Nitrogen vs. Air in Tires: Deciphering the Inflation Dilemma

Car enthusiasts will go a long way to improve their ride. From engine tuning to larger wheels, these people will do anything to enhance their ride. This also includes inflating the tires with nitrogen rather than the good old air. You didn't know that existed? Well, it's a thing, and it became very popular recently, particularly among that enthusiast crowd.

But you came here because you probably heard about nitrogen inflation and wanted to learn more about it. Well, you arrived at the right place because here I will tell you everything there is to know about nitrogen inflation and whether it is the right solution for you. I will delve into more technical details but don't worry, everything I say will still be in a language that is easy to understand by the regular driver.

So, without further ado, let's have a closer look at nitrogen vs. air in tires as an inflation medium.

Understanding the Basics of Tire Inflation

Tire inflation is a fundamental aspect of vehicle maintenance that significantly influences the performance, safety, and longevity of tires.

However, although proper inflation will ensure optimal performance, the inflation medium can also have a notable impact on various aspects of how the tire operates.

The two most popular inflation mediums are regular air and nitrogen, both with their advantages and disadvantages. Let's have a closer look at each of them and see why they are the most popular inflation gases for tires today.

1. What is Air?

The gaseous atmosphere that envelops our Earth is what we call air. It consists of numerous gases, but the most common are nitrogen (N2), constituting about 78%, and oxygen (O2), around 21%. The rest 1% constitutes mainly carbon dioxide (CO2), neon (Ne), and helium (He), but also other gases in traces. Air also has water vapor, which varies in quantity depending on the humidity in the area.

Most tire shops, and in fact every compressor you use in your own garage, will use the surrounding air to inflate the tires. Thus, depending on the area you live in, the air will have slightly different properties, which is largely due to the distinct water vapor content.

2. What is Nitrogen?

Nitrogen, represented as N2 in its molecular form, is a colorless, odorless, and tasteless gas. As you have learned by now, air mostly consists of nitrogen, but because it is inert, our bodies can't use it. In fact, nitrogen doesn't react with other substances in normal conditions, like at atmospheric pressure and Earth temperatures.

Thus, there is an idea that its inert properties will make it a better solution for tire inflation than other, more reactive gases. For instance, oxygen, which is the second most abundant gas in the atmosphere, is very reactive and can corrode almost any surface.

When we refer to nitrogen inflation in tires, we are typically talking about high-purity nitrogen, often above 95%, which is significantly less humid because the nitrogen generation process removes most of the water vapor.

3. Why Inflate Tires with Air or Nitrogen?

Nitrogen inflation has become popular because it is more easily controllable. Namely, you will always know the quantity of nitrogen in your tires and plan how changes in temperature affect the pressure inside. In other words, the pressure changes will always correlate to the same temperature fluctuation, regardless of the conditions outside.

Standard air, which is still the most common inflation medium, doesn't always react similarly to changes in temperature because it consists of different gases. Thus, depending on when and where you inflate the tires, the air inside will have different properties regarding pressure fluctuations. Moreover, due to the presence of oxygen and water vapor, air can cause internal tire and wheel degradation.

Thanks to the more stable and predictable nature of nitrogen, it has been used for tire inflation in certain demanding applications, such as aircraft and racing cars, for some time. Moreover, these industries value reduced internal tire oxidation and less wheel corrosion.

However, it is important to note that nitrogen inflation brings additional costs to the already high running costs of today's cars. Moreover, it isn't as practical, as it requires keeping a pressurized bottle of nitrogen at hand, which isn't easy to acquire for home mechanics.

Hence, although nitrogen is potentially attractive, you will need to weigh down the advantages and disadvantages before splurging the cash. I mean, air has been used for over a century in the automotive industry, and although it's not perfect, it works.

Comparing Nitrogen and Air Inflation

In the context of tire inflation, there are numerous factors that affect the properties of nitrogen and air. From their physiochemical properties to practical implications, nitrogen and air cannot be more different. Both have their advantages and disadvantages, and each one suits different types of drivers. Let's have a closer look.

1. The Benefits of Using Nitrogen

The main benefit of using nitrogen is the fact that it's an inert gas. This means that it won't react with the rubber compound on your tires and oxidize them, but due to the low water vapor content, it also reduces wheel corrosion.

Overall, a tire filled with nitrogen should last longer and experience less dry rot, which could potentially increase its lifespan. Still, it is important to note that other factors also influence dry rotting, like sun exposure and ozone levels in the atmosphere.

Furthermore, since you will always know the exact nitrogen quantity, tire pressure changes will be more stable. Nitrogen as a gas also doesn't hold or transfer heat as readily as oxygen, meaning less heat-related stress and expansion. As a result, the pressure will remain stable during high-temperature changes.

Another benefit of having nitrogen in your tires is lower pressure loss over time. Namely, nitrogen molecules are larger than oxygen molecules, meaning less of the gas will permeate the atmosphere. In other words, you won't need to re-inflate your tires as frequently if you opt for nitrogen, though the differences won't be huge.

2. The Advantages of Using Air

There are quite a few reasons why air is still widely used in the automotive industry, but the most significant one is the fact that it is readily accessible. You can inflate your car tires with a simple hand/feet pump using the surrounding air. No need for pressurized bottles or any other equipment.

In addition, air compressors are standard equipment at all automotive service centers and many home garages, making it easy for drivers to maintain correct tire pressure.

Air inflation also costs nothing. Sure, some energy is used to pressurize the air, but service centers never charge for inflation. Moreover, these air compressors are readily available at many gas stations, and you can use them at no additional cost.

An overlooked factor of inflating tires with air is that it encourages good tire maintenance habits. Namely, the fact that air escapes the tires more easily means it requires more frequent pressure checks. And if I had to weigh down the effects of nitrogen inflation and improper inflation, I would say that the latter is more damaging to automotive safety.

3. Performance Differences Between Nitrogen and Air

The performance differences between nitrogen and air are only measurable by precise instruments. In other words, you probably won't feel any difference in how your vehicle drives, especially during everyday driving. In fact, only race car drivers will probably be able to tell the difference.

With that said, overall, nitrogen-filled tires have more stable pressure over larger temperature fluctuations. As a result, in theory, nitrogen should provide you with more predictable handling and slightly improved fuel efficiency. Again, you probably won't feel the difference, but precise measurements show it is there.

Still, despite the advantages of nitrogen, most drivers will be well-served by the good old air. Sure, the pressure fluctuations will be higher, but they are still within the safe parameters. The key to maintaining this performance is regular pressure checks and adjustments, which are a critical part of tire maintenance, regardless of the inflation medium used.

Practical Considerations for Nitrogen and Air Inflation

Before opting for nitrogen due to its neutral properties, you should also consider the practical considerations, which impact availability, cost, environmental impact, and the potential effect on the tire's lifespan.

1. Accessibility and Cost of Nitrogen

Nitrogen isn't readily available to home mechanics, i.e., you can't really buy it in the store. Sure, there are specialized stores that sell large pressurized bottles of nitrogen, but they are expensive. Moreover, nitrogen requires special maintenance and storage that is probably not possible in a home garage.

Moreover, nitrogen inflation services are typically found at select tire shops and dealerships, making it potentially inconvenient for drivers who need to top off their tire pressure. No gas station offers nitrogen inflation, at least not one that I know of.

In addition, you should also consider the cost associated with nitrogen inflation. Unlike air, which is often available for free or at a nominal cost, nitrogen inflation services typically come with a fee. This cost can vary significantly depending on the service provider, but it is always higher than using air. For some drivers, the added cost is an investment in their cars, but for most of us, it is an unnecessary cost.

2. Environmental Impact of Nitrogen vs. Air

Nitrogen-filled tires lose less pressure over time and maintain the pressure better during temperature fluctuations. As a result, they could potentially improve fuel efficiency, thus reducing emissions. However, the difference is mostly negligible. In fact, fuel efficiency depends more on other factors, like driving habits and proper tire inflation.

On the other hand, the production of nitrogen involves higher energy consumption than inflating your tires with air. Industrial nitrogen generators separate nitrogen from atmospheric air using methods like pressure swing adsorption or membrane separation, both of which require significant energy inputs.

Moreover, nitrogen needs to be pressurized into bottles and then transported, which adds to its environmental impact.

3. Impact on Tire Lifespan

In theory, nitrogen should prolong the life of your tires. That is because this gas doesn't react with the rubber compound and reduces internal oxidation, thus limiting dry rot. Moreover, nitrogen will keep your tires properly inflated for longer, thus limiting accelerated and irregular wear.

However, regular air inflation coupled with diligent tire maintenance practices—like routine pressure checks and adjustments, tire rotations, and visual inspections for damage—can also effectively prolong tire lifespan.

Sure, the oxygen in the atmosphere will oxidize the rubber compound faster, but your tires will still last for at least 6-8 years before a replacement is imminent, even when exclusively filled with air. In fact, regular tire maintenance will negate the effects of regular air and prolong their lifespan.

Can You Mix Air and Nitrogen in Tires?

Sure, there is nothing wrong with mixing air and nitrogen when inflating your tires. For example, you can re-inflate your tires with air if that is the only available solution at the moment, even if they were filled with nitrogen before. At the end of the day, air consists largely of nitrogen (78%).

Still, there are some considerations you need to have in mind.

1. Understanding the Mixing Process

When you initially inflate your tires with nitrogen, the existing air inside the tire is purged to increase the nitrogen concentration, usually above 93-95%. However, if a nitrogen-filled tire loses pressure and needs to be topped up, and if nitrogen isn't readily available, it's perfectly acceptable to use regular air.

Sure, the nitrogen concentration will be diluted, but keeping your tires properly inflated is a much more important safety consideration than using nitrogen. Thus, if you are on the road and only have the air compressor at the gas station available, you should use it rather than driving on underinflated tires.

2. Effects on Tire Performance

Mixing nitrogen with air will definitely reduce the benefits of using just nitrogen. After mixing the two, you can expect quicker pressure loss due to permeation, increased internal oxidation (oxygen is re-introduced inside the tire), and increased temperature-related expansion and contraction. However, it is important to note that the changes will be minimal and not perceptible during everyday driving.

3. Safety Considerations

There are no safety considerations when mixing nitrogen with air, i.e., it's not dangerous to do that. A more critical factor would be underinflation, which can severely impact your car's handling and fuel efficiency. Therefore, I highly recommend re-inflating your tires if they are below the manufacturer-recommended pressure, even when only air is available.

Making the Right Choice for Your Vehicle

Before opting for nitrogen instead of regular air, there are a few things to consider, largely related to budget constraints, availability, driving conditions, and your personal preferences.

1. The Type of Car

Owners of high-performance sports cars that often bring them to track days or autocross events might want to use nitrogen. The differences in performance will be small, but the stable pressure definitely helps when the tires overheat due to prolonged track day sessions.

Still, if you never bring your car to the track, there is no reason to use nitrogen. This is because air is perfectly adequate regarding performance, but also cheaper and more readily available. Additionally, if you travel long distances frequently and won't always have access to nitrogen inflation services, standard air inflation might be a more practical choice.

2. Expert Opinions on Nitrogen vs Air in Tires

Experts don't agree on many things, and that includes nitrogen vs. air as inflation mediums. Now, I am not a scientist, but I have driven hundreds of different cars in my life and even more tire models. What I learned is that the benefits of nitrogen are marginal for everyday driving and perhaps even for most owners of performance cars. In fact, I think that the added cost and inconvenience of nitrogen inflation isn't justified.

3. Key Takeaways for Consumers

So, what is the key takeaway of nitrogen vs. air as an inflation medium? Well, proper tire maintenance is much more important than the inflation medium. This includes regular pressure checks (at least once every month), regular rotation (on every oil change or at a 5,000-8,000-mile interval), and visual checks (at least once every six months).

Conclusion

After reading my thoughts on nitrogen vs. air as an inflation medium, what is your thought on the subject? Are you prepared to marginally improve the handling characteristics of your car by adding inconvenience to your inflation schedule? Or are the stable pressure and less oxidation important to you? Do tell us in the comments below – we'd like to hear!