Nitrogen is the preferred gas for filling aircraft tyres. It's dry nitrogen supplied in bottles, so there is no moisture to cause corrosion or to "steam" in a hot tyre, which would alter the pressure.

Gas used in the tires of an Aeroplanes

Introduction:
The tires of an airplane play a crucial role in maintaining safe and efficient operations. They need to withstand high speeds, heavy loads, and various weather conditions. To ensure optimal performance, aircraft tires are filled with a specific gas that possesses certain desirable properties.

Gas used:
The gas used in the tires of airplanes is nitrogen.

Reasons for using Nitrogen:
There are several reasons why nitrogen is chosen over other gases for filling airplane tires:

1. Stability: Nitrogen is an inert gas, which means it does not react easily with other substances. This makes it more stable compared to other gases like oxygen or helium. Oxygen can degrade rubber over time, and helium can leak more easily due to its smaller molecular size.

2. Reduced fire risk: Nitrogen is non-flammable, which reduces the risk of tire fires. In the unlikely event of a tire overheating or experiencing a blowout, the absence of oxygen in the tire reduces the chance of combustion.

3. Pressure retention: Nitrogen molecules are larger than oxygen molecules, which makes it harder for them to escape through the tire's rubber. This results in better pressure retention, as nitrogen-filled tires tend to lose pressure at a slower rate compared to those filled with compressed air.

4. Temperature stability: Nitrogen-filled tires are more resistant to temperature changes. The consistent pressure provided by nitrogen helps maintain tire performance even in extreme temperature conditions experienced during aircraft operations.

5. Moisture prevention: Nitrogen is a dry gas, meaning it contains little to no moisture. This is beneficial for airplane tires as moisture can lead to corrosion, which can weaken the tire structure.

6. Improved tire life: Due to its stability and resistance to degradation, nitrogen-filled tires can have a longer lifespan compared to those filled with compressed air. This can result in cost savings for airlines, as they have to replace tires less frequently.

Conclusion:
In conclusion, nitrogen is the gas of choice for filling the tires of airplanes due to its stability, reduced fire risk, pressure retention, temperature stability, moisture prevention, and improved tire life. These properties contribute to safe and efficient aircraft operations.