Whenever you come across a fuel station to check air pressure in your car you may have seen nitrogen gas filling stations and attendants have suggested you for filling nitrogen gas instead of normal air.
The reason is that the amount of nitrogen is present in the air is around 78% while at the same time, the amount of oxygen is only 21 percent. Vapor, carbon dioxide and noble gas are present in the remaining part.
Just as every gas spreads on heating and contracts when it gets cold. In the same way, the air filled in the tyre behaves and the tyre is likely to grow when the gas spreads while the tyre filled with nitrogen gas is less likely to grow and stays stable for a long time due to its property of less expansion.
The second problem of normal air filling is humidity that is harmful for your car tyres. Vapor is present in normal air affects the tyre pressure and also damages the tyre rim of steel and aluminum. The oxygen present in the tire gets paired with water vapors and destroys the rim.
Car handling and mileage also gets better by using nitrogen gas and you will not need to keep checking the tyre pressure frequently.