Well, each tire will carry a marking for recommended pressures both lowest and highest. Don't exceed the high value, as it can cause the tire to burst, which actually can lead to injuries. Going below or staying at the low end of the recommended value can lead to pinch flats and the tire rotating on the rim during braking. This isn't as bad as the tire blowing out but still not a nice thing to encounter during a ride. Low pressure can give better traction, particularly on soft surfaces.
When you are not sitting on it.
how much air is in the tire
Because the air inside the tire is under pressure. Gas always flows from a region of higher pressure to a region of lower pressure. As the pressure inside the tire is greater than the pressure outside, the air always comes out of the bicycle tyre.
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.
ANY tire gauge measures air pressure in PSI.
The inflation pressure is on the sidewall of the tire.
The correct air pressure for your 2003 Road King standard tire is 18 pounds. The tire air pressure is dependent upon the type of tire.
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.
The air pressure for many tires is 32 pounds. The sidewall of the tire will be stamped with the correct pressure for the tire.
Air is put in with a pump or a compressor, either way it becomes pressurised to inflate the tire.
Because I don't know what your teacher is looking for:At a pressure above atmosphericCompressedConfined
Depends on the vehicle the tire is mounted on. That is what determines the correct air pressure not the tire. The correct pressure is listed in the owner's manual and normally on the driver's door post. The pressure written on the tire sidewall is the maximum pressure the tire can handle.