How to estimate GCWR (Gross Combined Weight Rating)

Discussion in 'Tow Vehicles, Hitch & Towing' started by davekro, Nov 18, 2019.

  1. davekro

    davekro Active Member

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    I read somewhere that how much 'people weight' and 'cargo weight' you would you carry in your TV, affects your actual safe maximum trailer towing weight capacity (in a convoluted way I still do not understand). There is a rating we'd ALL love to know for our TV, GCWR (Gross Combined Weight Rating is the mythical maximum total loaded TV weight + Loaded Trailer wt.). Unfortunately, most auto manufacturers do NOT publish this spec. and for my 2017 KIA Sorento, a zillion web searches, emailing my Kia salesman and that dealers service dept.... Crickets. HAH, the manual says: "Warning. Before towing, make sure the total trailer weight, GCW, GVW, GAW and trailer tongue load are all within the limits." Nowhere does the manual give a number for GCW or GCWR!

    Maybe someone has heard of a rule of thumb to arrive at a ballpark GCWR for TV's. I want to use that data point not to max out my (supposed/ implied 5000 lb tow cap, but to learn if it is really WAY less once you account for the actual weight of the TV and all people, cargo & tongue wt. and balance with the TV's GVWR limits .

    Using my vehicle, cargo, tongue wt. max as an example, what would you say the maximum trailer weight would be here specifically? (not including tongue wt, which is included in TV 'cargo')
    2017 Kia Sorento SX AWD, 3.3L V6, 5000 tow cap, 350 max tongue wt.
    GVWR 5622
    Curb Wt. 4101
    Cargo cap 1521 (5622-4101)
    Cargo Wt. 600 (2 people, pets, generator, coolers, Tools/Chrgr, Wood, Clothes/misc)

    Cargo Cap 1521 - 600 cargo - 350 Tongue = 571 lbs of capacity left over in TV I guess.

    The goal of this exercise is NOT to learn the maximum trailer weight, so I would choose to tow that amount. I want to know this number so I know with 'X' weighted trailer, I am towing 'Y%' of my capacity. Where 'Y' might be somewhere between 65% to 80% of capacity. It is helpful when shopping for 'how much more Pup size' do we feel comfortable towing. Then factor that into our size/model selecting process.
    Thanks for any insights or additional considerations.
     
  2. SteveP

    SteveP Well-Known Member

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    What you have above is the vehicle cargo capacity. GCWR is the maximum weight your vehicle, vehicle cargo, trailer and trailer cargo combined should weigh. It can't be calculated but should be provided by the manufacturer based on the drive line, suspension and brake systems. If your manual lists towing capacity restrictions, such as "3500 pounds with a 150 pound driver, you should subtract the 150 lbs from your cargo weight and subtract the remainder from your tow allowance. 3500 - 450 = 3100 lbs tow capacity. This may still be a bit high because you may also need to subtract the weight of fuel and fluids in the vehicle.
     
  3. bheff

    bheff Well-Known Member

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    These numbers can get confusing. It is good to physically write down what your vehicle is capable of, trailer weight, tongue weight and passenger weights and do some math. My Jeep lists max towing cap at 4500lbs, 450 tongue weight with a maximum occupancy weight at 900lbs
    I take this as if I had max tongue weight my occupancy weight would be reduced to 450lbs. Any reduction in tongue weight would give me room to add occupancy weight (or cargo).
     
  4. davekro

    davekro Active Member

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    So my TV: (5000 tow cap) - (600 cargo*) = 4400 actual max trailer tow wt. that sounds like it considers all the known factors.
    (My manual states that curb wt. is ‘How the dealer delivers the car to the customer w/ a full tank of gas, but w/o wt. of extra options.’
    *The manual says to count all passengers, it does NOT exclude the driver. So my trailer capacity should be 4400. (+/- any changes to my 600 lb cargo wt.

    Thanks Steve! Now I feel confident of what my specs allow for a max. So our current 10’ box pup dry 1560, maybe 1900 loaded appears to be at about 43% of our towing cap. Nice to have room to know if we (for us) went big that might look like a slide out pup 10’ box with a front compartment or a 12’ box w/o frt. compartment, we can safely consider approx. 3000 dry/3500 loaded. With the 3.3L v6, 290hp, 3500 lbs at 80% of our 4400, would feel like a workable weight going up Donner summit in the Sierra’s occasionally (7000’), though we usually camp in the 3500’ elevations.
     
  5. davekro

    davekro Active Member

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    Yeh, before posting above, I gathered all the specs together on an Excel sheet so I could include all the numbers above. ;)
     
  6. rabird

    rabird Howdy!

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    at a minimum , curb wt (equipped for towing) + 150 lb driver + tow capacity or ~9300lbs
    ie an empty vehicle has its max tow rating.

    That would be how an American truck is rated, ie for every lb or cargo or people the tow rating is reduced.

    Foreign cars that publish a GCVWR usually have some buffer that allows some cargo while maintaining max tow rating.
     
  7. jmkay1

    jmkay1 2004 Fleetwood/Coleman Utah

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    I don't have the exact set up as you, but my Toyota 4 runner also has a tow rating of 5000 and I can tow my Max gvw of 3500 without too many problems. I do experience slow up in the mountains. I now keep company with the big rigs as I don't have the pick-me-up to pass going up hill. On the steeper inclines things slow up even more and I can really feel my engine work hard. Even noticed my car turns the AC off so it can use the power to where it really needs it. So with that said, I would not want to tow any more than what I have with my set up.
     
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  8. Orchid

    Orchid Sharp Shootin' Grandma

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    Is there not a sticker inside the driver's side door with this info?
     
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  9. GreyFox

    GreyFox Well-Known Member

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    Not convoluted at all - regardless of vehicle one must not exceed the TV's payload capacity. Usually that number is reached long before one comes anywhere near a vehicle GCWR, stated or not.

    For the simple reason your Kia Sorento is not considered by the manufacturer to have been designed for towing - it's a family vehicle, grocery getter, etc.
     
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  10. bheff

    bheff Well-Known Member

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    Mine is stated on the same sticker as tire pressures on the "B"pillar of the driver side door.
     
  11. davekro

    davekro Active Member

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    Exactly the really world apples to apples info that is particularly helpful! Here in Calif. we may take an occasional trip up and over the 7000’ Sierras or the shorter but steep Grapevine. For those times, I am fine even doing 40-45 mph (not tacking too high) with the big rigs in the slow lane. If you felt you ‘had to pass’, I’m guessing even our mid 3L V6s could tack up to 55 mph (4000 rpm?) to pass one big rig. Mostly we travel to about 3500’ elevations.
     
  12. davekro

    davekro Active Member

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    This sticker ‘only’ lists GVWR and GAWR for each axle. What vehicle do you have that lists GCWR on this sticker or even in the manual?
    I really am curious if anyone’s door sticker -OR- manual lists a GCWR (Gross COMBINED Weight Rating).
     
  13. davekro

    davekro Active Member

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    Does your tire sticker list “GCWR” or “Weight of combined passenger and cargo should never exceed xxxx lbs.” like my tire sticker does?

    Thank you for mentioning the tire sticker. I had not thought to look at that one. Interestingly, mine says: “Weight of combined passenger and cargo should never exceed 1120 lbs.” But the specs for the Sorento say “cargo capacity 1521” (which is GVWR - Curb wt.) Curb wt. is stated to include a full tank of gas (118 lb), so the 400 lb difference is a mystery.
     
  14. GreyFox

    GreyFox Well-Known Member

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    Any vehicle considered by the manufacturer to be suitable for towing will list the vehicle's GCWR as determined by that manufacturer in the owner's manual for that vehicle. Those vehicles not specifically considered suitable for towing will not have this information listed in the owner's manual. In no situation, regardless of vehicle, have I ever seen GCWR listed on a door jamb sticker.
     
  15. davekro

    davekro Active Member

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    You are saying that all (or most) trucks and large fullsizeD SUVs would list a GCWR in their manual? What is listed as GCWR in your Sierra’s manual?
     
  16. GreyFox

    GreyFox Well-Known Member

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    Yes - all.

    My 2012 5.3L 4WD Crew Cab Short Box Silverado with a 3.42 axle ratio is listed on Page 9-92 of my 2012 Owner's Manual - Maximum Trailer Weight 9500 lbs (which is fantasy as I'd never tow anything anywhere near that heavy with this truck) and 2) GCWR 15,000 lbs.

    Go to these 2 pages and you can see how when towing even just a 19' travel trailer weighing under 4800 lbs totally loaded & ready to camp I am just barely within the limits of this truck and no where near it's GCWR because I'm just within the truck's primary limiting factor - payload capacity, or more correctly lack thereof.

    https://photos.google.com/share/AF1...?key=YTZrWHhLU0VrOWFnakV4el9jMXJodi1ISVItaGFR

    https://photos.google.com/share/AF1...?key=YTZrWHhLU0VrOWFnakV4el9jMXJodi1ISVItaGFR
     
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  17. bheff

    bheff Well-Known Member

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    In the middle above the red box. Screenshot_20191119-130854_Photo Editor.jpg
     
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  18. Rusty2192

    Rusty2192 Well-Known Member

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    GM is starting to put a ton of information on their door jamb sticker on at least the new HD trucks, which is awesome. Hopefully all other manufacturers will follow suit. The numbers are unique to the exact truck as it rolled off the line.
    DF4837FA-B0EE-475A-B102-EDC7ED1FB39C.jpeg
     
  19. davekro

    davekro Active Member

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    Great use of Excel to capture all the data for overview! Thanks for showing that GCWR is not really a a useable factor due to, as you point out, GVWR limits will be encroached way before GCWR is even in sight. Thanks for showing the math that clearly describes that fact. Propane tanks, empty weigh ≈ 16.6 lbs. I assume the dry weight of your trailer must include two empty 20 gal propane tanks.
    Thanks for the detailed info!
     
  20. McFlyfi

    McFlyfi Active Member

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    I love this! Simply and elegantly describes what your MAX tow capability would/could be, when properly equipped by the manufacturer. And describes how adding anything to the vehicle reduces its tow capacity.
     

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