What is NOT allowed on the front axle of buses concerning tires?

Buses are subject to specific safety regulations regarding their tires, especially for the front axle, due to the critical role these tires play in steering and stopping. The use of re-grooved or recapped tires on the front axle of buses is not permitted. This restriction is in place because re-grooved or recapped tires may compromise the structural integrity and performance of the tire, potentially leading to failures. Unlike new tires, which are designed and tested for optimal safety and performance, re-grooved or recapped tires may not provide the same level of reliability and traction.

The remaining options are allowed because new tires ensure the best performance, while bias and radial tires can be used as long as they meet the relevant standards for commercial vehicles. Each type has its applications and regulations, but the use of re-grooved or recapped tires, particularly on the front axle, poses an unacceptable risk. This choice emphasizes the importance of maintaining high safety standards in commercial transportation, especially for vehicles that carry passengers.