Weight calculations for dummies

I have read all of the threads on GVWR, tongue weight, etc. and I am still confused. Since I am an engineer, I suspect it isn't the math that bothers me. After a lot of painful reading, writing, and calculating, we determined that my Ford F150 was going to be over GVWR by a few hundred pounds. So, I traded it for a new F350 Diesel. I know it has the capacity. What I can't do is figure the numbers.

According to the door sticker and the window sticker, the truck has the 11,500 lb option. The door sticker says we have a 11,500 lb GVWR. So far so good. Nowhere on the sticker or elsewhere on ford data sheets is there a value for the truck's weight. On the wheel and tire sticker, it says that max load for the truck is 3,500 lbs. I assume that is based on the capacity of the tires (SRW model). I still don't know what Ford says the vehicle weighs.

Edit I did some further research (using the tables referenced below). According to the Ford tables:
The GVWR is 11,400 (per sticker)
Payload for the crew cab 4X4 is 3,870. That would make the calculated vehicle weight 7,530 (more sensible to me). So the tire/inflation sticker claims 3,500 lb capacity and Ford 3,870. More confusion.

We went to a closed state weigh station the other night. The scale (there are two platforms about 40 feet apart) isn't big enough on a single platform to hold all four wheels. So we weighed the front and back wheels separately. Front weighed 5,460 and the rear 5,300. It makes no sense that the truck with just us in it weighs 10,700 lbs. That would give us less than 1,000 lbs load carrying. Also, even though I am not a mechanical engineer, I am pretty sure that weighing front and back separately and adding the results does not give true weight. An f350 can't weigh 5 tons! I am guessing it should weigh between 7 and 8,000 lbs.

There are lots of numbers on the stickers and on ford's spec sheet (Ford Truck Specs).

We will look for a bigger scale. In the meantime, there must be a way to get a reasonable estimate of what the truck weighs.

What does the 3,500 lb capacity number on the tire and inflation sticker mean? Is it a truck spec or tire capacity?

Any idea what the truck weighs?

How do you use the axil weight ratings. I assume to calculate load, you first need to know what weight the truck puts on the axil and then the difference is the capacity (like for a 5th wheel). If you go by the readings we got when weighing each axil the other night, there is virtually no capacity.

Your help would be most appreciated.

18 Replies

Ron_Gratz
Explorer
Dec 30, 2013
What were the front and rear axle weights for the new weighing?

Ron
Seattle_Lion
Explorer
Dec 30, 2013
Thanks for the great information. Last night we went back to the state weigh station and much more carefully weighed each axel. This time we got sensible results. With both of us in the truck along with our usual stuff, the total weight was 8400lbs. Given our GVWR of 11,500 lbs, we have 3,100 lbs additional payload capacity. Our tongue weight is a bit under 1,000 lbs, which means we have a bit over 2,000 lbs for our lunch.

The expected net weight of the truck is in the 7,700 lb range. Add in all the extras (moon roof, power seats, etc.) as well as us, it is easy to see how we can weigh in at 8,400 lbs. This extra capacity is a big relief. Our 2013 F150 only had 1,250 lbs of payload capacity.

So, yes, you can get the correct weight by weighing each axel. Makes sense.
JIMNLIN
Explorer III
Dec 29, 2013
Any idea what the truck weighs?

Kinda like asking how much a rock weighs. The trucks GVWR/FAWR/RAWR/wheelbase/2wd vs 4x4/ cab selection/diesel vs gas/etc all figure in how much a trucks front and rear axles weighs.
Be sure and get the trucks separate front and rear axle weights as a single gross weight gives you nothing. You have no idea if the rear axle is overloaded.

How do you use the axil weight ratings. I assume to calculate load, you first need to know what weight the truck puts on the axil and then the difference is the capacity (like for a 5th wheel). If you go by the readings we got when weighing each axil the other night, there is virtually no capacity.

Your help would be most appreciated.

The F350 has three different RAWR (6390 rawr/6730 rawr and a 7000 rawr). I'll guess the 11500 lb GVWR package has the max 7000 RAWR. By the way the 7000 RAWR axle rating on the vehicles certification placard which is located on the drivers side door post is Fords number and "IS NOT" the axle mfg number.

Looking at Fleet Fords.com spec sheets shows a base F350 SRW rear axle weighs from 2700 lbs for a reg cab up to 3100 lbs for a 172" wheel base 4x4 crew cab.
Many F350 SRW owners report 2900-3100 lb rear axle unladin weights which leaves approx 3900-4000 lb payload for a 7000 RAWR. All depending on the trucks selected configurations.
Reported weights are for that particular owners truck. We have no idea how much extras that owner is carrying above the trucks shipping weight or as delivered.

Use Fords specs for a rough figure on weights but get the trucks axle weights for actual scaled weights.
gmw_photos
Explorer
Dec 28, 2013
To the OP, it should weigh probably right around 8K. Our '06, 172"WB, crewcab dually diesel was something over 8K pounds the one time I scaled it by itself. But I don't remember how much fuel was in it, and what might have been in the bed or inside as far as a few tools, etc.
It will depend somewhat too of course on which trim level and accessories you have also. Ours is Lariat with a sunroof and all the cowgirl cadillac gimmicks, so that stuff adds up.

As has been said, a CAT scale is good choice, or if you have a scrap metal recycler close by, that would work too.

Edit: oh yeah.... I forgot a dually has six tires....so that's six times those pesky 80 "pound" tires......;) :R
Francesca_Knowl
Explorer
Dec 28, 2013
352 wrote:
You didn't mention the additional 80 pounds each per tire pressure. That's another 320 pounds:?

:B
You ARE kidding around....right?
lbrjet
Explorer
Dec 28, 2013
As Skip said your truck should weigh about 8K. I have never seen a truck sticker that has a vehicle weight. You typically back into that number by subtracting the payload from the GVWR. Weigh it on a Cat scale. They are accurate to within 20lbs per axle.
352
Explorer
Dec 28, 2013
You didn't mention the additional 80 pounds each per tire pressure. That's another 320 pounds:?
Francesca_Knowl
Explorer
Dec 28, 2013
Seattle Lion wrote:

What does the 3,500 lb capacity number on the tire and inflation sticker mean? Is it a truck spec or tire capacity?

The one question you've asked with an easy answer...I think.
That is strictly related to tire load capacity, and applies only to tires of the same size/type that are indicated on the sticker.
Ron_Gratz
Explorer
Dec 28, 2013
Seattle Lion wrote:
---Front weighed 5,460 and the rear 5,300.---

Looks to me as though you weighed the front axle twice.

Detailed specifications for your truck can be found here.

Ron
handye9
Explorer II
Dec 28, 2013
If you had a factory UVW, it would only be a ball park number. The factory has no idea what options or aftermarket equipment will be added by dealers and customers. Things like spray in bed liners, step bars, bed mats, bed covers, and bed caps, etc, add weight to the truck and reduce payload pound for pound. Because of this, payload will vary from one truck to another. GVWR as printed on your door post, will remain constant.

Example:

I have 10000 GVWR

Truck weight 7680 with full fuel, 100 lb WD hitch, and driver

I have 2320 payload available for passengers, cargo in truck bed, and trailer tongue weight.

or

I can remove the WD hitch and I have 2420 payload available for passengers, my slide in camper, and tongue weight from a utility trailer.

My brother has an identical truck, that weighs 270 lbs more. His available payload is 270 lbs less. The difference is, he has a fiberglass bed cap where I have a tonneau cover, and, he is heavier than I am.