6,000 lbs is a reasonable estimate load for your vehicle.

12,000lbs (6 tons) mean it can hold up 2X the total weight.

Most jacks are relatively inexpensive Chinese made devices that are validated at their "test" with virtually no safety margin.

Quality control is often indifferent, and there is no accounting for their claimed capacity over time as parts wear.

For regular use, they should be derated by at least 30% and ideally 50% just to ensure a reasonable safety margin.

That changes it from 12,000lbs to 6,000lbs right off the bat.

Clearly, no cheap consumer grade jack is suitable to carry the maximum rated load day in, day out, for any length of time.

It will fail with very few load cycles.



Turning to your vehicle and allegation that 5,700lbs is the right weight on your truck's sticker. Is the unladen weight reasonable?

That is the weight without fuel, accessories, and yourself in it.

Clearly, if you are going to jack it up, you are going to have some fuel in the tank, and you might have to get inside.

Work it out, that is going to add anywhere from 200 to 500lbs or more, depend on how fat you are.



A reasonable and prudent calculation is to use the GVWR of the vehicle, not the unladen weight, in calculating loads.


Reason --- when you bring a customer's truck in, you cannot be certain what is inside it.

Can you rule out a nearly fully loaded vehicle even if it appears empty (e.g. an RV?)?

One fitted with tanks to hold heavy stuff? Gear?

So the relevant load is to use the GVWR as the standard weight.

That makes the weight 8,600 lbs --- assuming that there is no evidence of overloads.


Then there is the safety of lifting one place / corner / area of the vehicle.

Although technically, many lifts involve 3 wheels "on ground", at least 2 wheels are on the ground at all times, the reality is the weight of a vehicle is unevenly distributed.

That can also be impacted by uneven loading / bad design that overload the axle / side well beyond the "sticker".

Therefore, a straight division of 8,600 lbs by 4 is not appropriate.

A reasonable prudent estimate is to take the heaviest possible load from the GVWR for that Axle /side combo to start.

That typically get you 2,200 lbs just to start for "one corner" "static" load.

But --- have you considered that by lifting one corner, you are really lifting 1 side / front or rear?

So that weigh really need to be doubled ?

That gives you 4,400 lbs.

What about a safety margin?

What if the truck was carrying a load of lead bricks directly over the axle you are trying to lift?

That is conceivable if you are out there on the road changing a tire.

Make it 5,000lbs for a small (but prudent safety margin).


Want a worse case?

Customer using a jack when towing a trailer, and when you lift the rear wheel to change a tire, you are lifting not only the side of the car, but being held "down" by the trailer that will be far beyond its "tongue weight" normally.

See that trailer you have in your avatar?

How much weight does that add to the side if you are trying to jack UP the rear wheel without decoupling the trailer to change the rear tire?

Quite a bit. More than tongue weight is likely.

There goes your safety margin.




So now, we have a jack nominally rated for 12,000lbs, but derated to 6,000lbs to account for quality, wear and tear, and misuse.


We have a plausible and design load of 5,000 lbs (one side) with a very small safety margin ON A TRUCK THAT have an empty weight on the sticker of 5,700lbs.


1,000lbs is negligible as a difference --- because many things can slew the calculation one way or the other.



Have you considered taking training in mechanical engineering and learning about things like safety margins, error bars, and things like that?

They are really interesting things to learn on the way to spouting ASTM and lecturing about your brilliance.


I am not going to say one MUST have a 12,000lb jack.

Clearly, the jack the vehicle comes with is not rated for 12,000lbs.

But you can bet your last rupeee that the jack is rated for GVWR even if that is not stamped on it, giving it a safety margin of roughly 40% between anticipated load and the expected weight of the vehicle.

Why?

If a vehicle's "comes with" jack failed --- the manufacture of the vehicle will be sued in a class action suit, costing tens to hundreds of millions.


Don't believe me?

Go and take your vehicle's come with test.

Run a destructive test to see what is the "yield" strength of the jack.

I bet you the jack is good to GVWR plus a bit. I would off hand estimate it is GVWR plus 30% for yield strength.


The OP's rule of thumb, IMHO, represent good safe cautious technician practice.


You, on the other hand, is not in need of not multi-million dollar test equipment, tests, but basic common sense typical of a competent and prudent engineering technician.


Looking at the size of the trailer you are towing --- I strongly hope for people around you that you don't load your trailer like you use jacks.


Only a brain dead know it all would use the "reaction force on a single wheel under static loading ( resting )" as the basis for calculation with basically zero safety margins.


Have you considered enrolling in a basic mechanical engineering technicians course?

 

My 2008 V-10 XLT SC LB 4.30 2X4 Auto weighs 6940 with fuel and I(200).

 

Resurrecting an old thread - my '08 F350 caliper setup doesn't look anything like the one in the original video. Two things irking me at the moment - 1) Jackass re-manufacturers caliper comes with the mounting bracket - requiring you to remove the two loctited bolts and exchange the bracket.

2) Ford really outdid them selves with those stupid spring clips on the ends of the pads - they rust, and I'm still trying to figure out how the hell the outside pad gets clipped into the bracket/