Be tire smart and never mix and match tires with different speed ratings on your vehicle. Doing so will cause serious problems with the handling of your vehicle. But… if you’re like most of us, you probably don’t know what a speed rating is. It’s time we found out.
What Are Speed Ratings?
Speed ratings are set by the tire manufacturers based on U.S. government standards. Ratings offer a regulated way to compare how well a tire handles.
The ratings range from A to Z, with A being the lowest rating and Z being the rating for a tire that can handle maximum speeds of 149 mph or better. In theory, the higher the letter the better the grip and better the stopping power of the tire. Conversely, the higher the letter, the faster the tread on the tire will wear and the sooner you’ll have to replace your tires.
You can find the speed rating for your tires on the sidewall of the tire. It’s that letter than follows the tire size. According to Michelin, speed ratings originated to judge which tires could perform well on Germany’s no-holds-barred Autobahn.
Not all letters are used often. Commonly found ratings include L for light trucks and off-road use, M and N for spare tires, S and T for family sedans and vans, H for sports sedans, V and Z for sports cars, and W and Y for exotic sports cars. You’ll sometimes see tires with two letters, such as HR or VR. The second letter indicates the tire is a radial tire and has nothing to do with the speed.
Speed ratings are required on all tires that were manufactured since 1991. Generally speaking, the higher the speed rating and the larger the tire, the more it will cost. You can comparison shop for cheap Goodyear tires, for example, with a more expensive model of the same brand, and it will likely have a higher speed rating.
The type of tire you need for your vehicle depends on several factors, including how you drive and the type of vehicle you own. Generally, you’ll want a higher speed rating on your tires if you do a lot of highway, high-speed driving. For an SUV that you use to run errands in town and take the kids to school, H-rated tires are probably sufficient.
Why Mismatched Tires Are Undesirable
Having tires with different speed ratings can dramatically affect the handling of your car. Your car’s handling will drop to accommodate the lowest speed rating of tires on your car. In addition, having tires in the front of your car with a lower speed rating than those in the back of your car can lead to over-steering, a situation where the vehicle turns more sharply than is directed by the driver.
Knowing your tires’ speed rating is just a part of being a knowledgeable consumer and car owner. Such understanding can also help you better choose the tires that are best-suited for the way you drive your vehicle and not just settle for the tires the tire company wants to sell you.