What do the letters on tires represent?
2 Answers
The letters on tires represent the speed at which the tire can carry a specified load under specified conditions. The speed levels represented by tire letters are as follows: 1. Q is 160 kilometers per hour; 2. R is 170 kilometers per hour; 3. S is 180 kilometers per hour; 4. T is 190 kilometers per hour; 5. H is 210 kilometers per hour; 6. V is 240 kilometers per hour; 7. W is 270 kilometers per hour; 8. Y is 300 kilometers per hour; 9. Z is ZR speed above 240 kilometers per hour. Methods to protect tires: 1. Check if there are any attachments on the tires; 2. Check the tire pressure when the tires are cold; 3. Reduce the driving speed in time when the road condition is poor.
Those alphanumeric codes on tires actually represent size and performance parameters. I often study this, for example, a typical 205/55R16 91V. 205 indicates the width of 205 millimeters, affecting the contact area and grip. 55 represents the aspect ratio of 55%, meaning the sidewall height is 55% of the width—lower numbers feel sportier but compromise comfort. R stands for radial construction, the standard tire type widely used. 16 is the wheel diameter of 16 inches, which must match the vehicle's rim size. 91 is the load index, corresponding to a carrying capacity of about 615 kilograms—higher numbers mean greater load capacity. V is the speed rating, indicating a maximum speed of 240 km/h—higher letters suggest the tire is more suitable for high-speed driving. Choosing the wrong tires based on these parameters can lead to unstable handling or increased fuel consumption, so I always check if the tire specifications match before driving to ensure safe operation. These numbers may fade as tires age, necessitating timely replacement.
