Towing a TT - Info for those new to Towing

[dperino73]

Hi John,
Thank you so much. This does help a lot. I also read through your guide for towing (several times) and I was mostly able to follow and get a lot of good information, but I am having a hard time applying to our trailer, TV, and current family travel needs.

I am due with our 3rd child in September and we have a 5 and 3 year old. We plan to get right back into a pick up truck after this lease is over, but with and infant and the littles, the idea of a pick up for the next three years was daunting. It is a daily challenge now at 6 months pregnant.

These are my best guestimates for the new SUV and our current Ram:
2018, 7 passenger (3rd row) Durango
400 front
100 back
50 3rd row - come September
150 - 200 gear

2015 Ram Outdooorsman
Full back seat (3 across)
5' 7" bed
5.7L Hemi 3.55 Rear Axle Ratio

375 front
100 back
250-300 gear

We were extremely comfortable pulling the TT for the past 3 years with the Ram. I know the Durango is going to feel a lot different. I am just trying to figure out if the temporary difference is tolerable, and safe, for a limited number of relatively local trips before we get back into a pick up truck, and likely, a larger TT.

[JohnB]

Hi dperino73,

I did some digging for you. Dodge really wants to hide certain specs on the Durango online but I found enough to get started and run into issues.

Originally Posted by dperino73

These are my best guestimates for the new SUV and our current Ram:
2018, 7 passenger (3rd row) Durango
400 front
100 back
50 3rd row - come September
150 - 200 gear

We were extremely comfortable pulling the TT for the past 3 years with the Ram. I know the Durango is going to feel a lot different. I am just trying to figure out if the temporary difference is tolerable, and safe, for a limited number of relatively local trips before we get back into a pick up truck, and likely, a larger TT.

I will try and explain this in a simple manner, anything you do not understand, feel free to ask for some clarifications.

First is your 2007 T1950. This is listed in our brochures as a 5,500# GVWR with a dry (unloaded) weight of 3,770#. The dry (unloaded) tongue weight is listed as 420#.

Their is an actual weight sticker in the camper that you can look at or take a pic and post. It is in a kitchen or bath area top inside cabinet door. That will give us your model's weight the day it left Sunline with any options on it. See if you can get that info.

Using the brochure weights, with a family of 5 soon to be it is very easy to gain 1,000# of camping gear, clothes, pots and pans, LP gas, a battery, spare tire and the list goes on. I know 1,000# sounds like a lot, but it is not really that much. Small items, 10#, 20# etc all add up. You may be more like 1,200# with your full family. And that is not out of the ordinary.

Estimating the camper "loaded" weights:

GVW: 3,770# + 1,000# cargo = 4,770#
GVW: 3,700# + 1,200# cargo = 4,970#

Loaded Tongue Weight (TW): 420# + 180# loaded = 600# TW

Now lets see how the 2018 Durango lines up with that "estimated" camper and the weights in your tow vehicle (TV).

Passengers: 550# September. (Note: in 3 years this can go up with a growing family.)
Must have gear in TV: 200#

Total cargo in TV: 550# +200# = 750#

Truck must support 600# TW + 750# passengers and gear = 1,350# GVW

2018 Durango Standard Payload available with a std 6,500# GVWR: 1,360# to 1,290# pending engine and trim options: See here under "Payload" https://www.dodge.com/compare/detail...Code=CUD201811

Adding the 7,100# GVWR option with the 5.7 liter engine may be able to increase the payload. I cannot "yet" find what that payload is. It might be 600# more than the 1,290# but again, I cannot find it online.

We are into TV weight support issues short of the 5.7 hemi and the 7,100# GVWR option. It "appears" you can only get the 7,100# GVWR option with the Hemi. Short of getting that option, the Durango cannot hold up the weight even with a WD hitch in the 3.6 liter engine.

The 3.6 liter engine is only rated for 40 sq feet of frontal area. The 5.7 Hemi ups the frontal area to 60 sq. feet. See page 349 in the 2018 owners manual under the towing section. https://www.mopar.com/dodge/en-us/ca...rs-manual.html

Any of the Sunline 2 axle TT's trip the 60 sq ft requirement. Front area is the wind drag rating for the truck. If you exceed that number then the towing performance will go down. They just do not tell you how much. The wind drag eats into the tow ratings of the truck. To size up a TV to have a good to acceptable performance we have to add extra "reserve capacity" in the truck to make up the shortfall.

I myself normally sort out "reserve factor" with the GCWR's versus the tow ratings of the truck. The tow ratings do not account for normal camping needs. All the cargo in the truck reduces the tow ratings. The 6,200# tow rating needs to be reduced by the 750# of people and cargo. 6,200# - 750# = 5,450# tow ratings not yet adding in any reserve capacity for exceeding the 60 sq ft ratings.

Bottom line: The 3.6 liter will not be a good fit. There is not enough payload or pulling capacity in the truck. The 5.7 hemi with the 7,100# GVWR option has better chances but it still needs to be flushed out.

What else is needed to go to the next steps on flushing out the 5.7 Hemi with the 7,100# GVWR option is: (these need to be listed for the 7,100# GVWR option)

Front axle curb weight
Front axle rating: GAWR-FRT

Rear axle curb weight
Rear axle rating: GAWR-RR

After those weights/ratings then I can complete the rear axle check and the actual pulling performance needs.

It is hard enough to find that info on the standard 6,500# GVWR setup. For the 6,500# STD setup, there is a GAWR-RR of 3,900#. But I have no rear axle curb weight. The max TW is 740# on the RWD 5.7 Hemi and 720# TW on the AWD Hemi. The 5.7 L has a GCWR of 13,100# but again I need real axle weights to sort out the pulling performance calcs yet to do.

We have to check that the 600# of camper loaded TW and the passengers in the rear seat and mid seat plus cargo does not overload the rear axle even if we are at or under 7,100# GVWR.

This much I can say, it is going to be real close if it will work on the Durango and only will it have a chance with the 5.7 Hemi and the 7,100# GVWR option. You may be able to pull the camper, but odds are favorable the weights and axle ratings will be a problem.

Maybe you can see if you can find some of the missing axle info. I will look more too.

Question: Does it have to be a Durango? Is a GM Suburban/Tahoe or Ford Expedition an option? They have more weight and towing capacities then the Durango.

Hope this helps

John

[Ketchakah]

Hello All,
Is there a source for Factory specs for specific TTs ? I have a Satt 20ft. I would like to know its specs and what was standard equipment.
Where could i find this ?

Thanks Ketch

[Thomascine]

Originally Posted by Ketchakah

Hello All,
Is there a source for Factory specs for specific TTs ? I have a Satt 20ft. I would like to know its specs and what was standard equipment.
Where could i find this ?

Thanks Ketch

Look under Files. You may find what you are looking for in the brochure.

Sunline Coach Owner's Club - Sunline Owner's Files - Sunline Brochures

[Digmenow]

Two adults. More info on cargo in the CAT Scale section.

Your Truck: 2002 Ford Super Duty F-250, 7.3L Powerstroke, 4 x 4 Supercab.
Wheelbase (in)
141.8
Length, Overall w/o rear bumper (in)
227.0
Width, Max w/o mirrors (in)
79.9
Height, Overall (in)
80.4
Overhang, Front (in)
37.4
Overhang, Rear w/o bumper (in)
47.8
Front Bumper to Back of Cab (in)
139.2
Cab to Axle (in)
40.0.

If you know the rear axle ratio we need that too. 3.73

Curb Weight
5,665 lbs

Gross Vehicle Weight Rating
8,800 lbs

GAWR-FRT 5200
GAWR-RR. 6084

Have you modified the truck from the factory? No.

CATScale results with trailer attached with WD hitch, full tank of diesel, too many automotive tools (probably 100 to 150 lbs) in a big poly cargo box.
Steer Axle: 4350 lbs
Drive Axle: 4440 lbs
Trailer Axle: 7680 lbs

Receiver and Tires: Reese Dual Cam with 1200 lb trunnions

And what type/brand of tires do you have? Hercules Terra Trac HTS LT265/75R-16 Load Range: E (10 Ply)

Sunline 280SR SE with alloy wheels. 225/75R15 Goodyear Endurance
Speed Rating N
Load Index 117
Load Range E

We need to look at the dry GVW of the TT and the GVWR as a starting place.


We also need to know the dry tongue weight, Not sure

length 29' coach plus front A frame and rear bumper with spare.


and where cargo holes are and water tanks are located.
Cargo: small front baggage on door side less than a foot deep, approx 18" tall and 48" long.

Large rear fitting directly under queen bed with front third at floor level (two side sliding drawers).

Kitchen Grey tank ahead of axles. Black (I think) and Bath Grey tank aft of axles.

Full Water heater tank in left rear corner.


Where do you camp:
Maryland, Pennsylvania, Delaware, Virginia, West Virginia todate.

Do you plan to do cross county trips, local trips (20 to 50 miles) or mixture of mild to longer distance such at 500 to 2,000 miles trips once a year?
Longest intended trips will be from Baltimore to Niagara Falls or Disney Fort Wilderness. Otherwise, under 3 hours usually.

Do you know if you are needing to haul fresh water with the camper?
Not at this time. Potential far into the future boondocking.

Are there many hills or mountains where you will go camping? Appalachian range.

How far above sea level will you be towing at? Less than 1000 feet for the most part.

I think that's it. Whew.

TT interactions with the TV: Here we are gaining information first about the TT and TV. Tell us your make/year and model TT so we can look it up on the web. Floor plans and dry weights tell how the camper is built and how it could load. Does it have 8% dry tongue weight per GVW, 10%, 14% etc in the dry setting? Where the storage is located helps tell where the weigth will go in relation to tongue weight. With knowing some about the camper floor plan and how you use it helps give an estimate for what tongue weight could be. It’s not exact but you can get close. If you have 8% dry tongue, we have to work at getting that up into the 13% range. If it starts in the 13 to 15% dry range and the floor plan loads towards the tongue, we need to watch out as it can be 16 to 18% when loaded and that means very high tongue weight per TT GVW. The loaded TT should be at least in the 13% range, 15% is better if the TV can handle it. 10% is the low end guideline but we caution to not go that low. Pending the TT, if your propane tanks go empty it can drop the tongue weight a few % and put you into the more unstable area if you start at 10%.

By knowing your camping family size and where they go camping it helps with the cargo weights in the truck and an estimate of how much “stuff” they will haul. A family of 5 with 3 teen age’ers can add up. And just an adult couple can add up too. The estimate of a 1,000# of camping gear is real. Many times is can be 1,200 to 1,500# with full water. My DW and I have 1,200# with no bikes and no fresh water. The bigger the TT, the more stuff you bring. By knowing the towing distances and areas you will camp at we have a better handle on if this is a heavy towing situation or a light one.

Predicting loaded tongue weight of a new camper is something that takes a fair amount of investigating on and what “stuff” weighs. The TT catalogs use dry weights. Since we have nothing for a loaded tongue weight dry is better then nothing. However dry weights do not include added options, battery weight, LP gas weight and no cargo added after the day it leaves the factory. If you see a TT on a dealers lot, look for a weight sticker in one of the cabinets. This is a better indication of the trailer actual empty weight. There is no rule of thumb for a loaded tongue weight I know of that is accurate. Using a % of the GVWR for a tongue weight may be close or it may be way off. Floor plans and where you can store gear drives the tongue weight. We can help you estimate the tongue weight by knowing your floor plan, expected cargo and dry tongue weight. The one wild card is where your fresh tank is located if you need to haul water. Often times catalogs do not list where the tanks are per floor plan. Some fresh tanks unload, load or are neutral to the tongue weight. It is however something you need to consider if you need to haul fresh water.

Now we have gathered some good information about your camping family, a brief look into intended use and we have a base to start looking at ratings and other stable towing attributes.

Now to the ratings. So what is the definition of the TV ratings in regards to towing? I’ll take a stab at it. This is my boiled down opinion. They are not legal limits per say in the RV world but can get you into a legal situation if you are in an accident and found at fault as you are operating a vehicle beyond it's intended use.

GVWR, GAWR and GCWR are an automakers intended maximum use limit for each specific area being rated. Certain design safety factors may exist on each limit in accordance with government set regulations. Exceeding these limits can subject the driver and vehicle to combinations of conditions not tested or that goes beyond the design intent safety factors resulting in a system failure.

Now we sit down and start doing a little figuring.

Truck weight with cargo: For an optimum setup we need to stay within the TV ratings and have some extra capacity for unexpected things within reason. The ideal way to do this and to prove to yourself we have the estimate right is to load up your truck with the all the people and pets and “must have” gear in the truck and weigh the front and rear axle. Fill up that gas tank before you go. Cost is about $7 to $9 at a truck stop.

If you want to we can help you come up with a guesstimate of loaded truck axles. There is a lot on the internet today that can get us close. The biggest hurdle is what does the truck weigh with no people inside and full of gas? Again the best way is weigh it, however if you want, we can guesstimate a loaded truck GVW and axle weights.

GAWR: With some math and knowing the people you told us where in the truck and their weight we can estimate your TV axle loads. We need to say within the GAWR on both front and rear axles when we hitch up the loaded TT tongue and adjust the WD hitch correctly. If you have a family of 5, that is a fair amount of payload in the truck and it can use up a lot of your ratings in the lighter trucks. You need to have enough capacity left on the rear axle to carry your expected loaded tongue weight when all the “must have” weight is already in the TV. If you over load the rear axle it can aggravate TT sway or you can have a mechanical failure. If you went to the scale, it is then easy math to subtract the unhitched front and rear axle weight from your trucks GAWRs. The difference gives us the max weight carrying ability per axle available before you reach the limit.

GVWR: Your TV manufacture also places a GVWR on the TV. Passengers, cargo and TT tongue weight need to be within this rating. When you push this limit it can aggravate the effects of TT sway and your ability to stop the truck. The truck is then considered overloaded in relation to it’s max use limit. The trucks brakes are intended to stop the weight of the truck, the TT’s brakes are made to stop the TT weight. Exceeding the weight limits can affect your stopping pending how far over you go. The manufactures give you some loading freedom on how you split the TV gross weight per axle. The axle ratings combined are higher then the GVWR on smaller trucks but the total weight of the truck is capped by the GVWR. The TV has to be a stable towing platform for the anti sway controls system to work effectively. If you are over the ratings it is that much harder to create the stable towing platform needed. Again subtract the actual loaded truck weight with no TT hitched from the GVWR and what is left can carry the TT tongue weight and maybe some more camping gear.

TV Stability: Tires and truck suspension play a large roll in TV handling and rig stability. Cushy riding tires are not great for towing. When the side walls flex the truck can become unstable with a TT pushing on it. The truck is actually wiggling around flexing in the side walls. There is no tow rating for tire side wall stiffness by the tire manufactures or TV manufactures that I am aware of. If your truck is over weight, odds are your tires are at or over their ratings. This aggravates left to right stability of the TV to hold the TV rigid when wind gusts or semis pass you even with a good anti sway hitch. If you have P rated tires which can be cushy, the best with what you have as a starter is to, air up the rear tires to max cold side wall pressure. The front must be at least at door sticker pressure. This concept also works for LT rated tires and in many cases the LT tire is soggy too unless at higher pressures. The front tires can take more air until you start getting a bouncing action. Take them up in 5 psi jumps until bouncing starts, then stop and back down 5psi and see if it goes away. When not towing, you can air them back down to door sticker. You can find the front end bounce point just driving around empty. Some TV’s can take full max cold pressure in the front, some bounce too much and must be less but can still be more the door sticker pressures. As with the TV so is the TT. Air up the TT tires to max cold side wall pressure. A soggy TT tire can accelerate sway.

If your truck is very soggy left to right even after you air up the tires you may need a different brand or type tire. There are times you just cannot get way from it. All tire brands are not created equal. Just a change in tires can take a stable towing rig and make it unstable and visa versa. When you go with a heavier truck the tires get stiffer by design for the extra weight. It is a side benefit of 3/4 and 1 ton trucks. But still, even LT tires differ in stiffness between brands.

GCWR: Now we look at your GCW. Can you pull it and what strain are you putting on the truck? The GCWR limit is a pull rating for the most part for your TV drive train but is also plays into a stability part. If the TT gets too heavy for the total weight of the TV, the TT can negatively affect TV stability when we tow with a conventional hitch. If you stay within the GCWR you stay away from over working your TV while pulling and getting grossly out of weigth proportion. Ideally for folks starting out towing, the truck should be heavier then the loaded TT or at least equal. It is the battle of the masses here and the big guy wins when large adverse towing conditions exist. A larger % heavier TT then TV can push the truck given the right circumstances. The rear of the truck may slide or the front of the truck may flex heavy in the side walls of the tires. It is very much aggravated during wet or slippery conditions when the big TT is pushing the truck. This does not mean it is not possible to tow a heaver TT then the truck, but it aggravates conditions to create an unstable TV with small light trucks and light truck suspensions. Larger trucks have the same problem, it just takes more weight difference to get to this point.

Towing Reserve: For the pull rating if you have excess capacity, meaning your GCW is less then your GCWR, you have reserve pulling power left in the truck. The frontal area of the TT eats up pull rating when you go over 60 sq feet of area in many brands of TV’s. And the TT you are looking at, 8 feet wide 10 feet tall is above this. So we need to look at your truck GVW and about where you will land in TT GVW. When you add the 2 together if you stay at about 8 to 10% less GCW then the GCWR of the truck this gives you some reserve in case you add a pop cooler or extra food in the camper etc. Towing at capacity is not fun if you are towing in hilly areas. The further away you are the less worked your truck is. If you have a lot of mountains or a lots of hills where you tow, you may find the 8 to 10% number needs to be more in the 15% to overcome that harder towing. If you are at high elevations we even loose more power on engine with no turbo charger or super charger like diesel trucks have. If you are above the 3500 to 4,000 feet and up, let’s talk more on this reserve factor. The higher you go above sea level the less power you have on a gas engine to start with. A V8 turns into the power of a V6 at around 8,200 feet.

WD hitch and anti sway controls. If you have a heavy trailer tongue weight, most times above the 500# range, they need a WD hitch large enough in ratings plus a little room to grow to line up with your loaded camper weights. Pending your TV, you may even need a WD hitch with less then 500# tongue weight. Also do not get confused by dry catalog weights, the loaded tongue weight with camping gear is what counts. And IMHO you need good anti away controls even if you do not require a WD hitch as TT's present wind effects not seen on sailboats, utilty trailers etc,

The are many good brands of hitches on the market, however sorting thru which one is best for your application can be a little daunting at times. Here at Sunline Club we can talk about our experinces and see if they fit your situation. Regardless of what hitch you get, the WD hitch must be set up correctly to put the front end of the truck back in the proper weight range to allow good TV steering control and to unload some of the heavy tongue weight off the TV rear axle that was gained with this long rear overhang we have.

We also need to watch the truck receiver. While we checked the rear axle ratings, the TV receiver has to handle the WD hitch. The best approach is to have the receiver rated in WD mode equal to or greater then the WD hitch spring bars. This way you do not over torque the receiver by accident when towing in large dips or pot holes creating a hard back flex in the hitch.

The next area is TT length verses TV wheel base. The longer the WB the more stable the truck is to start with for towing. The TV manufactures do not put a rating on this but it is an important part of having a stable towing rig. If your TV is at it’s GVWR, it’s GAWR-RR and you have light suspension, a short WB can have a larger pronounced effect in stability on the TV. The TV tires play a roll in this as well. Long TT, soft tires, light suspension, short wheel base and a TV at it max ratings all adds against itself for long term towing stability. So what is a guide to go by? Here is one that is a guide. It does not declare what rear over hang they are determined from but it is better then nothing. http://rv.org/p10382.htm If you are outside these limits combined with at or exceeding your TV limits that points to a tow rig with out a lot of margin for things to go wrong. A good WD hitch setup properly, a good effective anti sway hitch, proper TV loading, good tongue weight and stiff TV tires can help overcome minor short falls in wheelbase length.

And lastly a very important part of towing, you the driver. You have to be on the defensive all the time. The TV and TT will take longer to stop then normal. Your speed, keep it under control. 55 mph is a good place to start with as an upper limit. In some states it is also the legal towing limit. Check the state you are towing in. Regardless of law or not, towing fast accelerates everything that can go wrong faster. Keep an eye in the rear view mirror for approaching large vehicles. Busses, large trucks. Keep to the right as much as practical to minimize the bow wave effect of the large vehicle passing you.

As you can see there is more to TT towing then just GVWR, GAWR and GCWR. Hopefully some day the TV and TT manufacture will create a real TT towing rating system that takes into account the special things a TT presents when towing on the ball.

While this took a little bit of time I hope you now have a better understanding of where all there numbers interact with each other. Come back to us with all your numbers and we can help you sort this out.

Hope this helps

John

PS For some more on explaining the ratings, Towing Guides Help. Here is just one from Ford. Most all brand TV’s have these. I just picked this one as I can find it easier. The terms are fairly industry standard.

What to know before you tow

Towing Tips by Ford

Towing a Trailer –Being Equipped for Saftey by the NHSTA

[JohnB]

Hi Dig,

Good info. Are you having towing stability issues? If so, try and describe the best you can what you are feeling in the truck and what is going on around you outside when the towing instability is occurring?

Glad to help dig into this with you if needed.

Thanks

John

[Digmenow]

My main concern is that when I follow the Reese directions for the dual cam, they are not providing enough weight transfer. The front end feels light and is at least an inch higher than when unhitched. If I shorten the chains to provide more WD, the cams come nearly parallel to the frame and I wonder if that affects the sway control.

A separate yet related issue is the worn steering box (other steering parts have been checked and replaced as needed) on which I have tightened the lash screw a quarter of a turn to take up around 75% of the slack but I fear over-tightening and destroying the gears with so much camping left this season. I'll probably need to install a new Red-head steering box but I was hoping to put it off until Spring '20.

My impression, having towed in both loose and semi tight settings, is that the sway control is actually steering the truck slightly when the steering wheel is in that area of play that still remains. It changes direction abruptly, albeit in a minor way which is pretty easily corrected so that I must be constantly alert to any change in direction that I did not initiate.

Going beyond semi tight to tight (and nearly parallel) alleviates most of that issue but I just don't know if I still have proper sway control.

[BenB]

Hi Dig,

I'm sure JohnB will add his knowledge, but your setup is very close to what we have. Our T264SR is similar weight to your trailer and we have the reese dual cam with 1200# bars. Our loaded tougue weight is right about 1200#. It sounds like you may be on the right track your front end is probably high if you are measuring an inch or more after WD. With a light nose you will see some steering effects. While I dont know if shorting the chain bringing the dual cam closer to the trailer actually will change the amount of sway control, if you get too short the cam can come up on the frame when flexed. To give more tongue lift and still have plenty of chain you can tilt the hitch head back lowering where the cams ride. On ours when hitched it has 6 links under load and the front end is a 1/2" higher than unloaded. The half inch is measured over the front axle, if you are measuring your inch at the bumper you may not be as bad when measuring the at the axle.

[Digmenow]

Thanks, Ben! Oddly, the 280's PO pulled it with an '05(ish) F-250 and the ball DID have a back tilt to it which I took out, thinking I could improve over what the dealership had done. On further review, mayhaps I should add it back in.

[JohnB]

Hi Dig,

I have limited access until Sunday and can provide more then.

Can you post a few pics of the hitch from the side hooked to the truck as you go camping?

I need to clearly see the entire hitch, rear bumper if truck to front of trailer wall in the pic.

The words you are describing do not align with the correct setup of the WD on the truck and for proper clearance and setting of the DC. If the DC and chains are not setup with the proper clearance between the trunnion bar and the cam arm, you can break the DC arm off in a turn. We can help you dial it in.

And I know about the Ford front end wander. I took mine a tweak at a time on the gear lash screw of the steering box. If you make it too tight, the steering wheel will not return to center going around a turn. If you find that point, you went too far. Back it off a little and that is about as good as you can get short of new gears.

We also need fender well dimensions, front and rear wells. Measure straight vertical up through the center of the axle. Need all four wheels and the following dimensions. All with camper and truck loaded ready to camp

1. Truck unhitched.

2 Truck and trailer hitched but no WD bars on. Dead weight on truck

3. Truck and camper hitched, with WD bars in tensioned with your last settings.

4. Trailer ball height. Ground up to top of ball coupler or top of frame but always in the same place. Need with camper level and then for settings 2 and 3 above.

Do all this on straight and ideally level hard surface drive way/ parking lot etc.

More on Sunday

Thanks

John