Originally Posted by
cyccommute
I read Kapusta’s statement as a change in pressure of a filled vessel with altitude. That would depend on the vessel. A cylinder of gas filled at sea level is going to have the same pressure at altitude as at sea level. A tire filled at sea level and taken to altitude might show a slight change in pressure but that is because the “vessel” in that case is elastic. That is going to complicate the problem because the tire expands (slightly) which would result in a decrease in pressure (Boyles’ Law).
Well then you read it wrong because this is NOT what I said. I never said the true air pressure in the tire or vessel changes. I said the READING OF THE TIRE GAUGE changes because what it is reading is the difference between the pressure in the tires (or whatever vessel) and the atmospheric pressure. As altitude increases, atmospheric pressure decreases and the difference in pressures increases, thus the reading of the tire gauge increases.
If you are going to argue with me, at least argue with what I am actually saying.