How to interpret sidewall markings on tyres:

1. The sequence of numbers and letters on your vehicle’s tyres make up the tyre size code. This information can be broken down in the following way 

    

1)   Tyre Width – The first 3 numbers of the tyre size represent the width of the tyre. This is measured in mm from sidewall to sidewall. For example, a tyre size of 195/65R16 would measure 195mm across the width. 

2)  Profile – The profile of the tyre refers to the height of the sidewall which is measured as a % of the tyre’s width. For example, if your tyre size is 195/65R16, the profile of 65 is equal to 65% of the 95mm width. 

3)  Tyre Construction – The letter ‘R’ means that the tyre is of radial construction. This method of construction is used by most tyre manufacturers today. Some fewer common constructions are ‘D’ for diagonal and ‘B’ for Bias Belt.  

4)  Rim Diameter – The rim diameter refers to the size of the alloy or steel rim in inches.  

5)  Load Index – The load rating on a tyre is essentially the maximum weight a tyre can carry when the tyre is inflated to its recommended pressure. 

Take a look at the table below which shows the weight each index specification can carry: 

6)  Speed Rating Index – A tyres speed rating indicates the top speed a tyre can perform at under optimal conditions.  

For example, a tyre with a speed rating of H can perform at speeds up to 130mph. This is only under optimal conditions. This may not be the same where road surfaces are comprised by snow, rain etc…