Tread Depth; Tyre Designations - Vauxhall Corsa Owner's Manual

Tread depth

Check tread depth regularly.
Should the front tyres show greater wear
than the rear tyres, have both front wheels
exchanged with the rear wheels so that
the tyres with deeper tread are on the
front axle.
For reasons of safety, tyres should be
replaced when their tread depth has worn
down to 2 to 3 mm (winter tyres: 4 mm).
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The legally permissible minimum tread
depth (1.6 mm) has been reached when
the tread has worn down as far as one of
1)
the wear indicators (TWI ). A number of
wear indicators are spaced at equal
intervals around the tyre within the tread.
Their position is indicated by markings on
the tyre sidewall.
General information
z The risk of aquaplaning is greater if the
tyres are worn.
z Tyres age, even if they are used only very
little or not at all. A spare wheel which
has not been used for six years should be
used with care.
1)
TWI T W I
= read ear ndicator.
z Never fit used tyres the previous history
and use of which you do not know.
z So as not to impair brake cooling, use
only wheel trims approved for use on
your vehicle.

Tyre designations

Meanings:
e.g. 155/80 R 13 79 T
155 = Tyre width in mm
80 = Aspect ratio in %
(tyre height to tyre width in %)
R = Belt type: Radial
13 = Wheel diameter in inches
79 = Load index
e.g.: 79 corresponds to 437 kg
T = Speed code
Speed code letters:
Q Up to 100 mph (160 km/h)
S Up to 112 mph (180 km/h)
T Up to 118 mph (190 km/h)
H Up to 130 mph (210 km/h)
V Up to 150 mph (240 km/h)
W Up to 168 mph (270 km/h)