So THAT’s Why Plane Wheels Aren’t Filled With Regular Air

The closer you look at a plane, the more clever design details – like that little black triangle that helps airline staff to get the clearest possible view of the wings – you might notice.

But not even the keenest eye would catch another of the vehicles’ smart adaptations: the gas that goes into their tyres.

Since 1988, the Civil Aviation Authority has said that brake wheels on most commercial aircraft are “required to have tyres inflated with nitrogen, or other suitable inert gas”.

Speaking to HuffPost UK, Stuart Algar, Head of Airworthiness at the UK Civil Aviation Authority, said: “Nitrogen is better than air for a number of reasons. It is an inert, non-reactive, non-flammable gas.”

Inert gases are stable and tend not to react to other chemicals under normal conditions.

Nitrogen isn’t combustible either, meaning it won’t burst into flames if one of the plane’s tyres bursts when leaving, or landing on, the ground. Oxygen, however, which is present in regular air, makes everything around it burn faster.

In the 1980s, a plane wheel exploded and burst into flames after a brake overheated. These tyres had been filled with regular air instead of nitrogen.

″[Nitrogen] also responds more predictably to temperature changes, especially at high altitudes or different climates. Unlike air, nitrogen contains no moisture, which helps maintain a stable pressure and prevents corrosion within the wheels,” Algar added.

The icy temperatures planes face at cruising height could pose an issue when planes land, because their wheels get very hot due to the immense friction placed on the tyres.

That sudden contrast can lead any moisture to vaporise, adding extra pressure from the temperature shift, which might make tyres burst. Aircraft tyres have about six times as much pressure as car tyres.

“On top of these benefits, nitrogen also has larger particles than oxygen, which minimises the amount of gas leakage from the tyres so that they maintain their pressure for longer,” Algar added.

Per Air Canada, plane tyres only last for about 300-450 landings, on average.

Quartz added that most planes lease, rather than outright own, their tyres.

When they inflate their tyres, the publication continued, planes place their wheels in a safety cage to prevent any disasters from affecting the rest of the aircraft.