"Viperdoc" wrote:
The thread on brakes raised a question from the past- why nitrogen in
the tires of big jets and heavies? Air is around 78% nitrogen anyway,
and the coefficient of expansion of the remaining 20% that's oxygen
can't make that much difference in volume.

Why not just use dry air? I couldn't imagine that dry air or dry
nitrogen could make that much difference in corrosion, either.

I seem to recall someone giving me the rationale for this a long time
ago, but also seem to remember thinking it didn't make that much sense
at the time.

Consumer Reports noted:

"The National Highway Traffic Safety Administration (NHTSA) has seen
reduced aging of tires filled with nitrogen. Though the data does support
that passenger car tires could benefit by all the claims made for nitrogen,
tire manufacturers say that they already design tires to perform well with
air inflation. And while nitrogen will do no harm, manufacturers say that
they don't see the need to use nitrogen, which generally adds $5 or more
per tire charge."

From: http://blogs.consumerreports.org/car...nitrogen-.html

Also CR's Q&A answers imply that if you have a lot of tires (as on a truck)
then using N2 may be a net win, but probably not in other cases:

"The positive benefits of nitrogen in high(er) service pressure
applications, such as used in large truck tires, has been documented in the
industry. Our test centered on passenger tires, only. We are not
discrediting the use of nitrogen, but it is not a substitute for regular
inflation checks."

From: http://blogs.consumerreports.org/car...en-tires-.html