What is prohibited regarding tire types on the same axle?

Mixing radial and bias tires on the same axle is prohibited because it can create handling issues and affect vehicle stability. Radial tires and bias tires have different construction characteristics and flexibilities, which can lead to uneven wear, altered traction, and compromised performance. This is especially critical on the same axle, where consistent tire behavior is essential for optimal handling and safety. Vehicles are designed to operate most effectively with tires that provide similar performance in terms of traction, load-bearing capacity, and handling characteristics. Selecting the same type for each axle ensures that the vehicle responds smoothly to steering inputs and maintains the intended alignment between tires.

While using oversized tires, retreaded tires, or mismatched brands might lead to other performance concerns or legality issues, the mixing of radial and bias tires poses a direct risk to the vehicle's control, particularly during cornering or emergency maneuvers. Hence, regulations prioritize maintaining uniformity among tires within the same axle for safety reasons.