How are tow ratings determined in the first place?

[belchfire]

I'm not asking what my tow rating is, I'm asking how GM (Ford, Ram, etc) comes up with the tow rating for any given design.  Is it a calculation involving the mass of the tow vehicle and the power to pull, factored by the braking to stop?  Something else entirely?

[asilverblazer]

SAE J2807

 

But manufacturing in large quantities has another element to it...

 

I suspect that in addition to the above, manufacturers probably have some of their own internal validation standards, along with a cost benefit analysis of how hard to stress components before warranty costs get too high. In theory, the truck should be able to complete the SAE J2807 through the warranty period at a minimum.

 

Manufacturer A may choose to run a riskier operation where the failure rate may be higher, betting that fewer trucks will be stressed at maximum.

 

Manufacturer B may choose a more conservative approach to make sure a larger portion of the trucks do not fail at maximum. 

 

All trucks certified using the SAE J2807 where able to pass the test at least once in testing...

[newdude]

Here is a nice description of the SAE J2807 procedure.

 

SAE J2807 Tow Tests - The Standard (motortrend.com)

[belchfire]

So ..... If someone were to heavily modify a truck (like Hennessey) how would they determine the upgraded tow rating?   Is it purely testing, or is there any evaluation included?  I read the article and it sounds like it's entirely test related; which makes it difficult to upgrade the towing specs on a one-off conversion.

Edited October 7, 2021 by belchfire

[shakenfake]

Well a lot of it is determined on the size of the truck. So even a modified truck you are looking at the same tow rating as before because of how large the truck is. That's why a lot of the smaller engine trucks have a large capacity but struggle when they are not even close to the max capacity.

[newdude]

17 hours ago, belchfire said:

So ..... If someone were to heavily modify a truck (like Hennessey) how would they determine the upgraded tow rating?   Is it purely testing, or is there any evaluation included?  I read the article and it sounds like it's entirely test related; which makes it difficult to upgrade the towing specs on a one-off conversion.

 

 

It wouldn't increase because the GVWR of the truck is the same.  Its limited by frame, brakes, gearing.  The truck was SAE certified in stock configuration and mods like Hennessey would have no bearing on changing that #.  

Edited October 8, 2021 by newdude

[asilverblazer]

Found this article...

 

For the lay man, changing the ratings (officially) is probably a fools errand.

 

https://www.worktruckonline.com/145897/re-rating-gvwr-why-and-how-its-done

 

Can you change all the hardware to physically change a rating? Sure.

[NWI Denali]