When passing a truck on an open highway, it's essential to provide extra clearance due to several factors:

A. Size and Speed Difference: Trucks are larger and often travel at slower speeds compared to regular passenger vehicles. This means it takes longer to overtake them safely.
B. Wind Gusts: Trucks can create significant air turbulence, especially when traveling at high speeds. This turbulence can affect the stability of smaller vehicles passing close by.
C. Visibility: Due to their size, trucks can block visibility of the road ahead. It's important to ensure you have adequate space and visibility to complete the pass safely.
D. Reaction Time: In the event of unexpected maneuvers by either the truck or other vehicles, having extra clearance provides more time to react and avoid potential accidents.
E. By doubling or tripling your normal passing clearance, you increase safety margins and reduce the risk of collisions or dangerous situations while passing a truck on the highway.