In July 2010, we wrote an article, advising against filling tires with nitrogen. At that time, most of the information available came from the companies promoting the service. Since that time far more sources are questioning the worth of nitrogen inflation.
Exaggerated claims in advertising have become very common. Few people bother to check or even read "between the lines." Many products and services are geared more toward an increased profit margin than any benefit to the customer. In my opinion, nitrogen tire inflation certainly seems to fit this bill.
Air contains roughly 79 percent nitrogen already. Many of the machines used to inflate tires, simply remove most of the oxygen and inflate tires for up to ten dollars each. Very profitable, but what is the benefit to the tire owner?
Nitrogen Inflation benefits the tire dealer's bottom line
Here are some of the claims along with the truth
Nitrogen will not leak out of the tire - The contention is, the molecules are larger than those of oxygen, and so they will not leak out of the tire. This is vastly overstated if not false. Tires are designed to hold pressure and leak less than three percent a year, on average. Nitrogen will not change this by any significant amount. If it did, the oxygen would leak out of an air-filled tire, and only the nitrogen would remain anyway. Not using caps on the valve stems will result in far more pressure lost.
Better fuel mileage - This argument is derived by comparison to a tire that has too low a pressure. For instance, a tire fully inflated with nitrogen will get better fuel mileage than an under-inflated tire. Yes, but so will a tire properly inflated with air. The nitrogen makes no difference, only the inflation.
Tires will not wear as fast - Properly filled tires will last far longer than tires that are run with low air pressure. The gas that inflates the tire has no bearing, as long as the proper pressure is maintained.
Oxygen will cause the rubber in a tire to break down - Ozone from the atmosphere degrades tires, from the outside. The adhesives, belts and materials will also degrade over time. Many experts agree; six years is the maximum safe life of an automobile tire. There is virtually no difference between a tire filled with nitrogen or air, in this time frame.
Nitrogen filled tires are good for the environment - perhaps the most absurd claim of all. Properly inflated tires save wear and a very small amount of fuel. All vehicles built since 2007 have tire-pressure monitoring systems or TPMS. If a tire should get low, a warning light informs the driver.
Don’t buy the nitrogen fairy-tale
Aside from the cost, many people are reluctant to add air to their nitrogen filled tires. This is understandable after shelling out money for something and being told how great it is. The fear is unfounded as air is 79 percent nitrogen. Running around on an under-inflated tire is a problem; filling with air is not.