Tire Pressure/Contact Area/Weight

Radial tires don't have much sidewall stiffness but it must contribute some. I would think that the effect of the sidewall stiffness decreases the calculated weight because some of the weight is being supported structurally and the lack of accuracy in the contact patch (at worst an oval shape or at best a rectangle with rounded corners) increases the calculated weight. I.e. overestimating the contact patch area would indicate higher loading for a given psig. Therefore they may be offsetting to some extent. (Hard to wrap my head around this so don't know if my logic will hold up.)

Probably the load is a bit more then 3700 lbs .
Part of the load is carried by the constuction of the tire.
I state that , but discussable to about 100 lbs a tire.
So most likely the real load is about 3800 lbs .
And also inacuracy of determination of surface on ground plays a part.
You could test it by weighing per wheel .

Also you can put for instance 30 psi on tire and then determine the surface again , then probably lower then 3700 outcome because of more deflection so more load carried by the construction of tire.

Lotta google hits on this, and they get rather technical. I'll defer to them.

Simplified answer; Yes, you are correct. Give the parameters you describe, ceteris paribus, the weight (on the ground) is 3,700 lbs.

Longer answer; In reality there are many things that come in to play. First and foremost is one's ability to accurately measure the total surface area of the contact patch. Typically a tire has a tread pattern on it, in addition, the surface that a tire is sitting on is not likely to be flat. Most importantly, modern tires have a mechanical structure (e.g. steel/nylon/kevlar) inside them which significantly alters the shape of the contact patch.

However, it sounds to me like you're asking a basic physics question. In that case, 50 PSI is 50 PSI, and if that is the pressure inside your tire then 50 is also the average PSI on the contact patch.

Cheers,
-Mark

PSI (pounds/sq in) is exactly what it implies. My front tires have aprox 7 X 10 contact area and at 100 psi they do indeed carry 7000 lbs each. Granted the middle of the 70 sq in area may carry slightly more than the edges because of the stiffness of the tire.

Not real life numbers. Just a mathematical example to test the hypothesis and start a discussion on a cold winter day. If true, could be a way of figuring weight on each tire, knowing the pressure and contact patch. I know of a high school science teacher that slipped sheets of paper under the front, rear and sides of a tire to enable measuring the tire contact patch to come up with the weight on the tire as stated. Force (weight) = pressure x area.

It sounds like your mixing capacity with maximum ability. The actual tire contact patch is very small. Unless you are talking an aired down offroad tire. Even then the contact patch is marginally bigger. At 50psi and 3700lb capacity, sounds like an oversized load D tire, maybe. Many E rated tires max out at 80psi. F, G and H rated tires are found in commercial size. Usually 17.5" or 19.5" for smaller trucks (Ford, Chevy and Dodge). 19.5" and up will likely be found on motorhomes or other commercial equipment.