What is the most effective way to use mirrors when driving a commercial vehicle?

Effective mirror use means scanning regularly with brief glances, every 5 to 8 seconds while driving normally, and more often before any lane change or turn. Each scan should be a quick check, not a long stare, because your eyes need to return to the road ahead. Use both the flat (West Coast) mirror for accurate distance judgment and the convex (spot) mirror for wider angle. The flat mirror shows objects at their true size and distance; the convex makes them look smaller and farther away than they actually are, so do not judge gaps from a convex mirror alone. Both mirrors are needed because neither alone covers all the blind spots around a tractor-trailer. Adjust mirrors before driving so you can see the side of the trailer and the lane next to it.