Speed rating (H in 95H)

How to read it

USTMA says the speed symbol, also known as a speed rating, indicates the speed category of the tire’s maximum speed capability, and that the ratings come from laboratory tests that relate to performance on the road. Ford’s manual describes it as the speed at which a tire is designed to be driven for extended periods under a standard condition of load and pressure. It follows the Load index (95 in 95H) in the service description. The letters mostly rise through the alphabet, but BFGoodrich notes that H sits between U and V. NHTSA and Ford say US federal law doesn’t require a speed rating, so not every tire has one.

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Tire speed rating chart

From the charts published by USTMA and Bridgestone, with the letters below M from Bridgestone, Alliance and Pirelli.

What the rating certifies

USTMA says speed ratings are not applicable if tires are underinflated, overloaded, worn out, damaged or altered, and do not imply that a vehicle can be driven safely at that speed, particularly in bad road and weather conditions. Bridgestone’s chart notes the speeds are from standardized laboratory tests, and that actual capability depends on pressure, load, condition, wear and driving conditions. BFGoodrich describes the rating as the maximum speed at which the tire can carry its rated load under specified conditions, not a recommendation to drive there. The US federal standard does not test to the letter: its high speed test runs every car and light truck tire for three 30-minute stages at 140, 150 and 160 km/h (FMVSS 139).

Z and ZR

Bridgestone Australia and Pirelli list Z as over 240 km/h (149 mph). BFGoodrich says Z was once the highest rating, until W and Y were added. On a tire, Z appears within the size as ZR.

Differences between charts

Ford’s owner’s manual converts from miles per hour and gives Q as 159 km/h, R as 171 km/h and Y as 299 km/h, where USTMA and Bridgestone give 160, 170 and 300 km/h.