philh wrote:
ktmrfs wrote:
Really all a dry nitrogen fill does is eliminate water vapor which can go from gas to liquid and have a bigger pressure change effect. For those us where a few PSI is no big deal, no problem. Could do basically the same thing with plain dry air. All gases obay boyles law for pressure vs. temperature.
You can not get passenger vehicle tires hot enough to transform to vapor... If you did happen to get them that hot, then you have bigger problems.
All you need is a temperature change. if there is even a few degrees temp change will change the amount of water liquid turning to water vapor or vice versa in an enclosed tire. Water doesn't need to get anywhere near boiling to evaporate and go from liquid to gas.
Every air compressor I've been around ends up with water in the tank even if you drain it almost daily. Follows what one would expect from the physics of air compression. Being a contained system the compressor RH for water vapor is then near 100%. Air going into the tire is at a lower pressure than the tank, hence air cools, lowers the dew point, condenses some amount of water into the tire, but still at or near 100%RH. temp change will then cause water to either condense (temp drop) or evaporate (temp rise) till all the water is a vapor. Messes around with ideal gas behavior,
So unless the tire shop has some form of water removal and drains the tanks often, you will get some amount of water in the tire.
The vapor obeys boyles law, the liquid does not. That affects how temp changes affect tire pressure.
Again, for most consumer applications, it will not make enough difference to be signficant or affect operation.
