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How to read the size of your tyres

Not sure the tyre size your vehicle requires? This may help...

Jamie Cartwright avatar
Written by Jamie Cartwright
Updated over 3 years ago

Your tyre size is always written as a sequence of numbers and letters on the tyre sidewall. In the example below we will use a tyre size 185/55 R15 81H – which can split into 5 parts:

  • Width (185) – the width of your tyre in millimetres

  • Profile (55)- This is the size between wheel rim and the top of the tyre, measured as a percentage of the tyre width

  • Tyre size (R15) – This is the diameter of the rim in inches

  • Load index (81) – this refers to the load capacity in kilograms of the tyre. This number is an index, with the number referring to a KG load.

  • Speed index (H) – this refers to the maximum speed the tyre can be safely driven at. This letter is an index, with the letter referring to a KPH speed.

For more information on reading the information on your tyre watch this video click here.

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