Good Sam Club Open Roads Forum: Travel Trailers: Some Towing Math and Questions
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 > Some Towing Math and Questions

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Polishmagnum

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Posted: 02/28/21 10:03am Link  |  Quote  |  Print  |  Notify Moderator

Hello all, new to the forum. A little about my camping setup, I currently have a 2017 RAM Bighorn 1500. My current trailer is a Dutchmen 222ES, a three bed hybrid. Canvas flip out beds. It is 26 foot long, including the tongue, and weighs 4700 pounds, curb weight. It can handle nearly 2000 pounds of cargo, for a total weight of 6700. Of course I never put a ton of stuff in it. I tow this effortlessly, dont even notice it back there, for the most part. The canvas beds can be noisy in some camgrounds, so I am looking at a new TT, hard sides.

I am looking for some opinions on towing capacity of my truck. It is an 8 speed transmission, 3.92 rear end, crew cab Bighorn. Trailer Life towing guide from 2017 lists its towing capacity at 10140 pounds.

I am an engineer, so I am trying to figure this tow capacity for real. I did the math on this three different ways, one based on trailer life rating minus the weight of me, passengers, payload, etc times a factor of safety of .85. This rating comes out to be 7500 lbs. The second way, based on GCWR of both units, comes out at 8255. The third way based on hitch weight, comes out at 7326. I didnt factor tire diameter into this, or anything that crazy, but it could affect it. You can only get so nerdy about this.

So weight, it seems I should be around 7500 pounds max. Does this make sense to people on the forum? The trailer I am looking at has a curb weight of 6100 pounds and a GVWR of 7700 pounds. So it can hold like 1600 pounds of stuff. I wouldnt put that much in it, and also that 7700 number is in line with my math. Thoughts?

Now on to length. I dont want to be all stressed out towing this thing as a result of wind pressure due to length. As I said, my current camper is 26ish feet long, and the new one would be about 31 feet long, both have tongue included. Five feet, no big deal right? Do people safely pull 30-33 foot TT's with half ton trucks, in general? Also, I found an online formula for length based on wheelbase of TV, and my math here says I should be between 25 and 28 feet. I do not know if that is the box length, or total length with the tongue.

So all that being said, what are your opinions of my thoughts, and do normal people pull such trailers safely with half ton trucks??

Thanks in advance, and sorry for all the nerd speak.

MFL

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Posted: 02/28/21 10:46am Link  |  Quote  |  Print  |  Notify Moderator

Lots of ways to figure weight capability, but most times comes down to truck payload limitation, and hitch wt. Overall length will matter, considering wind causing sway. A good WDH helps for sway, and some are designed with this in mind.

Tires will make a difference, some change to LT tires, if P-rated currently. If P-rated, raising PSI, especially on rear will help.

If you can stay within your truck RAWR and receiver hitch rating, it should work. Of course all people, gear, anything in truck, plus loaded to camp hitch wt all take away from your payload. Your payload is on the driver's door, not to exceed xxxx.

Jerry





Polishmagnum

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Posted: 02/28/21 10:57am Link  |  Quote  |  Print  |  Notify Moderator

Right, I used the information on the door for some of the math. I accounted for 800 pounds of people (very high) and a full bed (estimated). What do you mean by RAWR?

MFL

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Posted: 02/28/21 11:05am Link  |  Quote  |  Print  |  Notify Moderator

Rear axle wt rating, on door sticker (3,800 guessing). If you loaded your truck to go camping, full fuel, people, pets, and gear, then weigh truck axles separately. Example rear axle weighed 2,500, and rating 3,800, you could add another 1,300 to rear axle.

Welcome to the forum, hope this helps! [emoticon]

Jerry

Lwiddis

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Posted: 02/28/21 11:18am Link  |  Quote  |  Print  |  Notify Moderator

Possibly you won’t load 1600 pounds of stuff but 1200 is likely. Tooo close to the TT’s max for me. I want a full freshwater tank, big batteries and plenty of propane. I don’t want to leave the bicycles at home nor the BBQ etc.


Winnebago 2101DS TT & 2020 Chevy Silverado 1500 LTZ Z71, 300 watt solar-parallel & MPPT, Trojan T-125s. TALL flag pole. Prefer USFS, COE, BLM, NPS, TVA, state & county camps. Bicyclist! 14 year Army vet-11B40 then 11A - (MOS 1542 & 1560) IOBC & IOAC grad


Gdetrailer

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Posted: 02/28/21 11:20am Link  |  Quote  |  Print  |  Notify Moderator

Polishmagnum wrote:

Hello all, new to the forum. A little about my camping setup, I currently have a 2017 RAM Bighorn 1500.

I am looking for some opinions on towing capacity of my truck. It is an 8 speed transmission, 3.92 rear end, crew cab Bighorn. Trailer Life towing guide from 2017 lists its towing capacity at 10140 pounds.


Regardless what "Trailer Life" says..

Need MORE info on the truck.

Regardless of all that "towing capacity" sales brochure or Trailer Life double speak, you actually need to figure out just how much available cargo you have for YOUR truck as it left the factory.

Max towing numbers are typically based from the most bare bones stripped down basic 4x2 regular cab short bed bottom trim levels.. Every option added takes weight away from the cargo giving the vehicle less cargo capacity.. EACH vehicle IS different because of the "options" so no real "cookie cutter" approach can be used.

Trailer tongue becomes "cargo" of your tow vehicle which takes away available cargo from your vehicle.

Several easy ways to get this information.

The newer vehicles now must have a tire/cargo weight sticker which is typically a yellow sticker placed on the drivers side in or around the door post or door. Can't miss that sticker it should be yellow and will specify the max available cargo for that vehicle..

That number should include the weight of fuel plus driver.

Second way is to get the empty or unladen weight of the vehicle, subtract that from the GVWR..

That gets you available cargo weight not including fuel and driver.

Now why the fuss?

Typically what happens is your vehicle will run short on available cargo weight before ever getting close to the maximum towing weight.

Once you have the available cargo weight, you can divide that weight by .15 (15%) and that gets you the max weight you can tow with tongue weight of 15%.

Example, say you have 1200 lbs of available cargo on your tow vehicle..

1200 / .15 = 8000 lbs max towing..

Not familiar with Ram payload packages but typically depending on your vehicles configuration with many half tons, you can see available cargo weights as low as 1000 lbs and as high as 2000 lbs.

The Trailer life numbers you mentioned of 10140 lbs would mean that YOUR truck would HAVE to have 1521 lbs of available cargo, it may, or it may not have that..

Recommended tongue weights for bumper pull are from 10%-15% of the weight of the trailer. For better stability 13%-15% is pretty much where you want to be when loaded.

More for consideration, unless otherwise noted, many trailers do not include propane or battery weights in the tongue weight when shipped from factory on their stickers.. you may need to add those weights in to the tongue weight..

WD systems also become cargo of the tow vehicle, so that also will take away some cargo on the tow vehicle..

As far as figuring in a "safety factor", not a bad idea, it isn't something a lot of folks do, instead they will use the unladen weight of the trailer then add in their guestiment of weight they will haul in order to justify the largest and heaviest trailer they can tow..

Make it easy, just use the GVWR of the trailer as your max weight range you are shopping for(even though you may never use up all of the cargo weight of the trailer).. Doing it this way ensures you have a trailer that is well within your vehicles capability without the need to count potato chips or popcorn kernels..

For instance in my example with 1200 lbs cargo I showed 8000 lbs max, buy a trailer that is 8000 GVWR OR LESS..

Yes, it angers the folks who have found the trailer of their dreams with 3,000 lbs of cargo on the trailer because it will severely limit their size they want, so be it.. better to be safe than sorry.. You want the dream trailer, bump up to a more capable tow vehicle..

Polishmagnum

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Posted: 02/28/21 02:38pm Link  |  Quote  |  Print  |  Notify Moderator

Thank you all for so many thoughts! MFL, I cannot see an image you may have posted, but yes, GAWR on my door sticker is 3900 lbs.

Most of the information I used to calculate all this came off the door sticker, using my VIN on MOPAR site for original specs, and also from RAM website.

Yes, my truck is listed as having 1510 lbs. of cargo capacity. I used this in the calculations. GVWR-Curb Weight=Cargo, for truck. I got the same 1510 number that RAM posted. Cargo being people, bed full, whatever I add to truck.

I think I'm ok with my numbers, and I think sticking to a trailer with a GVWR around 7500 is a reasonable plan. But the real question, are there many sane, reasonable people towing say 7500 GVWR trailers at about 31 feet with a half ton? I'd like to hear from anyone, because I'm old enough to know the book figuring doesnt always correlate to real world...haha! Thanks everyone!

nickthehunter

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Posted: 02/28/21 02:54pm Link  |  Quote  |  Print  |  Notify Moderator

Polish - the tongue weight of the trailer also counts as cargo on the truck. If your trailer weighs 7500 lbs loaded and ready to go camping, you can estimate the tongue weight will be 12% of that = 900 lbs. Take the 900 lbs plus add the people in the truck (you prev said 800 lbs) = 1700 lbs. That puts you 190 lbs over you cargo rating (1510 lbs.) (also known as payload rating) without putting anything in the bed of your truck.
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Polishmagnum

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Posted: 02/28/21 03:05pm Link  |  Quote  |  Print  |  Notify Moderator

Ahhhhh didnt see that! Yea I didnt count tongue weight against cargo of truck. Thanks for that!

Polishmagnum

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Posted: 02/28/21 03:17pm Link  |  Quote  |  Print  |  Notify Moderator

http://changingears.com/rv-sec-calc-trailer-weight-tt.shtml?truck_gvwr=6900&truck_gvwr_unit=e&truck_gcwr=15950&truck_gcwr_unit=e&truck_gtwr=&truck_gtwr_unit=e&truck_tongue=1100&truck_tongue_unit=e&truck_rgawr=3900&truck_rgawr_unit=e&truck_gvw=5390&truck_gvw_unit=e&truck_rgaw=2245&truck_rgaw_unit=e&trailer_gvw=6000&trailer_gvw_unit=e&trailer_tongue=618&trailer_tongue_unit=e&margin=.2&tongue_percentage=

I used one of the calculators in the link you provided, and I got a very similar number to what I got. However, I understand the tongue weight being part of cargo. I used 800 for people, but that was really on the heavy side to be safe, more realistic is 600 probably. I need to ponder this, but I would have to really load up the trailer (its base weight is 6100 lbs.) to make it weigh 7500 loaded.

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