I think you are over limit with your current 3 horse trailer.  Most 3/4 ton trucks are rated for about 13,000lbs towing.

Looking at Edmunds for the 2008 specs it shows 13,350 for towing max for the shortbed quad cab.

You need to check your owners manual and see what your truck is rated at.  Also look at the sticker on the door that shows you max weight per axle and take your truck/trailer and drive across a certified scale. To see if you have maxed out your tires or axle.

Rear axle, u joints, rear suspension, transmission.........all things you don't want to fail when you're on the road

Gard

My main concerns for a one time cross country trip with a 3/4 ton truck and trailer that size would be more safety related. My big concerns would be single rear tires and how much weight they are rated for vs the actual weight they are carrying. As has been said before, heat is your tires enemy, and an extended trip with several hours at a time of driving at highway speeds can cause more heat build up in the tire, especially in an overloaded condition. The other concern would be stopping power(distance). I'm not saying I wouldn't do this, just that if I did, those would be my main concerns. I would address both of those concerns if I did this by lowering my driving speed. I'd pay very close attention to my tires and tire air pressure as well.The other thing I would do is to drive very defensively in order to address the reduced stopping ability.

Again, I'm not saying I would or wouldn't do this, because until I looked at your particular truck, trailer, tires, and what your plan is, I don't know. I also don't know your driving habits and experience. But if I were looking at doing this, these are some of my concerns and what I would try to do.

I haven't read everything here...  Don't do it.

My friend blew up her 2004? Dodge 3/4 ton hauling a 3H alum trailer with 8' shortwall hauling 3 horses on a regular basis. The last trip that truck made was coming back from Tennesee.

If you're going cross-country - you're gonna have even bigger hills. You're going to have to haul hay and water. 4 people = 1000 pounds (their weight + clothing, bedding, etc.)  4 horses = 4800 pounds. Water is 8.64 pounds per gallon and you need 10 gallons a day, per horse. Plus everything that gets dumped into the waste tanks by the humans.

Hay at 60 pounds per bale. 1/2 bale per horse, per day. Taking any grain for the horses? 4 pounds per horse per day? or more?

You need to add all of this up. 20% of the trailer weight will be on the truck + passengers + fuel and anything else you put in the bed of the truck. That's essentially your "payload". Your GVWR minus the weight of the truck gives you your allowed payload.

Who is telling you that your truck can pull it? 

Slidinspots.. Let's think this through a bit.  Your truck is rated to 8800 pounds total.  So... 4400 pounds per axle is what Dodge designed the axles & tires to support.

Your present trailer is rated to 15210 pounds.  That means fully loaded.  As a rough estimate 20% of the total trailer is on the truck hitch ... so 15210 x 20% = 3042 pounds on the hitch.

4400 - 3042 leaves 1358 pounds ... but wait the truck weighs something... less on the back ... let's say 1000 pounds now, you have 358 pounds.  But wait again.  the hitch weighs 150 pounds (my B+W did)  you're now left with 208 pounds.  That's two svelte girlfriends and their horses riding with you in your present trailer. 

Hitch to a 4 horse trailer with LQ and two guys and their horses ... Your truck is overloaded...

There is always some margin of overload designed into trucks.  It's your call how much margin you want to use and spend in repairs.

Those "desperate" riders won't be faced with the repair bill, you will

I am SO glad you asked the question about pulling!  I'm sitting here with the spec's from the panel on the door frame of my F-150, 4x4 (w/ off road and towing package).  It appears my rear axle is rated to 3550 GAWR.  I'm moving up from a steel stock to an aluminum horse trailer and want to know my limits.  My understanding from the discussion, I should take off the weight of the truck (about 1000 lbs) which leaves me about 2500 lbs I can put on the rear axle.  Also, of the trailers I'm looking at, up to one fourth of the weight of the trailer will be sitting on the rear axle, so I can consider up to 10,000 lb gross weight.  Am I in the ball park?

As an asside, I've been watching for trailers on Craigslist and have asked trailer weights of the one's I'm interested in.  It's amazing how many times I get "I don't know, I need to look it up".

Thanks

You're in the ball park, but the ass end of an F150 weighs closer to/probably a little over 2000#.  What year is it?  This site can help if its newer than 02.

https://www.fleet.ford.com/showroom/rv_trailer_towing/default.asp

I just visited the Ford site.  I have a 2001.  Can I assume the 2002 specs would work?  Fifth wheel?  Once again I'm seeing reference to axle ratio.  Where do I locate that? 

One more question. . .under the engine designation next to 4.4, 4.6, 5.4. . . is "sefi".?????

Appreciate your answers.

Ford uses a Sequential Electronic Fuel Injection system to get fuel to each cylinder. What this means is that the SEFI engines inject fuel, one cylinder at a time for better control. SEFI is the better system than the old throttle body injection system, that injected fuel into the manifold.

Whoa !! For a 2001 F150 the max legal load is 1542 pounds. (701 Kg)

From here >> http://www.internetautoguide.com/car-specifications/09-int/2001/ford/f-150/index.html

Are you considering a GN trailer?? 1500 pounds isn't much for a GN trailer.

The max trailer weight you may tow is the Combined Gross Vehicle Weight Rating minus 4044 pounds.  The CGVWR is in your manual.  The 4044 pounds is from the above site as curb weight (pounds = Kg x 2.2)  Remember passengers, optional equipment, and stuff in the bed count too.

I'm not sure what country that site is for (everything is metric?), but in the US the legal payload is generally determined from the axle ratings, not the GVWR.  Motor vehicle manufacturers can make recommendations, not laws.  This means to find out what the pickups payload is requires a trip to the scales compared to guessing. 

My Dmax states a payload of ~2600# on the door, compared to the GVWR-curb weight formula of ~2000#.......compared to the ACTUAL legal payload of ~3000# it is register/tagged for here in SC.

I do not intend to get in a lengthily discussion here, this fact has been beat to death all over the web.  A quick read over any of the hotshot forums or a simple call to an individuals respective states 'diesel cop' will likely explain this concept to those unfamiliar. 

3horse,

The 3550 you listed sounded funny to me, so I took a look around.  Seems like thats the front axle.  Take a look here,

http://www.ford-trucks.com/specs/2001_f150_1.html

The tag on the door frame says. . . (I didn't mention before, this is an extended cab, along with full size bed, the 4x4, tow and off road pkg)

GVWR 6500LB/2948KG

REAR GAWR 3550LB

So I guess my quandery . . ./  concern. . ./ let me say this back to you, my limit is 1500 load on the rear axle, hence the trailer should not weight over (considering 20-25% of loaded weight of the trailer on the axle) 6000-7500.  The most weight I've ever pulled has been 5500, the truck wasn't straining, overdrive was off, and I didn't have the brake controller attached at the time.

Let me say this is the most information I've gotten in a very long time.  Glad I found this site.  Thanks you for your advice. 

Just finished going through the 15 pages of Ford specs.  On the 14th page under "Payload and Towing Weights"  it says max trailer tow is 8000 lbs.  An aluminum GN EBY I recently looked at, a 3 horse slant, 4' short wall, unloaded is 5500 lbs.  Gross weight loaded is 9800 lbs.  I have no plans of pulling three horses.  Mostly one at a time and sometimes two (when my spouse rides too).  I guess my question has been answered.  It's doable.  Woooo.