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Old 10-28-2018, 07:06 PM   #1
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2018 27' Globetrotter
Mooresville , North Carolina
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Are my Tongue weight and Cat Scale Conclusions Correct for 2018 Globetrotter / 2018 G

Iíve read many posts regarding tongue weight calculations / axle loads / etc. In summary, they suggest 1) Weighing your TV w/o the RV attached 2) Weighing TV and RV with weight distribution applied and 3) Weighing TV and RV w/o weight distribution applied. This will give you the information you need to determine your tongue weight, etc. but I could not find how you apply steps 1, 2 and 3 to get to your conclusion. I wanted to post this to see if my conclusions are correct.

In summary, it appears to me I have not exceeded any axle ratings on my TV and have not exceeded any gross axle ratings on my RV. Iím not sure I have computed the tongue weight correctly. It appeared to me if I take weight of my steer and drive axle with weight distribution applied, 9,680 and subtract the weight of my truck only loaded for a trip, 8,832, the difference of 1,048 would be the weight of the trailer that is being added to my TV as tongue weight.

It also appeared to me that if I take the difference in my steer axle, drive axle and trailer, with and w/o weight distribution, that would show me the amount of weight shifted by the weight distribution bars. In this case, 100lbs is being shifted from the drive axle to the steer axle and 60 lbs. was being shifted from the drive axle to the RV.

One other item that was initially confusing to me was that dry weight of the RV is 6,603lbs and the weight of the RV with weight distribution on the CAT Scales was 6,320. I couldnít understand how it could be less. My conclusion was that the majority of the tongue weight of the trailer was being carried by the TV. If that is the correct conclusion then it appears to me the cargo of the TV could be greater than the 997lbs shown on the RV stamp on the outside as longer the RV didnít weigh more than 3,800lbs for each axle or 7,600 in total.

Are these conclusions correct?

Thanks for any input you can provide.


Specs
2018 GMC Sierra SLT 2500HD Duramax Diesel

5,200 GAWR Front
6,200 GAWR Rear
10,000 GVWR
13,000 Maximum Trailering Capacity

2018 Airstream Globetrotter with options of 2 A/C's / 160W Factory Solar / Electric Awning

6,603 Curb weight
997 Cargo Weight Available
7,600 GVWR (3,800 each axle)

02/21/18 Truck full of diesel / no passengers

Steer Axle Drive Axle Total
4,680 3200 7,880 (A) Curb Weight of truck at Cat Scales. Full of diesel and fluids / no passengers

10/12/18 (1) Truck full of gas / 1 driver/RV Hitch w/o WD bars/generator/gas can/air compressor/Yeti with ice/chairs/fan/cooler/grill and stand/bed cover/leveling blocks

Steer Axle Drive Axle Total
4,780 3660 8,440 (1)
42 42 Add Equalizer W/D Bars (21lbs each to rear axle)
75 75 150 Add Spouse as passenger
4,855 3,777 8,632 (B) Adjusted Weight loaded w/o RV attached and ready for trip
10,000 GVWR
1,368 Cargo Available


(B) - (A) 752 Cargo / Passengers added to truck from Curb Weight


Steer Axle Drive Axle Trailer Total
4,600 5080 6380 16,060 With Weight Distribution and RV loaded for trip with full fresh water tank
4,500 5220 6320 16,040 W/O Weight Distribution and RV loaded for trip with full fresh water tank

100 (140) 60 20 weight Shifted (20lb rounding)

9,680 Weight of Truck with Weight Distribution
8,632 Adjusted Weight loaded w/o RV attached and ready for trip
1,048 Tongue Weight added to Truck from the loaded RV
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Old 10-28-2018, 08:32 PM   #2
CLOUDSPLITTER "Tahawus"
 
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2003 25' Classic
Zanadude Nebula , Milky Way
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Welcome Aboard!! 👍

I'm a bit confused...

Three Cat tickets are really all thats needed to confirm proper weight distribution...it may take more than three passes to get that conformation.

Here are three CAT tickets for us...TV alone, Rig with no wd, rig with WD set & rig LEVEL.👍
Notice that I have returned all but 100lb to the steering axle...the breakdown.
560 to the FA
160 to the AS
720 moved

Bob
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Old 10-28-2018, 09:22 PM   #3
kpm
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Quote:
Originally Posted by GOUSC View Post
Iíve read many posts regarding tongue weight calculations / axle loads / etc. In summary, they suggest 1) Weighing your TV w/o the RV attached 2) Weighing TV and RV with weight distribution applied and 3) Weighing TV and RV w/o weight distribution applied. This will give you the information you need to determine your tongue weight, etc. but I could not find how you apply steps 1, 2 and 3 to get to your conclusion. I wanted to post this to see if my conclusions are correct.

It also appeared to me that if I take the difference in my steer axle, drive axle and trailer, with and w/o weight distribution, that would show me the amount of weight shifted by the weight distribution bars. In this case, 100lbs is being shifted from the drive axle to the steer axle and 60 lbs. was being shifted from the drive axle to the RV.

[...]

Are these conclusions correct?

Thanks for any input you can provide.
I think you are almost there but you'll need another trip to the scales. You're correct, you need three weighings, but you need to do them with your rig loaded for camping, one right after the other, without adding/removing load to the TV or trailer in between. I weigh the whole rig first as weight #1, then remove WD bars for weight #2, then drop the trailer and weigh the TV for weight #3. You can use the CAT scale phone app to make the process very fast, basically drive on/drive off - no need to talk with the weighmaster over the intercom.

As far as the calculations go, it is convenient to put them all together in a spreadsheet. Here is a link to my weights and calculations for last season. You can navigate to any cell and read the formula to see how the calculation is performed. The spreadsheet also contains some links to articles describing the calculations. It is easy to copy/paste the whole sheet into your own spreadsheet and put your own numbers in it. My weight distribution isn't bad, but I will make some adjustments in spring to improve my FALR. The weights posted by ROBERT CROSS show a very well tuned weight distribution system. As he says in his post, as you tune your weight distribution you will have to reweigh and redo the calculations to see the effect of your adjustments.

Hope this helps.
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Old 10-28-2018, 09:25 PM   #4
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Are my Tongue weight and Cat Scale Conclusions Correct for 2018 Globetrotter / 2018 G

Your numbers are fine - you are well below your front/rear axle ratings and GVWR, fully loaded and ready for camping with WD applied. I like that you are pushing 100lbs back to the steer axle with WD - Good job! Youíll never transfer much more than that with your tongue weight and a 20í long, 9,500lb TV.

Enjoy the tow - great truck, I've got one too, and a similarly sized trailer, and the same hitch. My CAT numbers are similar.
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Old 10-28-2018, 10:27 PM   #5
CLOUDSPLITTER "Tahawus"
 
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2003 25' Classic
Zanadude Nebula , Milky Way
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"My CAT numbers are similar."

Post them? 😳

We see very few tickets...they would help everyone.

I understand how a longer wheelbase would require more WD to return the needed steering weight, but not how it removes that need...😳

Bob
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Old 10-28-2018, 10:54 PM   #6
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Are my Tongue weight and Cat Scale Conclusions Correct for 2018 Globetrotter / 2018 G

Last weekend I ran through a closed truck weigh-in station on I25 near Denver and I was at 4600 / 5100 / 6700 for steer / drive / trailer with WD applied. Same ratings as the above 2500HD with duramax.

No water. 2 passengers. 300lbs in the bed. My tongue is 990 and trailer is 8,800 gvwr.

Those numbers were a bit low because I was dry and did not have my typical payload. On the cat scales Iím typically at 4600 / 5400 / 7500 wet with more gear in the truck and in the trailer, again with WD applied.

On the duramax you only ever see about 100 lbs difference on the steer axle with and without WD applied. On the duramax 2500 I always strive to return the front axle as close to its normal weight as possible as measured with no trailer attached, by applying the appropriate amount of WD. Once you are there, you just canít seem to push it much further though, no matter how much tension you put on the equalizer bars... That was what I was getting after above.

The above example shows 180lbs off the front axle with no WD, and 80lbs off with WD (WD put 100lbs of the 180 back). So not bad - more than 50% of the weight was returned.

WD should be used, always. My point was that restoring the axle to something close to its original weight (100lbs returned in the above example) is the best you will get with the heavy duramax front end, overall vehicle weight and length (in my experience)

On my other TV (7500lb gvwr suv with independent suspension) I regularly return more than 100% of the weight to the steer axle to drive towards for a more balanced front / rear % weight distribution.
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Old 10-28-2018, 11:19 PM   #7
CLOUDSPLITTER "Tahawus"
 
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Zanadude Nebula , Milky Way
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Oh... I see a closed station...😂

More than 100% now I know your kidding.

Bob
🇺🇸
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Old 10-29-2018, 06:57 AM   #8
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2013 20' Flying Cloud
Westerly , Rhode Island
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Quote:
Originally Posted by GOUSC View Post

One other item that was initially confusing to me was that dry weight of the RV is 6,603lbs and the weight of the RV with weight distribution on the CAT Scales was 6,320. I couldnít understand how it could be less. My conclusion was that the majority of the tongue weight of the trailer was being carried by the TV. If that is the correct conclusion then it appears to me the cargo of the TV could be greater than the 997lbs shown on the RV stamp on the outside as longer the RV didnít weigh more than 3,800lbs for each axle or 7,600 in total.

The definition of GVWR for the trailer is the trailer, by itself sitting on the weight scale, so no, the tongue weight that is transferred to the TV does not get added back to payload.
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Old 10-29-2018, 09:53 AM   #9
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2018 27' Globetrotter
Mooresville , North Carolina
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Thanks for all the responses.

I have attached my CAT scales as suggested since it may help others trying to do this. I realize that all three measurements should be at the same time and these were 13 days apart. We had 2 trips within this time frame. The 1st picture is the Truck only weight. The Truck was weighed at the conclusion of the 1st trip still fully loaded / full fuel / but no spouse or WD bars. I adjusted the CAT scale weight by splitting the passage weight among the steer and drive axle and added the Equalizer WD bars to the drive axle. While not exact, I feel it gives a close approximation for my purpose.

The second picture is the truck loaded the same as the 1st picture and RV packed and loaded for the second trip / 2 passengers / full fuel / with and w/o weight distribution.

I looked at the spreadsheet link attached and copied / pasted it to a 2nd Tab in my spreadsheet. It would not copy the formula's and would only bring over the text. However, I did look at the formula's and it appeared to me I did my calculations correctly with regard to weight transferred / axle weights, etc.

I really do appreciate the link for determining tongue weight and % of tongue weight. I did my calc based on RV weight with W/D less the actual weight of the TV fully loaded and arrived at 1,048. The link indicated it should be based on the RV weight w/o weight distribution. This gave me 1,088 and a % of 14.65%, see below.

Other Results
Gross Combined Weight 16,060
Truck Weight (hitched w/ WD) 9,680
Truck Weight (hitched w/o WD) 9,720
Truck Weight (truck only) 8,632
Truck Contents Weight 752
Trailer Weight 7,428
Trailer Contents Weight 825
Tongue Weight w/o WD 1,088
Tongue Weight Percentage 14.65%
Tonque Weight w/ WD 1,048

This also gave me the total trailer weight of 7,428 which is within the 7,600 GVWR for the Globetrotter. I realize "the definition of GVWR for the trailer is the trailer, by itself sitting on the weight scale" The response was that the tongue weight that is transferred to the TV does not get added back to payload.

However, Iím hoping you guys can clarify this further for me. The load on my RV axle with W/D is 6,380 which is a lot less than the 7,600 GVWR so my tires and RV axles are not near their limit when driving. However, when I park and move 2 passengers inside my RV at 300 lbs that puts my trailer weight at 7,728 which is over the 7,600 GVWR for the RV. Am I over my limit when I park and also when 2 other adults come inside to visit? Or, when RV shows have 6-8 people in the RVís adding addtíl weight inside the RVís.

Iím assuming the response will be that the tongue and stabilizer jacks and take that load, (tongue weight), off of the axles / tires and there is no problem while parked. If that is the answer, then why canít the same be true for adding addtíl payload in the RV when the W/D bars and TV carry the majority of tongue weight while travelling? Iím sure Iím missing something simple but help me connect the dots on this one.
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Old 10-29-2018, 02:37 PM   #10
CLOUDSPLITTER "Tahawus"
 
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I believe your making this much more complicated than it is.

The CCC should be on a sticker,(usually on the inside of the closet door....
This is the moving CCC limit.
The AS axle ratings will be on the exterior build plate...

All the above is the Airstream Factory guesstimate.

The 'hitched' AS axle weight rating with WD set is what you don't want to exceed...take into account the unsprung weight of the tires, est. 150lb. Load your trailer to within 100lb of what the AS axles are rated for.


I will admit that is a blanket statement...it may not apply 100% to the older trailers.
If you look closely at the photos above you will notice that AS installed two 3500lb axles on a trailer with a GVWR of 7300lb with a cargo carry capacity 676lb...I load carefully but am hard pressed to stay under the AS axle weight limit.>😳 (see my CAT ticket above)

I would try to get that 80lbs back to the TV front axle...and go camping.

Bob
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Old 10-29-2018, 03:19 PM   #11
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It would seem to me that your trailers tongue weight of 1048 is properly accounted for. So then given the tow capacity of your TV being 13,000, I think that means you can handle up to 1,300 of tongue weight. This is based on the 10% rule of thumb. So I think you are ok with the 1048 tongue weight of your trailer.


1) Does your TV sag when the trailer is attached with equalizer bars?
2) Is the trailer level front to back?
if the answers are no/not much to 1, and yes to 2, then I would think you are ok.


Best Regards,
Gene
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Old 10-29-2018, 04:08 PM   #12
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Quote:
Originally Posted by gene3 View Post
It would seem to me that your trailers tongue weight of 1048 is properly accounted for. So then given the tow capacity of your TV being 13,000, I think that means you can handle up to 1,300 of tongue weight. This is based on the 10% rule of thumb. So I think you are ok with the 1048 tongue weight of your trailer.


1) Does your TV sag when the trailer is attached with equalizer bars?
2) Is the trailer level front to back?
if the answers are no/not much to 1, and yes to 2, then I would think you are ok.


Best Regards,
Gene
1) No sag when attached to equalizer bars. Using 5 washers.
2) Trailer level from front to back.

I did a double check on the TV hitch stamp and it can handle 1,500lbs tongue weight. The 1,300lbs tongue weight came from the VIN lookup for my vehicle. I would think the stamp on the hitch would control. The hitch stamp also says 13,000 max trailer weight to tow.
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Old 10-29-2018, 04:37 PM   #13
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The hitch stamp tells you only what the hitch is capable of. That hitch could be mounted on any TV, so the lowest number between the TV sticker and hitch should govern. Tongue weight added to cargo and passengers in the TV should be less than the passengers and cargo rating on the sticker in the drivers door frame. Measured values loaded for camping with WD applied should be less than the ratings (prefferrably less than 80% of) all of the following-TV GVWR, TV GCVWR, TV FAWR, TV RAWR, TT GVWR, TT axle ratings, TT wheel ratings, TT tire ratings. Finally the TV front axle weight should be around halfway back from the weight of the TV-TT combination with WD off to the weight measured with the TV alone.

Al
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Old 10-29-2018, 05:11 PM   #14
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Quote:
Originally Posted by ROBERT CROSS View Post
Oh... I see a closed station...😂

More than 100% now I know your kidding.

Bob
🇺🇸
You say that as if you think it is not possible to return the front axle weight to more than 100%. Not so. Trailer attached and bars cinched up on my Cayenne, the front axle is 20 lbs more than without the trailer attached. This distribution allows for me to not exceed my rear axle max.
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