Why is it dangerous for the rear wheels to cross the center line while making a left turn?

When making a left turn in a commercial vehicle, it's essential for the driver to manage the position of the rear wheels carefully. The reason it is dangerous for the rear wheels to cross the center line while making a left turn is that this maneuver can put those wheels directly into oncoming traffic lanes. This situation significantly increases the risk of a collision with other vehicles that may be traveling in the opposite direction. Maintaining the position of the rear wheels in a safe area, specifically away from the center line, helps ensure the vehicle remains clear of other road users and minimizes the likelihood of accidents.

Furthermore, managing the turn properly also allows for better control of the vehicle and prevents the potential for off-tracking, which can occur if the rear wheels deviate too much from the path established by the front wheels. Keeping the rear wheels safe from crossing into oncoming traffic is a critical aspect of safe maneuvering, particularly in a larger vehicle where blind spots and turning radiuses are much more pronounced compared to regular passenger vehicles.