how to read the side of your tyre

Young Man Pointing

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without the technical mumble jumble.

If  you are needing to replace an odd number of tyres (1 or 3) we will need to match tyres on the same axle by the same tyre size, load rating (no more than +2 or -2, see below) and same tread pattern. 

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and less tech speak.

If  you are needing to replace an odd number of tyres (1 or 3) we will need to match tyres on the same axle by the same tyre size, load rating (no more than +2 or -2, see below) and same tread pattern. 

The sidewall of a tyre contains a lot of information needed by tyre technicians to keep your vehicle happy, safe and legal.

But what do all these numbers and letters mean?

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1. Tyre Width

In the above picture, 195 is the width in millimeters of the tyre from side wall to sidewall. The above tyre is 195mm from one sidewall to the other.

2. Aspect Ratio or Profile

The next numbers in the above picture, 55, is the measurement in mms of the height from the top of the rim to the top of the tyre, or in more technical terms, the aspect ratio of the tyre. As in this example, the tyre has an aspect ratio of 55, so would have a height equal to 55% of its width.

3. Tyre Construction

The letter R represents how the tyre is constructed. The letter R means that the tyre has radial construction where the internal ply cords extend across the tyre from bead to bead in a radial direction.

4. Rim diameter in inches

The rim diameter, 16 in the above example, is the width of the rim in inches from outside lip of rim to outside lip.

5. Load Rating

This number is particularly important as it tells you the maximum capacity of your tyre when it is inflated to its maximum safe pressure. In the above example, 87, refers to the index rather than the weight. You can copy this website address and paste it into you browser,  https://www.tyresizecalculator.com/charts/tire-load-index-chart  to find a load index table which will determine the load in kg for each rating. In this example, the load index of 87 has a maximum load weight of 545kg per tyre. If the load rating is 87, the tyre on the same axle can not be more than 89 or less than 85.

6. Speed Rating Index

This number denotes the maximum speed a tyre can sustain when it is correctly inflated and under load. As with the load index, this letter references a look-up table which indicates the maximum speed of a tyre. You can copy this website address and paste it into you browser,  https://www.tyresizecalculator.com/charts/tire-speed-rating-chart  to find a speed index table which will determine the speed in kmph for each rating. In the above example the speed rating is V and has a maximum speed of 240kmph under load.