“…They don’t have to be on a slight bias, they just are. Thats the Pirelli patent. The Michelin patent is a single ply at exactly 90?..”
Not only are these statements contradictory, the first sentence is just plain wrong. I only know of one radial tire that was built with 15 degree ply angle - and that one is no longer produced. Frankly, those ply angles are bias belted territory and I think the feds would have problems with labeling these as radials.
Absolute zero pressure, as with absolute zero temperature, is that point where molecular activity ceases. It’s a mathematical extrapolation, and has not been acheived in the physical world we live in. Any and all pressure measured and discussed are all references to something else, in the case of the simple tire gage…generally a simple bourdon tube (a sealed metal curved hollow banana connected to a needle)…it’s a reference to approximately “ambient” at sea level at 23 degrees celcius with (if memory serves) 30% relative humidity, which is 29.92 inches of mercury (in a manometer).
Aneroid (a sealed metal bellows canister with a 29.92in internal pressure) aircraft altimeters, which must calculate the altitude via small changes in the air pressure, have compensation knobs to compensate for variations in ambient pressure. The pilot requests of the tower the ambient pressure in inches of mercury, sets that into the altimeter, and then can read his correct altitude. Knowing the altitude of the runway (from his reference materials) and his correct altitude (adjusted for ambient) he can then determine how high above the runway he is.
Now, to the tires. The gages are calibrated at the factory to zero PSI being at 29.92 inches of mercury. Everything is referenced to that.
Now to some simple laws. If the volume remains constant and the temperature remains constant, the pressure also remains constant. However, compressing a given amount of matter (reducing volume) raises temperature and pressure. Therefore, it is possible to reduce the volume in the tire by adding enough weight, thus compressing the air and increasing the temperature and pressure.
In short, a given amount of air can be put into a smaller container, or, in the case of the tire, the container can be made smaller and pressure increased.
Dennis. am I crazy? Or just missing something.