I did some back of the envelope calculations on this Nitrogen thing.
Based on the ideal gas law (PV=mRT) my understanding is your tire pressure
will vary in proportion to temperature regardless of what kind of gas you
have in the tires. Just for kicks, if you inflated them to 32 psi @ 120F
and drove somewhere cold, down to -60F you would lose 10 psi.
Another observation: Since you really can9t pull a vacuum on a tire without
breaking the bead you are starting off with air at 14.7 psi. Air is 79%
Nitrogen. After inflating to 32 psi, my back of the envelope calculations
indicate you9re now at 90% Nitrogen. The percent of moisture inside the
tire hasn9t changed since liquids are significantly more dense that gases.
As for moisture, are the inside of your tires/wheels more susceptible to
moisture than the outside? Unless you always park in a garage, the outside
of the tires see a lot of moisture cycling.
Nitrogen and Oxygen are right next to each other on the periodic chart. So
no real difference in molecule size.
Another observation: I have some Goodyear Polyglas of the early 70s vintage
that still look like new, hold air, etc. That would make them over 30 years
old. I don9t plan on taking any long trips on them. My point is, why is
the shelf life of new tires, many of which are in a climate controlled
storage, now so short. My conspiracy theory is that the tire manufacturers
have started using a cheaper method to make tires. Then they want to shift
the blame for tire failure onto the consumer because they ran them past
their expiration date. Planned obsolescence and CYA.
Sorry for the long dissertation, I9m just really having a hard time with
this Nitrogen in the tires thing.
I9ll crawl back under my rock now.
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