Mondolfo Ferro AQUILA ALLIANCE Manual De Uso página 126

to withstand internal air pressure and all other stress
arising from use.
A tyre section shows the various parts it consists of:
1 - The tread. This is the part in contact with the ground
when the tyre rolls. It comprises a rubber compound
and a "pattern" that is suitable for ensuring good
resistance to abrasion and good grip in dry and wet
conditions, as well as quiet operating conditions.
2 - Edge or bracing. This is a metal fabric or textile insert,
in the area of the outer bead part. It protects the cas-
ing plys from rubbing against the rim.
3 - Casing. This is the resistant structure and comprises
one or more layers of rubber plys. The way the plys
comprising the casing are arranged give the structure
its name. The following structures are possible:
Conventional: the plys are inclined and arranged so
that the strands comprising a ply overlap with those
of the adjacent ply. The tread, which is the part of the
tyre in contact with the ground, is part of the sidewalls
and so during rolling, sidewall flexure is transmitted
to the tread.
Radial: the casing consists of one or more plys with
the cords in a radial direction.
A radial casing in itself is quite unstable. To make
it stable and prevent bad tread movement in the
area of contact with the ground, the casing and the
undertread are reinforced with an annular structure,
usually called belt. The tread and sidewall work with
different, independent rigidities, so during rolling,
sidewall flexure is not transmitted to the tread.
4 - Side ring. This is a metal ring comprising several steel
strands. The casing plys are secured to the side ring.
5 - Belt. This is a non-flexible circumferential structure
comprising cross-plys at very low angles, positioned
below the tread, to stabilise the casing in the foot-
print area.
6 - Centring band. This is a small marking which indicates
the circumference of the top part of the bead and is
used as a reference to check exact tyre centring on
the rim after mounting.
7 - Protective band. This is a circumferential marking in
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