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WHEELS AND TYRES
525
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 dimension designation, such as:
235/60 R18 103 V.
235 Tyre width (mm)
60 Ratio between tyre wall height and tyre
width (%)
R Radial ply
18 Rim diameter in inches
103 Codes for the maximum permitted tyre
load, tyre load index (LI)
V Speed rating for maximum permitted
speed, speed rating (SS). (In this case
240 km/h (149 mph).)
Load index
Each tyre has a certain capacity to carry a load, a
load index (LI). The car's weight determines the
load capacity required of the tyres. The lowest
permitted load index is specified in a load index
table.
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 per-
mitted speed for each speed rating (SS). The
only exception to these regulations is winter
tyres
3
, where a lower speed rating may be used.
If such a tyre is chosen, the car must not be
driven faster than the speed rating of the tyre (for
example, class Q can be driven at a maximum of
160 km/h (100 mph).) The top speed at which
the car can be driven depends on road condi-
tions, not the speed rating of the tyres.
NOTE
The maximum permitted speed is specified in
the table.
Q 160 km/h (100 mph) (used only on win-
ter tyres)
T 190 km/h (118 mph)
H 210 km/h (130 mph)
V 240 km/h (149 mph)
W 270 km/h (168 mph)
Y 300 km/h (186 mph)
WARNING
The lowest permitted tyre load index (LI) and
speed rating (SS) for the tyres for each
respective engine variant are shown in the
table, "Load index and speed rating". If a tyre
with too low a load index or speed rating is
used, it may overheat and be damaged.
Related information
•
Tyres (p. 504)
•
Dimension designation for wheel rim (p. 524)
•
Approved wheel and tyre sizes (p. 593)
•
Approved tyre pressures (p. 595)
•
Load index and speed rating (p. 594)
3
Both those with metal studs and those without.
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