What is one of the primary reasons to avoid backing up with leaned wheels?

Avoiding backing up with leaned wheels is primarily crucial because it can lead to the risk of tipping. When the grader's wheels are leaning, it creates a situation where the center of gravity is altered, and maneuvering the grader in reverse increases the chance of destabilization. In essence, leaned wheels can compromise the balance of the machine, making it more susceptible to rolling over, particularly on uneven terrain or when navigating tight spaces. Ensuring the wheels are not leaned when backing up helps maintain a stable operational posture, thereby enhancing safety for the operator and the equipment. The other options do not address the safety implications directly, focusing instead on visibility, speed, and tire wear, which are not the primary concern when considering the dangers of backing up with leaned wheels.