Passenger Tire Service Description

Most tires today have a service description branded on the side wall after the tire size. This service description consists of two parts: The load index and the speed symbol. The load index is a number usually between 75 and 115, which defines tire's load capacity at maximum inflation. Higher numbers mean greater load capacity. The speed symbol is a letter usually between P and Z. which defines the speed capability of the tire. In the past, this letter might have been part of the tire size; this continues to be the case with Z rated tires. Tire companies have charts which define equivalent loads and speed for all load indexes and speed symbols that make up the tire service description.

NOTE: When replacing tires, never install a tire that is a smaller size or lesser speed rating than that used as original equipment. The speed ratings only apply at the tire's full pressure. An under-inflated tire will not meet its speed rating capability.

The chart below shows the common speed rating on tires.
Speed Symbol Maximum
S 160 km/h (112 mph)
T 190 km/h (118 mph)
U 200 km/h (124 mph)
H 210 km/h (129 mph)
V 240 km/h (149 mph)
Z Over 240 km/h (Over 149 mph)