When purchasing or replacing tyres, it is necessary to familiarise oneself with the sequence of characters visible on the sidewall of each model. It looks like this: 205/45 R17. The first number is the cross section width measured between the tyre sides in millimetres.
The second part is the height of profile (aspect ratio), i.e. a percentage to tyre width, e.g. 55 is 55% of 205, i.e. 112.75 mm. ”R” indicates the tyre type (R - radial, D - diagonal). The last number denotes the width of a rim in inches.