The speed rating of a tyre is displayed on the sidewall. You will find it at the end of the tyre's size. It is always represented by a letter - in the following example the tyre speed rating is "V".
Speed ratings are based on tests in which engineers run the tyre at 6.2 mph steps, in 10 minute increments, until the required speed has been met.
Tyre Speed Rating Table
The following is a table with each speed rating: