Do-It-Yourself High Performance Car Mods

Tire Sizes

The modern sizing system for tires is a peculiar mishmash of millimeters, inches, and percentages, with several letters thrown in for good measure. They are relatively easy to understand once you know the code, however. Consider a street tire with the size designation P225/50ZR16.

The P in the code stands for passenger car. Many tires leave off this letter altogether. Occasionally, you will see a tire designation starting with some other letters, such as LT for light truck.

The 225 is the approximate width of the tire in millimeters. This is as measured at the widest point, so the tread width will be slightly less. Although the number is given to the nearest millimeter, in reality, the measurement may not be quite that accurate.