Appendix 3
About
Tyres.
On
our trip we
departed
Sydney with
four European
made tyres
which had
done about
20,000 km.
They were too
new to toss
out, and we
left home
quite
prepared to
renew them
along the
way. Two
tyres
developed
slow leaks
which allowed
air to bleed
along between
the plies and
escape some
centimetres
away.
Plugging the
exterior leak
did not
prevent
further loss
of air. At
Darwin we had
new Olympic
Marathon
tyres fitted
and these
gave good
service, and
now some
20,000km
later they
appear to
have another
half life
available.
I carried a
spare second
hand tyre and
rim for the
car, slung
under the
rear of the
van, but this
was never
used. The
caravan had
its own
spare, which
we used (we
bought an
additional
van tyre in
Darwin)
because of
excessive
wear caused
to the left
tyre due to
the natural
road camber
together with
the type of
independent
suspension
fitted.
Many
travellers had
their car festooned
with spare tyres,
which looked
suspiciously like
retreads. The air
drag caused by
exteriorly mounted
spares plus their
extra weight would
increase fuel
consumption.
Carrying a good
spare, plus perhaps
one extra tyre and
rim should be
adequate.
The
following
information has
been gleaned from
the booklet,
`Dunlop Olympic
Tyre Facts' and my
thanks go to that
company for
supplying me with
the booklet.
Tyre
Construction.
RADIAL
PLY tyres
have one or
more plies or
layers of
nylon,
polyester or
rayon textile
casing cords
extending
from bead to
bead at an
approximate
90 degree
angle to the
centre line
of the
tyre.
A belt
consisting of two
or more plies of
textile, fibreglass
or steel cord set
at a low angle of
between 12 and 25
degrees to the
centre line runs
around the tyre
just under the
tread rubber. The
belt stabilises the
radial casing
giving the long
tread life and
excellent handling
properties of these
tyres.
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