What is the primary function of wheel chocks for parked trucks?

Wheel chocks serve a critical role in ensuring the safety of parked trucks. Their primary function is to prevent the vehicle from rolling, which is essential when the truck is parked on an incline or even on a flat surface where unintended movement could cause accidents or injuries. By securely positioning wheel chocks against the tires, they create a blockade that restricts the motion of the wheels, effectively stabilizing the vehicle and ensuring it remains in place until it's time to drive again.

The other options relate to aspects that are not the core purpose of wheel chocks. For instance, improving tire performance and increasing fuel efficiency pertain more to tire conditions and maintenance rather than stabilization of the vehicle itself. Similarly, while wheel chocks can indirectly provide extra traction by preventing tire movement, their main goal is specifically related to maintaining the position of the parked truck. This focus on preventing rolling is critical for safety during loading, unloading, or when maintenance work is being performed.