Speed category symbol
The speed category symbol is part of the tire marking system used to indicate the maximum speed at which a tire can operate safely under its specified load-carrying capacity. It is usually a letter found on the tire's sidewall, often in conjunction with the tire's load index, as part of the service description.
Example of a Speed Category Symbol
If a tire is labeled as 225/50R17 94V, the letter V is the speed category symbol.
Common Speed Symbols and Their Limits
Here’s a list of some standard speed symbols and their corresponding maximum speeds:
| Speed Symbol | Maximum Speed (km/h) | Maximum Speed (mph) |
|---|---|---|
| Q | 160 | 99 |
| S | 180 | 112 |
| T | 190 | 118 |
| H | 210 | 130 |
| V | 240 | 149 |
| W | 270 | 168 |
| Y | 300 | 186 |
| ZR | Over 240 | Over 149 |
Key Points
- How It's Determined: The speed symbol is established during testing to ensure the tire can handle specific conditions without failure.
- Why It's Important: Using a tire with a speed rating below your vehicle’s potential speed can lead to unsafe driving conditions and legal issues.
- Z-Rated Tires: Tires with "ZR" are rated for very high speeds (usually above 240 km/h or 149 mph) and often have a secondary speed symbol like "W" or "Y" to specify the exact limit.
When choosing tires, it's essential to select ones with a speed category that matches or exceeds the requirements of your vehicle's performance.