The tyre size is located on the tyre sidewall and consists of 4 parts. Sample size 205/40 R17 describes the most important parameters that are necessary for drivers when selecting tyres for a car.
Tyre width – it is a key value which is provided at the beginning of the sequence of characters and is expressed in millimetres. Tyre widths change every 10 millimetres, so we have such models as: 205/ 215/ 225/. The tyre width is the distance from the extreme point of the outer sidewall and the furthest point of the inner sidewall.
Aspect ratio - this is the second value describing the tyre parameters; it indicates the profile height i.e. the percentage ratio of tyre sidewall height to tyre width. Using the example, with a tyre size of 205/40 R17, a profile of 40 should be noted, so the profile height is nothing more than 40% of the model width of 205 mm.
Tyre type – available in two variants, R - radial and D - diagonal.
Rim diameter - this is a value expressed in inches.