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Old 10-20-2010, 08:41 AM   #1
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Calculate tow weight

Is it accurate to calculate tow weight of a 5th wheel like so?

GVRW (5th wheel) - Pin Weight = Towing Weight.

I'm assuming the pin weight becomes part of the tow vehicle's GVW but I haven't been able to confirm the above formula.
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Old 10-20-2010, 09:33 AM   #2
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In sizing a towing vehicle, you need some idea of the actual loaded weight of the tow vehicle with all options, accessories, driver, passengers, cargo, hitch, full fuel tank, etc. - this is higher than the manufacturer's published curb or base weight which is a base vehicle with only a 150 lb driver. If you already own the proposed towing vehicle, a trip to the scales may be the best $8.00 you ever spent! With this laden curb weight of the tow vehicle (LCW), the following formulas may be used:

Maximum allowable loaded trailer total weight = Tow vehicle GCWR - Tow vehicle LCW

Maximum allowable loaded trailer pin/hitch weight = Tow vehicle GVWR - Tow vehicle LCW

These formulas can be used for either 5th wheel or TT-type trailers. A conservative approach is to use the trailer's GVWR for estimating its loaded total weight and 20%-25% (5th wheel) or 10%-12% (TT) of the trailer's GVWR for estimating its loaded pin/hitch weight.

These formulas will keep you within the manufacturer's tow vehicle ratings. That's important to some purchasers, and not to others.

Rusty
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Old 10-20-2010, 10:10 AM   #3
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Quote:
Originally Posted by 19gc45 View Post
Is it accurate to calculate tow weight of a 5th wheel like so?

GVRW (5th wheel) - Pin Weight = Towing Weight.

I'm assuming the pin weight becomes part of the tow vehicle's GVW but I haven't been able to confirm the above formula.
If you scaled your fifth wheel and it weighed, say, 15,000#, that would be the tow weight of that fifth wheel. Yes, some of the weight is transferred to the bed of the truck, but the truck would still be towing 15,000#.
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Old 10-20-2010, 10:12 AM   #4
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To Linda's point, the total weight of the trailer is what's being towed. Some of the weight is, indeed, carried on the trailer's axles, and some is transferred to the tow vehicle as pin or hitch weight, but that doesn't change the trailer's total weight.

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Old 10-20-2010, 05:20 PM   #5
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Thumbs up

Thanks
That's not the answer I was hoping to hear but...hope for the best, prepare for the worst.
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Old 10-20-2010, 05:27 PM   #6
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Rusty, what is the GVWR of your 5th wheel?
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Old 10-20-2010, 08:21 PM   #7
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The Mobile Suite's GVWR is 16,000 lbs. The truck's GCWR is 26,000 lbs with a trailer tow rating of 18,400 lbs. It'll go over the scales soon.

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Old 10-21-2010, 02:39 AM   #8
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Old 10-21-2010, 11:03 PM   #9
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Ken Lenger's weight calculator demonstrator should help: Tow Vehicle/Trailer Calculations Demonstrator
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Old 11-02-2010, 03:25 PM   #10
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Quote:
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Ken Lenger's weight calculator demonstrator should help: Tow Vehicle/Trailer Calculations Demonstrator
Hi & thanks
I tried the calculator, but it doesn't work in Opera, Chrome or Firefox (in my descending order of choice). It works in IE Explorer but crashed repeatedly. Blame that on IE Explorer.
So I found another one that's more universal if anyone else has had problems.
Nothing wrong with Lenger's calculator, just using it. All my info is organized in Opera, so it was a pain jumping back & forth.
Here's the other one:
Fifth Wheel Weight Calculator
The site also has a TT calculator.
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Old 11-07-2010, 03:12 PM   #11
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Humm, it works in FF when I call it up. I must allow scripts to temporarily run on that page though.
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