Stole this off another forum...Honda's Official stance on Nitrogen
The dealers do this nitrogen trick to suck money from your wallet.
Here's a good article from the September, 2006, Honda Service News regarding Honda's position on it as well:
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Nitrogen Inflation: What’s Our Position?
Surf any automobile tire-related website these
days, and you’ll likely see something mentioned
about nitrogen inflation. It’s becoming a hot topic.
We’ve gotten a number of inquiries lately
concerning American Honda’s position on this
practice.
When it comes to inflating automobile tires, it’s
our position that ordinary, dry compressed air—
which is about 80 percent nitrogen already—is
the best choice. That’s because it’s more readily
available, and the benefits of using nitrogen
simply don’t appear to outweigh those of using
compressed air.
The practice of inflating tires with nitrogen really
isn’t anything new; it’s been around a long time.
It’s been commonly used on aerospace vehicles,
commercial and military aircraft, military vehicles,
race cars, and even heavy off-road construction
equipment. Here’s why:
• To meet rigid safety and performance specs,
the required tire inflation pressures are often
very high, especially in the aerospace industry.
The tire inflation pressure for NASA’s space
shuttle, for instance, is a whopping 315 psi!
• Nitrogen is an inert gas; it doesn’t combust or
oxidize.
• The process used to compress nitrogen
excludes water vapor. Water vapor can expand
if the temperature climbs above 212°F.
• Tires inflated with nitrogen leak slower over
time than those inflated with compressed air.
Automobile tires, on the other hand, are subjected
to an entirely different set of conditions. Here’s
why inflating tires with nitrogen offers no real
advantages:
• Although tires inflated with nitrogen leak
slower over time than those inflated with
compressed air, they still leak and need to be
reinflated to maintain proper pressure. If you
can’t find a place that offers nitrogen
inflation—and there aren’t yet all that many
places that do—your only option left is to
reinflate with compressed air. Doing that
drops the nitrogen purity.
• Nitrogen offers no better protection against
road hazards such as cuts and punctures. So
no matter what you inflate the tire with, you
still need to check the condition and pressure
of the tires at least once a month as
recommended in the O/M.
• Tires that are inflated with compressed air and
properly maintained offer the same fuel
economy, tread wear, and ride comfort as
those inflated with nitrogen.
• Nitrogen for automobile tires is produced by
nitrogen generators, which typically get about
95 percent purity. But to actually get that
level of purity into an automobile tire, you
would have to deflate and inflate that tire with
nitrogen several times. If you’re not careful
doing this repeated deflation and inflation
process, the purity level winds up being closer
to 90 percent (compared to the approximate
80 percent nitrogen already in compressed
air). Because of this, those claims of less
pressure loss with nitrogen aren’t valid.
So here’s the bottom line: Nitrogen is an ideal gas
for inflating tires in aircraft, military vehicles, race
cars, and heavy off-road equipment, but when it
comes to automobile tires, it offers no apparent
advantages over ordinary, dry compressed air.
Our advice to you: Just stick with the air you
breathe.