Don't put air in your tires

Science bares out that filling tires with nitrogen gas prevents premature wear and increases fuel economy.


“Nitrogen, on the other hand, has a very large molecular structure. A molecule of nitrogen is about four times larger than a molecule of oxygen. Hence, tires filled with high-purity nitrogen typically lose no pressure over a one-month period.”

A MATTER OF SCIENCE

Everyone from large tire chains to local tire shops sell nitrogen inflated tires. Oftentimes, they make use of exaggerated claims as to the effects of using nitrogen. So, what’s fact and what’s hype?

A study by Nader Jalili and Prakash Venkataraman of Clemson University (www.clemson.edu), deriving its results from laboratory testing, found that fuel economy gains, minus real-road conditions, could be as high as 23 percent. They also estimated that due to decreased oxidation, tread wear can be reduced as much as 50 percent.

Other studies that actually depended upon using sets of tires on the open highway have corroborated the results. Lawrence R. Sperberg of the Probe Forensic and Testing Laboratory observed that in a test of 54 truck tires subjected to real-world driving conditions tread wear was reduced 26 percent.

A more telling study was one undertaken by Konrad Mech of Drexan Corporation. That study followed the lives of almost 1,300 tires, all with identical maintenance, in order to ensure that the tires stayed properly inflated at all times.

Because of careful attention paid to proper tire inflation (probably more careful than that practiced by an average fleet), the study found a 3.3 percent improvement in fuel economy in tires that used nitrogen gas. Perhaps more astonishingly, the study found an 86 percent increase in tread life in the same tires.

With varying different numbers as it pertains to an exact improvement in fuel economy and tread life, it is important to keep in mind that tire size and driving conditions can affect results. However, science does bare out that the results are positive, showing real promise for long-term cost savings when using nitrogen gas in tires.

TOOLING UP FOR NITROGEN INFLATION

Inflating tires with nitrogen is a pretty straightforward process. Using a nitrogen tire inflation machine, simply connect the shop air hose to the machine and use the machine’s hose on the shop’s tire applications. This includes not only adding air to tires during maintenance and tire replacement, but using it to fill the air tank in the shop’s bead blaster.

Nitrogen inflation equipment generally operates at about 10 percent less than the shop’s air compressor’s rated capacity. So, being that most shops have an air compressor of about 150 psi, the equipment will generate something along the lines of 135 psi of pure nitrogen gas on demand. As long as the shop’s air compressor keeps running, a nitrogen inflation machine will not run out of nitrogen and will continue to generate nitrogen gas.

Furthermore, these pieces of equipment often come with several hoses allowing shops to fill as many as six tires at once.

If a shop converts over to nitrogen and, due to an on-road breakdown or other circumstance, finds it has to fill a tire with regular air, there is no need to fear. Studies have found that from a practical standpoint a tire that is filled with 96 percent nitrogen is just as good as one filled completely with nitrogen.

If a tire is filled fully with regular air, there is also no problem posed by simply removing the valve core and then refilling the tire completely with nitrogen. Tires can go between 99 percent nitrogen air and 78 percent nitrogen air with no problems.

For this reason, nitrogen inflation equipment often will purge a tire of regular air, fill it with nitrogen and then purge it again before refilling it. All the equipment is doing is creating a high enough concentration of nitrogen gas that oxidation is essentially non-existent.

When considering switching over to and maintaining tires with nitrogen air, a best practice is for a fleet to estimate the costs for tooling up for nitrogen inflation and see how long it would take to make the money back as the result of decreased tire costs and fuel savings.

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