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Dimension designation for tyre

Designations for tyre dimension, load index and speed rating.

The car has an approval for the complete vehicle with certain combinations of wheel rims and tyres.

Designation of dimensions

All tyres have a designation of dimensions, for example: 245/45 R19 98 W

245Tyre width (mm)
45Ratio between tyre wall height and tyre width (%)
RRadial ply
19Rim diameter in inches
98Codes for the maximum permitted tyre load, tyre load index (LI)
WSpeed rating for maximum permitted speed, speed rating (SS). (In this case 270 km/h (168 mph).)

Load index

Each tyre has a certain capacity to carry a load, a load index (LI).

Speed rating

Each tyre can withstand a certain maximum speed. Tyre speed rating, SS (Speed Symbol), must at least correspond with the car's top speed. The table below shows the maximum permitted speed for each speed rating (SS). The only exception to these regulations is winter tyres1, where a lower speed rating may be used. If such a tyre is selected, the car must not be driven more quickly than the tyre is rated for. For example, cars with Q rating tyres must be driven at speeds not exceeding 160 km/h (100 mph). The road conditions and applicable road traffic rules determine how quickly the car can be driven, not the speed rating of the tyres.


The maximum permitted speed is specified in the table.
Q160 km/h (100 mph) (used only on winter tyres)
T190 km/h (118 mph)
H210 km/h (130 mph)
V240 km/h (149 mph)
W270 km/h (168 mph)
Y300 km/h (186 mph)


The lowest permitted tyre load index (LI) and speed rating (SS) for the tyres for each respective electric motor variant are shown by the specifications. If a tyre with too low a load index or speed rating is used, it may overheat and be damaged.
  1. 1 Both those with metal studs and those without.