Where may regrooved tires be used on a school bus?

Regrooved tires are specifically not permitted for use on school buses due to safety regulations and the need for optimal performance in various driving conditions. School buses are responsible for transporting children, and therefore, the standards for tire safety and reliability are particularly stringent. Using regrooved tires could compromise traction and handling, especially under wet or adverse conditions, which is why they are banned for these vehicles.

In contrast, the other options incorrectly suggest that regrooved tires could be used on certain wheels of the school bus. However, the overarching regulation focuses on the safety and operational integrity of school buses, thus leading to the conclusion that the prohibition of regrooved tires is in the best interest of passenger safety, particularly for young children.