Allison 6sp: Tow limits versus GCWR

[Lchronister]

Much much research went into the purchase of the truck, with the notion of what 5th wheel we wanted to purchase.
We love love our 2017 Deisel Duramax 2500HD Long bed crew cab. All of the research we did on the manufacturers websites showed us 18,100 towing capacity. With a Gross COMBINED weight of 25,000 and some change.
After the purchase of the truck and the 5th wheel, we read the manual (plus the duramax addon manual) from cover to cover.
To our surprise, the GCWR is listed at the 25,000 but the trailer rating is only 12K?
This is totally baffling us? We calculated the dry weight of the truck, added a full tank of gas, the weight of the fifth wheel hitch, people weight, and a couple hundred extra pounds of 'stuff' and we came up with 7,735 lbs. The GVWR of the truck in and of itself is 9900.
So even fully loaded with rocks or something crazy at 9900, there should be a towing capacity of 15,000 plus.
Where is my math wrong here? How can the Gross Combined weight be so large, but you cant pull the difference (legally).
Truck GVWR = 9900
Truck Towing GCWR = 25000
5th wheel GVWR = 17000

 

[2004LB7]

I think you may be off on some of your numbers

See here: http://www.chevrolet.com/content/da...ing-printablechart-silverado2500HD-020917.pdf

And here: http://www.chevrolet.com/truck-life/trailering-and-towing-guide

 

[Lchronister]

Exactly what we saw!

So the link you pointed us to is where we got our original numbers before we made any purchases.
Duramax® 6.6L Turbo-Diesel V8 Fifth Wheel = 18,100 pounds
BUT.... That is the highest rating for the line. In the manual, 18,100 is listed for the 4x2 regular cab long box. So in essence, on that general chart, they listed the MAX

However, ours is 4x4, crew cab, long box. listing in the manual(2017 Duramax Diesel Owner's Manual Supplement):
Max. Trailer weight = 12,400 lbs
GCWR 25,300 lbs

Note at the end of the chart "The Gross Combination Weight Rating (GCWR) is the total allowable weight of the completely loaded vehicle and trailer including any passengers, cargo, equipment, and conversions."
Also: "Trailer rating limited to 14,500 pounds with conventional hitch." <---this confirms the assumption that the chart is listing 5th wheel limits.

So why a 4x2 is able to pull 5700 more lbs? There is not a 5700 lb difference in these two trucks.

And also, the math: 25,300 GCWR minus the weight of the GVWR(9900 lbs) of the truck is 15,400 (should be the max trailer weight, not 12,400)

???

 

[THEFERMANATOR]

The 12K trailer tow rating is the bumper pull rating utilizing a class 5 hitch system. Your 5th wheel tow rating will be the 25K minus whatever the truck weighs.

 

[Dozerboy]

X2 a conventional hitch is not a 5th wheel. As long as your truck has a GCWR of 25000lbs and you have tires that will suport the weight you have on each axle you are good as far as the law is concerned.

Sent from my SAMSUNG-SM-G900A using Tapatalk

 

[Lchronister]

Per the 2017 Duramax Diesel Owner's Manual Supplement:
"Trailer rating limited to 14,500 pounds with conventional hitch."

Isn't that a class 5?

Max trailer weight (not conventional hitch) for my truck is listed at 12,400 lbs (in the same manual) which is even less than a conventional hitch... shake my head.. I'm still so confused.

Calculation of the weight on each axle... brings up more math problems!!
Truck is rated maximum tongue weight, 5th wheel at 3000 lb (manual). The GAWR is 6200 lb (the sticker on the truck)... so another discrepancy! My trailer kingpin weight is 3010 lbs.

 

[beach_33]

My boat and trailer weigh just a little over 16,000 and I pull it with my 2016 on the factory class 5 with zero hesitation and zero problems

 

[Lchronister]

Im not concerned that my truck will pull the trailer, its well within the limits of the Gross Combined.

My main concern is getting pulled over and cited by the cops.

And more importantly, if there would be an accident, if the insurance company would cover it.

Third concern is voiding the truck/trailer warranty?

What numbers do they use, if at all?

 

[zakkb787]

I really don’t think you’re gonna have any issue as long as your tag is within the 25k limit if that’s the size tag you have. Highly doubt you have a fifth wheel that’d be required to be pulled by a semi.

 

[malibu795]

Truck gvwr+Trailer gvwr does not equal GCWR

GCVWR minus truck tare is "towing capacity"

Truck GVWR is FA+RA
Trailer GVWR is Coupler+axle capacity(90% of trailer MFG fail to plate trailers accordingly and just plate by axle capacity)

Being a SRW truck your biggest concern should be weight on your rear axle.

 

[THEFERMANATOR]

When I sold trucks back in 06, GM only listed the bumper pull hitch ratings, pin style(aka fifth wheel or goose neck) were not listed. They simply worked by gcvwr minus truck weight gave you the max pin tow rating. This was straight from the GM tow guide in 06. Back then they only had class iv hitches, so all the max tow ratings were listed as 10K, but the gcvwr minus truck weight could go much higher on some models. Stay within the manufacturers gcvwr limit which you say is 25K lbs, don't exceedthe weight rating on either your steer or rear axles, and you're safe.

 

[THEFERMANATOR]

Found this link with a screen shot of the GM guide showing max 5th wheel weight for a 2500hd 2x4 duramax truck as 18,100 lbs. But keep in mind this number goes down as truck weight goes up because you cannot exceed the 25,000 gcvwr limit.

http://www.tfltruck.com/2016/11/201...chevy-silverado-2500-hd-payload-towing-specs/