Ferrari 458 Spider Owner's Manual page 29

Correct reading of tyre manufactured in the EU
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Example: 235/35 ZR20
235 = Nominal width (distance in mm from side to side)
35 = Height/width ratio as a percentage
Z = Tyre to be used for speeds of over 240 km/h (149 mph)
R = Radial tyre
20 = Rim diameter in inches
W = Tyre that supports a maximum speed of 270 km/h
The tyre manufacture date is included in the description of the tyre:
DOT ... 1009 means that the tyre was manufactured in the 10 week
th
of 2009.
Correct rim reading
Example: 8.5" J x 20"
8.5 = Rim width in inches
J = Shape of rim flange
(side projection where tyre bead rests)
20 = Rim diameter in inches
(corresponds to the diameter of tyre to be fitted)
For further information on tyres, see page 235.
General
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