Final answer:
The speed rating designation rated for speeds above 149 mph (240 kph) is Z.
Step-by-step explanation:
The speed rating designation that is rated for speeds above 149 mph (240 kph) is Z. The Z rating indicates a maximum speed capability above 149 mph, making it suitable for high-performance vehicles. This rating ensures that the tires can handle the increased stress and heat generated at high speeds.
Learn more about Speed rating designations for tires