The tires air pressure in no way decreases it’s circumference. The notion that because the diameter is less when a tire is low the circumference lessens is …hogwash! Example: If one were to measure the diameter (distance form the ground to the top of the track) of the military’s main battle tank, …

The OP statement is not correct. We used to use a band to squeeze a difficult tire to seal it to the rim. The band was broken several times by some technicians who did not remove it quickly enough after the initial seal. If the diameter did not increase then the band would not have snapped.

Increasing the pressure in a tire changes not only its circumferemce, it also changes it “cord” profile, that shape you’d get should you cut across the tire and look at the shape. Just as increasing the pressure in a balloon makes it get rounder, increasing the pressure in a tire causes the “cord pr…

flybyya wrote: The tires air pressure in no way decreases it’s circumference. Go out to your car, mark the top of both rear tires, let a lot of air out of one of them, drive a short distance in a straight line, examine the marks, and report back to us.

lion9car…utube has a demo of just such a test and it showed little if any measurable difference. But this is a gross test, not done at speed and over time where cumulative small changes become quite significant. Auto engineers, tire manufactures and every one it seems with a degree and a real “need…

In my 2007 Grand Cherokee, if I add pressure to one tire, I can observe the instrument panel display pressure indication rise without the car moving at all! This does not square with the differential speed theory. I plan to check this out with Chrysler for their explanation. I am thinking there mig…

“Not correct. The pressure is stretching the tire and the cords it’s made of. Ever tune a guitar? You’re stretching wires as you do it.” Steel probably does not stretch enough to matter at the stresses of a normal tire pressure. When you tune a guitar, you are probably distorting the wood more tha…

BLE - not true, that’s how inflation monitors that depend on wheel speed work. And when you tune your guitar, the change in pitch results directly from stretching the wire. The flexing of the wood works against this, not for it. As I said, there’s about 6000-8000 pounds of tension on the tire belt…

What keeps these inflation monitors from reporting a false low tire when you are taking a long radius turn on a highway? When a string breaks on a guitar, the sudden release of that string’s tension makes the rest of the strings go sharp, so the wood does flex. Also, when restringing a guitar, by …

They probably average over several minutes, long enough for those variations to even out. But if you drive in a circle for that long, I guess it would fool them! Maybe that’s another reason the government required the in-wheel sensors, instead.

Low Tire = Smaller Circumference.......?

The Show

circuitsmith January 14, 2012, 9:21pm 11

red rolfe, yes you must have sensors in the wheel, which are more costly when the car is made, but a more accurate direct measure.

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Low Tire = Smaller Circumference.......?

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