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Reading Your Tire
Being able to read and comprehend the information printed on a tire's sidewall will make it easier for you to understand your tires and assist you in choosing a replacement set. |
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Tire Sizing System |
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On the sidewall of a tire, its size, performance, etc. are shown by using numerical symbols.
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Below is an example of lSO notation of a radial tire: |
Tire Service Description |
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| Many tires come with a service description added on to the end of the tire's size. These service descriptions contain a two-digit number (load index) and a letter (speed rating). The LOAD INDEX is a numerical code associated with the maximum load a tire can support. The higher the tire's load index number, the greater its load carrying capacity. The SPEED SYMBOL indicates the maximum speed at which the tyre can carry a load corresponding to its Load lndex under service conditions specified by the tire manufacturer. |
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Tire Aspect Ratio |
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| The aspect ratio of a tire is determined by dividing a tire's section height by its section width when the tire is: Inflated to maximum air pressure, Mounted on the approved measuring rim, and under no load. High performance tires usually have a lower aspect ratio than other tires. This is because tires with a lower aspect ratio provide better lateral stability. When a car goes around a turn lateral forces are generated and the tire must resist these forces. Tires with a lower profile have shorter, stiffer sidewalls so they resist cornering forces better. |
 As the lowering of the profile of a tire increases the cornering force, it can be regarded as an improvement to the tire's handling performance. In addition, as the lowering of the tyre profile decreases the section height and increases the wheel diameter of the tyre even when the outside diameter is not changed, it can also be regarded as an improvement in the visual appeal of the tire. |
