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Using nitrogen in tires
Should you stop putting plain air in your tires?
Proper tire inflation is the single most important thing you can do to help maintain your tires. But should you stop putting air in tires and convert to nitrogen? (After all, 78% of the air in the atmosphere already is nitrogen, while only about 20% is oxygen.) Are the benefits there to support the investment of using 100% nitrogen in your tires? (It often costs a few dollars a tire to fill them with nitrogen.)
Inflating tires with nitrogen is not a new idea. Nitrogen has been used to inflate airplane tires and racing tires for a number of years, but it's only recently that nitrogen gas has become more readily available and cost-effective.
Here are a couple important benefits to using nitrogen which may make it a viable alternative to air:
More consistent tire pressure
Many people understand that tires can and do lose air through a faulty or dirty tire valve, or through a bent rim. What is not as well understood is that air can also naturally permeate through the inner liner, fabric and tread rubber, because the air molecule is simply so small. Nitrogen, on the other hand, is a relatively larger molecule and does not seep through the inner liner as readily. It may take six months to lose 2 psi using Nitrogen, but only about a month to lose a comparable amount of air.
In addition, it is well understood that tires filled with air can fluctuate as much as 2 psi for every 50ºC change in ambient temperature. Why? Air often contains moisture, which naturally absorbs heat. This explains why tires with a lot of moisture tend to run hotter and have higher pressure readings, though when the tires are cold, the moisture turns to water vapour, which reduces the pressure. Nitrogen will have less moisture and hence less contraction and expansion in extreme temperatures.
You may have heard about a vehicle with new tires installed that then goes outside in the dead of winter. The next morning, the tires are riding on the rims because the air pressure is so low. This is much less a concern with nitrogen, according to the Be Tire Smart website.
Moisture has another insidious effect on tires and wheels because it leads to oxidation and promotes aging from within, which suggests reduced tire life and performance.
According to the Tire Retread Information Bureau, “Among the benefits of nitrogen inflation: less inflation pressure loss for a more stable, consistent tire pressure; cooler running tires; longer tread life; less oxidation of tire components, and reduced rim and wheel corrosion. The result is increased tire life, improved fuel economy, reduced tire aging .…”
Why hasn't nitrogen made it to the mainstream until recently? That's because, before now, the ability to store pure nitrogen in a compressed form was an expensive proposition. With the equipment to do this becoming more affordable, many tire dealers are investing in nitrogen tanks to provide their customers with a choice.
Although nitrogen allows for a more consistent tire pressure for a longer period of time, it remains imperative that consumers measure the pressure in their tires on a monthly basis and adjust as necessary by following the recommended tire pressure on their vehicle's tire information label.
Although you can add air to a nitrogen-filled tire, if you wish to regain all the advantages of pure nitrogen, you will need to visit your tire dealer to have the tire emptied and refilled. That's a downside, as every time you top up your tire pressure at a regular gas station, you add ordinary air and reduce the ratio of nitrogen in your tires.
Under-inflation is the leading cause of tire failure and is responsible for over one million tons of unnecessary greenhouse gas emissions entering our atmosphere. Over-inflation is also on the rise because people look too often to the tire sidewall for their correct tire pressure. In some cases, this misconception is never corrected.
For more information and other tire tips, visit www.betiresmart.ca.
Posted Dec. 15, 2008. © CarTest.ca. Updated Nov. 19, 2010.