Nitrogen Tire Inflation: A Lot of Hot Air?

Nitrogen Tire Inflation: A Lot of Hot Air?

Should your store look into nitrogen inflation of your delivery truck tires? Here’s what I’ve discovered about nitrogen-inflated tires and whether you should look into it for your own business.

Nitrogen-inflated tires: Are they the newest “snake oil” on the block? Is there a real benefit for distributors? What about motorists? Your customers and neighbors are probably already — or will be soon — asking you about nitrogen as a tire inflation media. As a parts pro, you may need some information on this subject.

First off, no, nitrogen will not blow up. That was hydrogen in the Hindenburg. Nitrogen is used in tires on the Space Shuttle, every commercial airliner, Tour de France bicycles and most race cars. Nitrogen is not flammable.

We all know the benefits of having proper tire inflation pressure. Properly inflated tires will run cooler and last up to 30 percent longer, and that’s good, especially for those of us running deliveries all day. A vehicle with properly inflated tires will handle and brake as designed. Properly inflated tires have less rolling resistance, thus better fuel mileage.

If you check your delivery truck tires at the same temperature every week and fill them only with true dry, compressed air, you don’t need nitrogen for tire inflation. And by “dry,” I mean using a refrigerated or membrane drier on your compressed air source. For the remainder of us, there’s nitrogen. Nitrogen has two main benefits. First, it leaks much less than compressed air. Second, it’s “dry” and therefore is better for the lifespan of the tire.

In order to get the benefits of nitrogen, there are some basic quality requirements. The inflated tire must have at least a 95 percent concentration of nitrogen. Not 94.5 percent — at least 95 percent. Why is this a problem? Some equipment and procedures are not capable of delivering this needed purity level. Without the needed purity level, you’re not getting the full benefit.

Let’s talk about pressure. The National Highway Traffic Safety Administration (NHTSA) says that the pressure loss from an air-inflated tire may be up to 5 percent per month. That means in the usual three months between vehicle services, there will be a 15 percent drop in inflation pressure. Yes, the owners’ manual in the glove box recommends that pressure checks be performed monthly. Is the average driver following these recommendations? Do your delivery drivers? Probably not.

Bridgestone’s Real Answers newsletter says that nitrogen leaks at approximately 1/6 the rate of compressed air. So, the same tire, filled with 95+ percent nitrogen will lose one psi per month under the same conditions. Note that monthly pressure checks are still required, as per the manufacturer.
Wait a minute, what about the new Tire Pressure Monitoring Systems (TPMS) on newer cars? Do you still need to check air pressure? Yes, because the system only sets a warning light when the tire is 25 percent under or over inflated. A tire 25 percent low will cause wasted fuel and poor handling and may fail because of extreme heat.

This discussion of TPMS leads to the other advantage of nitrogen. Nitrogen is dry; there’s no water vapor or oxygen. The TPMS sensors have small holes that the inflation media must pass through. Any dirt or water may clog or rust the hole, rendering the sensor useless. The water vapor also corrodes the valve core.

Water vapor is the culprit responsible for the large temperature-related pressure changes. A tire inflated with compressed air may contain enough water vapor to condense into liquid at low temperature conditions. This will cause a drop in pressure. The water vapor may also turn into steam at high speeds, causing an over inflation problem. Over time, water vapor also attacks alloy wheels, valve stems and cores and the steel belts in the tire.

What about oxygen? Oxygen is an oxidizer, and is the cause of sidewall “dry rot.” This is the reason Ford recommends that tires be replaced every six years, regardless of tread depth.
OK, what do the car and tire manufacturers say about nitrogen? Well Acura and Honda say ‘no!’ GM puts limits on the recommendation. Why? While both GM and Honda recognize the benefits of quality nitrogen inflation, they have a problem, as they should, with providers that can’t meet the necessary quality criteria. Remember, you need at least 95 percent purity in the inflated tire. Both of these OEMs warn about reduced effects from poor-quality nitrogen providers and/or topping off with regular compressed air.

Michelin, Goodyear and Bridgestone/Firestone recognize that nitrogen leaks less than compressed air. These companies also stress the need for monthly pressure checks.

Finally, nitrogen tire inflation has caused some semi-religious experiences for some users. I have heard of huge mileage increases, ride quality improvement, reduced back shifting out of overdrive while climbing hills, increased stability while hauling heavy loads and on and on. If any of these happen to you, you may use them in your discussions, but use the disclaimer “your results may vary.”

Need another reason? The U.S. Department of Energy says that this country is wasting more than million gallons of gas a day because of incorrectly inflated tires.

Mike Demers owns and operates Son’s Auto Supply, an ASE Blue Seal Certified distributor, in Westmont, NJ.

Sources of Information on Nitrogen:
• 2003/22775ti.html
• Bridgestone Real Answers Volume 8, Issue 3
• The Goodyear Tire & Rubber Company PSB #2004-09
• Michelin North America PM-03-05
• Tech-Tip_0106 Tires + Nitrogen Gas (GM Fleet and Commercial)
• Passenger tires inflated with nitrogen age slower: Part 2 of 2. Author: John M Baldwin, David R. Bauer, Kevin R. Ellwood, Ford Motor Co. September 20, 2004
• EPA 4250-K-93-001 Your Car and the Environment
• Acura Tech Line Summary Article BTS060804

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