1.  The first number (205 in this example) is a three-digit number which refers to the overall width of the tire, in millimeters

2.  The second number (55) refers to the aspect ratio, which is the relationship between the tire's height and its width. In this example, the sidewall's height is about 55% ofthe tire's width

3.  The letter following the aspect ratio is usually an "R," standing for "radial"

4.  The next number indicates the diameter of the wheel rim on which the tire will fit (16 inches, in this example).

5. The final number and letter represent the load index and speed rating. The load index is an assigned number ranging from 0 to 279 corresponding with the load carrying capacity of the tire-that is, how much weight it is certified to carry at maximum inflation pressure. The rating can be matched against a load index chart to determine corresponding maximum weights.

6. The speed rating is a letter which indicates the range of speeds at which a tire is certified to carry a load (see the speed symbols chart to determine your tire's maximum speed). Each tire is assigned a rating from A (lowest) to Z (highest) with one notable exception: the "H" rating falls out of sequence between "U" and "V" and is used for tires certified for speeds up to 130 mph. The "Q" rating is the lowest, commonly used for passenger cars. A "V" rated tire is certified up to 240 km/h or 149 mph.

It's important to note that markings do not always appear exactly as they do in this example, as tires can be certified under a variety of designations.