Speed rated refers to the fastest speed a tire can handle before it no longer performs as designed. This rating indicates the maximum speed a tire can maintain for a sustained period under specific conditions, as determined by standardized tests. The higher the speed rating, the better control and handling you'll typically have at higher speeds.
Understanding Tire Speed Ratings
The concept of speed rating was developed as part of a system to help control the safe performance of tires at standardized speeds. It's a crucial safety feature that tells drivers and mechanics the maximum speed at which a tire is certified to perform safely under expected operating conditions (correct inflation pressure, proper load).
How Speed Ratings Work
Speed ratings are represented by letters of the alphabet, typically found as part of the tire's size and service description on the sidewall. Each letter corresponds to a specific maximum speed the tire can safely handle. While the reference doesn't list the specific letters, the system is standardized globally.
Here's a table showing some common speed ratings and their corresponding maximum speeds:
| Speed Rating | Maximum Speed (mph) | Maximum Speed (km/h) |
|---|---|---|
| L | 75 | 120 |
| N | 87 | 140 |
| P | 93 | 150 |
| Q | 100 | 160 |
| R | 106 | 170 |
| S | 112 | 180 |
| T | 118 | 190 |
| U | 124 | 200 |
| H | 130 | 210 |
| V | 149 | 240 |
| W | 168 | 270 |
| Y | 186 | 300 |
| (Y) | Above 186 | Above 300 |
| Z | 149+ | 240+ |
Note: Z-rated tires were historically the highest rating (over 149 mph). Today, W and Y ratings specify higher speeds, but Z is still used, often alongside W or Y ratings for tires capable of speeds over 149 mph.
Why Speed Ratings Matter
Choosing a tire with the correct or higher speed rating than recommended by the vehicle manufacturer is important for several reasons:
- Safety: Tires operating beyond their rated speed can overheat, leading to failure.
- Performance: As mentioned in the reference, a higher speed rating generally means the tire offers better control and handling capabilities, especially at higher speeds or during demanding maneuvers.
- Vehicle Capability: Vehicles designed for higher speeds require tires engineered to withstand the stresses associated with those speeds.
- Insurance and Warranty: Using tires with an inadequate speed rating can potentially void tire warranties or affect insurance claims in case of an accident.
It is generally recommended to replace tires with ones that have the same or a higher speed rating than the original equipment tires specified for your vehicle.
