Rubber, just like any other tire. They're just stronger, thicker and better than e.g. car tires.
They are multi-ply tires filled to very high pressure. Most jet and large airplane tires are filled with nitrogyn.
Air
nitrogen
To avoid accidents when the airplane is landing.
Nitrogen is filled in aeroplane tyres.
i maen pericles
The airplane was made in 1343
Tires are made of rubber.
Nitrogen because it's inert and does not contain moisture.
They make tires just for airplanes. They've got to be light, but also strong enough to withstand being instantaneously loaded to many times the weight of the airplane without blowing out.
Aircraft tires can be filled with regular compressed air, however pure nitrogen is also often used.