JP7572605B2 - Pneumatic tires - Google Patents

Description

The present invention relates to pneumatic tires that are primarily used as winter tires and tend to have a large rubber thickness below the main grooves.

In recent years, there has been an increasing demand for lighter tires and reduced rolling resistance, and in general tires, for example, the rubber thickness of the tread portion, particularly the rubber thickness below the main grooves in the tread portion (under-groove rubber gauge) has been reduced (see, for example, Patent Document 1). On the other hand, pneumatic tires that are primarily used as winter tires tend to have a large under-groove rubber gauge, so it has been necessary to maintain a moderate under-groove rubber gauge and reduce the weight of tires through other factors.

For example, steel cords are generally used for the belt cords that make up the belt layer, and since they contribute more to the tire weight than other reinforcing cords (organic fiber cords), it is conceivable to reduce the tire weight by reducing the amount of belt cords (steel cords) used (wire diameter and number of strands). However, if the amount of belt cords used is reduced, there is a concern that durability will deteriorate due to breakdowns such as belt breakage. There is also a concern that shock burst resistance will decrease as the amount of belt cords used is reduced. Note that shock burst resistance refers to the durability against damage (shock burst) that occurs when a tire receives a large shock during driving and the carcass is destroyed, and for example, a plunger energy test (a test in which a plunger of a specified size is pressed against the center of the tread to measure the destruction energy when the tire is destroyed) is an indicator. Therefore, measures are required to reduce the tire weight while ensuring snow performance without deteriorating durability and shock burst resistance.

JP 2018-058515 A

The object of the present invention is to provide a pneumatic tire that ensures snow performance while reducing tire weight without compromising durability or shock burst resistance, thereby achieving a good balance between these performance characteristics.

In order to achieve the above object, a pneumatic tire of the present invention includes a tread portion extending in a circumferential direction of the tire to form an annular shape, a pair of sidewall portions disposed on both sides of the tread portion, and a pair of bead portions disposed on the radially inner side of the sidewall portions, the pneumatic tire has at least one carcass layer mounted between the pair of bead portions, and a plurality of belt layers disposed on the outer peripheral side of the carcass layer in the tread portion, and a main groove extending in the circumferential direction of the tire is formed on the outer surface of the tread portion, the carcass layer is composed of carcass cords made of polyester fiber cords, the breaking elongation of the carcass cord is 20% to 30%, and the product A=D×Ec of the corrected fineness D [unit: dtex/cord] per carcass cord and the end count Ec [unit: cord/50 mm] of the carcass cord per 50 mm in a direction perpendicular to the extension direction of the carcass cord is 1.8×10 ⁵ dtex/50 mm to 3.0×10 ⁵ dtex/50mm, the belt layer is composed of belt cords made of steel cords, the product B=S×Eb of the cross-sectional area S of one belt cord (unit: ^mm2 /cord) and the number of belt cords Eb per 50 mm in the direction perpendicular to the extension direction of the belt cord (unit: cords/50mm) is ^5.0mm2 /50mm to ^8.5mm2 /50mm, and the rubber thickness Ga under the main groove is 2.5mm to 4.0mm.

In the present invention, the above-mentioned product B for the belt layer, i.e., the amount (cross-sectional area) of the belt cord per unit width, is set as described above to reduce the amount of belt cord used, thereby reducing the tire weight. On the other hand, the rubber thickness Ga under the main groove is kept moderately large, preventing belt breakage caused by a reduction in the amount of belt cord used, and maintaining and improving durability. Furthermore, the above-mentioned product A for the carcass layer, i.e., the fineness of the carcass cord per unit width, is set within the above-mentioned range, so that braking performance (especially braking performance on snowy road surfaces) can be improved while ensuring durability. In addition, since the breaking elongation of the carcass cord constituting the carcass layer is within the above-mentioned range, the carcass cord can easily follow local deformation, and can fully tolerate deformation during the plunger energy test (when pressed by the plunger), thereby improving the fracture energy. In other words, the fracture durability of the tread portion against protrusion input during driving is improved, so that shock burst resistance can be improved. This collaboration allows for improved snow performance, durability, and shock burst resistance while reducing tire weight.

The "breaking elongation" of the carcass cord (polyester fiber cord) is the elongation percentage (%) at break of the sample cord measured by conducting a tensile test in accordance with JIS L1017 "Testing methods for synthetic fiber tire cords" under conditions of a gripping distance of 250 mm and a pulling speed of 300±20 mm/min.

In the present invention, it is preferable that the above-mentioned area B is 6.0 ^mm2 /50 mm to ^{7.0 mm2} /50 mm. By setting the above-mentioned area B within an appropriate range in this manner, it is possible to reduce the tire weight while suppressing deterioration in durability, which is advantageous in achieving both of these performance characteristics.

In the present invention, it is preferable that the above-mentioned rubber thickness Ga is 3.0 mm to 3.5 mm. By making the rubber thickness Ga appropriately large in this way, it is advantageous to effectively suppress belt creases and improve durability.

In the present invention, it is preferable that the belt cord is a cord with a 1×2 structure or a single wire. Since cords with such a structure have a small diameter, by using cords with such a structure while satisfying the above-mentioned product B, the thickness of the belt layer can be reduced while ensuring the reinforcing effect of the belt layer, which is advantageous for reducing the tire weight.

In the present invention, it is preferable that the diameter of the wires that make up the belt cord is 0.10 mm to 0.35 mm. By setting the wire diameter of the belt cord within an appropriate range in this way, the reinforcing effect of the belt cord is optimized, and the durability against belt creases and the steering stability can be effectively improved.

In the present invention, it is preferable that the modulus of the rubber constituting the tread portion is 3.0 MPa to 10.0 MPa at 300% elongation. By constructing the tread portion with rubber having such physical properties, it is possible to effectively improve snow performance and abrasion resistance. The "modulus at 300% elongation" is a value measured in accordance with JIS K6251.

The pneumatic tire of the present invention, with the above-mentioned configuration, ensures snow performance while reducing tire weight without compromising durability and shock burst resistance, achieving a good balance between these performance characteristics, making it suitable for use as a winter tire.

1 is a meridian cross-sectional view showing a pneumatic tire according to an embodiment of the present invention.

The configuration of the present invention will be described in detail below with reference to the attached drawings.

As shown in FIG. 1, the pneumatic tire of the present invention comprises a tread portion 1, a pair of sidewall portions 2 arranged on both sides of the tread portion 1, and a pair of bead portions 3 arranged on the tire radial inner side of the sidewall portions 2. In FIG. 1, the symbol CL indicates the tire equator. Although not depicted in FIG. 1 because it is a meridian cross section, the tread portion 1, sidewall portions 2, and bead portions 3 each extend in the tire circumferential direction to form an annular shape, which constitutes the basic toroidal structure of a pneumatic tire. The following explanation using FIG. 1 is basically based on the meridian cross section shown in the figure, but each tire component extends in the tire circumferential direction to form an annular shape.

Between the pair of left and right bead portions 3, a carcass layer 4 including multiple reinforcing cords (hereinafter referred to as carcass cords) extending in the tire radial direction is installed. A bead core 5 is embedded in each bead portion, and a bead filler 6 with a roughly triangular cross section is arranged on the outer periphery of the bead core 5. The carcass layer 4 is folded back around the bead core 5 from the inside to the outside in the tire width direction. As a result, the bead core 5 and the bead filler 6 are enclosed by the main body portion of the carcass layer 4 (the portion extending from the tread portion 1 through each sidewall portion 2 to each bead portion 3) and the folded back portion (the portion folded back around the bead core 5 in each bead portion 3 and extending toward each sidewall portion 2).

On the other hand, multiple belt layers 7 (two layers in the illustrated example) are embedded on the outer circumferential side of the carcass layer 4 in the tread portion 1. Each belt layer 7 includes multiple reinforcing cords (hereinafter referred to as belt cords) that are inclined with respect to the tire circumferential direction, and are arranged so that the belt cords cross each other between layers. In these belt layers 7, the inclination angle of the belt cords with respect to the tire circumferential direction is set in the range of 10° to 40°, for example.

Furthermore, a belt reinforcing layer 8 is provided on the outer periphery of the belt layer 7 for the purpose of improving high-speed durability. The belt reinforcing layer 8 includes a reinforcing cord (hereinafter referred to as a cover cord) oriented in the tire circumferential direction. For example, an organic fiber cord can be used as the cover cord. In the belt reinforcing layer 8, the cover cord is set at an angle of, for example, 0° to 5° with respect to the tire circumferential direction. As the belt reinforcing layer 8, a full cover layer 8a that covers the entire width direction of the belt layer 7 and a pair of edge cover layers 8b that locally cover both ends of the belt layer 7 in the tire width direction can be provided alone or in combination (in the illustrated example, both the full cover layer 8a and the edge cover layer 8b are provided). The belt reinforcing layer 8 can be formed, for example, by winding a strip material in the tire circumferential direction, in which at least one cover cord is aligned and covered with a coating rubber.

In the tread portion 1, a tread rubber layer 11 is disposed on the outer peripheral side of the above-mentioned tire components (carcass layer 4, belt layer 7, belt cover layer 8). In particular, in the present invention, the tread rubber layer 11 may have a structure in which two types of rubber with different physical properties (a cap tread exposed to the tread surface and an undertread disposed on its inner peripheral side) are laminated in the tire radial direction. A side rubber layer 12 is disposed on the outer peripheral side (outside in the tire width direction) of the carcass layer 4 in the sidewall portion 2, and a rim cushion rubber layer 13 is disposed on the outer peripheral side (outside in the tire width direction) of the carcass layer 4 in the bead portion 3.

The outer surface of the tread portion 1 may be provided with multiple grooves and multiple land areas defined by the grooves. The specific shapes of the grooves and land areas (the tread pattern formed by them) are not particularly limited, but in the present invention, a main groove 20 extending along the tire circumferential direction is always provided. In the following description, the thickness of the tread rubber layer 11 below the main groove 20 is referred to as the rubber thickness Ga.

The present invention is primarily concerned with the cords (carcass cords, belt cords) constituting the carcass layer 4 and belt layer 7, respectively, and the tread rubber layer 11 (rubber thickness Ga and physical properties), so the other basic structures of the tire are not limited to those described above.

In the belt layer 7 of the present invention, the product B=S×Eb of the cross-sectional area S per belt cord [unit: mm ² /cord] and the number of belt cords Eb per 50 mm in the direction perpendicular to the extension direction of the belt cord [unit: cord/50 mm] is set to 5.0 mm ² /50 mm to 8.5 mm ² /50 mm, preferably 6.0 mm ² /50 mm to 7.0 mm ² /50 mm. By configuring the belt layer 7 in this way, the amount of belt cords per unit width (cross-sectional area) is optimized, and the amount of belt cords used can be appropriately reduced, so that the tire weight can be reduced while ensuring durability against belt breakage. At this time, if the product B is less than 5.0 mm ² /50 mm, belt breakage cannot be sufficiently suppressed, and durability may decrease. If the product B exceeds 8.5 mm ² /50 mm, the effect of reducing the tire weight cannot be obtained. The ranges of the cross-sectional area S and the number of strands Eb are not particularly limited as long as the product B falls within the above ranges.

In the present invention, the belt cords constituting the belt layer 7 are preferably of a 1x2 structure or a single wire. Since cords of this structure have a small diameter, by using cords of this structure while satisfying the above-mentioned product B, the thickness of the belt layer 7 can be reduced while ensuring the reinforcing effect of the belt layer 7, which is advantageous for reducing the tire weight.

In the present invention, the carcass cord constituting the carcass layer 4 is composed of polyester fiber cords twisted together with polyester fiber filament bundles. The breaking elongation of this carcass cord (polyester fiber cord) is 20% to 30%, preferably 22% to 28%. Since the carcass cord (polyester fiber cord) having such physical properties is used for the carcass layer 4, it is possible to improve high-speed durability and shock burst resistance. That is, since the carcass cord has the above-mentioned elongation characteristics, it is possible to ensure the rigidity of the carcass cord appropriately and to exhibit good high-speed durability. In addition, since the carcass cord has the above-mentioned elongation characteristics, it becomes easier for the carcass cord to follow local deformation, and it becomes possible to fully tolerate deformation during the plunger energy test (when pressed by the plunger), and it is possible to improve the breaking energy. In other words, since the breaking durability against the projection input of the tread portion is improved during driving, it is possible to improve the shock burst resistance. If the breaking elongation of the carcass cord is less than 20%, it is not possible to obtain the effect of improving the shock burst resistance. If the breaking elongation of the carcass cord exceeds 30%, the intermediate elongation also tends to be large, which may reduce rigidity and reduce high-speed durability.

In the carcass layer 4, the product A=D×Ec of the correct fineness D per carcass cord (unit: dtex/cord) and the end count Ec of the carcass cord per 50 mm in the direction perpendicular to the extension direction of the carcass cord (unit: cord/50 mm) is 1.8×10 ⁵ dtex/50 mm to 3.0×10 ⁵ dtex/50 mm, preferably 2.2×10 ⁵ dtex/50 mm to 2.7×10 ⁵ dtex/50 mm. The above-mentioned product A is the fineness of the carcass cord per unit width in the carcass layer 4, and by satisfying the above-mentioned range, durability and snow performance (braking performance) can be improved. If the product A is less than 1.8×10 ⁵ dtex/50 mm, there is a risk that the snow performance will deteriorate. If the product A exceeds 3.0×10 ⁵ dtex/50 mm, the spacing between the carcass cords will become narrow, making it difficult to maintain durability. The ranges of the above-mentioned correct fineness D and end count Ec are not particularly limited as long as the product A satisfies the above-mentioned ranges.

Furthermore, the elongation of the sidewall portion of the carcass cord at a load of 2.0 cN/dtex is preferably 5.5% to 8.0%, more preferably 6.5% to 7.5%. Such elongation characteristics are advantageous for improving durability. If the elongation at a load of 2.0 cN/dtex is less than 5.5%, the cord rigidity will be high, and the compression strain at the wound end of the carcass layer 4 directly below the contact area will increase, which may lead to cord breakage (i.e., durability may be impaired). If the elongation at a load of 2.0 cN/dtex exceeds 8.0%, it becomes difficult to ensure rigidity. The "elongation at a load of 1.5 cN/dtex" of the carcass cord (polyester fiber cord) is the elongation percentage (%) of the sample cord at a load of 1.5 cN/dtex measured by conducting a tensile test in accordance with JIS L1017 "Testing methods for synthetic fiber tire cords" under conditions of a grip interval of 250 mm and a tensile speed of 300±20 mm/min.

Furthermore, the heat shrinkage rate of the carcass cord is preferably 0.5% to 2.5%, and more preferably 1.0% to 2.0%. The "heat shrinkage rate" refers to the dry heat shrinkage rate (%) of a sample cord measured when heated under the conditions of a sample length of 500 mm and heating conditions of 150°C x 30 minutes in accordance with JIS L1017 "Testing Method for Chemical Fiber Tire Cords". By using a cord with such a heat shrinkage rate, it is possible to suppress the occurrence of kinking (twisting, breaking, twisting, deformation, etc.) in the cord during vulcanization, which reduces durability, and the deterioration of uniformity. In this case, if the heat shrinkage rate of the cord is less than 0.5%, kinking is likely to occur during vulcanization, making it difficult to maintain good durability. If the heat shrinkage rate of the cord exceeds 2.5%, there is a risk of the uniformity deteriorating.

Furthermore, the twist factor K of the carcass cord, represented by the following formula (1), is preferably 2000 to 2500, more preferably 2100 to 2400. Note that this twist factor K is the value of the cord after dipping. By using a cord having such a twist factor K, it is possible to improve the cord fatigue property and ensure excellent durability. In this case, if the twist factor K of the cord is less than 2000, the cord fatigue property decreases and it becomes difficult to ensure durability. If the twist factor K of the cord exceeds 2500, the productivity of the cord deteriorates.
K=T×D ^1/2 ...(1)
(In the formula, T is the number of twists of the cord [turns/10 cm], and D is the total cord fineness [dtex].)

As described above, the carcass cord is made of polyester fibers, and examples of polyester fibers include polyethylene terephthalate fibers (PET fibers), polyethylene naphthalate fibers (PEN fibers), polybutylene terephthalate fibers (PBT), and polybutylene naphthalate fibers (PBN), with PET fibers being preferred. Whichever fiber is used, the physical properties of each fiber are advantageous in achieving a good balance between high-speed durability and steering stability. In particular, PET fibers are inexpensive, which allows for reduced costs for pneumatic tires. They also improve workability when manufacturing the cord.

The pneumatic tire of the present invention uses the above-mentioned cords, while the rubber thickness Ga under the main groove 20 is set to 2.5 mm to 4.0 mm, preferably 3.0 mm to 3.5 mm. Since the rubber thickness Ga is kept moderately large in this way, even if the amount of belt cord used is reduced as described above, belt breakage due to the reduction can be prevented, and durability can be maintained and improved. At this time, if the rubber thickness Ga is less than 2.5 mm, belt breakage cannot be sufficiently suppressed, and it becomes difficult to ensure durability. If the rubber thickness Ga exceeds 4.0 mm, it becomes difficult to ensure high-speed durability. The rubber thickness Ga is the thickness of the tread rubber layer 11 measured perpendicularly to the outermost reinforcing member from the deepest part of the main groove 20 to the outer surface of the outermost reinforcing member (belt reinforcing layer 8 in the illustrated example).

In addition to the above-mentioned features, in the present invention, the modulus at 300% elongation of the rubber (tread rubber layer 11) that constitutes the tread portion 1 is preferably 3.0 MPa to 10.0 MPa, and more preferably 4.0 MPa to 7.0 MPa. By constructing the tread portion from rubber with such physical properties, snow performance and abrasion resistance can be effectively improved.

The pneumatic tire of the present invention achieves a good balance between these performances by ensuring snow performance while reducing tire weight without compromising durability and shock burst resistance through the cooperation of the physical properties and structure of each of the above-mentioned components. Therefore, the pneumatic tire of the present invention can be suitably used as a winter tire.

The present invention will be further explained below with reference to examples, but the scope of the present invention is not limited to these examples.

The tire size is 245/40R21, and has the basic structure shown in FIG. 1. For the tread portion, the rubber thickness Ga under the main grooves and the modulus of the rubber constituting the tread portion at 300% elongation are set as shown in Tables 1 to 3. For the carcass layer, the material of the carcass cord, the breaking elongation (unit: %), the corrected fineness D per carcass cord (unit: dtex/cord), the number of carcass cords per 50 mm in the direction perpendicular to the extension direction of the carcass cord Ec (unit: cord/50 mm), and the product A = D x Ec of these are set as shown in Tables 1 to 3. For the belt layer, the cord structure, wire diameter, and cross-sectional area S per belt cord (unit: ^mm2 Pneumatic tires of Conventional Example 1, Comparative Examples 1 to 6, and Examples 1 to 21 were manufactured with the following values: number of belt cords per 50 mm in the direction perpendicular to the extension direction of the belt cord (unit: cords/50 mm), and the product B=S×Eb set as shown in Tables 1 to 3.

In Tables 1 to 3, the "breaking elongation" of the carcass cord was measured in accordance with JIS L1017, "Testing method for synthetic fiber tire cords," by conducting a tensile test under conditions of a gripping distance of 250 mm and a pulling speed of 300±20 mm/min. The "breaking stress" of the belt cord was measured in accordance with JIS G3510.

In the columns for carcass cord material in Tables 1 to 3, the case where polyethylene terephthalate fiber cord is used is indicated as "PET." In addition, in the columns for belt cord structure in Tables 1 to 3, the case where a 1x2 structure is used is indicated as "1x2," and the case where a solid wire is used is indicated as "solid wire."

These test tires were evaluated for tire weight, snow performance, shock burst resistance (plunger energy), high-speed durability, and belt breakage using the following evaluation methods, and the results are shown in Tables 1 to 3.

Tire Weight The weight of each test tire was measured. The evaluation results were shown as the amount of change (unit: kg) from the measured value of Conventional Example 1. Note that when the weight decreased, it was shown as a negative value.

Snow performance Each test tire was mounted on a wheel with a rim size of 21 x 8 1/2J, and the tire was air-pressurized to 240 kPa and mounted on a test vehicle with an engine displacement of 2000 cc. The vehicle was braked from a running state of 40 km/h on an icy and snowy road, and the braking distance until the vehicle came to a complete stop was measured. The evaluation results were expressed as an index using the reciprocal of the measured value, with Conventional Example 1 being set at 100. The higher the index value, the better the braking performance (snow performance) on icy and snowy roads.

Shock burst resistance (plunger energy)
Each test tire was mounted on a wheel with a rim size of 21×8 1/2J, and the air pressure was set to 220 kPa. In accordance with JIS K6302, a plunger with a plunger diameter of 19±1.6 mm was pressed against the center of the tread at a load speed (plunger pushing speed) of 50.0±1.5 m/min to perform a tire destruction test (plunger destruction test) and measure tire strength (tire destruction energy). The evaluation results were expressed as an index with the measured value of Conventional Example 1 taken as 100. The larger this value, the larger the destruction energy (plunger energy) and the better the shock burst resistance. In particular, an index value of "130" or more means that good performance was obtained.

High-speed durability Each test tire was mounted on a wheel with a rim size of 21 x 8 1/2J, the internal pressure of the test was set to 240 kPa, and a drum testing machine with a smooth steel drum surface and a diameter of 1707 mm was used to run the tire for 20 minutes under the conditions of an ambient temperature of 38 ± 3 ° C, a running speed of 120 km / h, and a load of 88% of the maximum JATMA load. After that, the running speed was accelerated by 10 km / h every 20 minutes, and the running speed until the tire broke down was measured. The evaluation results were expressed as an index using the measured running distance, with the conventional example being set at 100. The larger the index value, the longer the running distance until the tire broke down, and the better the high-speed durability. Note that an index value of "98" or more means that good high-speed durability equivalent to that of the conventional example was obtained.

Presence or absence of belt breakage After the high-speed durability test, the tires were disassembled and the presence or absence of breakage of the belt cord (belt breakage) was checked. The evaluation result was indicated as "yes" when the belt broke and "no" when no belt breakage occurred.

As can be seen from Tables 1 to 3, the tires of Examples 1 to 21 ensured snow performance and reduced tire weight without compromising durability and shock burst resistance, compared to Conventional Example 1, achieving a good balance between these performances. On the other hand, Comparative Example 1 had a small area A for the carcass layer, so snow performance was reduced and shock burst resistance could not be sufficiently improved. Comparative Example 2 had a small breaking elongation of the carcass cord, so shock burst resistance could not be sufficiently improved. Comparative Example 3 had a small area B for the belt layer, so belt breakage occurred. Comparative Example 4 had a large area B for the belt layer, so tire weight could not be reduced. Comparative Example 5 had a small rubber thickness Ga under the main groove, so belt breakage occurred. Comparative Example 6 had a poor high-speed durability because the rubber thickness Ga under the main groove was too large.

Reference Signs List 1 Tread portion 2 Sidewall portion 3 Bead portion 4 Carcass layer 5 Bead core 6 Bead filler 7 Belt layer 7c Belt cord 8 Belt reinforcing layer 11 Tread rubber layer 12 Side rubber layer 13 Rim cushion rubber layer 20 Main groove CL Tire equator

Claims (7)

A pneumatic tire comprising a tread portion extending in a circumferential direction of the tire and forming an annular shape, a pair of sidewall portions disposed on both sides of the tread portion, and a pair of bead portions disposed on the radially inner side of the sidewall portions, at least one carcass layer mounted between the pair of bead portions, and a plurality of belt layers disposed on the outer peripheral side of the carcass layer in the tread portion, wherein main grooves extending in the circumferential direction of the tire are formed on the outer surface of the tread portion,
the carcass layer is composed of carcass cords made of polyester fiber cords, the breaking elongation of the carcass cords is 20% to 30%, and the product A=D×Ec of the correct fineness D (unit: dtex/cord) of each carcass cord and the end count Ec (unit: cords/50 mm) of the carcass cords per 50 mm in a direction perpendicular to the extension direction of the carcass cords is 1.8×10 ⁵ dtex/50 mm to 3.0×10 ⁵ dtex/50 mm,
the belt layer is composed of a belt cord made of a steel cord, and the product B=S×Eb of a cross-sectional area S of one belt cord (unit: ^mm2 /cord) and an end count Eb of the belt cord per 50 mm in a direction perpendicular to the extension direction of the belt cord (unit: cords/50 mm) is 5.0 ^mm2 /50 mm to 8.5 ^mm2 /50 mm,
The pneumatic tire is characterized in that the rubber thickness Ga under the main groove is 2.5 mm to 4.0 mm. 2. The pneumatic tire according to claim 1, wherein the area B is 6.0 mm ² /50 mm to 7.0 mm ² /50 mm. The pneumatic tire according to claim 1 or 2, characterized in that the rubber thickness Ga is 3.0 mm to 3.5 mm. A pneumatic tire according to any one of claims 1 to 3, characterized in that the belt cord is a 1x2 cord or a solid wire. A pneumatic tire according to any one of claims 1 to 4, characterized in that the diameter of the wire that constitutes the belt cord is 0.10 mm to 0.35 mm. A pneumatic tire according to any one of claims 1 to 5, characterized in that the modulus of the rubber constituting the tread portion at 300% elongation is 3.0 MPa to 10.0 MPa. The pneumatic tire according to any one of claims 1 to 6, characterized in that it is a winter tire.

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