 03:07 PM

Quote:

Originally Posted by Boomerweps

I plan to do similar this year. But I'm too CHEAP to buy that scale

Just bought a new bathroom scale and will use the old one with a lever setup for tongue weights. Got to be extra careful. It appears they no longer make those all metal spring scales. They are all digital with GLASS tops. I'll have to use a plywood sheet for a base on the scaling rig.

I have a Sherline scale for sale if you're interested. $100 shipped to you. PM me if interested. Used two times in original packaging.

aircommuter · 01-05-2019, 03:12 PM

Nice part about those little scales is on can use it at home, CAT scales for me is 80 miles one way, the nearest quarry is 35 miles but can only weigh one item at a time. I used 4” hydraulic cylinders with gauges when I was checking the weight and balance for my floating RV after I finished building, it was only off by 75 lb side to side and was 2000 heavy to the rear for a bit of nose up attitude since they are like pushing a brick through the water they tend to go nose down.
As for the soft versus hard surface it seems pretty obvious that as long as there isn’t any motion it doesn’t matter, I wonder how long one has to stand on a bathroom scale before the body tissue stops compressing😁 Maybe cement shoes would help.