Is there something wrong with SAE J2807?
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Is there something wrong with SAE J2807?
I have a question that's been nagging me. A lot of truckers seem to recommend that I should not tow near the SAE J2807 limit for a truck.
I get that a bigger truck will handle the load better, and with reduced wear and tear. I also get that a bigger truck has higher maintenance costs and capital cost. So I don't really see an economic argument.
If there is a safety concern, then its implicit in that claim that SAE J2807 has some problem? If so, can someone elaborate?
Edit for link to include description of SAE J2807
http://fifthwheelst.com/SAE-J2807-Tow-Tests.html
I get that a bigger truck will handle the load better, and with reduced wear and tear. I also get that a bigger truck has higher maintenance costs and capital cost. So I don't really see an economic argument.
If there is a safety concern, then its implicit in that claim that SAE J2807 has some problem? If so, can someone elaborate?
Edit for link to include description of SAE J2807
http://fifthwheelst.com/SAE-J2807-Tow-Tests.html
Last edited by kehyler; Nov 10, 2018 at 04:32 PM.
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The purpose of SAE j2807 is to establish consistent rating requirements and processes so end users (customers) can reasonably compare similar class models in terms of trailering ability. Once you change the trailer type and conditions the outcome will be different. It’s basically used for paper comparison only and marketing.
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A few quotes directly from the document.
”It is acknowledged that there are a wide variety of conditions experienced while trailering which cannot be completely addressed within this document and in no way is this document intended to establish or limit manufacturers’ designs or instructions to the customer.”
”The performance requirements of this document are not intended to be used to establish minimum acceptable values for various aspects of trailering. The performance requirements and metrics specified in this document are selected considering carefully controlled specific trailers, combination load conditions and driving maneuvers to provide for objective comparisons of tow-vehicle performance.”
The key words being “for objective comparisons of tow-vehicle performance”. The acceleration, gradeability, and braking are valid tests but combination handling requirements are trailer type and loading dependent would result in a different outcome.
“Specific tow-vehicle TWR is to be calculated from the lowest GCWR value determined through testing to performance requirements in 4.3, 4.4, and 4.5 and also cannot exceed the value determined in 4.2.”
Bottom line is the established TWR by j2807 shouldn’t be taken literally in the real world by consumers as this is not it’s intended purpose.
”It is acknowledged that there are a wide variety of conditions experienced while trailering which cannot be completely addressed within this document and in no way is this document intended to establish or limit manufacturers’ designs or instructions to the customer.”
”The performance requirements of this document are not intended to be used to establish minimum acceptable values for various aspects of trailering. The performance requirements and metrics specified in this document are selected considering carefully controlled specific trailers, combination load conditions and driving maneuvers to provide for objective comparisons of tow-vehicle performance.”
The key words being “for objective comparisons of tow-vehicle performance”. The acceleration, gradeability, and braking are valid tests but combination handling requirements are trailer type and loading dependent would result in a different outcome.
“Specific tow-vehicle TWR is to be calculated from the lowest GCWR value determined through testing to performance requirements in 4.3, 4.4, and 4.5 and also cannot exceed the value determined in 4.2.”
Bottom line is the established TWR by j2807 shouldn’t be taken literally in the real world by consumers as this is not it’s intended purpose.
Thread Starter
5 Year Member
Joined: Apr 2017
Posts: 978
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A few quotes directly from the document.
”It is acknowledged that there are a wide variety of conditions experienced while trailering which cannot be completely addressed within this document and in no way is this document intended to establish or limit manufacturers’ designs or instructions to the customer.”
”The performance requirements of this document are not intended to be used to establish minimum acceptable values for various aspects of trailering. The performance requirements and metrics specified in this document are selected considering carefully controlled specific trailers, combination load conditions and driving maneuvers to provide for objective comparisons of tow-vehicle performance.”
The key words being “for objective comparisons of tow-vehicle performance”. The acceleration, gradeability, and braking are valid tests but combination handling requirements are trailer type and loading dependent would result in a different outcome.
“Specific tow-vehicle TWR is to be calculated from the lowest GCWR value determined through testing to performance requirements in 4.3, 4.4, and 4.5 and also cannot exceed the value determined in 4.2.”
Bottom line is the established TWR by j2807 shouldn’t be taken literally in the real world by consumers as this is not it’s intended purpose.
”It is acknowledged that there are a wide variety of conditions experienced while trailering which cannot be completely addressed within this document and in no way is this document intended to establish or limit manufacturers’ designs or instructions to the customer.”
”The performance requirements of this document are not intended to be used to establish minimum acceptable values for various aspects of trailering. The performance requirements and metrics specified in this document are selected considering carefully controlled specific trailers, combination load conditions and driving maneuvers to provide for objective comparisons of tow-vehicle performance.”
The key words being “for objective comparisons of tow-vehicle performance”. The acceleration, gradeability, and braking are valid tests but combination handling requirements are trailer type and loading dependent would result in a different outcome.
“Specific tow-vehicle TWR is to be calculated from the lowest GCWR value determined through testing to performance requirements in 4.3, 4.4, and 4.5 and also cannot exceed the value determined in 4.2.”
Bottom line is the established TWR by j2807 shouldn’t be taken literally in the real world by consumers as this is not it’s intended purpose.
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It's a baseline document.
Nothing more, nothing less. If a manufacturer advertises their tow ratings based on J2807, then they established they meet the specifications laid out in the document. When you have three different manufacturers stating their tow ratings, and only two of them base them from J2807, the third one is pulling ratings out their backside and can't be trusted.
The latest revision from 2016 is by subscription only, so here is the 2012 full version. https://www.automotive-fleet.com/fc_.../pdf/j2807.pdf
This document establishes minimum performance criteria at GCWR and calculation methodology to determine tow-vehicle TWR for passenger cars, multipurpose passenger vehicles and trucks. This includes all vehicles up to 14000 lb GVWR.
The latest revision from 2016 is by subscription only, so here is the 2012 full version. https://www.automotive-fleet.com/fc_.../pdf/j2807.pdf
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From: Midland County Texas, just west of the star in my avatar
https://www.sae.org/standards/content/j2807_201602/
If you don’t want to put out $78 or join SAE, then a web search will produce review and summary info from various magazines and websites other than SAE.
Is there something wrong with SAE J2807?
Not when used for its intended purpose, i.e., to compare tow ratings of tow vehicles from various manufacturers. But you still cannot rely on those tow ratings to match trailer weight to tow vehicle capacity, because it doesn’t consider payload capacity of the tow vehicle. IOW, it’s concerned with GCWR and ignores GVWR of the tow vehicle. If you use the tow rating determined by J2807, you’re probably going to be overloaded.
For example:
In addition to a vehicle’s base curb weight, the “Tow Vehicle Total Weight” (TVTW) for testing for ¾- and 1-ton trucks allocates 150 pounds for the driver, 150 pounds for a passenger, the weight of all tow package equipment, and 100 pounds of optional equipment (hitch ball, weight distribution bars, and such) split evenly between the front and rear axles.
