Mark Browne wrote:

Yes, but now the others on this group have a better understanding of the
factors involved.

I am not going to bother to run the numbers but the partial pressure of
any "normal" quantity of water vapor in a tire is not going to change
the tire pressure by an amount easily measured by anyone outside a
laboratory. It will have no significant influence.

Moisture will however contribute to corrosion and oxidation at elevated
temperatures in an oxygen bearing atmosphere. How much of a factor this
is in an application where tires are changed every few minutes anyway is
debatable.

I think your racer/writer/engineer friend might be disappointed when he
fails to see much, if any, measurable difference in his tire pressure.

Rick