If You Don’t Know the Tire Size You Need
Only tires specifically designed for your vehicle should be used. If you prefer a certain brand or require a specific performance category, be sure the tire you choose is consistant with the one recommended for that vehicle.
More about tires:
Q. What do all those numbers mean on the sidewall of the tire?
A. Here’s an illustration that should help you understand more about your tires.
1. P indicates a passenger (car-type) tire.
Other options would be no P indicating metric sizing (essentially the same as P-sizing, which has its heritage in Europe) or LT for light truck. LT tires are designed for heavier loads and more rugged service conditions.2. Width of the tire, in millimeters.
The higher the number, the wider the tire.3. Aspect ratio.
The height of the sidewall section compared to the width of the tire. Example: If this number was a 50, then the tire section is half as tall as it is wide. Short sidewalls deliver crisp handling. Tall sidewalls give a smoother ride. For a specific tire width, the smaller this number, the shorter the sidewall.4. Construction.
R indicates radial construction. Unless you specify the other option, bias (which would have a D [diagonal] or B [belted bias] in this position instead of an R), you are purchasing a radial tire.5. Wheel Size Designation.
In simple terms, this indicates the distance across the “doughnut hole” of a tire. You must match wheel diameter and the tire opening. A tire with a 15 size designation will not work on a 14″ wheel, and vice versa. Improper matching of wheel and tire size can cause serious injury or death during installation.6. Service Description.
Includes the load index (a number) and a speed symbol (a letter). About load index, remember: keep the number the same as or greater than the original tires’ load index. That number stands for a specific weight carrying capability. Key is that the higher the number, the greater load carrying capacity. So keep the number the same or higher, because your tires are matched to the weight of the car. Never choose a tire with a lower load carrying capacity than the original equipment tire size.As for the speed symbol, it means the tire is speed-rated on an indoor test wheel to the following speeds:
|N = 87 mph||U = 124 mph|
|P = 93 mph||H = 130 mph|
|Q = 99 mph||V = 149 mph|
|S = 112 mph||Z = 150+ mph|
|T = 118 mph||W = 169 mph|
|y = 188 mph|