Ever wondered what do all those numbers on your car tire’s wall indicate? Here is a simple explanation for those weird looking code.
For example, if you have P215/45R17 87V written on your tire, it translates to the following:
P = Intended use of the tire is for Passenger vehicles. (Read more on Tire intended use below)
215 = Width of the tire in millimeters i.e. 215 millimeters (Width as in what you get to see when you view your car tire from behind the car)
45 = The tire width to tire wall height ratio. i.e. 45% of the width will be the tire wall height (Wall height is the distance from rim edge to outer edge of the tire)
R = Indicates that it is a Radial tire.
17 = Diameter of the rim in inches.
87 = Load index of the tire (or the maximum weight that this tire can hold under the prescribed pressure)
V = Speed rating of the tire (or the maximum speed at which your car can move while on these tires)
Isn’t it weird that some of the numbers above are in metric units while others aren’t?
Intended use codes
We just mentioned that P stands for Passenger car. Similarly there are codes like LT for Light Truck, C for Commercial, ST for Special Trailer and T for Temporary spare tire purpose.
Tire load index chart and tire speed rating codes
If you want to know the complete set of load index numbers and tire speed rating codes, please refer to this Wikipedia page.
Load index code represents the load that ONE tire can take. Obviously, if that tire is fitted on a car that has four wheels, 4 times that value will be the maximum load that those tires can take under standard prescribed tire pressure. Similarly, you might want to look at the speed rating while changing tires next time.