Where to Find the Speed Rating on a Tire
Locating a tire's speed rating starts with the sidewall, where the complete tire size code ends in a letter that indicates the maximum speed capability for that construction. Many drivers miss this letter because it sits at the end of a long alphanumeric sequence that also includes width, aspect ratio, rim diameter and the load index. Reading the full sidewall inscription correctly matters when replacing tires, changing wheel sizes, or confirming that the installed rubber matches the vehicle placard and intended driving conditions.
Essential answer
The essential answer is that the speed rating appears on the tire sidewall as the final letter of the service description, immediately after the load index number. A typical marking such as 225/45R17 91W ends with W, which is the speed symbol for that tire. The letter is not a separate stamp hidden elsewhere; it is part of the tire size and load information molded into the rubber. Reading the full sequence from left to right makes the speed rating easy to distinguish from the width, profile and construction codes that precede it.
This marking describes a laboratory-tested maximum speed under controlled conditions, not a recommended cruising speed. The rating reflects the tire's ability to dissipate heat at sustained velocity. When drivers replace only one axle, mixing a lower speed symbol can reduce the vehicle's overall capability below the original equipment specification. The sidewall service description therefore acts as a quick compatibility check against the automaker's chosen tire performance envelope.
Identification and location
On most tires, the speed symbol is located on the outward-facing sidewall, but some directional or asymmetric designs print the full size and service description on only one side. If the letter is not immediately visible, checking the opposite sidewall or rotating the wheel slightly may reveal the molded characters. The speed rating follows the load index directly, so finding the two- or three-digit load number provides a reliable landmark for locating the letter at the end of that grouping.
The vehicle placard, usually found on the driver's door jamb, glovebox lid or fuel filler door, lists the original tire size, load index and speed symbol specified by the manufacturer. Comparing the placard with the sidewall helps identify whether the installed tires match the vehicle configuration. When aftermarket wheels or tires are fitted, the sidewall remains the authoritative location for the actual mounted component's rating, while the placard records what the original equipment required.