The tyre size can be found on the tyre sidewall. This marking is standardised in accordance with the ECE-R 30 regulations in force in Europe.
205 - tyre width. The main value shown on the sidewall of a tyre is its width. Manufacturers state it in millimetres and increase in 10 mm increments, hence the tens in differences between sizes such as 175/65 R14, 185/65 R14, 165/70 R14 ( this is , ofcourse, the first number). The width of a tyre does not usually coincide exactly with the information on the tyre marking, it depends mainly on the manufacturer of the model. The number 165 indicates to the user that the tyre is 165 mm wide. In other words, there is a 165 mm gap between one extreme point on the outer sidewall and the other most distant point on the inner sidewall. This dimension is called the cross section width of a tyre.
60 - aspect ratio. The second value in the tyre size record is the tyre profile indicator. It illustrates a percentage of the sidewall height in relation to the width of the tyre. Thanks to this, we can find out what percentage of the width of a product is its profile. Using the example of size 165/70 R14, a profile with a value of 70 means that the height of profile is equal to 70% of the 165 mm width, i.e. exactly 115.5 mm. The smaller values for the profile of the tyre size do not exceed 50 and apply to so-called low profile tyres. If you consider high profile tyres, you will notice that most tyres do not have a profile indicator, so a tyre with an 80% profile may have a designation that looks like 165 R13.
R - refers to tyres of radial construction. Radial tyres have a body with layers of fibres radially distributed at right angles. The letter R is intended for the group of radial construction tyres, it can also be found in the exemplary size of 165/70 R14. In this type of tyre, the carcass layers run radially from the theoretical centre of the wheel. The radial tyre model discussed is the most frequently purchased tyre in the world, covering 98% of all tyres sold.
The number 16 indicates the diameter of the rim, on which a given tyre should be installed; it is given in inches.