Every tyre has a sidewall marking – such as 185/70 R14 80 T – which identifies its size and characteristics. These markings can be analysed as follows:
185 The width of the tyre in millimeters.
70 The aspect ratio – this is the ratio of the tyre’s width to its height or ‘sidewall’. A ’70 series’ tyre is a tyre whose height is equal to 70% of its width. Low profile tyres have shallow sidewalls and correspondingly low aspect ratings.
R This denotes the tyre’s construction type – in this case it’s a radial. An R rated tyre should not be driven above 170km/h (106mph). A V rated tyre, by contrast, is capable of speeds of up to 149mph.
14 The diameter of the wheel rim in inches
80 Load index – this represents the maximum load capacity of a tyre when it’s driven at maximum speed. A tyre with a Li of 80 can bear a maximum load of 450kg.
