1 Cross section width
The first three numbers, in this case 195, refer to the section width of the tyre. This is the measurement, in millimetres, from the tyre’s inner sidewall to its outer sidewall.
2 Aspect ratio
The aspect ratio, or profile, refers to the height of the sidewall as a % of the section width. In our example, 55 means the height is equal to 55% of the 195mm width. The bigger the aspect ratio, the bigger the sidewall will be.
3 Construction type
The letter R means the tyre is a radial construction. Almost all new car tyres are radials.
The number to the right of the construction type is the rim diameter, measured in inches. In this case, it’s a 16” wheel.
5 Load index
The final number is the load index i.e. the maximum load (in kg) that the tyre can carry. See chart below