Air.
The center of a tire is called the rim, its what holds the air inside and the car standing ;D
psi
Compresion
Yes, you can refill a flat tire with air using a tire inflator or an air compressor.
A tool that measures air pressure in a tire or going through a pipe is called an air pressure gauge.
Most tires are supported by air pressure alone, not the tire, the tire controls things but is a casing to hold the air that hold the car up. There are tires called run flat that can work with out air pressure for a little while. In history there were solid rubber tires that did not require air at all, they were terrible.
Air rushes out because it is under pressure. Once there is no longer any pressure in the tire the air will stop flowing out. However there is still air in the tire it is just equal to the pressure outside.
When it is needed.The tire inflates when air is pumped in
Air leaves a tire when the valve is opened due to the pressure difference. Since the tire has more pressure than the air outside, the tire air will escape until the pressure equalizes.
Yes there most certainty is a limit to the amount of air that can be pumped into a bicycle tire. Put too much air in the tire and it will explode. The maximum air pressure for the tire is listed on the sidewall of the tire.
To release air from a bike tire, you need to press the small valve stem located on the inner tube of the tire. This will allow the air to escape from the tire.
Air leaves a tire when the tire valve is open due to the pressure. The pressure outside of the tire is lower than the pressure inside the tire.