JP2013169847A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of improving steering stability while maintaining superior ride quality and low road noise properties at a high level, in a pneumatic tire having at least two carcass layers.SOLUTION: In a pneumatic tire having at least two carcass layers and at least one belt layer, each carcass layer 4 includes an inclined carcass layer 42 in which the angle β of inclination of a carcass cord 42C with respect to the tire equator line E is ≥50° and <70°, and a radial carcass layer 41 in which the angle α of inclination of the carcass cord 41C with respect to the tire equator line E is substantially 90°. These two kinds of carcass layers 41, 42 are arranged on at least a sidewall part 2 so that the carcass cords 41C, 42C are across each other between the carcass layers.

Description

  The present invention relates to a pneumatic tire, and more particularly, to a pneumatic tire that can improve steering stability while maintaining a high level of excellent riding comfort and low road noise.

  As a carcass structure in a pneumatic tire having at least two carcass layers, a carcass layer (radial carcass layer) in which reinforcing cords extending in the tire width direction are arranged at 90 ° with respect to the tire circumferential direction is provided in the rubber layer. The so-called full radial tire (for example, see Patent Document 1), or the so-called half radial tire (for example, patent) provided with a carcass layer (inclined carcass layer) in which reinforcing cords are arranged at an angle smaller than 90 ° with respect to the tire circumferential direction. Document 2) is known.

  On the other hand, riding characteristics, low road noise characteristics, steering stability, and the like are important factors as characteristics required for pneumatic tires. Generally, these tire characteristics are mutually contradictory in terms of improvement means. It was related and it was difficult to make all the characteristics compatible.

  For example, the above-mentioned full radial tire is known to be advantageous in terms of riding comfort and low road noise among these tire characteristics, but when further improving the steering stability, Since the extending direction is limited to 90 °, there are restrictions on the design, and the materials and dimensions of tire components other than the carcass layer will be changed or new reinforcing members will be added. There is a problem that these tire characteristics cannot always be balanced. On the other hand, the above-mentioned half radial tire is known to be advantageous in terms of steering stability among these tire characteristics, and further has an advantage that the tire characteristics can be adjusted by the inclination angle of the carcass cord. When the inclination angle of the cord is changed, there is a problem that the belt lower part and the side wall part are also reinforced, which adversely affects riding comfort and low road noise.

  Therefore, it is required to achieve both riding comfort, low road noise performance and steering stability without adding new members and without sacrificing any performance.

JP 2005-007959 A JP 2009-292251 A

  An object of the present invention is to solve the above-described problems, and in a pneumatic tire having at least two carcass layers, while maintaining excellent riding comfort and low road noise performance, the steering stability is improved. It is an object of the present invention to provide a pneumatic tire that can be improved.

  In order to achieve the above object, a pneumatic tire according to the present invention has at least two carcass layers and has at least one belt layer on the outer peripheral side of the carcass layer in a tread portion. The layer includes an inclined carcass layer in which the inclination angle of the carcass cord with respect to the tire equator line is 50 ° or more and less than 70 °, and a radial carcass layer in which the inclination angle of the carcass cord with respect to the tire equator line is substantially 90 °. A kind of carcass layer is arranged at least on the side wall portion so that the carcass cords intersect each other.

  The present invention, as described above, by using a radial carcass layer in which the inclination angle of the carcass cord is substantially 90 ° and an inclined carcass layer in which the inclination angle of the carcass cord is 50 ° or more and less than 70 °, The effect of improving the riding comfort and low road noise property by the radial carcass layer and the effect of improving the steering stability by the inclined carcass layer can be obtained at the same time. Further, by laminating the radial carcass layer and the inclined carcass layer having different inclination angles, the deformation of the one carcass cord that is going to open at the time of traveling or the like can be prevented from occurring in the other carcass cord that intersects the carcass cord. Since it can be suppressed by the elongation tension, the tire rigidity can be appropriately increased in the overlapping region between the radial carcass layer and the inclined carcass layer. Particularly, since the inclination angle of the carcass cord of the radial carcass layer is substantially 90 ° and the inclination angle of the carcass cord of the inclined carcass layer is 50 ° or more and less than 70 °, the angle of intersection of the carcass cords between the layers is inclined. It can be made smaller than the case where carcass layers are laminated, and the reinforcing effect due to the crossing of the above carcass cords is kept to a level suitable for achieving both riding comfort, low road noise performance and steering stability. I can do it.

  In the present invention, the inclined carcass layer and the radial carcass layer have a turn-up structure in which one of the inclined carcass layer and the radial carcass layer is wound up around the bead core embedded in the bead portion from the inner side to the outer side in the tire axial direction. It is preferable that the other has a turn-down structure arranged on the outer peripheral side of the carcass layer having a turn-up structure and extending from the tread portion toward the bead portion along the carcass layer having the turn-up structure. By configuring the carcass layer in this way, compared to the case where all the carcass layers have a turn-up structure, the reinforcement effect due to the interaction between the bead core and the carcass layer is improved in riding comfort, low road noise characteristics, and steering stability. It is possible to achieve both the ride comfort, low road noise and steering stability more effectively.

  At this time, it is preferable that the inclined carcass layer has a turn-down structure and the radial carcass layer has a turn-up structure. By using the inclined carcass layer as the carcass layer having the turndown structure on the outermost peripheral side in this way, it is possible to more effectively achieve both riding comfort and low road noise performance and steering stability.

  Furthermore, it is preferable that the rolled-up portion of the carcass layer having a turn-up structure extends to a position where it overlaps with the belt layer. As a result, the overlapping region of the carcass layer having the turn-up structure and the turn-down structure in the sidewall portion, that is, the inclined carcass layer and the radial carcass layer is expanded, so that the inclined carcass layer and the radial carcass are more effectively used. The reinforcement effect by overlapping with a layer can be acquired.

  In the present invention, the inclination angle of the carcass cord constituting the inclined carcass layer with respect to the tire equator line is preferably 55 ° or more and 65 ° or less. By limiting the inclination angle of the carcass cords constituting the inclined carcass layer in this way, the intersection angle between the carcass cord of the inclined carcass layer and the carcass cord of the radial carcass layer is limited, so that the riding comfort and low road noise characteristics are reduced. And steering stability can be achieved more effectively.

It is a meridian half section view showing a pneumatic tire according to an embodiment of the present invention. It is a top view which extracts and shows the carcass layer, belt layer, bead core, and bead filler of the pneumatic tire which consists of an embodiment of the present invention. It is a meridian half sectional view showing a pneumatic tire according to another embodiment of the present invention. It is a meridian half sectional view showing a pneumatic tire according to still another embodiment of the present invention. It is a meridian half sectional view showing a pneumatic tire according to still another embodiment of the present invention. It is a top view which extracts and shows the carcass layer, belt layer, bead core, and bead filler of the pneumatic tire which consists of further another embodiment of the present invention. It is a meridian half sectional view showing a pneumatic tire according to still another embodiment of the present invention. It is a meridian half sectional view showing a pneumatic tire according to still another embodiment of the present invention.

  Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 shows an example of a pneumatic tire according to an embodiment of the present invention. In FIG. 1, 1 is a tread portion, 2 is a sidewall portion, and 3 is a bead portion. This pneumatic tire has a symmetrical structure on both sides of the tire center line CL. Two carcass layers 4 are mounted between the pair of left and right bead portions 3 and 3. These carcass layers 4 include a radial carcass layer 41 and an inclined carcass layer 42 described later. The radial carcass layer 41 is positioned on the inner peripheral side in the tread portion 1 and has a turn-up structure that is wound up around the bead core 5 from the inner side of the tire toward the outer side. On the other hand, the inclined carcass layer 42 is located on the outer peripheral side in the tread portion 1 and is disposed on the outer peripheral side of the radial carcass layer 41 having a turn-up structure in the sidewall portion 2, and the radial carcass having this turn-up structure. A turndown structure extending from the tread portion 1 toward the bead portion 3 along the layer 41 is provided. The inclined carcass layer 42 extends to the vicinity of the bead core 5, but is not folded around the bead core 5 from the tire outer side toward the inner side. A bead filler 6 having a triangular cross section made of rubber is disposed on the outer peripheral side of the bead core 5. On the outer peripheral side of the carcass layer 4 in the tread portion 1, two belt layers 7 (71, 72) are arranged over the entire circumference of the tire.

In the pneumatic tire having such a cross-sectional shape, the carcass layer 4 and the belt layer 7 are arranged as shown in FIG. 2 is a plan view schematically showing an extracted carcass layer 4, bead core 5, bead filler 6, and belt layer 7 of the present invention.
The radial carcass layer 41 disposed on the inner peripheral side of the tire and having a turn-up structure includes a carcass cord 41C extending radially in the tire radial direction, and the inclination angle α of the carcass cord 41C with respect to the tire equator line E is substantially 90 °. Is set to Note that substantially 90 ° in the present invention allows manufacturing errors with respect to 90 °. On the other hand, the inclined carcass layer 42 disposed on the outer peripheral side of the tire and having a turndown structure is provided on the outer peripheral side of the main body portion 41a and the winding portion 41b of the radial carcass layer 41 and is inclined with respect to the tire equator line E. The inclination angle β of the carcass cord 42C is set to be 50 ° or more and less than 70 °. Thus, the radial carcass layer 41 and the inclined carcass layer 42 are configured such that the carcass cords 41C and 42C intersect each other.

  The two belt layers 71 and 72 include belt cords 71C and 72C that are inclined with respect to the tire circumferential direction, and are disposed such that the belt cords 71C and 72C intersect each other between the layers. The inclination angle θ of the belt cords 71C and 72C with respect to the tire circumferential direction is set in a range of 22 ° to 27 °.

  In the pneumatic tire of the present invention, the radial carcass layer 41 in which the inclination angle α of the carcass cord 41C is substantially 90 °, and the inclined carcass layer in which the inclination angle β of the carcass cord 42C is 50 ° or more and less than 70 °. By using together with 42, it is possible to simultaneously obtain the effect of improving the riding comfort and the low road noise property by the radial carcass layer 41 and the effect of improving the steering stability by the inclined carcass layer 42. Further, by laminating the radial carcass layer 41 and the inclined carcass layer 42 having different inclination angles α and β, a deformation in which one carcass cord is opened at the time of traveling or the like intersects with the carcass cord. Since it can be suppressed by the elongation tension of the other carcass cord, the tire rigidity can be appropriately increased in the overlapping region of the radial carcass layer 41 and the inclined carcass layer 42. In particular, since the inclination angle α of the carcass cord 41C of the radial carcass layer 41 is substantially 90 ° and the inclination angle β of the carcass cord 42C of the inclined carcass layer 42 is 50 ° or more and less than 70 °, The crossing angle of the cord can be made smaller than the case where the inclined carcass layers are stacked, and the above-described carcass cords 41C and 42C have the reinforcing effect of riding comfort, low road noise and steering stability. It can be stored in a level suitable for achieving both.

  On the other hand, in the conventional pneumatic tire in which the two carcass layers are both radial carcass layers, when trying to improve steering stability, it is necessary to adjust the dimensions of tire constituent members other than the carcass layer or It was necessary to add a reinforcing member, but the improvement effect due to the dimensions of other tire components was small, and when a new reinforcing member was added, a problem (for example, an increase in tire weight) would occur. was there. In addition, in the conventional pneumatic tire in which the two carcass layers are both inclined carcass layers, the crossing angle of the carcass cords is large, so the reinforcing effect is too great, and the lower part of the belt layer and the side wall part are also strongly reinforced. Therefore, there is a problem that it adversely affects riding comfort and low road noise.

  With respect to such a conventional tire, the present invention adopts the above-described configuration, so that it is difficult to achieve at the same time by the structure of only the carcass layer 4, riding comfort, low road noise, and steering stability. It is possible to achieve a high balance between Furthermore, the present invention is not limited to the simple combination of the effect of the radial carcass layer 41 and the effect of the inclined carcass layer 42, and as described above, the distance between one carcass cord is as described above. Can be moderately suppressed by the elongation tension of the other carcass cord that intersects the carcass cord.

  At this time, when the inclination angle α of the carcass cord 41C constituting the radial carcass layer 41 is substantially out of the range of 90 ° and the carcass cord 41C is inclined, the riding comfort, the low road noise property, and the steering stability are obtained. And cannot be compatible. That is, if the carcass cord 41C is inclined in the same direction as the carcass cord 42C, the intersecting angle of the carcass cords 41C and 42C between the two layers becomes too small, and the effect of improving rigidity is obtained by the intersection of the carcass cords 41C and 42C. Absent. Conversely, if the carcass cord 41C is inclined in a direction different from that of the carcass cord 42C, the intersection angle between the carcass cords 41C and 42C between the two layers becomes too large, and the effect of improving the rigidity due to the intersection of the carcass cords 41C and 42C is excessive. Riding comfort and road noise worsen.

  In addition, if the inclination angle β of the carcass cord 42C constituting the inclined carcass layer 42 is smaller than 50 °, the intersection angle of the carcass cords 41C and 42C between the two layers becomes too large, the casing rigidity becomes extremely high, and riding comfort and Low road noise becomes worse. On the other hand, if the inclination angle β of the carcass cord 42C is 70 ° or more, it is substantially equivalent to the radial carcass layer 41, and the effect due to the intersection of the carcass cords 41C and 42C between the two layers cannot be obtained. It cannot be improved.

  In the present invention, the inclination angle β of the carcass cord 42C constituting the inclined carcass layer 42 may be in the range of 50 ° or more and less than 70 °, but more preferably, the inclination angle β is 55 ° or more and 65 ° or less. . As a result, the crossing angle between the carcass cord 42C of the inclined carcass layer 42 and the carcass cord 41C of the radial carcass layer 41 can be kept within a more preferable range, so that riding comfort, low road noise performance, and steering stability can be further improved. It is possible to achieve both effectively.

  In the present invention, the position of the winding end 41e of the carcass layer 41 having the turn-up structure is not particularly limited, but preferably, the winding portion 41b of the carcass layer 41 having the turn-up structure is a belt layer 7 as shown in FIG. It is preferable to extend to the position where it overlaps. That is, it is preferable that the winding end 41 e is positioned below the belt layer 7. In this way, by extending the rolled-up portion 41b of the carcass layer 41 having the turn-up structure to a position where it overlaps with the belt layer 7, the overlapping region between the radial carcass layer 41 and the inclined carcass layer 42 in the sidewall portion 2 is expanded. And since the area | region where the carcass cords 41C and 42C cross | intersect between layers increases, rigidity can be improved more effectively and the reinforcement effect can be acquired.

  Further, in the present invention, the position of the bead side end 42e of the carcass layer 42 having the turndown structure is not particularly limited, but the carcass layer is arranged such that the bead side end 42e is located below the bead core 5 as shown in FIG. 42 may be extended. By extending the carcass layer 42 in this way, the overlapping region between the radial carcass layer 41 and the inclined carcass layer 42 in the sidewall portion 2 is enlarged, and the region where the carcass cords 41C and 42C intersect between the layers increases. Thus, it is possible to increase the rigidity more effectively and obtain a reinforcing effect.

  Furthermore, in the present invention, the carcass layer 42 having a turn-down structure may have a hollow structure as shown in FIG. That is, the carcass layer 42 is configured to extend from the vicinity of the edge portion of the belt layer 7 provided in the tread portion 1 and extend along the carcass layer 41 having a turn-up structure toward the bead portion 3. A region A where the carcass layer 42 is not provided may be formed in the inner region in the tire width direction of the belt layer 7. By configuring the carcass layer 42 in this manner, the reinforcing effect by the intersection of the carcass cords 41 </ b> C and 42 </ b> C described above can be limitedly exhibited in the sidewall portion 2 and the bead portion 3.

  In addition, the structure of the carcass layer 4 in the above-described embodiments of FIGS. 3 to 5 can be appropriately combined.

  In the above description, the radial carcass layer 41 in which the inclination angle α of the carcass cord 41C is substantially 90 ° is arranged on the tire inner peripheral side to form a turn-up structure, while the inclination angle β of the carcass cord 42C is 50 Although the inclined carcass layer 42 having an inclination angle of greater than or equal to 70 ° and less than 70 ° is disposed on the tire outer peripheral side to form a turndown structure, in the present invention, the radial carcass layer 41 and the inclined carcass layer 42 having different inclination angles are connected between the layers. , 42C may be provided so as to intersect with each other, the arrangement relationship may be reversed. That is, as shown in FIG. 6, the inclined carcass layer 42 in which the inclination angle β of the carcass cord 42C is 50 ° or more and less than 70 ° is arranged on the tire inner peripheral side to form a turn-up structure, while the carcass cord 41C It is also possible to arrange a radial carcass layer 41 having an inclination angle α of substantially 90 ° on the tire outer peripheral side to form a turn-down structure. In the embodiment of FIG. 6, the configuration other than the radial carcass layer 41 and the inclined carcass layer 42 is the same as that of the embodiment of FIG.

  Furthermore, in the above description, the case where the two carcass layers 4 are provided is illustrated, but the number of the carcass layers 4 is not particularly limited as long as it is two or more. For example, as shown in FIG. 7, even when the carcass layer 4 includes three carcass layers 4, the carcass layer 4 has an inclined carcass layer 42 in which the inclination angle β of the carcass cord 42C with respect to the tire equator line E is 50 ° or more and less than 70 °. A radial carcass layer 41 having an inclination angle α of the carcass cord 41C with respect to the tire equator line E being substantially 90 ° so that the carcass cords 41C and 42C intersect each other between the two types of carcass layers 41 and 42. It only has to be arranged. However, when there are three or more carcass layers 4 and two or more inclined carcass layers 42 are included, the intersection angle of the carcass cords 42C and 42C increases between the inclined carcass layers 42 and 42, so-called bias structure. And the lower part of the belt layer 7 and the sidewall part 2 are excessively reinforced, which adversely affects riding comfort and low road noise. Therefore, in particular, when three or more carcass layers 4 are provided, the inclined carcass layer 42 is preferably only one layer.

  In the embodiment of FIG. 7, the radial carcass layer 41 located on the innermost circumferential side in the tread portion 1 and the other radial carcass layer 41 arranged on the outer circumferential side thereof are arranged around the bead core 5 from the tire inner side toward the outer side. An inclined carcass layer 42 that has a turn-up structure that is wound up and is positioned on the outermost peripheral side in the tread portion 1 is disposed on the outer peripheral side of the carcass layer 41 that has the turn-up structure, and the carcass layer 41 that has the turn-up structure. A turn-down structure extending from the tread portion 1 toward the bead portion 3 is provided. Thus, it is preferable that the two radial carcass layers 41 have a turn-up structure and the one inclined carcass layer 42 has a turn-down structure.

  Further, as shown in FIG. 8, even when the radial carcass layer 41 and the inclined carcass layer 42 both have a turn-up structure and a carcass layer having a turn-down structure is not included, By using the inclined carcass layer 42 in combination, it is possible to obtain the effect of achieving both riding comfort and low road noise performance and steering stability. In the example of FIG. 8, the carcass layer 4 is provided in two layers. However, when three or more carcass layers 4 are provided, the same applies even if all the carcass layers 4 have a turn-up structure. is there.

  As shown in FIGS. 7 and 8, when the carcass layer having a plurality of turn-up structures is provided, the winding ends of the carcass layers having the plurality of turn-up structures are arranged so as to be shifted by 10 mm or more without matching. It is preferable that the winding end does not have a large rigidity fluctuation point.

  Of course, the various preferred aspects described with the embodiment of FIG. 1 can be applied to embodiments having various carcass structures shown in other drawings.

  In the pneumatic tire whose tire size is 235 / 40R18 91Y, the conventional examples 1 to 2 in which the carcass structure, the arrangement of the carcass layer, the cord angle of the inclined carcass layer, and the cord angle of the radial carcass layer are different as shown in Tables 1 and 2 2, 14 types of test tires of Comparative Examples 1-2 and Examples 1-10 were manufactured.

  In the “Disposition of carcass layer” column, the first carcass layer from the tire inner circumference side is “No. 1”, the second carcass layer from the tire inner circumference side is “No. 2”, and these carcass layers are It shows whether it is a radial carcass layer or an inclined carcass layer.

  With respect to these 14 types of test tires, the longitudinal spring constant, lateral spring constant, steering stability, riding comfort, and road noise were evaluated by the following evaluation methods, and the results are also shown in Tables 1 and 2.

Longitudinal spring constant Each test tire is assembled to a wheel with a rim size of 18 x 8.5 JJ, air pressure is 230 kPa, mass corresponding to 75% of the maximum load capacity and mass of ± 50 kg of that mass are added, and the amount of deflection at that time is taking measurement. And the inclination calculated | required by carrying out linear regression of bending-load mass was made into the vertical spring constant. The evaluation result uses a measured value (N / mm), and the smaller the measured value of the longitudinal spring constant, the lower the reaction force in the radial direction and the better the riding comfort.

Lateral spring constant Each test tire is assembled to a wheel having a rim size of 18 × 8.5 JJ, air pressure is set to 230 kPa, and mass corresponding to 75% of the maximum load capacity is added. Further, displacement is applied in the tire rotation axis direction, and the tire rotation axis direction force at 5 mm and 10 mm is measured. And the inclination calculated | required by carrying out the linear regression of rotation axis direction displacement-force was made into the lateral spring constant. The evaluation result uses a measured value (N / mm). The smaller the measured value of the lateral spring constant, the lower the reaction force in the lateral direction, and the better the riding comfort during turning.

Steering stability Each test tire is mounted on a wheel with a rim size of 18 x 8.5 JJ, mounted on all wheels of a passenger car with a displacement of 2000 cc, the air pressure of all tires is 230 kPa, and the vehicle speed is 90 to 120 km / h on the test course. The sensory evaluation by the two test drivers was performed on the steering stability below. The evaluation results are shown as an index with Conventional Example 1 as 100. The larger the index value, the better the steering stability.

Riding comfort Each test tire is mounted on a wheel with a rim size of 18 x 8.5 JJ, mounted on all wheels of a passenger car with a displacement of 2000 cc, the air pressure of all tires is 230 kPa, and under the conditions of a vehicle speed of 60 km / h on the test course A sensory evaluation was conducted on the ride comfort of two test drivers. The evaluation results are shown as an index with Conventional Example 1 as 100. A larger index value means better riding comfort during normal driving. If the index value exceeds 85, it is an allowable range.

Road noise Each test tire is mounted on a wheel with a rim size of 18 x 8.5 JJ, mounted on all wheels of a passenger car with a displacement of 2000 cc, the air pressure of all tires is 230 kPa, and the test course is run at a speed of 100 km / h and low-frequency road. The sound pressure level of noise noise (125 Hz band) was measured. And the difference with the measured value of the prior art example 1 was calculated | required, and it was set as evaluation of road noise. The measured value is an A characteristic correction value (dB (A)) based on JIS C1509. The evaluation result uses the real value of the road noise difference, and the smaller this value, the better the road noise. If the road noise difference is less than +1.0 dB (A), the allowable range is satisfied.

  As can be seen from Tables 1 and 2, in all of Examples 1 to 10, the longitudinal spring constant and the lateral spring constant are not significantly increased as compared with the conventional example 1 in which the carcass layers are all radial carcass layers. While maintaining a conventional level of ride comfort and low road noise. In particular, in Examples 3, 6 to 10 and Comparative Examples 1 and 2 in which the carcass structure is shared in FIG. 1 and the arrangement of the carcass layer and the cord angle of the inclined carcass layer are different, the inclined carcass layer is at the outermost side. In Examples 3, 7, and 8 in which the cord angles of the respective carcass layers were set within a preferable range, the steering stability, the riding comfort, and the low road noise were highly compatible.

  On the other hand, in the conventional example 2 in which the carcass layers are all inclined carcass layers, although the driving stability is improved, the riding comfort and the road noise are significantly worse than the conventional example 1. Further, Comparative Examples 1 and 2 in which the cord angle of each carcass layer is out of the scope of the present invention cannot achieve both steering stability, riding comfort, and low road noise.

  In Table 2, the cord angle and arrangement of each carcass layer are set in the carcass structure of FIG. 1, but other carcass structures, that is, the carcass structure of Example 8 (Example 1) and the carcass structure of FIG. Example 2), the carcass structure of FIG. 3 (Example 4), and the carcass layer of FIG. 5 (Example 5), the cord angles and arrangement of each carcass layer are as in Comparative Examples 1-2 and Examples 6-10. Even in the case of setting, the steering stability, riding comfort, and road noise were evaluated in the same manner as in Comparative Examples 1-2 and Examples 6-10 with respect to Example 3.

DESCRIPTION OF SYMBOLS 1 Tread part 2 Side wall part 3 Bead part 4 Carcass layer 5 Bead core 6 Bead filler 7 Belt layer

Claims (5)

In a pneumatic tire having at least two carcass layers and having at least one belt layer on the outer peripheral side of the carcass layer in the tread portion,
The carcass layer includes an inclined carcass layer in which an inclination angle of the carcass cord with respect to the tire equator line is 50 ° or more and less than 70 ° and a radial carcass layer in which an inclination angle of the carcass cord with respect to the tire equator line is substantially 90 °; A pneumatic tire characterized in that these two kinds of carcass layers are arranged at least in a sidewall portion so that carcass cords cross each other.   One of the inclined carcass layer and the radial carcass layer has a turn-up structure that is wound up around the bead core embedded in the bead portion from the inner side to the outer side in the tire axial direction, and the inclined carcass layer and the radial carcass layer The other is disposed on the outer peripheral side of the carcass layer having the turn-up structure, and has a turn-down structure extending from the tread portion toward the bead portion along the carcass layer having the turn-up structure. The tire according to claim 1.   The pneumatic tire according to claim 2, wherein the inclined carcass layer has the turn-down structure, and the radial carcass layer has the turn-up structure.   The pneumatic tire according to claim 2 or 3, wherein a rolled-up portion of the carcass layer having the turn-up structure extends to a position where it overlaps with the belt layer.   The pneumatic tire according to any one of claims 1 to 4, wherein an inclination angle of a carcass cord constituting the inclined carcass layer with respect to a tire equator line is 55 ° or more and 65 ° or less.

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