Nitrogen or compressed air in your tires, which one is better?
There are many discussions about whether nitrogen or compressed air is better to use in your tires. Using nitrogen is known for certain benefits such as a more stable tire pressure over the long term, less changes in pressure with different temperatures and fuel saving. Nitrogen is often used in heavy applications in demanding environments such as airplanes, mining, commercial vehicles and racing. But are these statements true and are they beneficial for your daily car? We wanted to get to the bottom of this and have outlined all the facts and myths of nitrogen for you.
What is nitrogen?
But first what is nitrogen? Normal air consists of 78% nitrogen, 21% oxygen and 1% miscellaneous gases such as neon and argon. Nitrogen is a colourless, odourless, and dry gas. It is inert, meaning that it is non-flammable and non-reactive under normal circumstances.
Normally, ‘regular’ air will seep out of microscopic pores in the tires, this will cause a decreasing inflation pressure. Because nitrogen consists of bigger molecules this process will become slower. When air gets pressurized, the moisture in it turns into a liquid. When this air is pumped into your tire, this liquid will come with it as well. When you are driving, your tire will heat up which will turn the liquid into a gas. This makes it expand which increases the tire pressure. With nitrogen this does not happen since nitrogen is ‘dry’.
Consumer Reports did a test to discover the differences in tire pressure between nitrogen and compressed air. They tested 31 pairs of tire models and filled one with air and the other with 95% pure nitrogen. They set the inflation pressure to 30 psi at room temperature, put the tires outside and waited a year. After that year they checked the inflation pressure again. The results showed that the tires filled with air lost on average 3.5 psi and the ones filled with nitrogen 2.2 psi. This means that there is only a difference of 1.3 psi between the two methods. Important to note is that all tires lost pressure, regardless of the type of air.
Consistent tire pressure is important for efficient fuel economy. Decreased tire pressure increases the rolling resistance, causing an increase in fuel needed. As mentioned above, the difference in air pressure between air and nitrogen is negligible, making nitrogen not much more efficient in saving fuel. As long as you keep your tire pressure on the right level, you will be fine.
Nitrogen is said to increase the lifespan of your tires and wheels. The oxygen in normal air retains moisture which could oxidize the internal wall casing of your tires. Because nitrogen is dry, it does not retain any moisture. However, before these damaging effects could take place, your tire will probably need replacement because of the usable depth left. In this case it would only be beneficial if your car is in storage or driven rarely.
Availability and cost
As where regular air is either free or very cheap, the costs for nitrogen vary. It can become quite costly to fill up all four of your tires with nitrogen. Because the process of filling up your tires with nitrogen takes more time, it is also more expensive. Besides the costs, its availability is more limited. Not every car dealer, car wash or gas station has this option available, causing you to search longer for a place to fill up your tires.
Conclusion: Is nitrogen better for your tires?
So what can we conclude from these pros and cons of nitrogen? Unless you drive a race car, have a car that is in storage or rarely drive it does not provide you with any extra benefits. It probably only costs you more time and money. Using nitrogen does not substitute regular tire pressure checks. Just make sure to check your pressure once or twice per month, and your tires will stay in excellent condition!