All That's Trucking

Nitrogen Tire Inflation: Good Enough for NASA

April 2, 2013

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This display at the Hunstville, Ala., Space and Rocket Center got me thinking about nitrogen and tires.
This display at the Hunstville, Ala., Space and Rocket Center got me thinking about nitrogen and tires.

On a family trip to the U.S. Space & Rocket Center in Hunstville, Ala., last week, we were intrigued to see this display on the tires used on the now-retired space shuttle.

It says space shuttle tires (made by Michelin, by the way) don't explode in space because they're filled with nitrogen, which has more stability at different altitudes and temperatures than regular air.

As you may know, some fleets run their truck tires filled with nitrogen, as well. I haven't heard the argument about more pressure stability at different temperatures, but maybe that's one nitrogen proponents should look into.

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As Equipment Editor Jim Park explained in this 2010 article in HDT, proponents say relatively pure nitrogen is a superior medium for inflating tires compared to air. It's a naturally occurring inert gas making up roughly 78% of the air we breathe – the same air we compress to inflate tires.

Why Nitrogen?

The key benefit to nitrogen tire inflation is that it slows the natural pressure loss in tires. Oxygen is able to permeate tire rubber, producing the expected 1% to 5% loss of inflation pressure over a month or so. Nitrogen permeates more slowly because nitrogen molecules are physically larger than oxygen molecules. Barring leaks, poorly seated beads, bad valves, etc., a tire inflated with nitrogen will retain a constant pressure longer than one filled with air, minimizing the headaches caused by under-inflation or mismatched inflation across sets of duals, improving fuel economy and extending tire life.

Plus, proponents say, nearly pure nitrogen is devoid of moisture, so you won't have water sloshing around in the tire, possibly corroding steel wheels, or freezing tire valves in winter.

For this article, Jim contacted three fleets who use nitrogen to inflate their tires. Two out of three said they are very pleased with tire performance. The third was equally pleased, but said they got the same results using an automatic tire inflation system.

Sister publication Modern Tire Dealer has an interesting retrospective on nitrogen inflation on its website.
Sister publication Modern Tire Dealer has an interesting retrospective on nitrogen inflation on its website.

Nitrogen Inflation Through the Years

Interestingly, one of the top stories last week from one of our sister magazines, Modern Tire Dealer, took a historic look at the topic of nitrogen tire inflation. Although MTD's stories tended to focus more on passenger and light truck tires, it's still pretty interesting.

Back in 1967, MTD's November cover featured Gulf Oil Co.’s attempt to test market nitrogen inflation at 41 of its stores in Houston, Texas. Its supplier, Big Three Industrial Gas & Equipment Co., charged $6.75 for a 300-cubic-foot bottle of nitrogen. Gulf Oil charged its customers $1 per tire. (Jerry White, chairman emeritus of White Tire Supply Inc. in Beaumont, Texas, says he pays $23 for a 230-cubic-foot cylinder of nitrogen.)

By August 2005, MTD reported thatalthough public radio personalities Click and Clack talked about the advantages of nitrogen, they ultimately concluded that “none of these advantages are important to the average driver.” Several dealers disagreed with that theory, noting that if you maintain air pressure all the time, the benefits of nitrogen diminish, but the average customer doesn’t do that.

And of course we know a lot of truck drivers don't do it, either.

Have you tried using nitrogen in your tires?

Comments

  1. 1. Tim Orr [ April 01, 2013 @ 05:05PM ]

    To the best of my knowledge, dry air is no less stable with regard to pressure changes caused by temperature change than is pure nitrogen. Compressed air can be dried. There are many ways to do it. It is water and water vapor that are the bugaboos, and if you store tires outside and there's water sloshing around in them when you mount them, or if you slop on water-based lube in order to mount them, it won't much matter whether you use nitrogen or air. You have less pressure loss with nitrogen because the nitrogen molecules diffuse through the rubber more slowly. People differ on whether it's because one molecule is larger than another. Nitrogen also won't rust wheels or oxidize rubber. Truck tires are a very different situation from passenger car tires. With truck tires, you can get a high enough percentage of nitrogen into the tire the first time you fill it, but with passenger car tires, because they're so small, you have to flush them out with nitrogen to get the percentage up. On big construction tires and aircraft tires, where tire fires are a hazard, nitrogen is good because it does not support combustion.

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Author Bio

Deborah Lockridge

Editor in Chief

All That's Trucking blog is just that – the editor's take on anything and everything related to trucking, with the help of guest posts from other HDT editors. Author Deborah Lockridge's career as an award-winning trucking journalist started in 1990.

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