Final answer:
Using a mixture of different-sized tires can be dangerous, especially on the same axle. It may cause uneven wear, handling issues, and increase the risk of accidents. High friction is also desirable in sports like rock climbing for safety and better grip.
Step-by-step explanation:
A mixture of different-sized tires can be dangerous if used on the same axle. This is because mismatched tires can lead to uneven wear, poor handling, and potential safety issues, such as blowouts or loss of vehicle control, especially at high speeds or during emergency maneuvers. It's generally recommended by safety experts and vehicle manufacturers to use tires of the same size, type, and tread pattern on all wheel positions to ensure optimal performance and safety. Using different-sized tires on an axle can also cause mechanical problems, such as damage to the differential due to the wheels rotating at different speeds.
It can also be dangerous to use different-sized tires on different axles, although not as risky as on the same axle, as it can affect the car's handling and potentially lead to uneven braking and vehicle instability. Both these practices can compromise the safety of the vehicle's occupants and other road users.
To give another example where more friction is desirable, in sports such as rock climbing, the climbers need shoes with high friction to grip the rocks or wall surfaces better, which ensures a more secure climb and reduces the risk of slipping.