Tire having an improved bead structure

Abstract

Tire comprising: a pair of bead structures (3), said bead structures comprising at least one bead core (4) and at least one bead filler (5); a carcass structure (2) being turned up around said bead cores; a belt structure (14) a tread band (16) a pair of sidewalls (17) each one of said pair of bead structures comprising: at least one first reinforcing layer (8) which is wound around said turned up carcass ply (22) so as to at least partially envelope said bead core and said bead filler; at least one second reinforcing layer (9) axially outwardly of the first reinforcing layer; at least one antiabrasive layer portion (13) placed in an axially outermost position of a bead structure portion designed to be in contact with the rim; wherein: said at least one antiabrasive layer portion has a thickness higher than or equal to about 3.5 mm, preferably of from about 4.0 mm to about 7.0 mm, said thickness being measured in correspondence of the bead core; the end portion of said turned up carcass ply is placed at a height hi which satisfies the following relation: hi = c1 x h wherein c1 is a number ranging from about 0.15 to about 0.50, preferably from about 0.20 to about 0.30, and h is theradial distance, measured at the tire equatorial plane, from the tire nominal rim diameter to the carcass structure. Preferably, said tire is a heavy load vehicle tire.

Description

technical field [0001] The present invention relates to a tire having an improved bead structure. [0002] In particular, the present invention relates to a heavy duty vehicle tire having an improved bead structure. Background technique [0003] As is known, a tire generally comprises: a pair of bead structures, each of which comprises at least one bead core and at least one bead filler; a substantially torus-shaped carcass structure comprising at least one carcass ply, usually having a plurality of reinforcing elements extending between two bead structures, the opposite side edges of said carcass ply being turned over said bead core; a belt structure attached to the carcass structure at a radially outer position; a tread strip attached to the belt structure at a radially outer position; and a pair of sidewalls attached to the Attached to two laterally opposite sides of the carcass structure. [0004] During the rolling process of the tire under load, both the bead struct...

AI Technical Summary

Problems solved by technology

As a result, there arises a problem that fatigue cracks are formed at the end portions of the turned-up carcass ply due to repeated occurrence of said bending deformation, and the growth of these cracks causes failure of the carcass structure.

Furthermore, said bending deformations may cause problems of heat accumulation, which may lead to separation between adjacent tire structural elements in the bead area, in particular the turned-up carcass ply and the adjacent tire structure. component separation

Therefore, the durability of the bead structure is reduced

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