P = Passenger Car Tire
P designates this tire as a passenger car tire. An LT before the tire size would mean the tire is a light truck tire.
245 = Section Width Tread (mm)
Width of the tire from one sidewall to the other measured in millimeters. For example the tire is 245 millimeters wide.
45 = Aspect Ratio (Ratio of Sidewall height to width)
The aspect ratio refers to the height of the sidewall. It is a percentage of the section width. For example, the sidewall height is 45% of the 245 section width which equals 127.5.
Z = Speed Rating S = 112mph T = 118mph
Speed rating designates the maximum speed at which a properly installed and inflated tire can be driven on. For example, the speed rating is Z which means it has the highest speed rating. Z rated tires will also have a W or Y speed rating indication after the load index which denotes the actual mph the tire is rated for.
R = Radial Construction
In this example, the R designates this tire as a radial tire. Radial tires have layers of fabric whose cords run at right angles to the circumference of the tire and whose tread is strengthened by additional layers around the circumference making it the most common type of automotive tire.
19 = Wheel Diameter (inches)
Wheel Diameter specifies the size, in inches, of the wheel that a tire fits. For example, the tire will fit a 19 inch wheel.
98 = Load Index
Load Index indicates the maximum load carrying capacity of the tire. It is very important to only install tires with a load index that meets or exceeds your vehicle manufacturer’s specification.
W = Speed Rating
Speed rating designates the maximum speed at which a properly installed and inflated tire can be driven on. For example, the speed rating is W which means it can be driven at speeds up to 168 mph.