Engineers have calculated the right tire pressure for optimum safety and to prevent premature wear on tires. They do this by considering the load range on each axle and the type of tire used. Optimum safety includes good control of the car during braking and turning.
I would not recommend changing the recommended tire pressure under normal conditions. Changing a manufacturer's recommended tire will also mean that the right tire -pressure need to be re-calculated.
Also note that the correct tire pressure has to be checked in the morning before driving or if the vehicle has not moved for several hours. That is what engineers call "COLD" pressure. After traveling for some time and then stopping to check the pressure say at a gas station will not give you the right reading. This is because normal pressure increase under driving condition. Unfortunately mechanics re-adjust these tire pressures under these conditions. Under such conditions, a well set tire will read higher that normal pressure. That is OK. However, the mechanics typically releases pressure to compensate. This is counter productive and actually to leads to under inflation..