Don't put air in your tires

Science bares out that filling tires with nitrogen gas prevents premature wear and increases fuel economy.


 

“Nitrogen in tires?” says one anonymous automotive instructor incredulously. The air already is 78 percent nitrogen. Shop air is just as good.

That is the feeling among many vehicle owners and maintainers.

The use of high-concentration nitrogen gas in tires has been around for years, notably in racing (IndyCar, Formula 1 and Nascar), aircraft tires (commercial and military) and by vehicles used by NASA. However, even though this technology is hardly new, it still arouses the suspicion of many in the vehicle maintenance business.

Even technical experts who do not specialize in tires, or chemistry for that matter, just do not seem able to get their heads around the idea that nitrogen inflation poses many benefits exceeding that of old-fashioned shop air.

The logic is simple enough. Regular air already inflates a tire, so how can a different kind of air make any difference?

A simple understanding of chemistry answers this question. Just as a little bit of salt can melt ice, oxygen and water vapor can drastically change the properties of inert nitrogen gas.

So, what does that have to do with tires?

ENEMY NUMBER 1: OXIDATION

Anyone who has ever changed a tire can attest to the fact that it is important to clean the rim because the rust that forms can create air leaks after the replacement tire is installed.

First, the steel and aluminum oxides that are rust poses a health hazard to technicians unlucky enough to breath it in by mistake when breaking a tire bead. Furthermore, water vapor and oxygen in the shop air makes the rust in a rim increase until the point where it bubbles up and allows a path for air to escape.

Air escaping from a tire not only hurts fuel economy, it also creates premature tire wear. An underinflated tire poses not only a safety hazard to a fleet, it affects a business’ bottom line.

Additional dangers and consequences of improper tire inflation include reduced vehicle handling, tire failures and decreased stopping distances.

“Oxidation, more commonly known as rust, rot and corrosion, is the absolute enemy of anything composed of rubber or steel, (such as) the tires and wheels on your vehicle,” says Jay Lighter, CEO of NitroFill (www.nitrofill.com), a provider of leading nitrogen gas inflation equipment. “Without the presence of oxygen (in pure nitrogen gas), it is impossible for oxidation to occur.”

Another lesser known effect of oxidation is that according to laboratory research, oxygen works its way into the rubber molecules in the tire. The reason this is a big deal is that when oxygen reacts with rubber it changes its chemical properties making it more susceptible to wear.

Granted, there’s oxygen in the atmosphere contacting the tire’s tread at all times, but it isn’t being pushed into the rubber at 32 psi, 24/7.

ENEMY NUMBER 2: LOW TIRE PRESSURE

The negative effects of low tire pressure are obvious. All new light duty vehicles beginning with the 2008 model year come with Tire Pressure Monitoring Systems (TPMS). The systems which continuously monitor the inflation pressure in tires through sensors. This can help fleets keep their tires properly inflated.

It would be an error to assume that TPMS can solve any fleet’s tire inflation issues. A tire can often be 5 psi, or more, low on air without triggering a dashboard indicator light, simply because TPMS often measure the deviation in psi between tires. This means a light will not go on when a tire is 10 percent low on air, provided that all the other tires are equally low.

Furthermore, TPMS does not help if drivers do not warn their supervisors when the “idiot light” (driver lingo for the TPMS Malfunction Indicator Light) is on.

“The greatest disadvantage of oxygen, however, is its molecular size,” points out Lighter. “Oxygen has a very small molecular structure, so small in fact, that it is completely normal for air-filled tires to lose 1 to 3 psi per month from ‘permeation,’ the process through which the oxygen molecules in compressed air seep through the carcass of a tire.

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