What Do the Numbers Stand for on a Car Tire?

All tires have a series of numbers and letters located on the sidewall. When you go shopping for tires it would be a good idea to have knowledge about them in order to purchase the proper replacement. The workers at the tire shop know the significance of this alphanumeric code, but you may want to change brands or even the series and thorough knowledge would help to know what it is that you are looking to change to.

Each vehicle that you own may have a different series of numbers, but the formation is the same. An example of what a basic car may read is: "P185/60R 14 82H".

• The first letter indicates the type of vehicle that the tire was designed for. In this case, the tire is for a passenger car. Some other variations could be “LT” for a light truck, “T” for a temporary or spare tire.


• The next set of numbers, “185”, in this label, is the width of the tire. This number will always be listed in millimeters. Shorter or even narrower tires have a lower number. The wider the tire, the higher the number will be.


• The number that follows behind the forward slash is the tire’s aspect ratio. In other words, the tire’s height is a percentage of the width (The tires height is 60 percent of the width). The aspect ratio is important because if you decide to move to a larger tire, or even a smaller one, you will want to make certain that your vehicle has the accurate sidewall height in order prevent any alignment changes that are unwanted.  The aspect ratio or sidewall height, affects the feeling you get when you are simply turning your steering wheel.


• "R" represents the speed rating of the tire, and in this case, the "R" is for radial. Most cars will be radial, unless you have a sports car or even a classic car. Another example of the speed rating is "VR.” "VR" is for V-rated radial and would be labeled to classify cars that have a speed rating over 149 mph (miles per hour). The number fourteen that follows represents the wheel rim's diameter in inches.


• The Maximum Load-Carrying Capacity chart was designed to keep you informed on how much vehicle weight could four tires support. The next number is the series, "82," according to the chart, will support a vehicle weighing 4,188 pounds.


• Finally, the last letter stands for the amount of traveling speeds the tires can endure. This particular tire can sustain up to 130 mph. The faster you travel the hotter your tires become, and the threads on tires can separate. This last letter tells you how fast you can go and remain safe.