Pneumatic tire for passenger cars including specified steel cord

A pneumatic tire for a passenger car, comprising:

• a pair of bead portions;
• a toroidal carcass layer extending over both bead portions;
• at least two belt layers provided in a crown portion of said carcass layer;
• a tread portion positioned at an outer peripheral side of said at least two belt layers;
• side wall portions provided at the right and left sides of said tread portion;
• and
• a steel cord serving as a reinforcing material for reinforcing at least one layer selected from said carcass layer and said at least two belt layers,
• wherein said steel cord is formed by plying a plurality of filaments each having a diameter of 0.125 to 0.275 mm, has an inflection point on a stress-strain curve thereof within a range of over 1% of extension rate, and the reduction rate of the diameter of said steel cord, which is a rate of the diameter of the cord under a load stress one third of the tensile stress at breaking to the diameter of the cord under no load stress, is equal to or more than 20%.