I am SO Confused... Looking to haul a BH3670 but the numbers don't look right

PteJack

Member
I have a 2011 3500 Laramie Longhorn 4x4 SRW SB 6.7 Cummins, 3.73 diff.
I traded my 08 Ram 1500 SLT and bought this truck hoping to pull a retirement trailer but now I'm running into a confused state and become extremely frustrated!!! Specs!!!

I knew I wouldn't be able to pull a luxury Park Model like a Landmark but one would think an 10-11000lb Big Horn or a Montana or a 12000lb Brookstone would not be a problem.

The trailer I'm looking at is a 2009 Big Horn 3670 5th Wheel...
Dry weight 10820lbs
Pin Weight 2096lbs
Gross Maxium Weight 15500lbs (This is what axles are rated to carry and I will never hit)

I start to run the math

Longhorn GVWR 10100lbs
Curb/Base Weight 7407lbs (I don't think this includes a full tank of fuel)
Payload 2690lbs
Max Tow Cap - 13450lbs
GCWR 21000lbs

Everything looks good, Dry weight of the 5th wheel leaves 2630lbs room to the max towing cap. Room for the Generator(500lbs), Sat Dish (150lbs) and Washer and dryer (another 250lbs conservative)

BUT WAIT

now we add 500lbs for passengers, snacks, grandkids and granddogs in the truck, throw on that 250lbs for the washer and dryer my wife wants installed (which sits almost on top of the pin) in the trailer and poof, I'm over on the payload.

On top of this I still haven't added 125 liters of fuel.

2096+500+250+175 (for the hitch) and subtract 150 (for the passenger/driver already included in curb weight) = 2871lbs + fuel of payload sitting on the box and through the truck.

I'm still under for GCWR and max towing rate (I believe).

The other thing is base weight + Payload puts me over the GVWR of the truck.

2871+7407 = 10278lbs-150 (for the passenger/driver already included) + Fuel

I run into this same scenerio for almost every 5th wheel I look at.

Most of the units we would consider buying run between 10000 and 14000lbs dry with pin weights running between 1900 and 2300lbs. All are too heavy if you do the math.

Everyone I talk to assures me that the truck can take these type of loads and think I'm over analyzing the situation, but is it legal and is it safe to tow like this??

What if I blow a tranny, will it be covered by warranty?

Did I buy the wrong truck? I think I would have bought the dually had I known I was going to lose half my towing capability.

Anyway, what really irks me is that before I bought the truck, sales reps were all over me like a dirty shirt assuring me I could pull just about anything on a RV lot. I got the same thing from the RV Dealerships I consulted and proceeded with the deal.

Now that I'm seriously looking to buy the 5th Wheel, the RV sales reps all look at me now
like I have 2 heads when I tell them I can't pull a unit, that it is too heavy; that the truck is only rated for a 13450lb max trailer capacity until I pull up the towing chart I got from the RAM website. After they examine the chart, they just walk away shaking their heads, muttering, "I don't believe that, I've got people pulling these with 3/4 tons".

Just yesterday I saw a 3500 SRW Chev pulling a 16000lb Toyhauler loaded to the gills.

The owner says he doesn't even notice the weight and I'm sure that most of you will tell me that my Longhorn is more than enough truck to do the job, but I'm throwing this out to you experts who are pulling these big units so you can show me where my logic is flawed and reassure me that I won't have to unhitch my trailer and leave it somewhere because i'm illegal/overweight and most of all that it is SAFE to pull these types of units.

This is long winded and I apologize, but I need the piece of mind. I lost my parents to an accident and I don't want my wife and I to be taken out by having a 5th Wheel pin come through the truck for us; and I definitely do not want to put anyone else at risk by having the 5th wheel jump off the truck.

The only tow experience I have right now is that I received in the military where you jumped into a 5/4 ton or duece and a half, locked up to the heaviest trailer you could find, dragged it 300 kms to a training area then bounced around the field with it for a few weeks playing cowboys and indians...

Please help and enlighten me!!!

Also the listed pin weight in the brochures, is that Dry weight or what it would be if the unit was loaded to the max. 2069lbs seems awful heavy for a 10820lb unit, that's like 19% of the unit Dry weight. 13% of the GVWR of the unit as well.

Kindest regard,

Pte Jack

 

Invizatu

Senior Road Warriors
Pte Jack... I would not begin to advise you on this, but there is a website that is owned and operated by a fellow Heartland Owner and he is also a fifth wheel owner. The site has a worksheet that you plug your numbers in and it gives you the right answers. Go to www.fifthwheelst.com
I think from what I have read on other post, you just might be O.K. I am sure others with more expertise will chime in and give you the facts and their opinions.
Good Luck
 

Nabo

Southeast Region Director-Retired
Hey - we pull our Big Country 3650 (12286 lbs off the assembly line) with a single wheel Dodge 3500 without any problems. As towing anything, you just have to be sensible.
 

Tombstonejim

Well-known member
I am not trying to start a brand war and I have not looked up the Dodge numbers but they sure look low to me. You sure those are correct? By comparison my F250 numbers are
GVWR 10,000
Curb wt unk actual wt with fuel and me in it 7730
Payload 2900
max tow 15,500
GCWR 23,000
 

danemayer

Well-known member
Jack,

I'm pulling a Landmark (16,000 GVWR) with a GMC 3500 Diesel, Crew Cab, Long Bed, 4x4, SRW. 5th wheel towing capacity is a bit over 16,000. Payload is about 4,100.

What you've run into is that Dodge sold you a 1-ton truck with a payload only slightly more than a 3/4 ton. I think the difference between the Dodge 2500 and 3500 SRW is the addition on a single leaf spring to the suspension. That's why your payload is only 2690.

A couple of additional data points. Our Rushmore is loaded on options, including a generator and washer/dryer right up front. The pin weight spec is 2620 (empty weight), but measured pin weight is 3500. Measured total weight for the rig is 15,000. We're right at our vertical load limit, tow vehicle axle limit, etc. But we could put 900 additional pounds at the back of the trailer, on the doorside (not going to happen).

The truck tows the rig beautifully, including up and down the toughest mountains in Colorado.

You probably have plenty of engine and transmission to pull a large trailer. The way Dodge is spec'ing towing capacity is different from GM. Our GMC is rated at 9,100 for ball-hitch towing, and 16,800 for 5th wheel towing. The Dodge website is only providing a single number, which seems a bit low; but maybe there's some limiting factor other than engine and transmission.

The really weak area is vertical load. The overload might push the back of the truck down. Some people install air bags to level things up. There's speculation about possible safety issues and possible excessive wear on the rear axle and other components. Hard to know to what degree you'll experience problems. Anecdotal evidence from many people on this forum who have 3/4 ton trucks is that you should be ok.

There's been plenty of discussion about insurance coverage or legal issues if something bad happens and you're overloaded. I don't think I've ever seen any legal opinions on the subject - again, just speculation. My opinion: I wouldn't worry about getting a ticket for being overloaded; not likely anyone would know the actual pin weight to be able to compare it to the payload of the truck and I'm not sure the law addresses this for non-commercial vehicles anyway. Would your insurance claim be denied because you made a mistake on weight? Seems like they pay if you make a mistake and run off the road, or hit a tree. If your insurance policy doesn't disclaim coverage for driver errors, what would the grounds be for claim denial?

If your hitch is matched to the vertical load and towing weight of the rig, I don't think you'd have any exposures related to the hitch.

Finally, high speeds (above 55mph) are hard on the trailer tires and other components. If your truck rear axle is overloaded, going fast is only going to make things worse.

One other thing. Are you sure you have the right weights for the Bighorn 3670? Current model specs are somewhat higher. You might want to look at some of the other floorplans.
 

jolar3329

Well-known member
I haul my 2009 Bighorn 3670 with a 2004 GMC 2500 HD Diesel, single wheel, extended cab, 4wd. The loaded trailer weighs 15,500 lbs. The truck is rated for a 16,000 lb fifth wheel. I haven't had a problem in the 4+ years I've been hauling it.
 

JohnDar

Prolifically Gabby Member
My 2009 BH3670 came in at the RVSEF scales at 14525 lbs., with a pin weight of 2950 lbs. I have a combo W/D in the nose of it and had just about all of my gear on board (we don't full-time, however) and empty tanks. I think the ton of clothes the wife insists on hanging in the closet makes up most of the weight. The sticker on the rig has a dry weight of 12115 lbs. and a GVWR of 16000 lbs. Catalog pin weight was something like 2065 lbs., if I recall. When weighed, I had roughly 25 gallons left in a 56 gallon tank. Your 125 liters is only 31 gallons.
 

Birchwood

Well-known member
In your thread I only looked at two values ...the GVWR (10100lbs)of your truck and the Max GVWR (15500lbs)of your trailer.
Using the 20% weight ratio for your trailer you could have a pin weight of 3100lbs if fully loaded but you will probably never be loaded to the max.
If your truck weighs 7000 lbs (you said its higher ) you will be in a borderline situation .
7000lbs + 3100lbs =10100lbs.
 

westxsrt10

Perfict Senior Member
I can see this pin weight issue is going to bug you every mile while towing. Better look for a lighter RV or Duelly. Either way installing air bags will keep things level and shift a few lbs. to the front axle.
 

PteJack

Member
Thanks to everyone who has responded. RVing in Canada can be a stressful thing sometime, especially if you plan to go RVing in British Columbia.

Special thanks to Invizatu post and the link to the calculator on the www.fithwheelst.com website, I think I've found the error in my math.

I forgot that there is weight transferred from the trailer to the truck... DOH!!!
I guess the only way to really determine if the trailer is TOO heavy is to actually run it across a scale...

ASSUMPTION SCENERIO (numbers are sample only and some may be slightly out of whack as I have be recalcing as I write trying to figure the formula)

The unit dry weight is 10820, it has a pin rated to 2069 (assumption I still don't know if this is the pin actual dry or a max rating and I am trying to find that out)
(Weights taken from the 2009 3670 Brochure and confirmed by the current owner of the trailer)

Truck has GVWR 10,100, FAWR 5500 and RAWR 6500. The GCWR is 21000 and has a TWR (Tow Weight restriction) of 13500.

I run the scales without the trailer and find I'm weighing 8118lbs FA 4906 RA 3212

I hook up and run the scales again and find I weigh 10000lb FA 5000 RA 5000

This would mean the trailer is pushing 1882 lbs to the truck and the trailer weight should adjust from 10820 to 8932 (if I haven't added any weight to the unit)

Now doing the math

10000+8938 = 18938 (-2062) Under GCVR
5000 + 5000= 10000 (-100) Under GVWR

King pin is already figured into the GVWR at 1882 but IF Dodge KingPin vertical limit is set to 15% of the towing capacity (I cannot find any reference to this stat on the Dodge website and the dealership has no idea what I'm talking about here. I believe Ford and Chev and most hitch manufacturers set this to 25% of the towing cap of the TV) then King Pin weight can be upto 2025lbs which in this scenario I would only be under by -143lbs

I'm -500 on the FA, -1500 on the RA and with a GVWR of 15500 on the trailer I'm under by -4680

Verticle Load percetage on the Kinpin would be 17% (Kingpin load/GCVW I believe is the calculation)

Trailer passes weight restrictions (by a narrow margin)

Would this be how you justify a 3500 to tow a 10-12000 lb 5th wheel

Would this also be the way an enforcement agent would rate the combination??

Thanks
Pte Jack
 

PteJack

Member
Thanks for your reply Westxrst10, but no, I don't think so.

I want to confirm that the trailer is ok to pull, through the numbers, is legal to get me into British Columbia and will pull safely. Once that's done it's lock on and go.

I've already been stung a couple of times with promises and assurances only to be let down and don't want to go there again. The Longhorn I bought is one example. The decission would have been a no brainer and I wouldn't have had to do this kind of homework had I been delivered what I originally ordered, but assurances of the dealership and availability won the deal. Now I'm digging for answers.

BC has the strictest legistration for RVs that I know of right now. If I can meet their standards, I don't have to worry about going anywhere.

Regards,

Pte Jack
 

Sajo

Member
Well, here we go again! We tow with a 2500 Dodge, 6 speed trans, 6.7 cummins and tow a 2013 Big Country 3650 that we just purchased. Dry weight of the rv was 12,900 and I added wife, dog, me, and 37 gal. fuel. I did add a set of timbrens to support the rear suspension. We left Foley,Al. and once we got to I-65 I put the cruise on 60mps and locked in the tow mode. Down shifted twice to Montgomery, Al. which is almost uphill.... We are going north this weekend to Desota State Park which will have some pretty good hills so we will see. Right now I have all confidence with Dodge...........
 

danemayer

Well-known member
now we add 500lbs for passengers, snacks, grandkids and granddogs in the truck, throw on that 250lbs for the washer and dryer my wife wants installed (which sits almost on top of the pin) in the trailer and poof, I'm over on the payload.
What happened to this part of your calculation?
 

Nathan

Active Member
The unit dry weight is 10820, it has a pin rated to 2069 (assumption I still don't know if this is the pin actual dry or a max rating and I am trying to find that out)
(Weights taken from the 2009 3670 Brochure and confirmed by the current owner of the trailer)

Truck has GVWR 10,100, FAWR 5500 and RAWR 6500. The GCWR is 21000 and has a TWR (Tow Weight restriction) of 13500.

I run the scales without the trailer and find I'm weighing 8118lbs FA 4906 RA 3212

I hook up and run the scales again and find I weigh 10000lb FA 5000 RA 5000

This would mean the trailer is pushing 1882 lbs to the truck and the trailer weight should adjust from 10820 to 8932 (if I haven't added any weight to the unit)

Now doing the math

10000+8938 = 18938 (-2062) Under GCVR
5000 + 5000= 10000 (-100) Under GVWR

King pin is already figured into the GVWR at 1882 but IF Dodge KingPin vertical limit is set to 15% of the towing capacity (I cannot find any reference to this stat on the Dodge website and the dealership has no idea what I'm talking about here. I believe Ford and Chev and most hitch manufacturers set this to 25% of the towing cap of the TV) then King Pin weight can be upto 2025lbs which in this scenario I would only be under by -143lbs

I'm -500 on the FA, -1500 on the RA and with a GVWR of 15500 on the trailer I'm under by -4680

Verticle Load percetage on the Kinpin would be 17% (Kingpin load/GCVW I believe is the calculation)

Trailer passes weight restrictions (by a narrow margin)

Would this be how you justify a 3500 to tow a 10-12000 lb 5th wheel

Would this also be the way an enforcement agent would rate the combination??

Thanks
Pte Jack

If you rattled all that off to me. I would say have a nice day sir. But that is just me and I am a Police Officer in Massachusetts, not BC. ;)
 

jnbhobe

Well-known member
If you rattled all that off to me. I would say have a nice day sir. But that is just me and I am a Police Officer in Massachusetts, not BC. ;)

LOL I think in Pa you have to be within 2mi of a scale to pull you in to weigh a rig or have a set of portables with you or brought in.
 

PteJack

Member
Thanks for the question Danemayer;

That part of the question kinda goes out the window unless you know what the what your standing dry pin weigh is. If you know that, then you can start estimating how much weight is going to be distributed to the pin as you add load and distribute it over the length of the unit.
You can quickly calculate what payload you are putting on the tow vehicle (TV) because
1) the manufacture gives you an actual curb weight and payload capability for the truck
2) You can weigh stuff as it goes in and subtract that number from the payload capacity, and
3) it is a heck of a lot easier to just run the TV bare across a scale to get your actual weight. As you load weight, you won't actually be able to estimate axle weights, but you know how much you can put on and deduct from the payload capacity.

The is the second calculation I used is fictious, the numbers aren't real world. I guess what I'm trying to say is that you will never know if you are running over/under unless you do an actual scale run.
The second Calculation is a run to see if I understand the principles of determining if a unit is over or under my payload capacity and the dry pin weight of a unit is a good place to start. I can quickly determine if the unit dry is too heavy based on my first set of calculations.
If I know my TV payload limit is 2754lb and I run my TV 500lbs over my curb weight loaded for a trip (trip to the scales for accuracy), then the MAX my pin weight can be is 2254lbs to max out payload (no more can go into the TV). I should not be looking at units with a heavier base pin weight.

One thing I should do is allow a safety margin for pin fluctuation as I load the towed unit.

The Pin weight will now float as you load up the towed unit depending on where you place things in relation to the axles. Like a lever, the farther rearward from the axle, the more weight is added to the unit and removed from the pin, foward from the axles weight is distributed to the unit and the pin. The more foward, the more to the pin.

Once loaded and hooked up you are back in the dark. The only way to KNOW where you sit in regard to weight resrtictions is to run both units over a scale.

Most truck manufacturers provide a Verticle king pin limit on the websites (Chev and Ford), and if I remember correctly it is somewhere around 25% of the max Towing capacity of the TV. Dodge on the other hand does not provide this figure, and what I get from my dealership is that I am restricted to payload limit of the truck for all cargo including the pin weight.

This is why I am asking the questions that I am, I run a Dodge.

THanks Pte Jack
 

PUG

Pug
I pulled an 09 Cyclone 3950 loaded to the gills plus toys for two years with a Chev Duro 2500 SRW. It pulled it fine but was overloaded and scared me to think of blowing a rear tire on truck. I purchased a Dodge 3500 DRW and the difference was day and night as far as handling and peace of mind. Has anyone with a SRW ever looked at doing a conversion kit to a DRW? Here are some sites that discuss this.... http://dodgeforum.com/forum/dodge-cummins-diesel/77551-single-wheel-to-dually-conversion.html, this site is where a lot of the conversion kits can be obtained from: http://www.wheeladapter.com/dually_adapter_kits.php
 

TandT

Founding Utah Chapter Leaders-Retired
pteJACK

I have a 2006 5.9 Cummins 3500 SRW long bed 3.73 rear end and a 2011 BH 3670. (See my signature)

I have pulled this setup over 10,000 miles in the past year.

I am right at my GCWR and about 400 lbs over on my listed GVWR loaded.

I have Firestone Riderites on the TV and it handles it well.


You will get all kinds of opinions here.
It's good to be cautious, but IMHO your TV should have no problem pulling the trailer you are looking at.

Feel free to PM me with any questions. Trace
 

beardedone

Beardedone
I have an 08 Dodge dually with the 6.7 diesel and 3:73 gears and an automatic trans. I put airbags on it and tow a 09 Landmark. The unit weighs in between 23,000 and 24,000 lbs depending on circumstances and I have never had any problems. Dodge underrates their towing weights, probably because of warranty claims. You shouldn't have any issues and remember that "hotshotters" are using more Dodges than any other brand and grossing well into the 30,000 lb range. In many areas you can legally license these trucks to far exceed manufacturers limits, so what does that tell you about government concerns. They will license you to exceed manufacturer weight limits and then have the police give you a ticket, I think not! Also in B.C. they are strict on weights and safety in general but if you don't look overweight they will not bother you. If you use your head, drive at a reasonable speed and allow proper spacing for braking you shouldn't have any problems.
 

Speedy

Well-known member
Well, here we go again! We tow with a 2500 Dodge, 6 speed trans, 6.7 cummins and tow a 2013 Big Country 3650 that we just purchased. Dry weight of the rv was 12,900 and I added wife, dog, me, and 37 gal. fuel. I did add a set of timbrens to support the rear suspension. We left Foley,Al. and once we got to I-65 I put the cruise on 60mps and locked in the tow mode. Down shifted twice to Montgomery, Al. which is almost uphill.... We are going north this weekend to Desota State Park which will have some pretty good hills so we will see. Right now I have all confidence with Dodge...........

When you pulled out of the dealerships lot your BC did not weigh in at 12,900 unless they did not fill your propane tanks and provide you with a battery, 50 amp power cord, the manuals for the trailer. That's why dry weight is meaningless when trying to come up with "will my truck tow this". I weighted our BC 3650 just after leaving the dealership and with full propane tanks, battery, power cord, manuals, new patio chairs, x-chocks, leveling blocks, water hoses, sewer hoses and 1/3 full tank of fresh water we were at 13,665.

Once set up we went to Walmart and bought food for the week, didn't weight it but I'd say that added another 100 lbs to the axles.
 
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