Cavity noise reduction tire

A cavity noise reduction tire comprising:

• a tread portion, a bead assembly being disposed at each side of the tread portion, and a sidewall portion for connecting the tread portion and the bead assembly;
• and
• a sound-absorbing material attached to an inner side of the tread portion of the tire,
• wherein a ratio of a cross-section area B of the sound-absorbing material with respect to a cross-section area (A+B) of a space formed by an inner surface of the tire ranges from 23% to 29%,
• a left-to-right width W1 of a lower end of the sound-absorbing material is 55% of a maximum left-to-right width SW of the tire,
• a left-to-right width W2 of an upper end of the sound-absorbing material is 50% of the maximum left-to-right width SW of the tire,
• the sound-absorbing material is formed of a porous polyurethane foam having an elasticity of not less than 20% as measured according to JIS K 6401,
• the sound-absorbing material has a tensile strength of 2.3 kgf/cm2 or more, a density of 33 kg/m3 to 45 kg/m3 and an elongation percentage of 340% or more, thereby reducing a cavity noise and enhancing a low temperature durability,
• a vertical slope is formed at a lower portion of a side of the sound-absorbing material, and a slanted slope is formed extending from the vertical slope at an upper portion of the side of the sound-absorbing material such that W1 is longer than W2, and
• a plurality of grooves are formed on a top of the sound-absorbing material, each of the grooves extending in a direction parallel to a circumference of the tire, wherein each of the grooves is an arc shape having a radius determined by the following equation:
• R=0.0005×(W1)2+0.0475×W1.