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sliptap's avatar
sliptap
Explorer
Mar 18, 2020

New Truck - Is My Math Right?

Hi Everyone,

My wife and I recently purchased a truck for towing. I've been running the numbers to see which RV's we could purchase and would appreciate you spot checking my math.

Here are some base specs for my truck:

  • 6600 GVRW
  • 1330 Payload
  • 8000 Towing Capacity
  • GCVWR 13300
  • 5270 Truck Curb Weight


It's a 2018 F150 2.7 Ecoboost. I believe payload is my biggest limiter here.

Let's assume 620 lbs of guests (wife/fake kids/dog) and 125 lbs of additional cargo (WDH and 50 lbs gear).

Where I am stuck is calculating the hitch weight. I've read that I should assume 14% of a trailer's GVWR should align with the hitch weight. So if I assume a 4000lb GVWR trailer, then I would just barely be under my payload limits. That would be 560 lb hitch weight (4000*14%). This would assume I am diligent in what goes in the truck as well as not overloading the payload of the trailer.

The math = 1330 - 620 - 125 - 560 = 25lbs.

Am I correct with the hitch assumption? Am I missing anything else? For reference, we've been looking at Coleman Lantern 17B as a potential trailer and I believe that has roughly 3800 GVWR. I think our saving grace could be filling the truck with water at the camp site.

Thank you for any advice!
  • JIMNLIN's avatar
    JIMNLIN
    Explorer III
    Mar 18, 2020
    Your question a common one on a rv forum and always gets lots of ideas and opinions.
    Looks like your using brochure numbers however the truck GVWR and FAWR/RAWR from the drivers side door post sticker and is all thats needed to figure a safe in the bed payload.

    Our pickups carry weight which is limited by the truck FAWR/RAWR and in particular the rear axle as its carrying all of a trailer hitch load plus other gear in the bed.
    Load it up with people/gear/WD hitch/etc and drop by a set of scales and weigh the front and rear axles separately. Your trucks rear axle may weigh in the 2100-2200 lb range (estimate).
    Next look at the trucks certification placard on the drivers side door post and find its RAWR.
    Simply subtract the scaled rear axle number from that RAWR number. Use that as its payload.
    Never exceed a RAWR number ie;...tire/rear suspension/rear axle assy/wheel rating.

    Scaled axle weight numbers cab be used along with measurement when setting up a WD hitch system.

    The reason I'm using the trucks RAWR is in many cases using the mfg GVWR based payload can and have overloaded the trucks RAWR number.

    620 lbs of guests?? Usually guest are visiting in the trailer or are they riding in the truck.

    Fill the truck with water at the campsite ?? IMO you mean the camper ??

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