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.