Tire speed ratings indicate the maximum speed that a tire can safely maintain over time. The rating system was developed to help control the safe performance of tires at standardized speeds. The speed rating is a measure of what speed the tire can safely maintain for sustained periods of time. A higher speed rating will generally indicate that you will have better control and handling characteristics. The speed rating is usually the last item in the character sequence in the tires size code. The speed rating is represented by a letter from A to Z, ranging from 5km/h (3mph) to above 300 km/h (186 mph) . The following speed ratings are those you’re most likely to encounter for ordinary vehicles:
- M – Up to 81 mph
- N – Up to 87 mph
- P – Up to 93 mph
- Q – Up to 99 mph
- R – Up to 106 mph
- S – Up to 112 mph
- T – Up to 118 mph
- H – Up to 130 mph
- V – Up to 149 mph
- W – Up to 168 mph
- Y – Up to 186 mph
- Z – (See Below)
For tires having a maximum speed capability above 149 mph, a Z rating may appear in the size designation. Above 186 mph, a Z rating must appear in the size designation, including a Y speed symbol in brackets. It is important to note that tire speed ratings do not imply that the vehicle may safely be driven at the maximum speed for which the tire is capable, particularly under adverse weather or road conditions. The speed rating indicates a new tire’s performance in tightly controlled lab settings, not the open road. Tire condition, inflation level, extra cargo, road surfaces, and weather affect a tire’s maximum safe speed.
