Though it is important to have your tires serviced as necessary. Many people don't understand what the numbers mean that can be found on the site of the tire. It is common to be asked what they are when you call around to get replacement quotes, but have you ever taken the time to understand their meaning? Lake City Auto Care strives to educate our customers when they have questions. When you make the call for your next tire service, here is some information that breaks down what each number means.

1. First Letter indicates car-type for the tire.
Options would be P, which stands for passenger, no P indicating metric sizing (essentially the same as P-sizing) or LT for light truck. LT tires are designed for heavier loads and more rugged service conditions.

2. Width of the tire.

The higher the number, the wider the tire. Measurements are taken in millimeters.

3. Aspect ratio.
The height of the sidewall section compared to the width of the tire. For example, the picture above shows the aspect ratio being 65. To understand what difference in aspect ratio often times means is short sidewalls deliver crisp handling while 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 mphU = 124 mph
P = 93 mphH = 130 mph
Q = 99 mphV = 149 mph
S = 112 mphZ = 150+ mph
T = 118 mphW = 169 mph
y = 188 mph

It is recommend that the replacement tires match the speed symbol of the original tires since these match the speed capability of the vehicle.

Contact us today to schedule your next appointment.

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