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Author Topic: Is GVWR Really A Rating to Adhere To  (Read 273 times)

CWSWine

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Is GVWR Really A Rating to Adhere To
« on: October 06, 2018, 10:35:57 AM »
Will I think it is and here are some of the reasons I believe that.

I Quote
"There’s a common misconception that a truck’s GVWR is determined by adding gross axle weight ratings (GAWRs) together for all axles. Although this was a common way of calculating GVWR many years ago, it’s no longer an accurate method. The chassis manufacturer task of establishing a vehicle GVWR is much more difficult today due to advancement of safety system standards and how vehicles meet these requirements. This is why many trucks have a GVWR much lower than the combined axle ratings. It is not uncommon for a truck with a GVWR of 19,500 pounds to have a front axle rated at 7,500 pounds and a rear axle rated at 14,700 pounds. Safety standards that apply to braking, vehicle stability, and chassis manufacturer internal standards for durability, dynamic stability and handling can restrict GVWR even though the sum of the axle ratings exceeds 22,000 pounds. In this instance, the OEM set the GVWR at 19,500 pounds based on test results and vehicle dynamic performance to ensure a safe, reliable truck.

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“As a company or fleet, you’re placing your employees in these vehicles. It is very important to company wellbeing and employee safety to make sure the trucks you purchase are designed for their intended purposes, and GVWR and GCWR are specified properly for safe, efficient operation.”

By Bob Raybuck
Director of Technical Services 
NTEA"
End Quote

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SAE J2807 States that exceeding the GVWR is a reason to fail
Quote
"5.4 GVWR/Rear GAWR and Tongue Weight/Kingpin Weight Considerations

The tow vehicle shall be able to accommodate appropriate trailer tongue and/or kingpin weight to attain a particular TWR
without exceeding Rear GAWR and/or GVWR. Required minimum conventional trailer tongue weight shall be 10% of TWR and required minimum fifth wheel or gooseneck trailer kingpin weight shall be 15% of TWR."
End Quote
TWR = Trailer Weight Rating

http://fifthwheelst.com/documents/tow-test-standards-2016-02.pdf
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From Fords Towing Guides.
Quote
“5th-Wheel Towing Notes:
This information also applies to models with pickup box delete option (66D). Trailer kingpin load weight should be 15% of total loaded trailer weight. Make sure that the vehicle payload (reduced by option weight) will accommodate trailer kingpin load weight and the weight of passengers and cargo added to the towing vehicle. The addition of trailer kingpin load weight, and the weight of passengers and cargo, must not cause vehicle weights to exceed the rear GAWR (Gross Axle Weight Rating) or GVWR (Gross Vehicle Weight Rating). These ratings can be found on the vehicle’s Safety Compliance Certification LabeL”
End Quote
On Page 30

https://www.ford.com/services/assets/Brochure?bodystyle=Truck&make=Ford&model=SuperDuty&year=2018
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For me, there is just to much evidence like the manufacturers towing guides, the trucks user manual, SAE and now NETA using GVWR to brush it off as just for registration and not a real rating to adhere to.
« Last Edit: October 06, 2018, 10:39:58 AM by CWSWine »
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grashley

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Re: Is GVWR Really A Rating to Adhere To
« Reply #1 on: October 08, 2018, 08:57:09 PM »
Thanks for the excellent documentation!
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muskoka guy

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Re: Is GVWR Really A Rating to Adhere To
« Reply #2 on: October 08, 2018, 10:41:16 PM »
The axles are not the last word on gross weight. My chassis on my rv says, 26700 lbs, the final rating from coachmen say 24600 lbs. The coach mfg might have altered the original chassis by adding something that lowers the final gross weigh. In the end, they get the last word.

FastEagle

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    • Down the roads with us
Re: Is GVWR Really A Rating to Adhere To
« Reply #3 on: October 09, 2018, 03:16:48 PM »
The axles are not the last word on gross weight. My chassis on my rv says, 26700 lbs, the final rating from coachmen say 24600 lbs. The coach mfg might have altered the original chassis by adding something that lowers the final gross weigh. In the end, they get the last word.


It's all explained in 49 CFR part 567 (vehicle final stage certification).


https://www.gpo.gov/fdsys/pkg/CFR-2011-title49-vol6/xml/CFR-2011-title49-vol6-sec567-5.xml
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sightseers

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Re: Is GVWR Really A Rating to Adhere To
« Reply #4 on: October 09, 2018, 07:58:36 PM »
and yet,  there is no state or federal GVWR enforcement on privately owned trucks or motorhomes.

Weight enforcement is only on commercial trucks, and that is for road tax revenue...not safety.

In commercial truck scales they don't care about the truck's door listed GVW at all ... only the DOT sticker weight that you payed taxes on and the tire weight rating.

And the axle weight limit for 'commercial' road tax paying trucks is 20k lbs ! ...but the same axle on a motorhome or bus is legal at 23,000 lbs. 

it has nothing to do with safety...it's all about road tax money.   

on a privately operated truck, you can put one ton axles on a 1/2 ton truck and nobody cares..

« Last Edit: October 09, 2018, 08:06:50 PM by sightseers »

UTTransplant

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  • Cedar Falls, Iowa
Re: Is GVWR Really A Rating to Adhere To
« Reply #5 on: October 09, 2018, 08:24:37 PM »
Since the OP put this under the Towables topic, I am assuming that is what he is interested in, I also agree with him that it matters. I have told the story before related to me by a Physician’s Assistant I was seeing. She had the same truck we did, a Ram diesel 2500. Her previous truck pulling the toy hauler was a Tundra her salesman said would tow it fine (standard phrasing from a dealer, isn’t it?). She said they realized the problem when they replaced the transmission in the Tundra the second time.
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