Final answer:
Tires of mismatched sizes should not be used on the same vehicle to ensure safe driving conditions and avoid damage to the vehicle. Dual tires should not be touching, radial and bias-ply tires should not be mixed, and a tread depth of 2/32 inch is insufficient for front tires.
Step-by-step explanation:
When conducting a pre-trip inspection on a vehicle's wheels and rims, it is important to note that statement b is true: Tires of mismatched sizes should not be used on the same vehicle. This is essential for maintaining proper vehicle handling, safety, and to prevent uneven wear or damage to the vehicle's suspension system. Dual tires, mentioned in option a, should not be touching each other; they need space to prevent overheating and wear. Similarly, combining radial and bias-ply tires on the same vehicle, as mentioned in option c, is not recommended as it can cause handling problems and uneven wear. Regarding option d, a tread depth of 2/32 inch is below the legal safety limit for front tires; the minimum tread depth should typically be 4/32 inch for steer tires to ensure safe driving conditions.