Ever wanted to know what all those
letters and numbers were on you tires? 

Here are the basics!

Tire Class:
The character(s) before the size on the tire designate the tire's class as well as the ply. On the tire below, "P" means that this tire is a passenger car tire and is 4 ply. An "LT" before the tire size would mean it is a light truck tire and is constructed with more than 4 ply. It could be 6 ply, 8,10, 12 etc. 

The load rating on a tire which is typically shown as a letter, will tell you the ply: C = 6 ply   D= 8 ply   E = 10 ply. 
Notice how the number of the letter in the alphabet "C" is the 3rd letter multiplied times 2 = 6.  


Section Width - "215"

The section width is measured in millimeters on a metric tire. It is measured from sidewall to sidewall. The tire below has a width of 215mm.

Aspect Ratio - "65"
The aspect ratio is in reference to the height of the sidewall. It is a percentage of the section width. Using the tire below, 65 percent of the section width of 215mm equals 139.75.

Tire Construction
The "R" on the tire below shows radial tire construction.

Wheel Diameter
This shows the diameter of the wheel in inches.