Pneumatic tire

1. A pneumatic tire having at least two carcass layers, the carcass layers each having both end portions in a tire width direction extending to bead cores disposed in both bead portions, and the both end portions being wound up from an inner side in the tire width direction of the bead cores to an outer side in the tire width direction and extending outward in a tire radial direction, wherein

the carcass layers are formed by thermoplastic sheets and do not include cords, and a rubber layer is disposed at least between adjacent sheets of the thermoplastic sheets; and

the thermoplastic sheets have a relationship between a tensile yield strength α with respect to a tire circumferential direction and a tensile yield strength β with respect to the tire width direction satisfying a range of 1<β/α≤5.

2. The pneumatic tire according to claim 1 , wherein the thermoplastic sheets each have an average thickness satisfying a range of no less than 0.03 mm and no more than 1.0 mm, and an air permeation coefficient satisfying no less than 3×10 −12 cc·cm/cm 2 ·sec·cmHg and no more than 500×10 −12 cc·cm/cm 2 ·sec·cmHg.

3. The pneumatic tire according to claim 2 , wherein the rubber layer has a peeling strength from the thermoplastic sheets satisfying a range of no less than 50 N/25 mm and no more than 400 N/25 mm.

4. The pneumatic tire according to claim 3 , wherein the rubber layer is a rubber composition containing: a condensate of formaldehyde and a compound represented by formula (1), wherein R 1 , R 2 , R 3 , R 4 , and R 5 represent hydrogen, a hydroxyl group, or an alkyl group having from 1 to 8 carbons; a methylene donor; and a vulcanizing agent; and

a compounded amount of the condensate satisfies a range of no less than 0.5 parts by mass and no more than 20 parts by mass relative to 100 parts by mass of a rubber component, a compounded amount of the methylene donor satisfies a range of no less than 0.5 parts by mass and no more than 80 parts by mass relative to 100 parts by mass of the rubber component, and a ratio of the compounded amount of the methylene donor to the compounded amount of the condensate satisfies a range of no less than 1 and no more than 4.

5. The pneumatic tire according to claim 4 , wherein the thermoplastic sheets each have a tensile yield strength at room temperature satisfying a range of no less than 1 MPa and no more than 100 MPa.

6. The pneumatic tire according to claim 5 , wherein the thermoplastic sheets each have a breaking elongation at room temperature satisfying a range of no less than 80% and no more than 500%.

7. The pneumatic tire according to claim 6 , wherein at least two belt layers are provided on an outer side in the tire radial direction of the carcass layers, and

the thermoplastic sheet with a maximum width in the tire width direction has both end portions in the tire width direction positioned on an inner side in the tire width direction of end portions in the tire width direction of the belt layer with a maximum width in the tire width direction.

8. The pneumatic tire according to claim 7 , wherein the thermoplastic sheets have a relationship between an interval CW between the both end portions in the tire width direction of the thermoplastic sheet with the maximum width in the tire width direction, and a width BW in the tire width direction of the belt layer with the maximum width in the tire width direction satisfying a range of 0.10≤CW/BW≤0.95.

9. The pneumatic tire according to claim 1 , wherein the rubber layer has a peeling strength from the thermoplastic sheets satisfying a range of no less than 50 N/25 mm and no more than 400 N/25 mm.

10. The pneumatic tire according to claim 1 , wherein the rubber layer is a rubber composition containing: a condensate of formaldehyde and a compound represented by formula (1), wherein R 1 , R 2 , R 3 , R 4 , and R 5 represent hydrogen, a hydroxyl group, or an alkyl group having from 1 to 8 carbons; a methylene donor; and a vulcanizing agent; and

a compounded amount of the condensate satisfies a range of no less than 0.5 parts by mass and no more than 20 parts by mass relative to 100 parts by mass of a rubber component, a compounded amount of the methylene donor satisfies a range of no less than 0.5 parts by mass and no more than 80 parts by mass relative to 100 parts by mass of the rubber component, and a ratio of the compounded amount of the methylene donor to the compounded amount of the condensate satisfies a range of no less than 1 and no more than 4.

11. The pneumatic tire according to claim 1 , wherein the thermoplastic sheets each have a tensile yield strength at room temperature satisfying a range of no less than 1 MPa and no more than 100 MPa.

12. The pneumatic tire according to claim 1 , wherein the thermoplastic sheets each have a breaking elongation at room temperature satisfying a range of no less than 80% and no more than 500%.

13. The pneumatic tire according to claim 1 , wherein at least two belt layers are provided on an outer side in the tire radial direction of the carcass layers, and

the thermoplastic sheet with a maximum width in the tire width direction has both end portions in the tire width direction positioned on an inner side in the tire width direction of end portions in the tire width direction of the belt layer with a maximum width in the tire width direction.

14. The pneumatic tire according to claim 13 , wherein the thermoplastic sheets have a relationship between an interval CW between the both end portions in the tire width direction of the thermoplastic sheet with the maximum width in the tire width direction, and a width BW in the tire width direction of the belt layer with the maximum width in the tire width direction satisfying a range of 0.10≤CW/BW≤0.95.

15. The pneumatic tire according to claim 1 , wherein the at least two carcass layers comprises at least three carcass layers formed by the thermoplastic sheets and the rubber layer comprises at least two rubber layers, the thermoplastic sheets and the rubber layers alternating.