how to determine tow capacity per manufacturers specifications
11-12-2014, 07:12 AM
#1
how to determine tow capacity per manufacturers specifications
Let's say you have a truck with 12,500# towing capacity, 23,500# GCWR, 11,000# GVWR and the truck weighs 9,000# full of fuel, people and gear.
Take your truck to the scale and this is what you get:
Truck font axle: 5,000#
Truck rear axle: 4,000#
Total Weight: 9,000#
Hook up to the boat and this is what you get:
Truck front axle: 5,000#
Truck rear axle: 6,000#
Trailer axles: 12,500#
Total Weight: 23,500#
The trailer, if weighed completely on it's own would be 14,500# (23,500#-9,000#=14,500#). However, when you run it across the scale, your axles readings are 5,000#, 6,000# and 12,500# due to tongue weight being transferred to the truck. The vehicle has not exceeded manufacturers GVWR or GCWR.
Has the truck exceeded manufacturers maximum loaded trailer weight in this example? I have always assumed yes, by 2,000#, but now I am questioning my logic versus actual scale weights.
Take your truck to the scale and this is what you get:
Truck font axle: 5,000#
Truck rear axle: 4,000#
Total Weight: 9,000#
Hook up to the boat and this is what you get:
Truck front axle: 5,000#
Truck rear axle: 6,000#
Trailer axles: 12,500#
Total Weight: 23,500#
The trailer, if weighed completely on it's own would be 14,500# (23,500#-9,000#=14,500#). However, when you run it across the scale, your axles readings are 5,000#, 6,000# and 12,500# due to tongue weight being transferred to the truck. The vehicle has not exceeded manufacturers GVWR or GCWR.
Has the truck exceeded manufacturers maximum loaded trailer weight in this example? I have always assumed yes, by 2,000#, but now I am questioning my logic versus actual scale weights.
11-13-2014, 10:49 AM
#4
VIP Member
Yes, you have. You cannot exceed the Trailer Weight Rating, regardless of how much is being transferred to the truck.
While I like this conversation, now it's going to be used for the next 10 years for folks to justify their towing setup that doesn't add up on various calculators.
While I like this conversation, now it's going to be used for the next 10 years for folks to justify their towing setup that doesn't add up on various calculators.
11-13-2014, 02:12 PM
#5
I found this today. Seems to support using GVWR and GCWR to determine towing capacity. I'm surprised somebody would actually publish this calculator.
http://rvtowcheck.com/
http://rvtowcheck.com/
I like the way you think BGIII......sorry sydwayz
11-13-2014, 04:05 PM
#8
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Yep the tow rating is as simple as it sounds. Trucks often have headroom in CGVWR above the truck + max trailer weight. Lets you load the truck up then pull a trailer. (e.g., last weekend I had a 502 in the bed of my truck and the boat on a trailer behind it).
11-13-2014, 04:55 PM
#9
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I don't argue that it makes sense, but I'm pretty sure that's how it is in terms of official specs and ratings. 
In general I'm unhappy with performance/handling before I get to mfg limits anyway so it's not really an issue for me personally.
In general I'm unhappy with performance/handling before I get to mfg limits anyway so it's not really an issue for me personally.
11-13-2014, 05:00 PM
#10
You should be able to take your truck, trailer, passengers and stuff through a cat scale all at once and if the whole mess is under manufactures GCWR, you should be good to go. What parameters determine the tow rating if it doesn't equal GCWR minus total weight of tow vehicle as driven?
