Patent ID: 7909077
Filing Date: 2011-03-22
Classification: B60C,Y10T

Abstract:
1. A heavy duty tire comprising a tread portion, a pair of sidewall portions, a pair of bead portions each with a bead core therein, a carcass ply having a main portion extending from the axially inside of the bead core in one of the bead portions to the axially inside of the bead core in the other bead portion, and a bead filler disposed on the axially outside of the carcass ply main portion in each of the bead portions, the bead filler having: an axially inner surface abutting on the main portion of the carcass ply; an axially outer surface; and a radially inner surface, to have a radially outwardly tapered cross sectional shape, wherein the bead filler comprises: a main layer made of a rubber having a complex elastic modulus E* the fastening layer comprises a base portion and an axially inner portion to have a L-shaped cross sectional shape, an axial middle part having a substantially constant thickness of form 0.5 to 3.0 mm, an axial outer end part tapered towards the axially outside, and an axial inner end part having a thickness gradually increasing towards the axially inside and connected to said axially inner portion, the axially inner portion extends radially outwardly from the axially inner end of the base portion along the axially inner surface of the bead filler, the height Ha of the axially inner portion is in a range of from 35 to 100 mm from the bead base line, and not more than the height Hb of the main layer, and the radial height Hb is in a range of from 40 to 100 mm from the bead base line, and the thickness of the axially inner portion gradually decreases towards the radially outside of the tire so that, in a cross section of the tire including the rotational axis of the tire, when measured along a straight line X the thickness Tb from the axially outer surface of the bead filler to the interface between the axially inner portion and the main layer is 7.0 to 3.0 mm; the thickness Ta from the interface to the axially inner surface of the axially inner portion is 1.0 to 4.0 mm; the ratio Ta/Tb is 0.1 to 0.35; and a radially and axially inner part of the main layer is disposed between the axially inner portion and the base portion of the fastening layer and extends axially inwardly beyond a straight line drawn perpendicularly to the bottom surface of the bead portion passing through a centroid of the cross sectional shape of the bead core.