What is Nitrogen?
Nitrogen is a dry, inert gas used to inflate airplane tires, off-road truck tires, military vehicle tires, and race car tires for improved performance, more tire mileage and better fuel economy.
Why use Nitrogen?
- Less inflation pressure loss
- Reduced wheel corrosion
- Prevents inner-liner rubber deterioration by oxidation
- tires run cooler
- Increases tread life
- Increases fuel mileage
- Helps prevent uneven wear
Oxygen in compressed air permeates through the wall of the tire, thus reducing the tire’s inflation pressure. During it’s journey through the tire wall, oxygen oxidizes the rubber compounds in the tire, causing under-inflation and deterioration of the rubber . Dry nitrogen will maintain proper inflation pressure and will prevent auto-ignition, will not corrode rims, extends valve core life, and will help the tire to run cooler.
The biggest advantages – improved tire life
Experts in the tire industry indicate that oxidative aging is one of the primary causes of decreased tire life. Oxidative aging is caused by the diffusion of oxygen from the pressurized air cavity of the tire to the outside atmosphere. Tests have shown that if tires are inflated with nitrogen, there is a significant reduction in tire failure.
Why did race cars, military and off-road vehicles switch to Nitrogen?
Air is about 1/5 Oxygen, and oxygen, especially at high pressures and temperatures, is a very reactive element.
When oxygen reacts with things, the process is called oxidation. When oxidation is extremely rapid, it’s called “burning.
That’s one reason nitrogen is used in off-highway and aircraft tires. These tires run so hot they can actually catch on fire. Nitrogen doesn’t support combustion, so nitrogen-filled tires don’t add fuel to the flames. And nitrogen helps prevent slower forms of oxidation also.
Nitrogen prevents other types of corrosion as well
Oxygen and moisture corrodes aluminum and steel wheels. Oxygen also reacts with rubber, another type of “corrosion”. When this corrosion starts, the small particles break off and form rust and dust, which can clog vavle cores, causing them to leak. The rough surfaces created from the corrosive action on the wheels leads to tire beads that don’t seal properly, causing additional leaks .
Oxygen also ages the inner liner, the thin layer of rubber inside the tire whose function is to keep air away from the carcass. As the inner liner ages, more and more air molecules can pass through it, causing more pressure losses. These pressure losses in a truck tire can average 2 psi a month as a result of the air passing through the sidewalls. As it passes through the rubber, the oxygen can also corrode the steel cords, causing them to rust too.
How does Nitrogen help?
While both nitrogen and oxygen can permeate rubber, nitrogen does it much more slowly. It might take 6 months to lose 2 psi with nitrogen, compared to just a month with air. And nitrogen is far less reactive. It doesn’t cause rust or corrosion on steel or aluminum, and it doesn’t degrade rubber. Wheel surfaces stay smooth and clean, rubber remains supple and resilient.
Nitrogen also will not degrade the rubber seal in the valve core which extends valve core life and helps prevents core leaks.
Small bits of dust and debris as a byproduct of oxidative corrosion to the wheels and alloy rims can lodge in the valve core seat, causing air leaks.
Any other reasons for using Nitrogen?
Water!! The air around us is full of water vapor. Compressing air concentrates the water in it.
Draining the water from your compressor tank daily helps, but unless you have a really efficient air dryer system, chances are that there’s a lot of water in your compressed air.
When you compress air, it takes up much less volume, but the percentage of water by
volume is greatly increased.
…and what harm does this moisture cause?
Water vapor in compressed air acts as a catalyst, accelerating rust and corrosion. Water vapor also absorbs and holds heat. And when it changes from liquid to vapor, water expands tremendously in volume.
As a result, tires inflated with wet air tend to run hotter and fluctuate in pressure more. That’s one of the reasons why racing tires, where fractions of a psi can radically change the handling characteristics, are inflated with dry nitrogen.
Will my tires have 100% Nitrogen after they are filled?
In reality, no. The Ingersoll-Rand Nitrogen Generator puts out 98% pure Nitrogen. On an uninflated tire, there is still some air present, so after you refill with nitrogen, you’ll end up with about 95% nitrogen, which is enough to do the job. That can be increased slightly by filling up the tire with nitrogen without a valve core in the valve stem, and then letting the tire delate. Then install the valve core and refill to normal pressure with the nitrogen. (purging)
For fleets – reduced operating costs
Tires are one of the primary costs of operating a fleet of vehicles. Tire costs include procurement, maintenance and the cost of blowouts.
A typical truck tire with two retreads costs $480.00 and lasts
approximately 270,000 miles. Inflating tires with nitrogen will help to prevent premature casing failure and allow tires to be retread
multiple times, with confidence and reliability.
Inflating tires with nitrogen to eliminate oxidative aging can extend tire life by up to 25%.
Increasing tire life to 337,500 miles would save $120 per tire.
A fleet with 50 trucks and 900 wheel positions would save over $100,000 in tire cost by inflating with nitrogen.
The primary cost of maintaining tires is the cost of labor to check tire pressures and top off tires with compressed air on a periodic basis. Tire pressure must be checked and the tires topped off due to the diffusion of air through the tire. tires filled with nitrogen will not experience this diffusion and resulting loss of pressure. tires filled with nitrogen maintain pressure for a much longer period of time than tires filled with air. If a truck fleet conducts preventative maintenance on 5 trucks per day and presently spends 30 minutes per truck topping off tires, they could realize savings of $31,250 per year based on a labor rate of $50 per hour and 250 work days per year, by inflating tires with nitrogen.
A recent article from the Wall Street Journal states:
“One thing government and tire-industry officials agree on is the
importance of keeping tires properly inflated. The risks of
underinflation, which stresses tires by causing their sidewalls to flex more and the air temperature inside to rise, were highlighted during congressional hearings two years ago into the Firestone tire problems. Underinflation was identified as a factor in the failure of Firestone tires.”
Wall Street Journal, September 25, 2002.