Nitrogen use debatable

I read with great interest the letter to the editor published in the Jan. 21 issue of Tire Business titled, “Yes vote for N2,” and I wish to offer a reply to some key points made by Tarik N. Ayasun, president of Taray International Corp., which markets nitrogen inflation systems and equipment.

When we initiated the project, our objective at Consumer Reports (CR) magazine was to find out if there was a difference in inflation pressure retention between air and nitrogen. Pressure retention was, and continues to be, the major claim made by the nitrogen industry.

Proper inflation pressure will promote optimal tire performance, including longer tread life, preserve tire integrity and offer better fuel economy than tires that run under-inflated. That’s true if using nitrogen or air, provided that pressure is maintained properly.

CR also agrees with Mr. Ayasun that nitrogen has been shown to reduce the effects of oxidation or aging, but again, that is not what CR evaluated.

Mr. Ayasun asked if we spoke to anyone before we started the project. The answer is yes. We researched nitrogen generators to purchase, we spoke to the tire manufacturers and we attended industry conferences. Incidentally, more than one tire manufacturer claims that their tires are designed to perform optimally with air, and nitrogen is not a necessity or even recommended, though it does not appear to have any detrimental effects on tires.

CR does agree with Mr. Ayasun that air can hold unwanted water vapor, but not all air is created equal. The degree of water vapor can vary by region of the country and time of year based on relative humidity conditions, and by the quality of the pressurized air source. That is, is the air compressor well-maintained and does it have an air dryer system, etc.?

The CR test monitored tires sitting outside for one year, not run on the road. The nitrogen industry says air loss would be much greater than tires filled with nitrogen if run on the road, but we know of no study that supports this claim specifically.

Even in the so-called less demanding static test that CR ran, there was pressure loss with nitrogen. And that is particularly important considering the dormant spare tire that nearly every car has. This tire, too, should be checked regularly, and it every bit mimics CR’s static test.

Again, regardless of the gas medium used, tires need to be checked regularly.

Finally, CR tests were performed on passenger car tires, not airplane tires, truck tires or race car tires, etc. This most recent test—and a prior air loss study performed by CR—showed that all tires lose air over time. And some tires will lose much more than others.

CR did not see any clear distinction between use of nitrogen and air with regards to specific tire model and how well pressure was retained. In all fairness, a larger sample size of each tire model would have been desirable to make this claim, but it’s an interesting observation to note here.

Nor was there any trend in distinguishing pressure loss as ambient temperatures cooled off between nitrogen and air, which means monthly pressure checks are important as seasons change.

CR strongly believes consumers may be swayed unintentionally into purchasing nitrogen as a substitute for regular pressure checks and this is what we addressed.

Nitrogen-filled tires have to be checked routinely, just like those filled with air, and if the tires do need to be inflated up to the correct pressure, the consumer has to go back to the retailer for a nitrogen fill-up, which could be a major inconvenience.

Aside from maintaining proper inflation pressure, nitrogen may very well be worth the cost and inconvenience for its advantage of reducing tire aging.

Eugene Petersen

Tire program leader

Auto Test Division

Consumer Reports

Colchester, Conn.