[Motor31]

Per the same questions asked and answered by a tire rep at a rally this last summer.

Take the pressure cold before the tires rotate or become exposed to direct sunlight and air to the apropriate pressure for the load.

Never let air out during the drive after the tires have heated up if you have followed the above practice.

Pressure changes due to altitude are negligible. Just air the tires according to the load and manufacturers recomendations in compliance with the wheel manufacturers limits.