What is the minimum lining thickness at the shoe center for air drum brakes before rejecting the vehicle?

The minimum lining thickness at the shoe center for air drum brakes is established to ensure safe and effective braking performance. A lining thickness of 1/4 inch signifies that the brake linings have sufficient material to provide effective friction against the drum surface when braking, which is critical for preventing brake fade and ensuring a reliable stopping ability.

Using linings below this thickness may compromise the vehicle's braking system, leading to decreased stopping power and increased stopping distances, which could result in hazardous situations on the road. Therefore, maintaining at least this minimum thickness is essential for the safety of the vehicle and its passengers.

The other options suggest either significantly thinner linings that could easily lead to unsafe brake conditions or excessive thickness not typically required for effective function. Ensuring that the lining is at least 1/4 inch thick aligns with industry standards for safety and performance in air drum brake systems.