What are the optimal tire pressure settings for mixed terrain riding, taking into account both rolling efficiency and traction, and how do these settings change when transitioning from smooth roads to rough gravel or trails? Some sources recommend running lower pressures on mixed terrain to improve traction and comfort, but this can lead to increased rolling resistance and decreased efficiency on smoother sections. Others advocate for higher pressures to maintain speed and efficiency, but this can compromise traction and control on rougher surfaces. What is the ideal balance between these competing demands, and how do factors such as tire width, tread pattern, and rider weight influence the optimal pressure settings?