How to understand tyre sizing
Tyre have a code system moulded into their sidewall which allows you to understand their technical capabilities. This code provides information on tyre size, construction (e.g. radial), its load-carrying capacity and its speed rating.
For example, the code on a common fitment for Australian cars is:
205 indicates the nominal section width of the tyre in millimetres (205mm).
65 indicates its aspect ratio, a comparison of the tyre's section height with its section width (65 indicates the height is 65% of its width).
R indicates radial ply construction.
15 indicates the nominal diameter of the wheel rim (15 inches).
95H is a symbol indicating the maximum load capacity and speed at which the tyre can be safely operated, subject to the tyre being in sound condition, correctly fitted, and with recommended inflation pressures (95 represents a maximum load of 690kg per tyre; H represents a maximum speed of 210km/h).