For the same reasons, you should never reduce the air pressure in a hot tire to try to achieve the desired inflation pressure. Doing so will cause your tires, at normal temperatures, to be under-inflated. Also, never reduce tire pressures to increase traction in snow, ice or mud. To further extend the life of your tires, they should be rotated on a regular basis. Rotation will also maintain accurate handling and response and optimize traction.
Rotation is important because tires wear differently.
Also, the tires on any one vehicle wear differently. They are all mounted in different positions and some are drive tires while others are not. This means all four tires will wear in different areas. Rotation will allow them to wear evenly so that one area won't wear out quicker than another. Different seasons require different characteristics in tires.