Pneumatic tire
A pneumatic tire 1 includes a carcass 6 extending between bead cores of bead portions via a tread portion 2 and sidewall portions, and a belt layer 7 arranged on an outer side in a tire radial direction of the carcass 6 and inside the tread portion 2 . The pneumatic tire 1 has a noise damper 20 arranged on an inner cavity surface of the tread portion 2 . Glass transition temperature of the noise damper 20 is in a range of from −55 degrees Celsius to −45 degrees Celsius.
1. A pneumatic tire comprising:
a carcass extending between bead cores of bead portions via a tread portion and sidewall portions,
a belt layer arranged on an outer side in a tire radial direction of the carcass and inside the tread portion, and
a band layer arranged on an outer side in the tire radial direction of the belt layer and inside the tread portion, the band layer having an axial width larger than an axial width of the belt layer so as to cover the entire belt layer,
wherein
a porous noise damper is arranged on an inner cavity surface of the tread portion,
the noise damper has a glass transition temperature of −55 degrees Celsius to −45 degrees Celsius,
the tread portion arranged radially outside the belt layer is formed from a tread rubber having a hardness in a range of from 55 to 75 degrees,
the tread rubber loss tangent tan δ at 0 degree Celsius is not less than 0.4, and
the tread rubber loss tangent tan δ at 70 degrees Celsius is not more than 0.2.
2. The pneumatic tire according to claim 1 , wherein the noise damper density is in a range of from 10 to 40 kg/m 3 .
3. The pneumatic tire according to claim 1 , wherein the noise damper volume V 1 is in a range of from 0.4% to 30% of the tire inner cavity total volume V 2 .
4. The pneumatic tire according to claim 1 , wherein the noise damper tensile strength is in a range of from 70 to 115 kPa.
5. The pneumatic tire according to claim 1 , wherein the tread rubber is a rubber composition body having a value not less than 20, the value being calculated by (1.4×carbon black content (phr)+silica content (phr))/sulfur content (phr).
6. The pneumatic tire according to claim 1 , wherein the noise damper is made of a porous sponge material having interconnected cells and/or closed cells.
7. The pneumatic tire according to claim 6 , wherein the sponge material is a synthetic resin sponge that is an ether type polyurethane sponge, ester type polyurethane sponge, or polyethylene sponge.
8. The pneumatic tire according to claim 6 , wherein the sponge material is a rubber sponge that is a chloroprene rubber sponge, ethylene propylene rubber sponge, or nitrile rubber sponge.