Properties of nitrogen gas
There are many benefits to using nitrogen to fill tires, nitrogen molecules are larger than normal air molecules. These larger molecules also move slower than regular air molecules. Nitrogen is a dry inert gas which does not react with other gases to become toxic and is safe to inhale if you’re worried about that. Nitrogen is also safe because it is not flammable.
What does it matter? Tires deflate naturally over time, although air is about 78% nitrogen, 21% oxygen and 1% other gasses like water vapor and carbon dioxide. Oxygen molecules are smaller and thus the proportion of smaller molecules in air filled tires are higher than pure nitrogen filled tires. Smaller molecules will leak out of the tire faster over time resulting in under inflated tires.
How do I know if my tires were initially filled with nitrogen gas? Nitrogen filled tires will have a green valve cap on.
Benefits of nitrogen filled tires
Maintain correct tire pressure for longer; with nitrogen molecules being larger, it will take a longer time for the bigger molecules to seep through the tire rubber. Nitrogen filled tires takes a longer time to naturally deflate over time thus needs less maintenance.
More gas mileage; nitrogen filled tires have a more consistent tire pressure, driving with under-inflated tires will be less economical and will give you less gas mileage. With air filled tires losing air faster resulting in under-inflated tires more often. Under-inflated tires result in more rubber surface area of the tire being in contact with the road. The outcome will be that more force is necessary to move the vehicle, burning more fuel.
Increase tire lifespan; under-inflated tires caused by air filled tires will wear unevenly and thus wear out quicker. Tire lifespan will be significantly reduced. In air filled tires as oxygen leaks through the tire it reacts with the rubber degrading it over time.
Decrease corrosion; nitrogen is also a dry gas with no water vapor in it, less moisture in the tire will also result in less corrosion of the tire.
Better handling; tires inflated to the manufacturers recommended pressure also allows for the best handling of your vehicle and promoting safe driving and helping to prevent accidents.
Disadvantages of using nitrogen in tires
More expensive; filling tires with nitrogen is more expensive than filling with regular air. Once you put nitrogen in the tires you also need to maintain the tire pressure with nitrogen gas.
Finding a garage with nitrogen facilities is not always possible; finding a garage where you can fill your car with nitrogen might be a problem in the first place or you may be on holiday and far away from any garage with nitrogen gas facilities.
What if I can’t find any garage to top up with nitrogen?
Is it ok to mix regular air with nitrogen? If you need to top up your vehicle’s tires with nitrogen and you can’t find a place with nitrogen facilities, then top it up with regular compressed air. It is always a better option to drive with correctly inflated tires than under-inflated tires.
If you are filling your tires with nitrogen for the first time and not all of the air has been purged beforehand, then the efficiency of the nitrogen gas will be reduced. Mixing these to gasses is not dangerous though.
Conclusion
Nitrogen filled tires should be topped up every 2-3 months while air filled tires should be topped up every month. This does not mean you don’t need to inspect your tires in general. Inspect your tires at least every 2 weeks for slow punctures or other leaks. Tire maintenance is just as important as checking engine oil and cooling water.
Using nitrogen gas to fill your tires may not be the economical option in the end, the price tag is a bit steep and does not justify the benefits for a normal passenger car.
Race car drivers often use nitrogen in their tires because it offers more consistent tire pressure during races. Normal air has moisture in it and when heated during a race can cause bigger tire pressure changes. Where mere seconds count, the smallest changes in tire pressure may cause you to go faster or slower around a racing track.
Keep in mind filling tires with nitrogen does not protect you against other leaks like punctures, valve leaks or other mechanical loss of tire pressure.
