CAT Scale Questions

[P&DZ]

I finally had the opportunity to use a CAT Scale. This was a perfect opportunity since we were headed out for an 18 day trip and a worst case scenario loaded with food, beverages, clothes, bikes, kayaks, full propane tanks, solar panel, etc. The water tanks however were empty.

Scale Data as follows:
Steer Drive Trailer Total
Truck+Trailer with Anderson WDH 3,240 3,620 5,900 12,760
Truck+Trailer Anderson Hitch loose 3,180 3,680 5,880 12,740
Truck 3,480 2,640 6,120

Truck Specs: Camper Specs:
Payload 1,925 GVWR: 7,200
GVWR 7,600 GAWR 4,400 per axle
GAWR FRT 3,950
GAWR RR 4,300
GCVWR 16,700
Curb Weight: 5,675 (estimate)

If my calculations are correct:
Trailer Weight: 6,640
Tongue Weight with Hitch: 980
Payload: 1,417 (437 + 980)

Actual weight in the truck was 437lbs which included me, DW, cat, Kayaks, Tonneau Cover, few misc items.

Do these calculations seem correct?
Why do the first and second weights differ by 20lbs, is this expected scale error?

I was surprised only 60 lbs was transferred to the front axle with Anderson Hitch engaged? Is this expected weight transfer.

Is there anything I should be concerned about with these numbers? With the exception of the trailer weight it appears I have 27% margin with payload and 16%+/- front and rear axles.

Thanks!! Love this forum :)

[P&DZ]

So sorry, the spacing on the numbers got messed up when posted, but I think it is understandable?

[LewisB]

You've got a lot of GVWRs and GAWRs mixed together in the second paragraph and I'm not sure what goes where. Recommend you separate these out into distinct groups for truck and trailer. Rather than typing all the data, how about posting photos of the stickers and the weight tickets?

In the second weight, you state "Truck+Trailer Anderson Hitch loose".
1) Does that mean you just unloaded the WDH and the trailer was still connected?
2) Or does that mean the trailer was completely disconnected and free of the truck?

I'm a fifth wheel guy and certainly not an expert with pull-trailers. But it seems to me that you need 3 weight tickets to determine the actual weights of both the truck and trailer and the impact of the WDH;
Weight of truck axles (front & rear) and trailer axles (combined) with complete separation between the truck and trailer.
Weight of truck axles (front & rear) and trailer axles (combined) with WDH attached in a "loaded" condition.
Weight of truck axles (front & rear) and trailer axles (combined) with WDH attached but in an "unloaded" condition.

So the first weight gives you the true weight of both the truck & trailer. The landing gear on the trailer needs to be isolated from the truck. Some scales can give you front landing gear + axles, some will just combine those weights into a trailer weight.

The second weight gives you the "applied" weight on each axle (or group) including distribution effects from the WDH. This will allow you to determine applied hitch weight when level; recognize these weights will constantly be changing as the vehicle moves over the road encountering rises and drops, potholes, etc.

The third weight gives you the hitch weight before effects of the WDH; use this with the second weight to determine actual hitch weight and the load on the WDH as well as the impact on the full rig.

In some cases (like checking axle alignment) if may be necessary to get separate weights on each trailer axle, but I think this is fairly unusual.

Hope that helps.

[P&DZ]

Thanks LewisB, let me do a better job posting the numbers for yourself and the weight police:

CAT Scale Results
1. Truck + Trailer with Anderson hitch loaded
Steer 3,240
Drive 3,620
Trailer 5,900
Total 12,760

2. Truck + Trailer with Anderson Hitch Unloaded
Steer 3,180
Drive 3,680
Trailer 5,880
Total 12,740

3. Truck Only
Steer 3,480
Drive 2,640
Total 6,120

Truck Specs:
Payload 1,925
GVWR 7,600
GAWR FRT 3,900
GAWR RR 4,300
GCVWR 16,700

Trailer Specs
GVWR 7,200
GAWR 4,400 per axle

Please reference my calculations and questions in the original post.

Thanks.

[Cyberian]

With the WDH difference being so minor between loaded/unloaded, I'm curious what your weights would be without it, and bags if you needed them to keep your headlights pointed where they belong

[tech740]

That hitch has the sway control built in so I would say the hitch is still needed. I used to have one and I loved that hitch. Looks like you have 740 pounds available payload once hooked up so that is a good thing. Is the truck and trailer level when set up as you measured it? If not you may want to give the Andersen nuts a twist or two and see if you can level it or put some more weight back on the front axle. Really it looks like you are in good shape but with a little more transfer to the front axle you may feel better planted on the road. Happy Camping

[notanlines]

Whatever you decide, do not let anyone convince you that there is no need for a WDH and sway control. You absolutely do.

[P&DZ]

No need to worry about me giving up the hitch, what little weight distribution it is providing plus the sway control is worth it. I would like to know why so little weight is being transferred to the front axle. I will attempt tightening the nuts one or two more turns but they are pretty tight at between 4 and 5 teeth showing. Maybe I will give Andersen a call. I have not taken front and rear measurements before and after loading the hitch. From an eyeball perspective both the truck and trailer appear to be level. Certainly the front end is not pointing skyward and it rides fairly well. The other question I had has the 20lb difference in weight between the 1st and 2nd scale weights. Since I did n't add or subtract anything from truck or trailer should they be the same? Is this normal scale error? I calculated the available payload for this particular trip at 508lbs (1925 - 1417), tech740 calculated it at 740, am I missing something?

As always thanks for the help!

[sourdough]

Here's what I think I'm thinking...

Truck alone = 6120. Truck + trailer = gross 12,760. Trailer = 6640.

Truck alone = 6120 Truck + trailer = (truck) 6860. Tongue = 740

Tongue 740/6640 = 11.1% tongue weight

If I'm understanding the numbers you look to be in very good shape. The one thing I would not do for any reason is leave off the wdh/sway. If you've never set it up with the trailer loaded you may need to tune it a bit but otherwise looks pretty good. At 11% tongue weight I would definitely get it on the road and check it and make sure it doesn't want to wag due to a light tongue.

[P&DZ]

sourdough,
Ahhhh...thank you. I was not calculating the tongue weight correctly and therefor coming up with 980 rather than the correct 740. That makes me feel better. So far I have not experienced any wag or sway, even in the steep and winding downhill 6+% grade on I70 in the Colorado mountains. But I do watch my speed. What I do experience is a bit of a truck bounce when going over a bump.

[sourdough]

The sway control won't help the bounce. There are some things you can do for that.

A 1500 usually comes with P rated auto tires. If that's what you have you can upgrade to LT tires. Did that on my last two 1/2 tons. Replace the shocks with Bilstein 5100 shocks. As new as your truck is I'm not sure they would do what you want them to do. Best choice, and a good one with your situation, is air bags. I used AirLift 1000 bags and they stop the bounce. You do need to watch the inflation pressure loaded and unloaded so it doesn't make the ride harsh. They do not give you more payload (which you don't need) and I don't usually recommend them because that's what folks want them for, but, they will help with your situation.

[Wyldfire]

The Andersen will help the bounce. That is one benefit of the urethane bushings. Andersen reccomends 6 threads minimum showing. I find mine works best with 7.

[P&DZ]

I do in fact have P rated tires which came as orig equip with the truck. I do plan to upgrade to LT and Bilstein shocks when it is time to replace the tires. In the mean time I will follow Wyldfire suggestion to tighten the Andersen to 6 to 7 threads showing rather than the 4 to 5 I have been applying. The added tension may also transfer more weight to the front tires. The bounce is not severe, mostly a mild aggravation, but if tightening up the hitch does not work I will definitely consider the air bags sourdough recommended.
Attempting to manage further investment this year after 4 new Goodyear Endurance Tires, 2 new Duracell 6v batteries, and replacement equalizers among a few other misc odds and ends.

[sourdough]

I do in fact have P rated tires which came as orig equip with the truck. I do plan to upgrade to LT and Bilstein shocks when it is time to replace the tires. In the mean time I will follow Wyldfire suggestion to tighten the Andersen to 6 to 7 threads showing rather than the 4 to 5 I have been applying. The added tension may also transfer more weight to the front tires. The bounce is not severe, mostly a mild aggravation, but if tightening up the hitch does not work I will definitely consider the air bags sourdough recommended.
Attempting to manage further investment this year after 4 new Goodyear Endurance Tires, 2 new Duracell 6v batteries, and replacement equalizers among a few other misc odds and ends.



Good for you. It's a learning, growing, spending process. Good luck.

[Wyldfire]

More tension will transfer more weight

[Wyldfire]

If you haven't watched the install video on Andersen's website you might want to. They use a pretty long socket breaker bar to more easily turn the nuts to the proper tension. Little socket wrenches just don't cut it

[P&DZ]

I just re-watched the Andersen video. In the video it is recommended to hand tighten and then further tighten another 4 revolutions of the socket. I will try this approach and see if it results in more threads showing than I had been tightening. I do use a substantial socket wrench but also carry a socket breaker bar on the camper should I need it.

[john_w]

To easily get 6-7 threads showing on the Andersen hitch is to use your power tongue jack to raise the trailer and truck up a couple inches. Then tighten up the nuts and then retract the jack. That will load the chains up and at that point it’s much more difficult to tighten or loosen the nuts.

[Keystoned]

The Andersen will help the bounce. That is one benefit of the urethane bushings. Andersen reccomends 6 threads minimum showing. I find mine works best with 7.
Yup, I used to have one and 2 things need to happen.
1. the urethane should be squished a bit and
2. that usually happened when about half the nut was visible when tightening with the special socket they provide

If it's not tight enough then might as well not even try...lol

I'm sure more weight was transferred forward but I also had air bags on my truck to get the final level.

[P&DZ]

Thanks for the input. I am definitely going to crank it down to 6 to 7 turns as suggested. I am hopeful this will help the bounce. I won’t know if more weight is transferred to the front axle unless I take it back over the scales.

[skids]

Here's what I think I'm thinking...

Truck alone = 6120. Truck + trailer = gross 12,760. Trailer = 6640.

Truck alone = 6120 Truck + trailer = (truck) 6860. Tongue = 740

Tongue 740/6640 = 11.1% tongue weight

If I'm understanding the numbers you look to be in very good shape. The one thing I would not do for any reason is leave off the wdh/sway. If you've never set it up with the trailer loaded you may need to tune it a bit but otherwise looks pretty good. At 11% tongue weight I would definitely get it on the road and check it and make sure it doesn't want to wag due to a light tongue.

I like your sensible language Sourdough. Easy to understand.

[flybouy]

Speaking to the bounce ... I'd suggest shifting some weight around before spending and money. The 11% is a bit on the light side to me, especially using a WDH. It will only cost you a little fuel and a little time.

When you go on your next outing (loaded as usual) when you traverse that bridge or section of the road that creates the bounce safely stop. Move some weight forward, turn around and drive over the same road at the same speed.

[jadatis]

The 2 trailer axles you weighed together.
You can yudge the weightdivision between those 2 axles by the difference of deflection of the tire.
Measuring the deflection is of a high " hobby Bob" value, but it gives a good indication.
Same deflection on all 4 tires means each 25%of the 5900lbs .
So you can also adyust it for a staight trailer.
If you go for this you never wil have same deflection.
Often weightdivision is crossed between the axles.
For instance RF 20% ,LF 22%, RR 30% LR28%.
Then rear axle more load, so most likely front of trailer to high. The crossed difference RL you can not take away with changing the WDH.

And deflection is quadratical with the load on tire.
If deflection 2x as much, weight on tire 1.41x as much, so root. Or 2x load gives 4x deflection.

[flybouy]

The 2 trailer axles you weighed together.
You can yudge the weightdivision between those 2 axles by the difference of deflection of the tire.
Measuring the deflection is of a high " hobby Bob" value, but it gives a good indication.
Same deflection on all 4 tires means each 25%of the 5900lbs .
So you can also adyust it for a staight trailer.
If you go for this you never wil have same deflection.
Often weightdivision is crossed between the axles.
For instance RF 20% ,LF 22%, RR 30% LR28%.
Then rear axle more load, so most likely front of trailer to high. The crossed difference RL you can not take away with changing the WDH.

And deflection is quadratical with the load on tire.
If deflection 2x as much, weight on tire 1.41x as much, so root. Or 2x load gives 4x deflection.

Wow, just wow. So while that's an impressive theory how do you practically take the field measurements? Remove each tire and measure the deflection unloaded first? Then run a laser level across the surface and find a perfectly level place to then make sure the trailer is perfectly level? Then what? Run a laser level across the tire at that tires unloaded height and measure the difference? To what unit of measure? and where's the scale for deflection on that make, size, inflation tire?

I'm tired just thinking about this. Seems to me it would quicker and easier to find a scale that measures individual tire weights as apposed to axle weights if someone thinks there's really an imbalance side to side load that's a factor. But that's just me. JMMV

[P&DZ]

Marshall, Wow is right, while I am sure it is a great theory that made my head spin and I am an engineer (retired). I will however attempt to move some load up front although I am not sure how much is really available since the pass through storage is in the front and there are two 6v batteries and two full 30lb propane tanks on the tongue. One other consideration is there was no water in any of the tanks which is how we attempt to travel. If the fresh water tank (40gal) located approximately mid way between the axle and the front was full or partial it would add some additional weight to the tongue. the downside of course is it adds additional weight to the camper.

[Javi]

Marshall, Wow is right, while I am sure it is a great theory that made my head spin and I am an engineer (retired). I will however attempt to move some load up front although I am not sure how much is really available since the pass through storage is in the front and there are two 6v batteries and two full 30lb propane tanks on the tongue. One other consideration is there was no water in any of the tanks which is how we attempt to travel. If the fresh water tank (40gal) located approximately mid way between the axle and the front was full or partial it would add some additional weight to the tongue. the downside of course is it adds additional weight to the camper.

Watch out when partially filling tanks and driving; the hydrodynamic force inertia can bite you in the butt...

[JRTJH]

^^^ What Javi said !!!!!

A 45 gallon water tank, filled to the brim is 375 pounds of "ballast"

A 45 gallon water tank, half filled is around 200 pounds "slamming back and forth against your trailer "centerline"... If the tank is in the front of your trailer, there's not as much "dynamic force" applied 4' behind the hitch pivot point as there is if the tank is at the rear of the trailer, 30' behind the hitch pivot point.

Some tanks are molded with baffles in them. Those baffles are most often only in the bottom of the tank and only 2-3" in height, so having 10 or so gallons in the tank, the baffles are effective. Half full: not so much as the water level "sloshes above the baffles"....

Next time you're in a 10 or 12 foot rowboat, start rocking side to side and you'll see what 200 pounds of water, 30' behind your hitch ball can do to your "perception of sway at the steering wheel.....

[flybouy]

Marshall, Wow is right, while I am sure it is a great theory that made my head spin and I am an engineer (retired). I will however attempt to move some load up front although I am not sure how much is really available since the pass through storage is in the front and there are two 6v batteries and two full 30lb propane tanks on the tongue. One other consideration is there was no water in any of the tanks which is how we attempt to travel. If the fresh water tank (40gal) located approximately mid way between the axle and the front was full or partial it would add some additional weight to the tongue. the downside of course is it adds additional weight to the camper.

Several years ago DW and I took a nice long trip, headed to Dollywood we ended up "meandering" across 1/2 the country for almost a month. Anyway, I loaded up the trailer, used my SherLine tongue scale and had it set up great.

Unknown to me, the DW loaded a bunch of canned goods, several cases of water, and "extra" cloths in the camper, all in the very back on the floor.:facepalm: We got about 2 hrs down the road when I noticed the wind died down but the trailer was fighting me to stay straight. I pulled into a rest stop and told the DW something was off. She told me she placed "a few extra things" into the camper after I thought it was loaded. Good bless her soul, to her, packing a "few things" looks like the Queen of England taking a cruise in the Mediterranean.:eek:

A "redistribution" of weight solved the issue and taught me to never take off again without a "visual" of the inside first. :banghead:

[jadatis]

I already wrote, the deflection methode is of a high " hobby Bob" value. But meauring the deflection is not that difficult. Mesure from upper rimmedge to the ground, and from downunder-rimmedge to a little flat piece of material , you place flatt on the treath at the top of tire.

OK, not verry acurate, but enaugh for the purpose.
Even if you are able to read it 99% acurate, there is a difference, the top of tire is probably also a verry small part deflected, and rear and front side , seen fom beside, sidewall is a bit flexed so higher then unloaded( off the ground) . The tire becomes a bit oval when deflected.
What you need is the % deflection of free flexible part of sidewall, and that is roughly section hight minus 1 inch ( part in te rimedge+ treathdepth).
You could calculate it with the sises of tire( again roughly, because for instance a 255/
50R 16 is not exact 255 sectionwidth, but can be 258 , they round it down for standardisation reasons.

[travelin texans]

Wow, just wow. So while that's an impressive theory how do you practically take the field measurements? Remove each tire and measure the deflection unloaded first? Then run a laser level across the surface and find a perfectly level place to then make sure the trailer is perfectly level? Then what? Run a laser level across the tire at that tires unloaded height and measure the difference? To what unit of measure? and where's the scale for deflection on that make, size, inflation tire?

I'm tired just thinking about this. Seems to me it would quicker and easier to find a scale that measures individual tire weights as apposed to axle weights if someone thinks there's really an imbalance side to side load that's a factor. But that's just me. JMMV

Wow is right!
Been looking for the translator app on my phone but not sure what language it was???

[jadatis]

That I write a little strange english, is because its not my first language, I live and grew up in the Netherlands. This together with writing errors, because doing it on mobile phone, can give, that you think to need a translator app.
Typing on mobile, asks much of fine motorics, of this 60 year old man.

[skids]

That I write a little strange english, is because its not my first language, I live and grew up in the Netherlands. This together with writing errors, because doing it on mobile phone, can give, that you think to need a translator app.
Typing on mobile, asks much of fine motorics, of this 60 year old man.

It sounds like it "might" be founded on physics theories. But like they tell you in Engineering college, "Mother Nature is a bitch", meaning that the constants actually vary. I wouldn't trust the deflection of tires as spring constants...heck, a lot of them can't even hold air in them without blowing up! :) I live in a county in Colorado where you can't even find a flat enough spot to check your engine oil.

[LHaven]

Unknown to me, the DW loaded a bunch of canned goods, several cases of water, and "extra" cloths in the camper, all in the very back on the floor.
Good bless her soul, to her, packing a "few things" looks like the Queen of England taking a cruise in the Mediterranean.:eek:

I do believe Luci and Desi got an hour and a half movie out of this very premise!

[notanlines]

jedatis, kudos to you for your mastery of the English language. Having been in Amsterdam/Holland many times, the very best I can do in Dutch is "We nemen twee biertjes" (We will have two beers). And I shouldn't even mention how well you've tamed our language, not even living here, as opposed to those.....naw, Jim, better not go there.:nonono:

[sourdough]

jedatis, kudos to you for your mastery of the English language. Having been in Amsterdam/Holland many times, the very best I can do in Dutch is "We nemen twee biertjes" (We will have two beers). And I shouldn't even mention how well you've tamed our language, not even living here, as opposed to those.....naw, Jim, better not go there.:nonono:



I have to say, from my "older" point of view, that the mastery of another language is something to be acknowledged. I've lived all my life in the SW and Mexican is the "other" language. I know a lot of it because I've lived it all my life. I expect 100% enunciation and understanding of the English language from any "citizen". Those from another country will, and do, have problems with our "language". At that point in mind I think we just have to muddle through language anomalies as we go. I can communicate with anyone in English; I wish I had the ability/knowledge to communicate to everyone with any other dialect... I do not. Anyone, as an American citizen HAS to be able to express their thoughts "in our world" in understandable English; those from other countries, with different languages.....we have to try to figure out.

[P&DZ]

My hat is off to those who have mastered multiple languages and in particular those, like jadatis, who have mastered English as a second language. Having lived and worked across multiple countries in Europe I has always amazed at the number of people who spoke two or more languages fluently. As an American I felt extremely luckily that English is the universal language of business.