Tire Class – P
The first character(s) in a tire size designate the tire’s class. In this example, “P” indicates that the tire is a passenger car tire. An “LT” before the tire size designates a light truck tire, and no letter before the size indicates that it is a European metric tire.
Section Width – 205
A metric tire’s section width is measured in millimeters. This measurement is taken from sidewall to sidewall. In this example, the section width of the tire is 205mm.
Aspect Ratio – 65
This number refers to the height of the sidewall. It is a percentage of the section width. In this example, 65 percent of the section width of 205mm equals 133.25.
Tire Construction – R
The “R” in this example indicates radial tire construction.
Wheel Diameter – 16
This indicates the wheel diameter in inches.
The linear distance between the outside of the sidewalls of an inflated tire without any load on it (this does not include any sidewall decorations).
This is also known as the Section Height. This is figured as a percentage of the section width. A tire size of 205/60R15 would have a section width of 205 millimeters and a section height of 60 percent of 205 millimeters.
The width between the flanges of the wheel (the part the bead of the tire touches).