[77newell]

The analysis engineed in me is getting turned loose for a moment. The idea that tire pressure increases with altitude ain't necessarily so, to quote a song from a musical. It is not true if the pressure is measured in absolute terms, that is the pressure above a pure vacuum. It is true if it is measured as pressure above ambient pressure. So, while the absolute pressure, which uses absolute zero pressure as the reference, stays the same as the tire gains altitude, the pressure sensed by our gauges, which use ambient as the reference, increases only because the reference ambient pressure decreases in absolute terms.

In terms of the performance of our tires, only the gauge pressure, which uses ambient reference pressure, matters since that pressure is the one that determines the size of the contact between the tire and the road. Thankfully, that simplifies our task.

Personally, a gauge that was off by more than a couple pounds would bother me, even if I knew by how much it was off. I wouldn't be confident I was making the correction in the right direction on the typical fuzzy minded morning checks, and going the wrong way with the correction doubles the error. With a TPMS I wouldn't worry so much. I would set the alarms in moments of great clarity (supposing my fuzziness doesn't falsely lead me to think it's clarity) having accurately corrected for sensor errors, assuming the errors are consistent, and listen for alarms and avoid looking at the pressures.

Nah, I would look, I would mess up the mental calculation, I would presume I set the alarms wrong, and I would be so distracted driving I would head butt a semi and probably die. Sooo, the only thing to work for me would be to get the sensors reporting reliably and not get distracted. Hey, that's my personal illness, just like wanting to make sure we are talking the right pressure. I admit my OCD seems to have served me better than it has my significant others.