What does the writing on your tire mean?
At some point, you’ve likely walked through the tire department at an auto parts store, or disappeared into that part of Sears when you were a kid. Have you ever wondered what the letters and numbers on the side of those tires meant? Read on to understand some of the most common features explained by the letters and numbers on the sides of tires.
The first letter in the alphanumeric code used to identify your tire is usually the service designation. In other words, that letter tells you if it’s a passenger vehicle (P), a light truck (LT), or a special trailer (ST).
The three-digit number following the service designation is the width of the tire in millimeters from sidewall to sidewall.
The next number in the code is the aspect ratio. The aspect ratio is the relationship between the width of the tire from the wheel to the tread and the tire width from sidewall to sidewall. For example, if the width of a tire is 215 mm, and the aspect ratio is 65, then the tire's width from the wheel to the tread would be 65% of 215mm or 139.75, generally rounded up to 140mm.
Most tires on the road today are radial tires, indicated by the R on the tire following the aspect ratio number. You may also see tires with a B or a D, meaning bias-ply or diagonal bias-ply.
There are many sizes of tires available for your vehicle. You can check your vehicle’s user manual for the recommended rim diameter tire you should use on your vehicle.
The next number in the code is the load index. The load index tells you how much weight the tire can support. There is a table your tire specialist will have that converts the number on the tire to the maximum weight the tire can support. Ask for help if this is something you want more information about.
The letter following the load index is the speed rating. For example, an H tire can handle speeds up to 130 miles per hour, while a Y tire can handle speeds up to 186 miles per hour. It’s important to remember that because a tire is rated for a high rate of speed, it doesn’t mean the vehicle or the driver is similarly rated.
Putting the correct size and type of tire on your vehicle is an important part of making your vehicle safe to drive and a pleasure to ride in. The experts at AutoStream Car Care would be happy to help you find the perfect tires for your vehicle. If you’re in the Columbia, MD area, why not stop by or make an appointment to speak with their experts today?