What does 99y mean on tires?

The "99Y" on tires indicates the tire's load index and speed rating. The "99" refers to the load index, which signifies that the tire can support a maximum load of 775 kg (1,709 lbs). The "Y" is the speed rating, indicating that the tire is rated for speeds up to 300 km/h (186 mph). This combination helps consumers understand the tire's performance capabilities.