Weight calculations for dummies

Seattle Lion wrote:
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.Basically that is because Ford does not know how or what you will add to the truck after purchase. Load it up like your going camping and go to the local scales for an accurate ready to travel 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.

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.Fords are notorious for being heavy, so I would guess your actual weight is 8000+ pounds. What you actually got was front axle plus some percentage or rear axle weight. There is simply no way to balance the truck weighing each axle independently. You need to read the total weight with both axles on the same platform.

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?Like axle ratings for each axle, the tires have a rating placed on them by the tire manufacturer. That is the maximum that the tire is certified to carry. Generally speaking the sum of the four tires will equal the vehicles GVWR.

Any idea what the truck weighs?

How do you use the axle weight ratings. In reality, you don't. Axle ratings are the maximum weight ratings placed on that single component by the axles manufacturer. Remember Ford does not make the axle, they buy a semi finished component from an outside supplier. That supplier makes the axles with XXXX pound 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 axle the other night, there is virtually no capacity.

Your help would be most appreciated.

Like I said, you really need to find a local scales with a single platform large enough to take both axles. Look at local truck stops. Many will have Cat scales and can weigh each axle plus the loaded gross weight all at once.