Nitrogen in Tires: A Complete Guide
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Nitrogen in Tires: A Complete Guide

By Jason Collins | September 14, 2021

Traditionally, car tires are filled with compressed air made up of 78 percent nitrogen and around 21 percent oxygen.

However, the changing times have more people filling up their car tires with pure nitrogen. With more and more people taking to nitrogen-filled tires, it may have you questioning why that has become a new preference?

We have compiled a small guide that takes a closer look at nitrogen in tires, the pros and cons, and the best way to go about having nitrogen-filled tires.

Why Use Nitrogen in Tires

Why inflate with pure nitrogen instead of traditional air-filled tires? Nitrogen-filled tires do not lose tire pressure as quickly as tires inflated with compressed air. Nitrogen molecules are typically larger than normal air molecules, which means the air does not leak out as easily from your tires. A tired filled with nitrogen maintains its air pressure longer than regular air-filled tires.

A normal tire with regular air loses approximately one to two pounds per square inch per month. According to Consumer Reports, nitrogen slows down the rate of tire inflation loss to about one-third of regular air pressure loss.

Several benefits of nitrogen inflated tires prompt more people to choose nitrogen tire inflation. On the other hand, some disadvantages have others staying true to regular air in their tires. Let's take a closer look at the pros and cons of nitrogen inflation.

Nitrogen gas is dry air that is non-combustible, non-flammable, and non-corrosive in pure form. It is also environmentally friendly and does not oxidize with other substances or materials. It is these properties that make nitrogen in tires a more beneficial option compared to regular air.

Naturally, small amounts of air leak out of your tires over time, especially if you subject your vehicle to dramatic temperature changes. This is because your tire walls are slightly porous. When your tires get hot, the air inside them expands, and the additional air pressure pushes small quantities of air through the tire's permeable walls. This is why you need to occasionally top up your tire pressure even if you have a puncture or a hole.

The Benefits of Nitrogen Inflated Tires

They Keep The Tire Pressure Better:
As previously mentioned, nitrogen molecules are larger than oxygen molecules, making them less porous. This is extremely helpful for maintaining your tire pressure, especially if you are one of the estimated 85 percent of Americans who do not regularly check their tire pressure. Although tire-pressure monitoring systems (TPMS) come standard on vehicles, a National Highway Transportation Safety Administration found that only 57 percent of vehicles with TPMS have the correct pressure.

Effective in Hot Climates:
Another benefit of nitrogen in tires is that they maintain a constant tire pressure even during hot temperatures. This benefit further adds to ease of tire maintenance because there is less worry surrounding proper tire pressure, but this doesn't mean you shouldn't regularly check the pressure.

Improved Fuel Economy:
According to the Environmental Protection Agency, underinflated tires will reduce your car's fuel efficiency by approximately 0.3 percent for each one pound per square inch pressure drop of all four tires. Since nitrogen leaks slower than air-filled tires, you are more likely to maintain an accurate tire pressure with tires inflated with nitrogen. Since your tire inflation pressure is more easily maintained, you will notice a better fuel economy.

Increased Tread and Tire Life:
Tire wear over time is caused by the oxidation of the rubber. This is because oxygen molecules attack the bonds in the rubber over time and cause corrosion. On the other hand, nitrogen is an inert gas, which means that it doesn't react to many substances and is ideal for avoiding chemical reactions like oxidation and corrosion. Remember, if you use normal compressed air, there is 21 percent oxygen present in addition to the 78 percent nitrogen; so there is room for oxidation when using regular air-filled tires.

Cooler Tires:
Heat is the number one enemy for tires because hot tires can suffer from excessive sidewall flexing. This means that if your tires are hot, the side of the tire will bend and stretch and ultimately weaken the rubber. This sidewall flexing quickly wears out your tires and places your vehicle and its occupants at risk of a blowout. Inflating your tires with nitrogen reduces this risk because nitrogen helps keep your tires cool.

When you fill regular tires with compressed air, the air's natural humidity can become a problem and negatively impact the safety of your car. This is because water vapor absorbs and holds heat, which causes your tires to run hotter as you drive, especially on long distances. Filling your tires with pure nitrogen reduces the risk of tires running hot since pure nitrogen does not fluctuate air pressure.

Who Do Nitrogen-filled Tires Make the Most Sense For?

  • Racecar Owners: If you own a racecar, then pure nitrogen is the best option for your tires. Track tires benefit the most from 100 percent nitrogen purity because of the minimal pressure change.
  • New Car Buyers: A new car comes with brand new tires filled for the first time. That provides you with the opportunity to maintain pure nitrogen instead of a complete change from regular air to nitrogen only.
  • Those who live close to a nitrogen filling service.
  • Those who forget to check and maintain their tire air pressure regularly.

The Disadvantages of Pure Nitrogen in Tires

Nitrogen-filled tires cost about $5 or more per tire compared to regular air-filled tires. It, unfortunately, does not come cheap. That could be why pure nitrogen is more predominant in commercial airplanes and US military vehicles.

For fills of new tires with nitrogen, you can expect to pay between $70 and $175 at some outlets. Drains of regular air and refills of nitrogen on current tires may cost up to $30 per tire. Topping off your tires will see you paying between $5 and $7. Now, compare this to not paying anything for regular air at a tire store or $1 for a top-up at a local gas station.

Maintaining your air pressure may be easy with nitrogen-inflated tires; however, once your tires have pure nitrogen, they need to stay that way and be topped with pure nitrogen only.

Nitrogen Availability:
Nitrogen is not as readily available as regular compressed air. If your tires have regular air, you can top up at almost any gas or service station. You can fill up with nitrogen at tire centers, some car dealerships, and if you are lucky, at some discount superstores if they have an automotive center for nitrogen.

The Maintenance of Nitrogen Filled Tires

Green valve stem caps are an identifier of tires filled with nitrogen. It serves as a reminder that your tires should only be topped up with pure nitrogen. If you have purchased a new car and notice a green valve stem cap, it tells you that your tires have pure nitrogen in them and will need the right maintenance to suit nitrogen-filled tires.

If you need to fill your tires up with nitrogen for the first time since owning the vehicle, then instead go to a tire shop to ensure the proper inflation.

You can add normal air to nitrogen-filled tires; however, it isn't advisable because you will immediately lose the benefit of the higher nitrogen purity. If you want to keep your tires within one pound per square inch of the ideal pressure, then top off your tires at least four times a year, if not more.

Unfortunately, if you need to top off your nitrogen in your tires, you cannot go to your local gas station because regular air dilutes the nitrogen purity. As mentioned earlier, you need to go to a tire center, a car dealership, or even a Costco - where nitrogen is free.

If you want to keep your tires cool, increase your tire's lifespan and tread, and increase your tire's pressure retention, then nitrogen-filled tires could be the best choice for you. You may even enjoy some extra gas mileage if you regularly maintain your tires.