This information is based on a 1994 F250 4X4 IDI 7.3 turbo diesel, extended cab Long box with a 5 speed manual trans.


The tow capicity has to be calculated depending on the weight of the truck and the tongue weight of the trailer. This is derived from the GVRW of the truck. My truck has a total 8800lb GVRW. The (front) GAWF is 4600lbs and the (rear) GAWR is 6084lbs. Acording to the door sticker.
(I'm not exactly sure what the truck weight is but from what I have read they are about 7500lbs unloaded.
SO with GVRW at 8800lbs minus 7500lbs is 1300lbs. So 1300lbs is the max alowable trailer tongue weight. Tongue weight is usually about 10-15% of the trailer weight.
With these numbers at 10% tongue weight you could pull a 13000lb trailer.
At 15% tongue weight you could pull a 8666lb trailer.
Say the truck is 8000lbs loaded with fuel and gear. 8800lbs minus 8000lbs =800lbs.
With a 800lb tongue weight at 10% tongue weight you could pull a 8000lb trailer.
At 15% tongue weight you could pull a 5333lb trailer.
The weight inside the truck and trailer can always be changed by repositioning items inside from front to rear or vise versa. This is so not to excede the (front) GAWF of 4600lbs and the (rear) GAWR of 6084lbs.
Weight distribution hitches transfer more weight on the front axle through the torsion bars on the hitch. This allows more tongue weight/trailer weight but can only be seen on an actual truck scale.
So depending on how you load your truck and trailer will depend on the size/weight of trailer you can tow.

 

Hey,

Some pros in here will now more about the positioning of items than myself. But from what I gather the best thing to do is get your truck weighed. Then you can figure out what you have left for payload. Of course keeping in mind the front and rear axle ratings, the GVWR (like you mentioned) and the GCWR (Gross combined weight rating of trailer, truck, and all contents). One thing that can be overlooked is the max load for the tires and at what PSI. Maintaining the tires and the inflation is key to avoiding a nasty blowout. As for the percentage calculations it seems to vary from person to person and trailer to trailer. I'm sure more experienced towers can give you better info.

 

To an extent, yes. In the one example you gave, your GVWR is 8800 and the truck weight was 7500. This does not necessarily allow you a tongue weight of 1300 pounds unless the truck weight of 7500 pounds includes the occupants of the truck and all of your gear, fuel, etc. Everything you load into the truck adds to the vehicle weight and closes the gap between your truck weight and the GVWR.

Your percentages seem correct but keep in mind that most RV and trailer manufacturers are very conservative with their tongue / hitch weights. They figure their hitch weights with standard equipment only for purposes of advertising and brochures. You have to figure into that the weight of options that are installed as well. Having said that, you are correct in that you can adjust the tongue weight to a certain degree by transferring gear in the trailer toward the rear of the trailer.

Best bet it to weigh the truck. Weigh the whole truck and then each axle independently. It will give you the total truck weight but more importantly, it will also tell you how much weight you are carrying on each axle. It can be very easy to go over your GVWR and/or GCWR without going over your rear GAWR. Also, weigh the trailer. You can also weigh just the hitch to get an accurate hitch weight.

Your thought process is right. Remember that your GVWR is a gross weight which is the total allowable weight of the truck and its contents which will include your hitch weight. You can adjust the attitude of the truck with a WD hitch and this will transfer weight like you described. Just remember though, that there isn't any of this that will increase your GVWR or your GCWR. Good luck.

 

I always figured 60% tongue wt. learned this years ago from a u-haul dealer, for proper wt. distribution of trailer and for safety. Am I being to conservative? Never to old to learn.

 

The only thing I would add is something that has been mentioned in passing but possibly not highlighted strongly enough:

In figuring what you can tow, you have to consider each of the ratings as an absolute upper limit. NEVER exceed ANY of the ratings. It is far too easy to have a truck and trailer that are well within the combined weight rating but exceed the axle rating (usually at the rear) or the tire rating (also usually at the rear).

Weighing the complete rig is the only way to be sure unless you are way under all the limits -- and even then, don't blindly assume that each tire carries exactly half the weight measured for that axle - if you are even close to the tire load limit, based on half the axle weight, you really need to check the individual weight at each wheel unless you are 100% certain that the load in the truck is totally balanced. It is not unusual for a truck to be loaded a few hundred pounds heavier on one side than the other.

Of course all weights need to be with a full tank of fuel, and ALL passengers and other stuff loaded.

 

60% might be what a U-Haul dealer expects his (totally ignorant) customers to end up with -- by loading all their heavy stuff at the front of the trailer and/or loading everything forward of the trailer axle.

With a properly loaded trailer, the tongue weight ought to be 10-15% of the gross trailer weight. Somewhat more than that is ok when combined with a load equalizing hitch (assuming, of course, that none of the weight limits of the truck, trailer, or hitch are exceeded).

 

60% OF THE LOAD needs to be in the front of the axles, and 40% behind. That's what Uhaul says... that does NOT mean that 60% of the trailer's weight is on the tongue. Its counterbalanced by the 40% after the axle, to hopefully give you that magic 10-15% tongue weight.

As far as the original post, that's all very true as long as you also take into account the GCWR.

 

Thanks for the clarification. Out of all fairness to the dealer, I was a young kid, so you know how that went.ha ha .Makes me think of all the light loads I hauled.what a waste..

 

Chris, you have the formula right and what was said above about tires and the rear axel weight are also very important. I would just add that it's pretty easy to improve the numbers. I'm more familar with 5th wheel set ups but I would guess bumper pulls would be close to the same. The easiest and cheapest way to increase the RAWR is overload springs. Couple hundred bucks and they go on with hand tools. Next step up is air bags. More money and harder to install but easier to adjust up and down. And, don't forget to upgrade the tires. If your truck has the stock tires on it (fat chance) or tires that are the same as those that came with it, you will see that the RAWR is really the rating for the tires on the rear. The axle will handle considerably more. Now neither of these will change the numbers on the door but unless you are commerical nobody cares. What they will do is level the truck and stablize the rear axel which is what's carrying the load. You do however want to be safe so weigh everything so you know what you're dealing with. I don't know about that 15% figure for tongue weight on a bumper pull. I've heard it used for 5th wheels and it's about what mine is but on a bumper pull it seems it would be more. A lot of the tongue weight depends on the length of the tongue, the longer it is the less trailer weight there is on it. At least that's how it works with boat trailers. Best advice, hook up the trailer and take it to the scales before you buy it. Good luck, hope this helps.

 

Stanley brings up some good points. However, I would caution you that going over your GAWR brings with it the possibility of premature failure of components and if it's shown that you were over your ratings and that caused the failure, more than likely, you won't have any warranty coverage for repairs. Also, while you may not be a commercial hauler, if you're in an accident, especially one where you're at fault, and it's shown that you knowingly exceeded your ratings for your truck, you'll likely be subjected to one heck of a lawsuit.

Also, while airbags and/or overload/auxiliary springs may level your ride and help the truck handle the weight better, they will not raise your gross axle weight rating. That is determined at the factory when the truck is built and is stamped on the truck. You can add accessories to your truck to help you with load handling capabilities but nothing you do will change the GVWR, GCWR, or the GAWR. The only thing you could do to change the GAWR would be to swap in an axle from a heavier truck but it won't change the GVWR/GCWR.

 

It's a 94 truck, already too late for a premature failure. LOL.

 

Thanks for all the great info everyone.
The 1994 F250 in question is the truck I actually own and have up for sale right now.
I had the tow capacity question asked to me about my truck so I did some research and that was the reply I gave to the guy.

I have upgraded to a 2005 F350 crew cab short box diesel.
I was pulling my 27 bumper pull travel trailer with my '94. I never did weigh it.
I will definitly weigh my 2005 with the trailer. Mostly because I know what all the numbers mean now.

Thanks again.
Chris.

 

One thing I'm surprised nobody metioned....unless I missed it.

The GCWR (Gross Combination weight rating) is affected by the engine/trans/gear ratio.

The serious handicap I saw with your truck is the manual trans.
Your owners manual should give the GCWR for the available body/engine/trans/gear combinations.

Manual trans trucks usually have pitifully low tow ratings comapred to auto trans with the same engine/gear combo.

The GVWR, GAWRs, and GCWR don't usually equal each other.

On my 91 F250 the GVWR is 8800. The truck weighs 6100 fully fueled with me and the wife in it. That leaves a cargo capacity of 2700. The rear axle weight rating is 6000. Assuming that around 3000 on the rear (which is probably way high) putting 3000 more on the rear would exceed the GVWR.

I don't have the manual handy to look up the GCWR, but my 97 F150 with a 4.6 and 3.55 gear has a GCWR of 11,500. The 250 probably has a CGWR of 13,000 or maybe more since it has a 7.5 and 3.55's.

 

My 1994 F250 has a total 8800lb GVRW. The GAWF is 4600lbs and the GAWR is 6084lbs. Acording to the door sticker.

Those were the numbers I used in the calculations.

My 2005 CC SB 6.0 diesel auto is.
11000lbs GVWR.
Front GAWR is 5600lbs.
Rear GAWR is 6390lbs.
These are from the door sticker.

 

n3up, 6100lbs loaded, wow you might want to double check that. I don't think I've seen anyone come in that light with an extended cab. A 2700lb payload? thats almost a 1 and 1/2 ton load. Let's say I'm skeptical. My truck should be close to yours in weight and I'm 7500 with just me, my tool box and a tank of fuel. Which gives me a payload of 1300lbs. take me and the tools out and its 1500lbs or about 3/4 of a ton. Hence the name 3/4 ton truck. Just for what it's worth.