Run-flat tire with tread reinforcing rubber layer

• US 6,701,986 B2
• Filed: 06/28/2001
• Issued: 03/09/2004
• Est. Priority Date: 06/28/2000
• Status: Expired due to Fees

• Current Assignee: Sumitomo Rubber Industries Limited
• Original Assignee: Sumitomo Rubber Industries Limited
• Inventors: Tanaka, Masatoshi
• Primary Examiner(s): Johnstone, Adrienne C.
• Application Number:
  US09/892,768
• Publication Number:
  US 20020014295A1
• Time in Patent Office: 985 Days
• Field of Search: 152/532, 152/517, 152/537, 152/531, 152/209.14, 152/454
• US Class Current: 152/209.14
• CPC Class Codes: B60C 17/0009 comprising sidewall rubber inserts, e.g. crescent shaped inserts
• CPC Class Codes: B60C 2009/1871 with flat cushions or shear layers between belt layers
• CPC Class Codes: B60C 2009/1878 with flat cushions or shear layers between the carcass and the belt
• CPC Class Codes: Y10T 152/1081 Breaker or belt characterized by the chemical composition or physical properties of elastomer or the like

Abstract

A pneumatic tire comprises a tread portion, a pair of sidewall portions, a pair of bead portions, a carcass extending between the bead portions, and a tread reinforcement disposed radially outside the carcass in the tread portion. The tread reinforcement comprises a reinforcing rubber layer and a radially outer reinforcing cord layer. The radially outer reinforcing cord layer is made of cords disposed radially outside the reinforcing rubber layer. The reinforcing rubber layer extends across the substantially overall tread width and made of a rubber material having a hardness of not less than 70 degrees and a loss tangent of not more than 0.15. In a tire meridian section, the thickness of the reinforcing rubber layer being in a range of not less than 2 mm at the tire equator and gradually decreasing towards the axial edges of the reinforcing rubber layer.

Claims

1. A pneumatic tire comprising

a tread portion,

a pair of sidewall portions,

a pair of bead portions,

a carcass extending between the bead portions, and

a tread reinforcement disposed radially outside the carcass in the tread portion and comprising a radially inner reinforcing cord layer disposed on the carcass crown, a reinforcing rubber layer disposed thereon, and a radially outer reinforcing cord layer disposed radially outside of the reinforcing rubber layer,

the radially outer reinforcing cord layer composed of a first belt ply of cords laid at an angle of from 10 to 30 degrees with respect to the tire equator, and a band ply made of cords disposed radially outside of the first belt ply at a cord angle of not more than 5 degrees with respect to the tire equator,

the radially inner reinforcing cord layer composed of a second belt ply of cords laid at an angle of from 10 to 30 degrees with respect to the tire equator in an opposite direction to that of the cords in the first belt ply,

each said sidewall portion is provided on the axially inside of the carcass with a sidewall reinforcing rubber layer, which tapers towards its radially inner end and outer end from a central portion to have a crescent shape in a meridian section of the tire,

the reinforcing rubber layer extending across the substantially overall tread width and made of a rubber material having a JIS-A hardness of not less than 70 degrees and a loss tangent of not more than 0.15 measured at a temperature of 70 degrees C., a frequency of 10 Hz, and a dynamic distortion of plus/minus 2%,

in a tire meridian section, the thickness of the reinforcing rubber layer being in a range of not less than 2 mm at the tire equator and gradually decreasing towards the axial edges of the reinforcing rubber layer;

and wherein in a meridian section of the tire under a normally inflated unloaded condition, the tire has a profile of the tread portion or continuing through the tread portion to a maximum tire section width point in each of the sidewall portions where the radius of the curvature gradually decreases towards the axially outside of the tire from the tire equator.

5. A pneumatic tire according to claim 1, 2, 3 or 4, wherein

the belt ply cords are steel cords, and

the band ply cords are organic fiber cords.

7. A pneumatic tire according to claim 1, 2, 3, 4, or 6, wherein

the gradual decreasing of the radius of curvature of the profile continues to the maximum tire section width point in each of the sidewall portions.

2. A pneumatic tire comprising

a tread portion,

a pair of sidewall portions,

a pair of bead portions,

a carcass extending between the bead portions, and

a tread reinforcement disposed radially outside the carcass in the tread portion and comprising a reinforcing rubber layer and a radially outer reinforcing cord layer,

the radially outer reinforcing cord layer composed of two cross plies which are a radially inner belt ply and a radially outer belt ply disposed thereon, each ply made of parallel cords laid at an angle of from 10 to 30 degrees with respect to the tire equator, and a band ply disposed radially outside of the radially outer belt ply and made of cords disposed at a cord angle of not more than 5 degrees with respect to the tire equator,

each said sidewall portion is provided on the axially inside of the carcass with a sidewall reinforcing rubber layer, which tapers towards its radially inner end and outer end from a central portion to have a crescent shape in a meridian section of the tire,

the reinforcing rubber layer extending substantially across the overall tread width and made of a rubber material having a JIS-A hardness of not less than 70 degrees and a loss tangent of not more than 0.15 measured at a temperature of 70 degrees C., a frequency of 10 Hz, and a dynamic distortion of plus/minus 2%,

in a tire meridian section, the thickness of the reinforcing rubber layer being in a range of not less than 2 mm at the tire equator and gradually decreasing towards the axial edges of the reinforcing rubber layer;

and wherein in a meridian section of the tire under a normally inflated unloaded condition, the tire has a profile of the tread portion or continuing through the tread portion to a maximum tire section width point in each of the sidewall portions where the radius of the curvature gradually decreases towards the axially outside of the tire from the tire equator.

3. A pneumatic tire comprising

a tread portion,

a pair of sidewall portions,

a pair of bead portions,

a carcass extending between the bead portions, and

a tread reinforcement disposed radially outside the carcass in the tread portion and composed of a radially inner reinforcing cord layer disposed on the carcass crown, a reinforcing rubber layer disposed thereon, and a radially outer reinforcing cord layer disposed radially outside of the reinforcing rubber layer,

the radially outer reinforcing cord layer composed of a band ply made of cords disposed at a cord angle of not more than 5 degrees with respect to the tire equator,

the radially inner reinforcing cord layer composed of two cross plies which are a radially inner belt ply disposed on the carcass crown, and a radially outer belt ply disposed thereon, each ply made of parallel cords laid at an angle of from 10 to 30 degrees with respect to the tire equator,

each said sidewall portion is provided on the axially inside of the carcass with a sidewall reinforcing rubber layer, which tapers towards its radially inner end and outer end from a central portion to have a crescent shape in a meridian section of the tire,

the reinforcing rubber layer extending substantially across the overall tread width and made of a rubber material having a JIS-A hardness of not less than 70 degrees and a loss tangent of not more than 0.15 measured at a temperature of 70 degrees C., a frequency of 10 Hz, and a dynamic distortion of plus/minus 2%,

in a tire meridian section, the thickness of the reinforcing rubber layer being in a range of not less than 2 mm at the tire equator and gradually decreasing towards the axial edges of the reinforcing rubber layer;

and wherein in a meridian section of the tire under a normally inflated unloaded condition, the tire has a profile of the tread portion or continuing through the tread portion to a maximum tire section width point in each of the sidewall portions where the radius of the curvature gradually decreases towards the axially outside of the tire from the tire equator.

4. A pneumatic tire comprising

a tread portion,

a pair of sidewall portions,

a pair of bead portions,

a carcass extending between the bead portions, and

a tread reinforcement disposed radially outside the carcass in the tread portion and composed of a radially inner reinforcing cord layer disposed on the carcass crown, a reinforcing rubber layer disposed thereon, and a radially outer reinforcing cord layer disposed radially outside of the reinforcing rubber layer,

the radially inner reinforcing cord layer composed of a belt ply of cords laid at an angle of substantially 90 degrees with respect to the tire equator,

the radially outer reinforcing cord layer composed of a band ply made of cords disposed at a cord angle of not more than 5 degrees with respect to the tire equator,

each said sidewall portion is provided on the axially inside of the carcass with a sidewall reinforcing rubber layer, which tapers towards its radially inner end and outer end from a central portion to have a crescent shape in a meridian section of the tire,

the reinforcing rubber layer extending substantially across the overall tread width and made of a rubber material having a JIS-A hardness of not less than 70 degrees and a loss tangent of not more than 0.15 measured at a temperature of 70 degrees C., a frequency of 10 Hz, and a dynamic distortion of plus/minus 2%,

in a tire meridian section, the thickness of the reinforcing rubber layer being in a range of not less than 2 mm at the tire equator and gradually decreasing towards the axial edges of the reinforcing rubber layer;

and wherein in a meridian section of the tire under a normally inflated unloaded condition, the tire has a profile of the tread portion or continuing through the tread portion to a maximum tire section width point in each of the sidewall portions where the radius of the curvature gradually decreases towards the axially outside of the tire from the tire equator.

6. A pneumatic tire comprising

a tread portion,

a pair of sidewall portions,

a pair of bead portions,

a carcass extending between the bead portions, and

a tread reinforcement disposed radially outside the carcass in the tread portion and comprising a reinforcing rubber layer and a radially outer reinforcing cord layer,

the radially outer reinforcing cord layer composed of two cross plies which are a radially inner belt ply and a radially outer belt ply disposed thereon, each ply made of parallel cords laid at an angle of from 10 to 30 degrees with respect to the tire equator,

each said sidewall portion is provided on the axially inside of the carcass with a sidewall reinforcing rubber layer, which tapers towards its radially inner end and outer end from a central portion to have a crescent shape in a meridian section of the tire,

the reinforcing rubber layer extending substantially across the overall tread width and made of a rubber material having a JIS-A hardness of not less than 70 degrees and a loss tangent of not more than 0.15 measured at a temperature of 70 degrees C., a frequency of 10 Hz, and a dynamic distortion of plus/minus 2%,

in a tire meridian section, the thickness of the reinforcing rubber layer being in a range of not less than 2 mm at the tire equator and gradually decreasing towards the axial edges of the reinforcing rubber layer;

and wherein in a meridian section of the tire under a normally inflated unloaded condition, the tire has a profile of the tread portion or continuing through the tread portion to a maximum tire section width point in each of the sidewall portions where the radius of the curvature gradually decreases towards the axially outside of the tire from the tire equator.