Rating*	Maximum Speed (MPH)
Q	99 mph
S	112 mph
T	118 mph
U	124 mph
H	130 mph
V	149 mph
Z***	149 mph
W**	168 mph
Y**	186 mph
*Current tire speed rating markings include the use of the service description to identify the tire's speed capability (P215/65R15 95V -maximum speed 149 mph). Previous customs included the speed symbol in the size designation only(P215/65VR15) and the speed capability was listed as "above 130 mph". **Any tire with a speed capability above 149 mph, at the tire manufacturer's option, include a "ZR" in the size designation (P275/40ZR17). If a service description IS NOT included with the size description, the tire manufacturer must be consulted for the maximum speed capability(P275/40ZR17-- speed capability is >149mph). If a service description IS included with the size description, the speed capability is limited by the speed symbol in the service description (P275/40ZR17 93W = maximum speed 168 mph) Light truck tires are not speed rated. Speed rating passenger tires originated in Europe, where highway speeds can exceed 100 mph. The speed rating indicates the maximum speed a properly inflated tire will withstand for a determined time. Testing for speed rating certification is conducted in a laboratory setting. This rating system applies to all tire makers.