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Old 06-10-2021, 07:25 AM   #1
Walnuts
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Confused by the trailer weight versus gravity and reality

Hi All,
Hoping someone on here can help me, because this maths has me confused.

My TT is a 2021 318BR with a dry weight (from the sticker) of 7686 lbs, and GVWR of 9700 lbs.

Last weekend on the way to the campsite, decided to hit the Cat Scale. Propane tanks, 2 x grey, black tank and fresh water tanks were all full. A single battery on the TT.
The Cat scale said; 8320 lbs. I'll accept that, we tend to travel light with the accessories etc. there's only 2 adults and a 6 year old child.

Coming back from the camping weekend...I'd dumped all the tanks to empty. Had only used enough propane for the water heater (so not much).
Hit the same Cat Scale and the TT weight recorded at 7540 lb.

Now here's the issue...how can the weight of my TT (with some chairs, beers, onboard) be less than the weight from the factory?

I don't understand it.
Am I to believe that either the factory scale or the newly installed Cat scale is not calibrated?

For clarity, the axle weights on the TV were approx the same both going and returning for the trip.
Being a little OCD, I tend to pack things in the same places and conditions every time. <--- Nerd Alert!!!

Thank you in advance for any input, its appreciated.
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Old 06-10-2021, 07:31 AM   #2
Javi
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GVWR is the total weight of the trailer... includes the tongue weight which is resting on your tow vehicle when hitched...

All you measured was the axle weight of the trailer...
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Old 06-10-2021, 07:38 AM   #3
Walnuts
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Ok, so some of the TT weight is actually transferred through the TV and is counted on the rear axle weight of the TV?

At the factory there were 5 touch-points on the scale (twin axle and the front foot)?
At the scale, it was just the 4 wheels on the axles.

Thank you, that cleared it up for me. I appreciate the help.
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Old 06-10-2021, 08:03 AM   #4
Ken / Claudia
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Now go back to scale with same stuff in TV, your rear axle will be somewhere in the 1,000 lbs lighter. Front axle maybe several hundred pounds heavier.
Add both differences to your trailer axle wt.s, now you have the real trailer wts.
With all that weight added to rear axle, the front gets lighter. Hope not to much lighter.
The scales at least at DOT scales will be correct within 200lbs plus or minus. I would bet CAT are the same. They are made for really much heavier vehicles and 200 lb one way or another is nothing for a 105,000 lb truck/trailer.
I have no idea how, who or when CAT scales are certified. DOTs as I recall every 6 months. I had to have that information for each court case.
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Old 06-10-2021, 08:25 AM   #5
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OK... Six year old... hiding helium filled balloons where adults can't find them in the cabin. That is my theory.
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Old 06-10-2021, 08:37 AM   #6
Walnuts
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It's something he would do. ha ha.
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Old 06-10-2021, 02:05 PM   #7
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All you need to know and then some concerning CAT scales and accuracy for RV's: https://fifthwheelst.com/commercial-...ghing-rvs.html
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Old 06-10-2021, 02:05 PM   #8
flybouy
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You need to weigh the rig, then unhitch the trailer and weigh just the truck. The difference in the truck weight will be the pin weight yhat the truck is supporting. Add that number to the trailer axle weights to get the trailer weight. If you ho to catscale.com/how-yo-weigh/ they explain this with illustrations.
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