Pneumatic run flat tire
View Patent ↗A reinforcing rubber layer having a falcated cross-section disposed on an inner side in a tire width direction of the carcass layer in a side wall portion. An angle θ, with respect to the total tire width SW and a tire cross-section height SH, satisfies a relationship (SH/SW×6+3)°≦θ≦(SH/SW×6+8)°. Additionally, a height H 1 of a bead filler is from 15 to 35% of the tire cross-section height SH and a height H 2 of a maximum thickness position of the reinforcing rubber layer is from 35 to 55% of the tire cross-section height SH.
1. A pneumatic run flat tire comprising:
a carcass layer mounted between a pair of left and right bead portions,
a belt layer disposed on an outer circumferential side of the carcass layer in a tread portion, and
a reinforcing rubber layer having a falcated cross-section disposed on an inner side in a tire width direction of the carcass layer in a side wall portion; wherein
in a tire meridian direction cross-section, when a point where a tire equator plane meets a tread surface is T 0 , and a point where a straight line drawn parallel to the tire equator plane from a position 40% of a total tire width SW starting from the point T 0 meets the tread surface is T 1 , an angle θ formed by a straight line joining the point T 0 and the point T 1 with respect to the tire width direction satisfies a relationship (SH/SW×6+3)°≦θ≦(SH/SW×6+8)° with respect to the total tire width SW and a tire cross-section height SH; a height H 1 of an outer peripheral edge of the bead filler from a bead heel is from 30 to 50% of the tire cross-section height SH; and a height H 2 of a maximum thickness position of the reinforcing rubber layer from the bead heel is from 35 to 55% of the tire cross-section height SH.
2. The pneumatic run flat tire according to claim 1 , wherein a tan δ at 60° C. of rubber forming the reinforcing rubber layer is in a range from 0.02 to 0.15, and a dynamic elastic modulus at 60° C. is in a range from 5 to 20 MPa.
3. The pneumatic run flat tire according to claim 2 , wherein a tan δ at 60° C. of rubber forming the bead filler is in a range from 0.05 to 0.25, and a dynamic elastic modulus at 60° C. is in a range from 5 to 20 MPa.
4. The pneumatic run flat tire according to claim 3 , wherein a cross-sectional area of the reinforcing rubber layer in a tire meridian direction cross-section is in a range of from 190 to 270% of a cross-sectional area of the bead filler.
5. The pneumatic run flat tire according to claim 2 , wherein a cross-sectional area of the reinforcing rubber layer in a tire meridian direction cross-section is in a range of from 190 to 270% of a cross-sectional area of the bead filler.
6. The pneumatic run flat tire according to claim 1 , wherein a tan δ at 60° C. of rubber forming the bead filler is in a range from 0.05 to 0.25, and a dynamic elastic modulus at 60° C. is in a range from 5 to 20 MPa.
7. The pneumatic run flat tire according to claim 1 , wherein a cross-sectional area of the reinforcing rubber layer in a tire meridian direction cross-section is in a range of from 190 to 270% of a cross-sectional area of the bead filler.
8. The pneumatic run flat tire according to claim 1 , wherein a tan δ at 60° C. of rubber forming the reinforcing rubber layer is in a range from 0.02 to 0.10.
9. The pneumatic run flat tire according to claim 1 , wherein a dynamic elastic modulus at 60° C. of the rubber forming the reinforcing rubber layer is in a range from 5 to 15 MPa.
10. The pneumatic run flat tire according to claim 1 , wherein a tan δ at 60° C. of rubber forming the bead filler is in a range from 0.02 to 0.20.
11. The pneumatic run flat tire according to claim 1 , wherein a dynamic elastic modulus at 60° C. of the rubber forming the bead filler is in a range from 5 to 15 MPa.
12. The pneumatic run flat tire according to claim 1 , wherein a dynamic elastic modulus E 1 at 60° C. of the rubber forming the reinforcing rubber layer and a dynamic elastic modulus E 2 at 60° C. of the rubber forming the bead filler satisfy a relationship E 1 <E 2 .
13. The pneumatic run flat tire according to claim 1 , wherein a cross-sectional area of the reinforcing rubber layer in a tire meridian direction cross-section is from 200 to 250% of a cross-sectional area of the bead filler.
14. The pneumatic run flat tire according to claim 1 , wherein a turned-up edge of the carcass layer is disposed between the belt layer and the carcass layer.
15. The pneumatic run flat tire according to claim 1 , further comprising a belt cover layer.
16. The pneumatic run flat tire according to claim 15 , wherein the belt cover layer is formed from cords that include two types of organic fibers having different properties.
17. The pneumatic run flat tire according to claim 16 , wherein one of the two types of organic fibers has relatively high shrinkage and low elasticity as compared with another of the two types of organic fibers having a relatively low shrinkage and high elasticity.
18. The pneumatic run flat tire according to claim 17 , wherein the organic fibers having relatively high shrinkage and low elasticity includes at least one of nylon and polyester; and the organic fibers having relatively low shrinkage and high elasticity includes at least one of aramid and polyolefin ketone.