Tire speed ratings indicate the top speed a tire can carry a load at under specified conditions, ranging from A to Z which represents speeds from 5/3 to over 300 km/h. The rating system was developed in Europe and does not reflect total performance, only certified top speed. As manufacturer's produced tires that exceeded the original top rating of 210 km/h, higher limited speed categories like V (250 km/h) and Z were added. Tire designations now include the speed symbol and load index as the service description, like 205/60R15 91V, with "ZR" indicating tires capable of over 300 km/h. Consult manufacturers for maximum speeds of unlimited ZR tires or when no service description

1. Tire Speed Rating Explained
What Is Meant by Speed Rating?
The speed rating of a tire indicates the speed category (or range of speeds) at which the tire
can carry a load under specified service conditions. The speed rating system used today was
developed in Europe in response to the need to control the safe performance of tires at
standardized speeds. A letter from A to Z symbolizes a tire’s certified speed rating, ranging
from 5 / (3) to above 300 km/h (186 mph). This rating system, listed below, describes the
top speed for which a tire is certified. It does not indicate the total performance capability
of a tire.
When this speed rating system was originally developed, the Unlimited V category of over
210 km/h (130 mph) was the top speed rating a tire could achieve.
As manufacturers made more tires that did not fit this category, it was necessary to better
regulate performance at standardized speeds to ensure safety. The Limited V category of
250 km/h (149 mph) was then created, and the Z speed rating was added as the top speed
rating that a tire could achieve. W and Y limited speed symbols have been added as higher
speed categories.
Always consult the manufacturer for the maximum speed of Unlimited Z tires. Speed rating
is identified as a part of the tire’s sizing or service description.
In the latest attempt to standardize tire designations, all ratings except Unlimited ZR
incorporate the speed symbol and load index as the tire’s service description. For example:
205/60R15 91V
205 = Section Width in Millimeters
60 = Aspect Ratio
R = Radial Construction
15 = Rim Diameter in Inches
91 = Load Index (Service Description)

2. V = Speed Symbol
When “ZR” appears in the size designation with the service description, the maximum speed
is as indicated by the service description:
Tire Designation Maximum Speed P275/40ZR17
93W 270 km/h (168 mph) P275/40ZR17 93Y 300 km/h (186
mph)
For tires having a maximum speed capability above 240 km/h (149 mph), a “ZR” may appear
in the size designation. For tires having a maximum speed capability above 300 km/h (186
mph), a “ZR” must appear in the size designation. Consult the tire manufacturer for
maximum speed when there is no service description.
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