Your Guide to Tire Speed Ratings
When most people purchase tires, they are usually concerned about price, size and how many miles they might last. People don't pay much attention to the speed ratings of the tires. However, the speed rating should be a crucial part of the section process when you are buying new tires.
What Are Tire Speed Ratings?
When tire speed ratings were first developed in Europe, they were meant to match the speed capability of tires with the capability of the vehicles they were fitted on. This was especially important on Germany's speed limitless Autobahns. If the tires in question exceeded their maximum speed capability by a large amount, they were at risk of failing in a catastrophic manner, causing serious risk to the safety of both driver and passengers. Today, speed ratings are used to inform both automakers and vehicle owners of the maximum speed capability of their tires.
How Are Speed Ratings Measured?
The tire manufacturers rely on a series of controlled laboratory tests to verify the set maximum operating speed for a specific tire. The tire manufacturer sets a maximum operating speed based on several factors including the application of the tire, the compounds used to create it, and the probability of failure at speeds deemed excessive for the tire. Speed ratings are verified by running tires at ever-increasing speeds, in 6.2 mph steps in 10-minute increments. Engineers place a large diameter metal drum against the tire during the test to simulate the appropriate load. The test continues until the manufacturer achieves the desired speed rating for that particular tire.
|Speed Rating||Max Speed (mph)|
How Speed Ratings Affect My Tires' Performance
Speed ratings are merely a formal indicator of the top speeds the tires can safely handle. In other words, they themselves don't affect the performance, but simply measure it. You can find the speed rating recommended for your vehicle in the owners manual. As a safety precaution to the driver and occupants, the maximum operating speed of the vehicle is usually limited to the lowest speed rating given for the tires fitted on the vehicle.
How to Find My Tires' Speed Rating?
Speed ratings are included on the sidewalls of nearly every tire made in the United States, Canada, Europe, and other parts of the world. The rating is included within a special alphanumeric code that also denotes the tire's width, sidewall height, and wheel diameter size. This code appears on the sidewall in one of the following formats, with "S" denoting the speed rating:
- 225/50SR16 89S
- 225/50R16 89S
Each speed rating is assigned an alphabetical letter, ranging from "L" for the lowest rated tire (75 mph) to "Y", reserved for extreme sports cars capable of speeds over 186 mph. Most family sedans use ratings "P" (93 mph) through "T" (118 mph) for family sedans, vans, and light-duty trucks. Sports sedans and coupes regularly use "V" rated tires (149 mph) created from performance-oriented compounds.