Nitrogen Tire Filling: Benefits for Performance Tires?
Consumers are being hit with more marketing supporting nitrogen filling in tires. Is it truly beneficial in performance tires, including race applications? Most experts say yes, and many professional racing teams have made the switch.
Tires are typically filled with compressed air, which consists of about 78 percent nitrogen, 21 percent oxygen, and 1 percent other gases by volume. So all tires are filled mostly with nitrogen. Filling your tires with pure nitrogen offers two primary benefits: First it replaces smaller oxygen molecules with significantly larger nitrogen molecules, reducing the rate at which compressed gas seeps through tire walls. The result is tires maintaining their original pressure longer. Keeping inflation constant is important in that performance tires need to minimize tire deflection to transfer power to the track. Tires deflect more at lower tire pressures, resulting in pooorer power transfer, more tire heat being generated and potentially inconsitent performance. Racing tires can be filled with nitrogen at the pressure you wish to have during the race because inflation pressure doesn’t increase quite so much as with air. While not generally a consideration to racers, steady pressure is also key to optimal fuel economy.
Secondly, it eliminates moisture, Water vapor (humidity) can make up as much as 5 percent of the volume of air under worst-case conditions. Air containing water vapor can increase the pressure in a tire three to seven psi as it is heated, depending upon driving conditions and ambient air temperatures. Because nitrogen contains basically no water vapor, the pressure build-up due to heat is minimized. Therefore the tire’s hot pressure is very similar to the cold-inflation pressure, with much less change due to driving conditions. That means racers can set a cold tire pressure and more accurately predict the hot pressures.