• Corpus ID: 91359962

The Effects of Varying the Levels of Nitrogen in the Infl ation Gas of Tires on Laboratory Test Performance

@inproceedings{Hs2009TheEO,
  title={The Effects of Varying the Levels of Nitrogen in the Infl ation Gas of Tires on Laboratory Test Performance},
  author={Dot Hs},
  year={2009}
}

• Dot Hs
• Published 2009
• Environmental Science

Highway Traffic Safety Administration, in the interest of information exchange. The opinions, findings, and conclusions expressed in this publication are those of the authors and not necessarily those of the Department of Transportation or the National Highway Traffic Safety Administration. The United States Government assumes no liability for its contents or use thereof. If trade names, manufacturers' names, or specific products are mentioned, it is because they are considered es­ sential to the object of the publication and should not be construed as an endorse­ ment. The United States Government does not endorse products or manufacturers. Air is approximately 78 percent nitrogen (N 2), 21 percent oxygen (O 2), and 1 percent other gases. The inflation of tires with gas mixtures containing more than 90 percent nitrogen has long been claimed to be beneficial to tire performance, and commercial systems that use nitrogen to inflate tires are widely available. In an effort to study the effects of inflation gas composition on vehicle tire performance, new passenger car tires and light-truck tires were inflated with nitrogen, air, or a 50/50 N 2 /O 2 mixture and tested for performance in one of three laboratory tests: Static inflation pressure loss, rolling resistance, or accelerated oven-aging followed by a roadwheel durability test. In the 90-day static laboratory test, the inflation pressure loss for new tires inflated with nitrogen was approximately two-thirds of the loss rate of new tires inflated with air. Similar differences between nitrogen and air permeation rates in new tires were found under dynamic, loaded laboratory roadwheel testing. An analysis of oxygen levels in the inflation gas of 76 tires that were currently in service on passenger vehicles, and which were all originally inflated and topped-off with air (21% O 2), showed that the inflation gas dropped to an average of 15 percent O 2 after about three years of service. This can be attributed to the faster diffusion rate of oxygen through the tires relative to nitrogen during on-vehicle service, which increases the percentage of nitrogen in the tire cavity to well above the 78 percent N 2 in normal air. Therefore, barring tire punctures, deflation, etc., the relative benefits of nitrogen versus air inflation on pressure loss rate will reduce over time. The laboratory rolling resistance of new tires was tested at two different laboratories, using air or nitrogen inflation, and capped or regulated pressure. Inflating tires with nitrogen …