Tire
A tire is a ring-shaped cushion fitted onto a wheel rim as
a shock absorber and to provide traction. The pneumatic tire
(filled with compressed air) was patented in 1845 by R. W.
Thomson, and English engineer, who used a leather tread and
a rubber inner tube. Solid rubber tires were more popular,
however, until the pneumatic tire was reinvented by John
Boyd Dunlop, (1888) whose outer tube was of canvas covered
by vulcanized rubber. The modern tubeless tire (without inner
tube) dates from he 1950s.
The basic structure of a tire comprises layers (plies) of
rubberized fabric (usually polyester cord). The plies are
combined with “beads” -- inner circular wire reinforcements
-- and the outer tread and sidewalls on a tire-building drum.
The tire is then shaped and vulcanized in a heated mold under
pressure, acquiring its tread design.
Three types of tire are made: the bias-ply tire has the plies
with cords running diagonally , alternately in opposite directions;
the bias-belted tire is similar, with fiberglass belts between
plies and tread; the radial-ply tire has the cords running
parallel to the axle, and steel-mesh belts.
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