Accordion spiral overlay for a pneumatic tire

DRIVE October 30, 2013
Source
A pneumatic tire comprising a carcass (6) extending between bead portions (4) through sidewall portions (3) and a tread portion (2); and a belt reinforcement structure disposed radially outside of the carcass (6) and radially inside of the tread portion (2) is disclosed. The belt reinforcement structure comprises an overlay (9) comprising a strip (T) including parallel cords, wherein the overlay (9) is wound spirally and circumferentially from a first axially outer side of the overlay (9) to a second axially outer side of the overlay (9), the distance between corresponding parts of adjacent strip windings defining a winding pitch (PA, PB). The winding pitch (PA, PB) of the strip (T) changes in an axially inward direction of the pneumatic tire (1) towards the equatorial plane (EP) of the pneumatic tire (1) such that the winding pitch (PA) in a central region (7A) of the belt reinforcement structure is increased relative to respective first and second axially outer sides of the overlay (9) on each side of the equatorial plane (EP) of the pneumatic tire (1). The winding pitch (PB) of the strip (T) at both axially outer sides of the overlay (9) is in a range from 55% to 233% of the width (w) of the strip (T). The width of the central region (7A) is in a range from 1/3 to 7/8 of the width of the belt reinforcement structure. The overlay (9) comprises spaces in a range of from 4 mm to 20 mm or in a range of from 27% to 133% of the width of the strip (T) in the central region (7A) between axially adjacent edges of the strip (T) of the overlay (9).

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