How to Identify Tire Speed Ratings?
4 Answers
Automobile tire speed ratings primarily correspond to the specific maximum speed that the tire can support. Speed ratings are generally represented by letters from A to Z, with higher letters indicating higher maximum speeds. Below are some related extended information: 1. Definition: The speed rating indicates the maximum speed at which a tire can carry a specified load under defined conditions. Different tires will have English letters on their sidewalls to denote their speed ratings. These letters represent certified speed ratings ranging from 4.8 km/h to 300 km/h. 2. Spare Tire: The speed rating for a car's spare tire is M, which signifies a maximum speed of 130 km/h. However, when using a spare tire, it is advisable not to exceed 80 km/h to minimize wear on the drivetrain. Therefore, when using a spare tire, the vehicle's speed should be kept below 80 km/h.
You can directly check the letter symbols on the tire sidewall to determine the speed rating. Every time I help friends choose tires, I remind them to pay attention to this detail. For example, the marking 235/55R18 100V on my current tires - the final 'V' indicates a maximum speed capability of 240km/h. In reality, H-rated (210km/h) or V-rated tires are sufficient for daily driving, while sports cars may require W/Y-rated tires. The key point is to avoid speeding - last year a buddy with T-rated tires pushed to 180km/h and nearly flew off the highway when his car skidded during a turn. Always verify the original specifications on the door frame or manual before changing tires, as mixing different speed-rated tires is extremely dangerous.
The most practical method involves three steps: first, locate the alphanumeric code on the tire sidewall; then, refer to a chart to find the maximum speed corresponding to that letter; finally, memorize the common speed ratings. I usually keep a speed rating chart on my phone—H is 210 km/h, V is 240 km/h, and W is 270 km/h. Once during heavy rain on the highway, I saw a car ahead suddenly lose control and spin out—later I learned they had mixed V-rated and H-rated tires to save money. Two important reminders: summer tires typically have higher speed ratings, while winter tires of the same size may be one grade lower; tires older than five years may not perform to their rated speed, even if labeled with a V.
Tire speed ratings are a matter of life and death. The letter marking at the end of the specification, like the 'W' in '225/45R17 91W', indicates a maximum speed of 270km/h. But don't think you can actually drive that fast! Last time at the repair shop, I saw a BMW owner still speeding even though the tire sidewall was scratched by a curb. In reality, the speed rating becomes invalid once the tread is damaged. For regular family cars, a T-rating (190km/h) is sufficient, but for those who frequently drive long distances, an H-rating or higher is recommended. It's crucial to ensure that replacement tires on the same axle have the same speed rating. The mechanic mentioned that 80% of tire blowout accidents are caused by mixing tires with different speed ratings.
