Auto Talk: Should we stop adding air to our tires?

Autotalk

Obviously this headline was written to get your attention! Most people know the importance of maintaining proper tire inflation. But in the future, normal air might not be your only choice when inflating your tires. Over the years there has been some interest in other atmospheric gases—especially nitrogen.

The air we breathe is composed mostly of nitrogen—about 78% of the air by volume. Another 21% is oxygen and the rest is a mixture of other gases. This is the same air that generally goes into our tires when we fill them.

However, there are downsides to using normal air in tires. The oxygen content causes oxidation, which can contribute to tire degradation and corrosion. A tire is prematurely aged from the inside out as the pressurized air forces oxygen molecules through the tire, speeding up the oxidation process. As the rubber breaks down, it loses elasticity and strength, resulting in even more leaks. In contrast, nitrogen does not react negatively with tire rubber. Nitrogen molecules are also larger than oxygen molecules, and cannot escape as readily through porous materials. This dramatically slows leakage from tires—an important benefit because under-inflation is the leading cause of tire failure.

A tire filled with pure nitrogen maintains its pressure three to four times longer than an air-filled tire.

An under-inflated tire can result in decreased fuel economy, sluggish handling and heat buildup as the tire flexes excessively. A tire filled with pure nitrogen maintains its pressure three to four times longer, and also tends to run 20% cooler, than an air-filled tire.

Who uses nitrogen in their tires today? The list includes competitors in NASCAR and other motorsports; the space shuttle; most military and commercial aircraft; and even bicycles raced in the Tour de France.

Robert Blaes, owner of Stang Auto Tech in Broomfield (a AAA Approved Auto Repair facility), competes in motorsport events and has been using nitrogen for the last two years. "We tend to have much less tire pressure fluctuation due to heat buildup during events since we started using nitrogen in our tires," Blaes says. "Prior to using nitrogen, we would have to regularly adjust our tire pressure in between events."

Where does the nitrogen come from? A "nitrogen generator" can be used to separate the nitrogen out of atmospheric air and store it until needed. This is the most common method used by facilities offering nitrogen. Other facilities have bottles of the gas delivered ready-made.

While the numbers of service stations and repair facilities currently supplying nitrogen for tire inflation is limited, it's likely that more will offer this choice in the future.