Abstract: A pneumatic tire which comprises a tread portion provided on each side of the tire equator with axial grooves extending axially inwardly from the tread edges, the axial grooves inclined to one direction with respect to the tire axial direction to form a non-directional tread pattern, and the inclination angle of the axial grooves to the tire circumferential direction is decreased from the axially outer end to the axially inner end thereof so as to have a minimum inclination angle &bgr;min of less than 45 degrees, and a maximum inclination angle of from 60 to 85 degrees. Preferably, the radially outermost belt ply has a cord angle a of 10 to 35 degrees to the tire equator and the axial grooves inclined in the reverse direction to the belt cords, and |&bgr;min−&agr;|≦25 degrees.

Abstract: A pneumatic tire having an improved sidewall structure is disclosed, wherein a carcass comprises at least one carcass ply of cords, which comprises an axially innermost part extending through a sidewall potion from a belt edge to the axially inside of a bead core and an axially outermost part extending through the sidewall potion from the belt edge to the axially outside of the bead core, and the rubber thickness measured at the maximum tire section width point in the sidewall portion from the outer surface of the tire to the carcass cords in the axially outermost part being not more than 1.5 times the diameter of the carcass cords but not less than 0.2 mm.

Abstract: A pneumatic radial tire comprises a carcass comprising an outer carcass ply made of cords having a first heat-shrinkage-percentage K1 and an inner carcass ply is made of cords having a second heat-shrinkage-percentage K2 different from the first heat-shrinkage-percentage K1, and the cord tension of the inner carcass ply is smaller than the cord tension of the outer carcass ply. A method of making the tire comprises steps of making the outer carcass ply of cords having a first heat-shrinkage-percentage K1, making the inner carcass ply of cords having a second heat-shrinkage-percentage K2, wherein the first heat-shrinkage-percentage K1 at 150 degrees C. is 120 to 160% of the second heat-shrinkage-percentage K2 at 150 degrees C., and heating and vulcanizing a raw tire to heat-shrink the outer carcass ply cords in a larger degree than the inner carcass ply.

Abstract: A pneumatic tire comprises a carcass ply made of organic fiber cords extending continuously from one edge to the other and turned up around bead cores to form a pair of turned-up portions and a main portion disposed therebetween, the carcass cords having a difference in elongation percentage, wherein the difference Ea-Eb of the elongation percentage Ea in the main portion from the elongation percentage Eb in the turned-up portions is in the range of from 0.5% to 2.0%.

Abstract: A pneumatic tire comprises a carcass ply made of organic fiber cords extending continuously from one edge to the other and turned up around bead cores to form a pair of turned-up portions and a main portion disposed therebetween, the carcass cords having a difference in elongation percentage, wherein the difference Ea-Eb of the elongation percentage Ea in the main portion from the elongation percentage Eb in the turned-up portions is in the range of from 0.5% to 2.0%.

Abstract: A pneumatic radial tire comprises a carcass comprising an outer carcass ply made of cords having a first heat-shrinkage-percentage K1 and an inner carcass ply is made of cords having a second heat-shrinkage-percentage K2 different from the first heat-shrinkage-percentage K1, and the cord tension of the inner carcass ply is smaller than the cord tension of the outer carcass ply. A method of making the tire comprises steps of making the outer carcass ply of cords having a first heat-shrinkage-percentage K1, making the inner carcass ply of cords having a second heat-shrinkage-percentage K2, wherein the first heat-shrinkage-percentage K1 at 150 degrees C. is 120 to 160% of the second heat-shrinkage-percentage K2 at 150 degrees C., and heating and vulcanizing a raw tire to heat-shrink the outer carcass ply cords in a larger degree than the inner carcass ply.

Abstract: A pneumatic tire is provided which has an improved tread portion capable of preventing a wandering phenomenon caused by the rain-grooves of the roads and reducing the running noise of the tire. The circumferentially extending main groove is made up of parts having at least three pitch lengths wherein the short pitch length has a first cross-sectional shape and the long pitch length has a second cross sectional shape or a third cross section shape and the groove width at the tread face in the second and third cross sectional shapes is in the range of from 1.05 to 2.5 times that in the first-cross sectional shape.

Abstract: A pneumatic radial tire comprises a carcass comprising an outer carcass ply made of cords having a first heat-shrinkage-percentage K1 and an inner carcass ply is made of cords having a second heat-shrinkage-percentage K2 different from the first heat-shrinkage-percentage K1, and the cord tension of the inner carcass ply is smaller than the cord tension of the outer carcass ply. A method of making the tire comprises steps of making the outer carcass ply of cords having a first heat-shrinkage-percentage K1, making the inner carcass ply of cords having a second heat-shrinkage-percentage K2, wherein the first heat-shrinkage-percentage K1 at 150 degrees C. is 120 to 160% of the second heat-shrinkage-percentage K2 at 150 degrees C., and heating and vulcanizing a raw tire to heat-shrink the outer carcass ply cords in a larger degree than the inner carcass ply.

Abstract: A pneumatic tire which comprises a tread provided with circumferential grooves extending continuously circumferentially of the tire,in the cross section of the tire including the tire axis, the cross sectional shape of each of the circumferential grooves being composed of a pair of oppositely opposed radially outer portions extending radially inwardly from the tread surface,the outer portions being curved such that the axial width therebetween increases radially outwardly and the inclination angle of each outer portion to the groove center line (CL) increases radially outwardly, whereby running noise, especially air resonance noise and air pumping noise, is reduced.