Honda/Acura service note to tech's November 2012
Why using NITROGEN in tires ain't all that great
Just search the internet, and you’ll find plenty of info on filling tires with nitrogen. But when it comes to
filling automobile tires, we recommend only one thing: dry, compressed air.
Filling tires with nitrogen really isn’t anything new; it’s been around a long time. It’s commonly used in
commercial and government aircraft and vehicles, and even motorsport vehicles. To meet rigid safety and
performance specs, the required tire inflation pressures are often very high, especially in the aerospace
industry. The space shuttle’s tires, for instance, were filled to 315 psi!
Here’s what makes nitrogen ideal for these applications:
• Nitrogen is an inert gas; it doesn’t burn or oxidize.
• The compression process for nitrogen removes moisture, so it’s a dry gas. Since it’s dry, it has no
moisture to contribute extra pressure changes with temperature. Water vapor can expand if the
temperature climbs above 212° F.
• Tires filled with nitrogen leak more slowly over time than those filled with compressed air.
But automobile tires are subjected to an entirely different set of conditions. Here’s why we say no to
nitrogen:
• Nitrogen generators produce nitrogen gas from ambient air, but it’s at something less than 100 percent
purity. To get just that same level of purity into a tire, you’d have to deflate and fill it several times to
purge the remaining air. And if you don’t do that, the purity level drops even more. Compressed air is
already about 78 percent nitrogen.
• Although tires filled with nitrogen leak more slowly over time than those with compressed air, they still
leak. If you can’t find a place that offers nitrogen, your only option is to fill with compressed air, which,
as we’ve said, drops the nitrogen purity.
• Nitrogen doesn’t offer any better protection than compressed air against cuts and punctures from road
hazards. So no matter what you fill the tires with, you’ve still got to check their condition and pressures
at least once a month, as we clearly state in the owner’s manual. And on vehicles with TPMS, filling
the tires with nitrogen won’t reduce the frequency of the low tire pressure indicator coming on in cold
weather.
• Tires filled with compressed air and properly maintained offer the same fuel efficiency and
performance as those filled with nitrogen.
So here’s the bottom line: Although nitrogen offers certain advantages for commercial, government, and
motorsport applications, for automobile tires you’re better off with dry, compressed air.
Just thought y'all might ask about nitrogen
