SMART FORTWO CABRIO Operating Instructions Manual page 248

Tyres and wheels
Tyre condition
Check tyres at regular intervals, e.g. for:
external damage,
ageing,
foreign bodies in the tread,
cracks, bulges,
one sided or irregular tread wear.
Tyre tread
Do not undercut the minimum tread depth
of 3 millimetres for summer tyres and
4 millimetres for winter tyres.
Along with increasing tyre wear, the tyres'
grip and car's handling characteristics
deteriorate, particularly on wet or snow
covered roads. You should therefore
change tyres before they undercut the
minimum tread depth.
You should measure the tread depth with a
tread depth gauge, available from a qual
ified specialist workshop such as a smart
center.
246 Communications breakdown
Wear indicators integrated into the edge
of the tread provide an additional visual
sign as to whether the tyres need to be
changed or not. These indicators, howev
er, do not form narrow, continuous pat
terns until the depth of the remaining
tread to the base of the tread groove has
reached 1.6 millimetres (1/16 in). If you
can see this indicator, the tyre must be
replaced without delay.
Accident risk!
Always make sure the tyre tread is
adequate. Too shallow a tyre tread will
reduce the tyres' grip considerably and
increase the risk of aquaplaning on wet
or slushy roads and at high speeds. The
tyre's tread will then no longer be able
to cut through the water. You could lose
control of your vehicle, cause an acci
dent and injure yourself or others.
Accident risk!
Note that cracks, bulges or exter
nal damage could cause the tyre to
burst. You could lose control over your
vehicle as a result, cause an accident
and injure yourself or others. All tyres
exhibiting such defects must be re
placed without delay.
Tyres continue to age even if they are
used little or not at all. The operating
safety and roadworthiness of all tyres
gradually decreases. You should there
fore replace tyres that were manufac
tured more than six years ago.
The date of production is indicated in the
DOT number, which is displayed on the
side of every tyre. Since 2000, the last two
digits denote the tyre's year of produc
tion, preceded by two digits indicating the
tyre's week of production (WWYY).