The advantages of nitrogen tire inflation have been understood for many years. But there still is much debate as to the magnitude of those advantages, and as to whether filling up with the gas can provide your customers with a return on investment.
DIFFERENT BEHAVIOR & PERFORMANCE
Proponents of nitrogen will tell you that the gas has larger molecules than air, so migration through rubber is slower, and tires stay properly inflated longer. They also correctly note that nitrogen is drier than air, so corrosive moisture is reduced. And, since moisture holds heat, a dry tire should run cooler. Finally, nitrogen doesn’t expand and contract, or vary as much in temperature as air, so it’s argued that tires maintain a more consistent footprint, thus improving wear.
THE PROS
In a previous position as president of Roadway Tire Co., Peggy Fisher, now president of TireStamp, was keenly interested in nitrogen inflation for the reasons noted above. “A nitrogen-filled tire will lose only about two pounds per square inch (psi) over six months, as opposed to losing that amount in two months using air. Also, the moisture in air can attack a tire’s belts as it passes through, causing the casing to lose retreadability. Moisture in air also can attack wheels, creating small particles that can lodge in valve seats when a tire is aired or gauged.”
The problem with nitrogen back then was that nitrogen generators were very large and extremely expensive. “They were almost the size of a small house,” she recalls. “If I’d had today’s technology, I definitely would have tried it.” With today’s smaller, more affordable generators, testing to prove nitrogen’s benefits now is feasible, she says. If in her old position today, “I’d be doing it.”
THE CAVEATS
“To get the benefits of nitrogen, it has to be pure,” says Asa Sharp, OEM & national account executive, International Marketing Inc. “Tests have shown that you need 95 percent nitrogen in a tire.” The problem, he says, is make-up air on the road, where nitrogen probably isn’t available. “You can negate the benefits with as little as 10 percent air.”
Moreover, Sharp doesn’t believe reduced sidewall permeation is as important as it was 15 or 20 years ago. “Over the years, tire manufacturers have upgraded air retention through the use of barrier liners and new bonding techniques,” he says.
Tim Miller, marketing communications manager, Goodyear Tire & Rubber, agrees that the biggest problem with nitrogen is make-up air. “It defeats the purpose,” he says. And, as for nitrogen’s absence of moisture, “I think you can get the same benefit by using dry air.” That requires only the addition of an air dryer to a dedicated airing line.
“Using an air dryer would be better,” agrees Guy Walenga, engineering manager, Bridgestone Firestone North America. “We did a study on the age of tire casings, and found some up to 14 years old. Maybe they could last longer with nitrogen, but how much?”
As far as seepage is concerned, “Nitrogen can offer some benefit,” he admits. “Planes, race cars and mining equipment are good candidates because they have their own local facilities and don’t have to depend on outside sources.” But for truck tires, “We neither encourage nor discourage nitrogen use.”
“Today’s tires don’t lose that much air to begin with,” adds Al Cohn, director, new markets & support engineering, Pressure Systems International (PSI). “That’s due to better inner liner compounds. And air permeation isn’t the leading cause of underinflation anyway. Punctures and leaky valve stems are far more common causes.
“Nitrogen is of particular value for earth movers,” he continues, “because they use electro-brakes that generate a lot of heat, and nitrogen is fire-resistant.”
Regarding nitrogen’s reduced expansion and contraction, Michael Burroughes, product manager for Michelin North America Truck Tires, notes that “Our tires are designed to operate with air. They reach a thermal equilibrium – an ideal marriage of temperature and pressure. Nitrogen can alter that optimization.” However its use won’t void the company’s warranty.
A more subtle risk, he adds, is the perception that using nitrogen means that tire pressure doesn’t have to be checked. “You can’t neglect proper maintenance,” he says. “And checking pressure provides an opportunity to visually inspect tires.”
COST VS BENEFIT
“I know one fleet using nitrogen, reportedly with great success,” says TireStamp’s Fisher. “The fleet manager reports better treadwear and reduced tire failures. He says he’s getting better fuel economy, and that his tire costs have fallen from $7500 to $3500 per month.”
But such reports usually are short-term and largely anecdotal. “No one’s been using nitrogen for very long, so good data is hard to come by,” she says.
“We have one customer who just had a nitrogen generator installed in one of his shops,” says Curtis Decker, Continental’s field engineering manager. “It cost him $6200 installed, and has all the capacity he needs.”
But is it worth it? Shops have to determine that based on their specific circumstances. You might be able to justify the cost of a nitrogen inflation system by serving a niche market, but if you can’t garner enough tire inflation business from your customers to cover costs, you could lose big.
“I’ve talked to my tire supplier, and he assures me that the claimed benefits of nitrogen are true,” says Neil Brensinger, owner/maintenance manager, Service Truck Line, Schuylkill County, Pa. “But I know if you add regular air on the road, you lose those benefits.” Then there’s the question of buying a nitrogen generator. “They’re expensive,” he says, “and I’m not sure if there’s a return on the investment.”
“We haven’t really seen any data to support claims of benefits,” says PSI’s Cohn.
“There isn’t any cost/benefit data,” agrees Michelin’s Burroughes. Interested parties need to experiment.
To be practical, “It must have a payback,” says Bridgestone Firestone’s Walenga. “As the product matures, it may well prove worthwhile.”
The good news is that using nitrogen can’t do any harm. “There are no negatives except cost,” says Fisher. But if your customer uses it, he may see improved mileage and better wear. It’s up to you to determine if the system is a worthwhile investment.
Generating Nitrogen
Once huge in size and cost, nitrogen generators today can be as compact as small tool chests. Made by such companies as Parker Hannifin, Ingersoll-Rand, Champion Pneumatic, Kreska and Branick, they can be free-standing, wall-mounted, rollable, or even truck-mounted and completely mobile.
They work by moving ambient air, which is over 78 percent nitrogen, through one or more semi-permeable membranes, which extract the nitrogen and move it to storage-tank(s). Generally, they can be connected to an existing air system, or can use a separate, dedicated system. Nitrogen output can range from less than 2 to around 34 cubic feet per minute (cfm).
