Car tire numbers are explained using the letters and numbers printed on the side of the tire. These numbers tell you the tires purpose, the complete dimensions, the total load/weight capacity, speed rating and more. These specifications are referred to as the tire code. The specs on the sidewall of your tires will always include the tire size, radial construction, the type of vehicle the tire was made for, speed rating, and PSI inflation rating. The PSI inflation rating specifies the maximum PSI that the tire can safely hold. Tire specs also include something called load rating. This is important for hauling or towing a trailer. Read below for a complete tire guide.
Car tire numbers explained – Tires will have something similar like this printed on the side of it: P215/65R17 95H
The first letter means type of tire for certain vehicles.
P = Passenger vehicles tire
T = Truck vehicles tire
The 3 digit number (215) is the Width. This number refers to the tire width in millimeters. It is measured in millimeters from sidewall to sidewall.
The 2 digit number (65) is the Aspect Ratio. It is the ratio of the height of the tire’s cross-section to its width. The number 65 means the height is equal to 65% of the width of the tire.
The letter (R) stands for Radial. This means the layers run radially across the tire.
The number (17) is Wheel Diameter. It is the size of the wheel measured from one end to the other. It tells you the size of the wheel that the tire is intended to fit on.
The next number (95) is the Load Index. Load Index shows the maximum load that the tire can support when inflated properly. You can also find the maximum load on the tire sidewall in both LBS pounds and KG kilograms.
The last letter (H) identifies the Speed Rating. The speed rating tells you the maximum speed capability of a tire. A tire with an H speed rating has a maximum speed capability of 130 mph.
Here is a chart that will identify your tire speed rating. The last letter on your tire will be one of the letters below:
M = 81 mph
N = 87 mph = Spare Tires
P = 93 mph
Q = 99 mph = Winter Tires
R = 106 mph = Truck Tires
S = 112 mph = Cars and Minivans
T = 118 mph = Cars and Minivans
U = 124 mph = Sport Performance Cars
V = 149 mph = High Performance Cars
W = 168 mph = Ultra High-Performance Cars
Y = 186 mph = Ultra High-Performance Cars
If you are curious, the most common tire size is the R15. The most common tires used with the R15 size are the P235/75R15, P205/65R15, and the P215/70R15. An R15 tire is fitted with a 15-inch rim. The P tire variant is the most common R15 tire. This tire is made and designed for normal average passenger vehicles. The R16 is a bigger version of the R15 tire. The most popular variant of this tire is the P225/60R16 and designed for most passenger vehicles.
How To Read Tire Sizes and Specifications