Run-flat tire with tread reinforcing rubber layer

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.

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.

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.

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.