What does ZR mean on a tyre?

ZR tyre rating explained

ZR indicates the tyre is rated for sustained speeds above 149 mph (240 km/h). It was originally introduced as a catch-all high-speed designation before more specific ratings were developed.

Modern usage

Today, ZR is typically combined with a more specific letter rating that gives the exact maximum speed. For example:

• 225/40 ZR18 92W — The W tells you the exact limit is 168 mph
• 245/35 ZR19 93Y — The Y tells you the exact limit is 186 mph

The ZR prefix on its own simply confirms the tyre is designed for high-performance use. The additional letter after the load index gives you the precise maximum speed.