Gas molecules are always moving

Under common conditions, gas molecules are separated by large distances and continue to move irregularly. When the walls of the container are subjected to a large number of collisions, this manifests itself as pressure that we measure.

What temperature changes is the speed of movement

Heating increases the average kinetic energy of molecules. If the volume remains the same, the collisions will be more frequent and forceful, and the pressure will rise.

Why tires are affected by seasons

The gas in the tire is limited to an approximately fixed volume, and changes in ambient temperature will affect the internal pressure. This is one of the reasons why tire pressure needs to be checked in cold and warm weather.