Final answer:
When pump air into a deflated tire, the volume increases without much increase in pressure. Once the tire is filled to a certain point, the tire walls resist further expansion, and the pressure increases with more air. The pressure in the tire can also increase with temperature.
Step-by-step explanation:
To get some idea of how pressure, temperature, and volume of a gas are related, consider what happens when you pump air into an initially deflated tire. The tire's volume first increases in direct proportion to the amount of air injected, without much increase in the tire pressure. Once the tire has expanded to nearly its full size, the walls limit volume expansion. If we continue to pump air into it, the pressure increases. The pressure will further increase when the car is driven and the tires move. Most manufacturers specify optimal tire pressure for cold tires.