Pneumatic tire and method for manufacturing pneumatic tire

A method for manufacturing a pneumatic tire,

• the pneumatic tire comprising:
• a pair of bead portions disposed on both respective sides of a tire equatorial plane in a tire width direction;
• a bead core disposed in each of the pair of bead portions, formed by winding a bead wire in a ring shape, and having a polygonal cross-sectional shape in a tire meridian cross-section;
• and
• a carcass comprising a carcass body portion disposed extending between the pair of bead portions and a turned-up portion formed continuously from the carcass body portion and folded back from an inner side in the tire width direction to an outer side in the tire width direction of the bead core, the carcass being formed by coating a carcass cord with a coating rubber,
• the method comprising:
• causing the bead core to have a portion located on an innermost side in the tire width direction and a portion located on an outermost side in the tire width direction in a contour in the tire meridian cross-section each formed as a vertical line extending along a tire radial direction, where the vertical line is defined as an imaginary straight line contacting a plurality of exposed portions of the bead wire respectively located at the innermost side and the outermost side in the tire width direction when the pneumatic tire is mounted on a specified rim;
• causing the vertical line to have a length within a range of 20% or more and 30% or less with respect to a core height that is a height of the bead core in the tire radial direction, where an inner end portion and an outer end portion in the tire radial direction of the vertical line are defined as exposed portions each located at innermost and outermost sides in the tire radial direction among the plurality of exposed portions contacted by the imaginary straight line, and the length of the vertical line is defined as a distance in the tire radial direction between the inner end portion and the outer end portion;
• causing the vertical line to have a distance in the tire radial direction from a bead core bottom surface that is an inner peripheral surface of the bead core to an inner end portion in the tire radial direction of the vertical line within a range of 30% or more and 40% or less with respect to the core height;
• causing the length of the vertical line to be within a range of 20% or more and 28% or less with respect to the core height that is the height of the bead core in the tire radial direction,
• in the bead core, aligning a plurality of circumferential portions of the bead wire wound in a ring shape in the tire width direction to form a layer and layering a plurality of the layers in the tire radial direction;
• for a first layer that is the layer located on an innermost circumference in the tire radial direction, a second layer that is the layer layered on an outer side of and adjacent to the first layer in the tire radial direction, and a third layer that is the layer layered on an outer side of and adjacent to the second layer in the tire radial direction of the plurality of the layers,
• in two of the layers adjacent to each other in the tire radial direction, making the number of the bead wires in the layer located relatively on the outer side in the tire radial direction larger by two or more than the number of the bead wires in the layer located on an inner side in the tire radial direction and making a misalignment amount in the tire width direction between the bead wires each located at an end portion on one side in the tire width direction one-half of a thickness of the bead wire;
• and
• making a side on which the misalignment amount between the bead wires in the first layer and the second layer is one-half of the thickness of the bead wire opposite in the tire width direction to a side on which the misalignment amount between the bead wires in the second layer and the third layer is one-half of the thickness of the bead wire.

A pneumatic tire, comprising:

• a pair of bead portions disposed on both respective sides of a tire equatorial plane in a tire width direction;
• a bead core disposed in each of the pair of bead portions, formed by winding a bead wire in a ring shape, and having a polygonal cross-sectional shape in a tire meridian cross-section;
• and
• a carcass comprising a carcass body portion disposed extending between the pair of bead portions and a turned-up portion formed continuously from the carcass body portion and folded back from an inner side in the tire width direction to an outer side in the tire width direction of the bead core, the carcass being formed by coating a carcass cord with a coating rubber,
• the bead core having a portion located on an innermost side in the tire width direction and a portion located on an outermost side in the tire width direction in a contour in the tire meridian cross-section each formed as a vertical line extending along a tire radial direction, where the vertical line is defined as an imaginary straight line contacting a plurality of exposed portions of the bead wire respectively located at the innermost side and the outermost side in the tire width direction when the pneumatic tire is mounted on a specified rim,
• the vertical line having a length within a range of 20% or more and 30% or less with respect to a core height that is a height of the bead core in the tire radial direction, where an inner end portion and an outer end portion in the tire radial direction of the vertical line are defined as exposed portions each located at innermost and outermost sides in the tire radial direction among the plurality of exposed portions contacted by the imaginary straight line, and the length of the vertical line is defined as a distance in the tire radial direction between the inner end portion and the outer end portion,
• the vertical line having a distance in the tire radial direction from a bead core bottom surface that is an inner peripheral surface of the bead core to an inner end portion in the tire radial direction of the vertical line within a range of 30% or more and 40% or less with respect to the core height,
• in the bead core, a plurality of circumferential portions of the bead wire wound in a ring shape being aligned in the tire width direction to form a layer, and a plurality of the layers being layered in the tire radial direction,
• for a first layer that is the layer located on an innermost circumference in the tire radial direction, a second layer that is the layer layered on an outer side of and adjacent to the first layer in the tire radial direction, and a third layer that is the layer layered on an outer side of and adjacent to the second layer in the tire radial direction of the plurality of the layers,
• in two of the layers adjacent to each other in the tire radial direction, the number of the bead wires in the layer located relatively on the outer side in the tire radial direction being larger by two or more than the number of the bead wires in the layer located on an inner side in the tire radial direction, and a misalignment amount in the tire width direction between the bead wires each located at an end portion on one side in the tire width direction being one-half of a thickness of the bead wire,
• a side on which the misalignment amount between the bead wires in the first layer and the second layer is one-half of the thickness of the bead wire being opposite in the tire width direction to a side on which the misalignment amount between the bead wires in the second layer and the third layer is one-half of the thickness of the bead wire, and
• the bead core having a distance in the tire width direction between an end portion on an inner side in the tire width direction on a bead core top surface that is an outer peripheral surface in the tire meridian cross-section and the vertical line on the inner side in the tire width direction within a range of 25% or more and 40% or less with respect to a maximum width of the bead core.

A pneumatic tire, comprising:

• a pair of bead portions disposed on both respective sides of a tire equatorial plane in a tire width direction;
• a bead core disposed in each of the pair of bead portions, formed by winding a bead wire in a ring shape, and having a polygonal cross-sectional shape in a tire meridian cross-section;
• and
• a carcass comprising a carcass body portion disposed extending between the pair of bead portions and a turned-up portion formed continuously from the carcass body portion and folded back from an inner side in the tire width direction to an outer side in the tire width direction of the bead core, the carcass being formed by coating a carcass cord with a coating rubber,
• the bead core having a portion located on an innermost side in the tire width direction and a portion located on an outermost side in the tire width direction in a contour in the tire meridian cross-section each formed as a vertical line extending along a tire radial direction, where the vertical line is defined as an imaginary straight line contacting a plurality of exposed portions of the bead wire respectively located at the innermost side and the outermost side in the tire width direction when the pneumatic tire is mounted on a specified rim,
• the vertical line having a length within a range of 20% or more and 30% or less with respect to a core height that is a height of the bead core in the tire radial direction, where an inner end portion and an outer end portion in the tire radial direction of the vertical line are defined as exposed portions each located at innermost and outermost sides in the tire radial direction among the plurality of exposed portions contacted by the imaginary straight line, and the length of the vertical line is defined as a distance in the tire radial direction between the inner end portion and the outer end portion,
• the vertical line having a distance in the tire radial direction from a bead core bottom surface that is an inner peripheral surface of the bead core to an inner end portion in the tire radial direction of the vertical line within a range of 30% or more and 40% or less with respect to the core height,
• in the bead core, a plurality of circumferential portions of the bead wire wound in a ring shape being aligned in the tire width direction to form a layer, and a plurality of the layers being layered in the tire radial direction,
• for a first layer that is the layer located on an innermost circumference in the tire radial direction, a second layer that is the layer layered on an outer side of and adjacent to the first layer in the tire radial direction, and a third layer that is the layer layered on an outer side of and adjacent to the second layer in the tire radial direction of the plurality of the layers,
• in two of the layers adjacent to each other in the tire radial direction, the number of the bead wires in the layer located relatively on the outer side in the tire radial direction being larger by two or more than the number of the bead wires in the layer located on an inner side in the tire radial direction, and a misalignment amount in the tire width direction between the bead wires each located at an end portion on one side in the tire width direction being one-half of a thickness of the bead wire,
• a side on which the misalignment amount between the bead wires in the first layer and the second layer is one-half of the thickness of the bead wire being opposite in the tire width direction to a side on which the misalignment amount between the bead wires in the second layer and the third layer is one-half of the thickness of the bead wire, and
• the misalignment amount in the tire width direction between the bead wires each located at an end portion on inner end portions in the tire width direction of the first layer and the second layer being one-half of the thickness of the bead wire.