Have you ever taken a close look at your tires? There’s quite a bit going on there besides just the name brand of the tire. Most tires come marked with a code similar to something like this: P215/65R15.
These tire sidewall markings can actually tell you everything you need to know about your tires! The problem is, if you don’t know what you are looking at, it can just look like a bunch of gibberish.
In order to help you better understand your car and the tires that help make it go, we thought we would break down exactly what it is these codes stand for.
Tire Type (P)
The first position consists of one or two letters, in this case “P,” indicates the vehicle class and the intended use for the tire. The “P” in this case stands for passenger car, meaning this tire is suited for any motor vehicle with four wheels used for transportation that has no more than eight seats.
Other possible designations are “LT” (light truck), “ST” (special trailer) and “T” (temporary). In some cases, your tire may be missing this designation. The absence of the first letter is Euro-Metric and may have slightly different load-carrying capabilities.
Tire Width (215)
The next set of numbers (three digits) before the slash indicate the tire’s width in millimeters. The bigger the number, the wider the tire. Obviously, larger vehicles used for farming, OTR, mining and trucking will need much wider tires to help support the load.
Aspect Ratio (65)
Following the slash, there is next a set of two (in some cases three) numbers indicating the aspect ratio of the tire. The aspect ratio is the sidewall’s normal height, reflected as a percentage of the width. This means that the number (65, in this case) is a percentage.
In this case, the tire’s aspect ratio is 65% of 215, roughly 140 millimeters. If this number is represented by three numbers, it is stating the number of millimeters as opposed to a percentage.
The letter separating the final two sets of numbers indicates the manner of construction of the fabric of the tire. “R,” in this case, stands for radial construction. Other possible letters are “B” (bias belt) and “D” (diagonal belt).
Rim or Bead Diameter (15)
The final number is an indication, in inches, of the diameter of the rim the tire was designed to fit on. The tire in this example was meant to fit a 15-inch rim. The bigger the rim, the bigger the tire.
Hopefully, this helps shed some light and helps you gain a better understanding of your tires! In many cases, there are additional letters, numbers and sometimes symbols that have additional meanings, with the code above being the standard layout. These numbers cover areas such as load and speed indexes and conditional tires.
If you are curious about learning more about your tires, be sure to head to our blog to learn more!