One of the primary functions of tyres is to carry the load of the vehicle. But if you’ve encountered a flat tyre before, you know that technically, this isn’t true since the tyre isn’t really the one that supports the weight—it’s the air inside it.
The air carries the load, absorbs shock, and maintains the shape of the tyre to ensure it performs as designed. This is why it’s essential to maintain the correct inflation pressure. However, since practically all substances, including gas, expand when heated and shrink when cooled, the air pressure can also change as the temperature rises and falls. This is the reason it’s recommended to check air pressure regularly, at least every month.
The bad news is that, no matter how religiously you maintain your tyres, they can still lose pressure. Tyres have microscopic pores through which air can seep out, lowering the pressure gradually.
So what can you do to maintain more stable tyre pressures? One option encouraged by many manufacturers today is filling tyres with pure nitrogen instead of compressed air.
What’s the deal with nitrogen-filled tyres?
Pure nitrogen has been used as inflation gas in various tyre applications for years, including racing, aircraft, and heavy-duty equipment tyres. It’s a non-flammable, inert gas that doesn’t support moisture and can substitute air minus the negative environmental impact.
Because nitrogen molecules are significantly larger than oxygen, they will have a more difficult time escaping through the rubber, seeping out of the side wall at a much slower rate than oxygen. This means tyres inflated with nitrogen will have more consistent pressure, which can translate to longer tread life and improved fuel economy.
Air versus Nitrogen
If you’re like most drivers, you’re probably also confused as to whether it’s better to use nitrogen or stick to compressed air to fill your tyres. To help you decide which is right for you, let’s take a closer look at some of the factors you need to consider:
- Cost and convenience – Compressed air is almost universally available at a cheaper cost – free! Go to any petrol station and you should be able to locate an air hose to pump your tyres for free (although whether or not the hose is functional is an entirely different matter). Nitrogen, on the other hand, carries a cost, and that is if you can find a someone who can supply it.
- Tyre inflation pressure retention – As mentioned, nitrogen has larger molecules than oxygen, which means they will move and escape from the tyre more slowly than air, allowing them to maintain the inflation pressure longer.
- Tyre aging and wheel corrosion – Air is composed roughly of 78% nitrogen, 21% oxygen, and 1% miscellaneous gases. Oxygen is known for retaining moisture inside your tyres, which may eventually oxidise your internal wall casing and lead to premature tyre aging. Extreme moisture can also promote rust in wheels. Nitrogen, on the other hand, doesn’t support moisture. Therefore, the tyre and its components are protected from the damage caused by oxidation.
As with most new technologies, it’s wise to consult your car manufacturer or your manual first before considering nitrogen tyres to ensure it’s a suitable option. And if you do pressurise your tyres with nitrogen, remember that monthly air pressure checks are still necessary so you can continue to enjoy the car safety, performance, and tyre longevity you’re looking for.