PNEUMATIC TIRE

Abstract

Pneumatic tire which features: a belt layer (7) obtained by arranging a belt band obliquely with respect to a circumferential direction of the tire on the radially outer side of a carcass layer (4) in a tread portion (3); and a belt reinforcement layer (9) obtained by arranging an organic fiber band along the circumferential direction of the tire on the radially outer side of the belt layer (7); wherein the belt layer (7) is designed such that an angle of the belt band with respect to a circumferential direction of the tire is 31° or more and 37° or less; and wherein the organic fiber tape of the belt reinforcement layer (9) is designed such that, if the number of twists per 10 cm length is T (twists / 10 cm), the fineness is D (dtex) and the fiber density is ρ (g / cm³). 3 ) is a twist coefficient K, which is expressed as T × (D / ρ)1 / 2 is determined to be 900 to 2600 and the product of a load at 5% elongation LASE 5% (N) of the organic fiber tape and a number of ends E (tapes / 25 mm) of the organic fiber tape is 1000 N or more, and where the number of ends E is from 25 to 35 / 25 mm.

Description

Background 1. Technical field

[0001] The present invention relates to a pneumatic tire. 2. Description of the state of the art

[0002] It is known that, for the purpose of improving the durability of a tire at high speeds, a belt reinforcement layer, obtained by arranging an organic fiber tape, such as a nylon fiber tape, substantially parallel to the circumferential direction of the tire, is provided on the radially outer side of a belt layer (see JP 2005 / 239069 A, JP 2005 / 75289 A and JP 2003 / 237309 A).

[0003] JP 2005 / 239069 A discloses a tire in which a belt layer, consisting of a belt ply spirally wound with a belt cord, is provided outside a belt ply. The belt cord consists of a nylon fiber cord with a single-twist structure, a conditioned size of 1,400 to 2,800 dtex, and a cord elongation of 4.0 to 6.0% under a load of 44 N. The belt ply consists of a belt layer in which steel belt strands are arranged at an angle of 10 to 40° to the circumferential direction of the tire, and the bending stiffness of one of the belt strands is at most 50 gf cm.

[0004] US Patent 2006 / 0237113 A1 discloses a tire comprising a carcass, a belt structure, and a tread band. The belt structure contains at least two belt plies and at least one belt ply located radially outside the belt plies. The at least one belt ply extends over at least one axial width of the at least two belt plies and contains at least one first elongated element and at least one second elongated element. The elongated elements form coils that are substantially oriented in the circumferential direction of the tire. The coils are arranged alternately along an axial unfolding of the at least one belt ply. The at least one first elongated element is a hybrid cord containing at least one filament with a high modulus of elasticity and at least one filament with a low modulus of elasticity, which are twisted together.The elastic modulus of at least one second elongated element is lower than the elastic modulus of at least one first elongated element. Summary

[0005] Furthermore, a belt layer is created by positioning a belt band, such as a steel band, at an angle to the tire's circumference. This angle is generally set to approximately 20 degrees. Increasing this angle, for example, to more than 30 degrees, can improve braking performance on wet surfaces and steering stability. However, as the belt angle increases, the belt's stiffness around the tire decreases, deteriorating the contact patch shape and leading to reduced durability at high speeds or decreased ride comfort.

[0006] According to some embodiments of the invention, in light of the above points, it is desirable to provide a pneumatic tire that is able to improve durability at high speed and driving comfort, while maintaining braking performance in wet conditions and steering stability caused by an increased angle of a belt.

[0007] A pneumatic tire according to an embodiment of the invention comprises a belt layer obtained by arranging a belt band obliquely with respect to a circumferential direction of the tire on the radially outer side of a carcass layer in a tread portion; and a belt reinforcement layer obtained by arranging an organic fiber band along the circumferential direction of the tire on the radially outer side of the belt layer. The belt layer is configured such that the angle of the belt band with respect to a circumferential direction of the tire is 31° or more and 37° or less. The organic fiber band of the belt reinforcement layer is configured such that, if the number of twists per 10 cm length is T (twists / 10 cm), the fineness D (dtex) is and the fiber density ρ (g / cm³) is 3 ) is, where the twist coefficient K is defined as T × (D / ρ) 1 / 2The value is determined to be between 900 and 2,600. The product of a load at 5% elongation LASE 5% (N) of the organic fiber tape and a number of ends E, where the number of ends E is 25 to 35 / 25 mm, is 1,000 N or more.

[0008] According to the embodiments of the invention, the angle of the belt tape is set as above, and the twist coefficient of the organic fiber tape of the belt reinforcement layer, as well as the product of LASE 5% and its end count, are set as above. As a result, durability at high speeds and driving comfort can be improved, while wet braking performance and steering stability are maintained. Brief description of the drawing Fig. 1: A half-section of a pneumatic radial tire of an exemplary embodiment. Description of the preferred embodiment

[0009] An embodiment of the invention is described in detail below.

[0010] A pneumatic tire according to this embodiment is characterized by the configuration of a belt layer and by the configuration of a belt reinforcement layer, which is arranged on the radially outer side of the belt layer.

[0011] The belt layer is formed from at least one belt layer, which has been obtained by placing a belt band obliquely with respect to the circumferential direction of the tire on the radially outer side (that is, the outside in the radial direction of the tire) of a carcass layer in a tread section.

[0012] The belt reinforcement layer consists of an organic fiber tape arranged along the circumference of the tire on the radially outer side (i.e., the outside in the radial direction of the tire) of the belt layer. The organic fiber tape of the belt reinforcement layer extends essentially parallel to the circumference of the tire, that is, at an angle of approximately 0° (preferably at an angle of 5° or less with respect to the circumference of the tire), and the tape is arranged at predetermined intervals in the width direction of the tire. Such a belt reinforcement layer can be a cover layer, covering the entire width of the belt layer, or it can be an edge layer, covering the belt edge.

[0013] The Fig.Figure 1 is a half-section of a pneumatic radial tire for passenger cars as an example of a pneumatic tire. The tire has a pair of left and right bead parts 1, a pair of left and right sidewall parts 2, and a tread part 3 provided between the two sidewall parts 2, and a carcass layer 4 extending toroidally is provided between the pair of bead parts 1.

[0014] The carcass layer 4 extends from the tread section 3 through the sidewall section 2 and is folded from the inside out in the bead section 1 by a bead core 5, thus securing it. The carcass layer 4 is formed from at least one layer, which is obtained by arranging a carcass strip made of an organic fiber substantially perpendicular to the circumferential direction of the tire.

[0015] A belt layer 7 is arranged on the radially outer side of the carcass layer 4 in the tread section 3. The belt layer 7 is provided over the outer circumference of the crown portion of the carcass layer 4. The belt layer 7 can be formed from a single or multiple belt layers; in this example, it is formed from two layers, namely a first belt layer 7A on the inside and a second belt layer 7B on the outside. Such a belt layer is formed from a belt strip, such as a steel strip covered with rubber, and is obtained by arranging the belt strip obliquely at a specific angle with respect to the circumferential direction of the tire and at predetermined intervals in the lateral direction of the tire.The two belt layers 7A and 7B are arranged such that the belt bands intersect (that is, they are oblique in a bilaterally symmetrical manner with respect to the circumferential direction of the tire).

[0016] On the radially outer side of the belt layer 7, a belt reinforcement layer 9 is provided between the belt layer 7 and a tread rubber 8. In this example, the belt reinforcement layer 9 is a cover layer that covers the entire width of the belt layer 7. The belt reinforcement layer 9 is formed from an organic fiber tape arranged substantially parallel to the circumferential direction of the tire, the organic fiber tape being covered with a rubber. The belt reinforcement layer 9 secures the belt layer 7 in the circumferential direction, thereby creating a strapping effect that increases the stiffness in the circumferential and radial directions of the tire, as well as the belt bonding force.Accordingly, the belt reinforcement layer 9 suppresses the rise or diameter growth of the belt or the distortion of the belt edge caused by centrifugal force during high-speed driving, resulting in excellent performance as well as high-speed durability and steering stability.

[0017] In this embodiment, the angle of the belt band relative to the circumferential direction of the tire (hereinafter sometimes simply referred to as the "belt angle") in the belt layer is set to more than 31° and 37° or less (that is, 31° < belt angle ≤ 37°). This means that if the belt layer consists of a single belt ply, the belt angle of that single belt ply is set to more than 31° and 37° or less. If the layer consists of multiple belt plies, the belt angles of the belt plies arranged so that the belt bands intersect are each set to more than 31° and 37° or less relative to the circumferential direction of the tire. Setting the belt angle to more than 31° can improve wet braking performance and steering stability.If the belt angle is 37° or less, a decrease in tire stiffness in the circumferential direction can be suppressed, and a decrease in durability at high speeds can be suppressed. The belt angle is 32° or more and 35° or less.

[0018] With regard to the organic fiber tape used for the belt reinforcement layer of this embodiment, the type of organic fiber and the twist structure of the tape are not particularly limited. Various organic fibers, such as nylon, aramid, polyester, and rayon, can be used, and various twist structures, such as double and single twists, can be employed. It is preferred that at least one yarn of the organic fiber tape is made of nylon. For example, a nylon fiber tape obtained by twisting together a variety of nylon yarns and a hybrid tape obtained by twisting together a nylon yarn and another organic fiber yarn can be mentioned.A hybrid tape is preferably one obtained by twisting together a nylon yarn and an aramid yarn. Particularly preferred are a nylon fiber tape with a double twist structure obtained by twisting together two nylon yarns, and a hybrid tape obtained by twisting together a nylon yarn and an aramid yarn.

[0019] Examples of nylon fibers used here include Nylon 6, Nylon 66, Nylon 46, and similar types. Aramid fibers can be of the Para or Meta type, and other well-known aramid fibers can be used.

[0020] The organic fiber tape used for the belt reinforcement layer has a twist coefficient (K) of 900 to 2,600. A twist coefficient of K of 900 or higher suppresses fatigue resistance deterioration of the organic fiber tape and improves high-speed durability. Conversely, a twist coefficient of K of 2,600 or lower reduces the need to increase the number of ends of the organic fiber tape required to achieve the desired circumferential tensile strength. Consequently, tire defects such as separation due to an excessive number of ends are minimized, and high-speed durability is further enhanced.

[0021] Here, the twist coefficient K is defined as T × (D / ρ) 1 / 2, where T (twists / 10 cm) is the number of twists per 10 cm length of the organic fiber ribbon, D (dtex) is the fineness, and ρ (g / cm³) is the fiber density. 3). For example, in the case where a multitude of yarns (initially twisted yarns) are aligned and twisted together as in a double-twist structure, the number of twists T is the number of twists at the time such yarns are twisted together (the number of final twists). The fineness D of an organic fiber tape is also referred to as the nominal fineness. The fiber density p is the density of a fiber from which the organic fiber tape is composed. In the case of a tape consisting of a single fiber, p is the density of such a fiber, while in the case of a hybrid tape, ρ is the average density, calculated according to the mass ratio of the fibers from which the tape is composed.

[0022] In one embodiment, where the organic fiber tape of the belt reinforcement layer is a nylon fiber tape obtained by twisting a plurality of nylon yarns together, the twist coefficient K is preferably 1,100 to 2,600. It is particularly preferred that a plurality of nylon yarns (first twisted yarns), each obtained by twisting a bundle of nylon filaments in the Z-direction, are aligned and twisted together to a twist coefficient K of 1,100 to 2,600 in a direction opposite to the first twisting direction, i.e., in the S-direction. In this case, the twist coefficient K is particularly preferably 1,300 to 2,600.

[0023] In one embodiment, where the organic fiber tape of the belt reinforcement layer is a hybrid tape obtained by twisting a nylon yarn and an aramid yarn together, the twist coefficient K is preferably 900 to 2300. It is particularly preferred that a nylon yarn and an aramid yarn, obtained by twisting a bundle of nylon filaments and a bundle of aramid filaments, respectively, in the Z-direction, are aligned and twisted together to a twist coefficient K of 900 to 2300 in the direction opposite to the first twisting direction, i.e., in the S-direction. In this case, the twist coefficient K is particularly preferably 1300 to 2100.

[0024] The fineness D of the organic fiber tape is not particularly limited and can, for example, be 1,000 to 4,000 dtex, 1,500 to 3,500 dtex, or 1,800 to 3,000 dtex. The number of twists T is also not particularly limited and can, for example, be 20 to 60 / 10 cm or 25 to 55 / 10 cm. Furthermore, in the case of a double-twist structure, the number of initial twists can be set to the same value as the number of final twists.

[0025] In the belt reinforcement layer of this embodiment, the product of the load at 5% elongation LASE 5% (N) of the organic fiber tape and the number of ends E (tapes / 25 mm) of the organic fiber tape (i.e., LASE 5% × E) is set to 1,000 N or more. If the product of LASE 5% and the number of ends E is 1,000 N or more, the belt bonding strength can be increased to improve durability at high speed. The product of LASE 5% and the number of ends E is preferably 1,100 N or more, and particularly preferably 1,200 N or more. The upper limit is not particularly restricted and may be 3,000 N or less, or 2,500 N or less.

[0026] The LASE 5% of the organic fiber tape is not particularly limited and can be, for example, 30 to 100 N, 35 to 90 N, or 40 to 80 N. The LASE 5% value can be adjusted, for example, by selecting the type of fiber forming the organic fiber tape, or by adjusting the tape structure, the number of twists, the tape treatment conditions, and the like. For example, decreasing the number of twists can increase the LASE 5%. Additionally, tape treatment conditions can include immersion treatment, where the organic fiber tape is immersed in a resin fluid for adhesion treatment with a rubber (resin fluid composition, treatment temperature, tension, time, etc.), and the physical properties of the organic fiber tape can thus be adjusted.For example, if immersion treatment is carried out using a resin fluid such as a resorcinol formalin latex (RFL) or an aqueous-blocked isocyanate solution, and a low-temperature bath is used, and the tension applied to the organic fiber tape is set high, the LASE 5% can be increased. Here, the LASE 5% is measured according to JIS L1017.

[0027] The final number E of the organic fiber tape (the number of tapes per 25 mm width of the belt reinforcement layer) will be appropriately adjusted depending on the value of LASE 5%, so that the product of the two meets the above range and is 25 to 35 / 25 mm.

[0028] A tire blank (unvulcanized tire) is produced using the organic fiber tape described above. The belt reinforcement layer is wound onto the radially outer side of the belt layer, and the resulting tire blank is vulcanized to produce a pneumatic tire. When forming the belt reinforcement layer on the belt layer, the organic fiber tape described above, or a plurality of such aligned tapes, can be coated with rubber and wound spirally over the belt layer of the tire blank, or over a wide, rubber-coated layer of aligned organic fiber tapes. The former, i.e., spiral winding, is preferred. Examples

[0029] The invention is described in more detail below using examples. However, the invention is not limited to these examples. Measurement methods and testing procedures

[0030] The measurement and testing procedures in the examples are as follows.

[0031] Testing procedures for belts - Band diameter: An organic fiber band was folded to prevent twisting and processed into four bands, aligned and arranged parallel without sagging. The foot of such bands was dropped from a height of approximately 6.5 mm using a predetermined measuring device (foot (measuring head) diameter: 9.5 ± 0.03 mm, load: 1.666 ± 29.4 mN) to perform a measurement. - Tape strength: According to JIS L1017, an organic fiber tape was left to stand for 24 hours under constant thermostatic conditions of 20 °C and 65% relative humidity and then subjected to a tensile test at 20 °C and the breaking load of the sample was determined. - LASE 5%: According to JIS L1017, an organic fiber tape was left to stand for 24 hours under constant thermostatic conditions of 20°C and 65% relative humidity and then subjected to a tensile test at 20°C and the load at a strain of 5% was determined. Testing procedures for tires - Belt angle: With respect to an air-filled tire, the angle of the belt was measured with respect to the circumferential direction of the tire at the tire equator in the tread area (middle position in the width direction). - High-speed tire durability: According to FMVSS109 (UTQG). A 1,700 mm diameter drum tire with a smooth steel surface was used. The tire's internal pressure was set to 220 kPa, and the load was set to 88% of the maximum load specified in JATMA. After a 60-minute break-in period at 80 km / h, the tire was allowed to cool and the pressure was readjusted, followed by a main run. The main run started at 120 km / h. The speed was incrementally increased by 8 km / h every 30 minutes, and the tire was driven until failure occurred. The distance to failure was expressed as an index relative to the reference tire (Example 1) with a value of 100. A higher number indicates better high-speed durability. - Actual steering stability of the car: Test tires with an internal pressure of 260 kPa were mounted on a test vehicle with a 2,000 cc engine. The vehicle was driven by three trained test drivers on a test track and subjected to a sensory evaluation. The evaluation was performed on a scale of 0 to 10, and a relative comparison was made, with the tire of comparison example 1 receiving a score of 6. The average rating of the three tires was expressed as an index relative to the tire of comparison example 1, with a score of 100. A higher number indicates better steering stability. - Ride comfort: Each tire was inflated to an internal pressure of 260 kPa using the standard rim specified in JIS, and four tires of the same type were mounted on a passenger car with a 2,000 cc engine. On a test track with one good and one bad road surface, ride comfort was assessed sensorially by three test drivers and rated against comparison example 1. Comfort equal to that of comparison example 1 was rated as "adequate," as was comfort worse as "poor," and as good as it was rated as "good." - Wet braking performance: Test tires with an internal pressure of 260 kPa were mounted on a test vehicle with a 2,000 cc engine, and the water depth on the road surface was set to 1 mm. At a speed of 100 km / h, the brake pedal was applied, and the distance at which the vehicle came to a stop was measured and expressed as an index relative to the tire of comparison example 1 (100). A higher number indicates better wet braking performance. Examples / Comparative examples

[0032] A pneumatic radial tire for passenger cars with a tire size of 255 / 35ZR20 97Y and a belt reinforcement layer (9) as described in the Fig.The tire shown in Figure 1 was manufactured as a prototype. The belt angle of the belt layer and the configuration of the organic fiber tape forming the belt reinforcement layer (cover layer) were as shown in Table 1 below for each of the tires in the examples and comparison examples, and other configurations were consistent across all tires.

[0033] In particular, a 2 + 2 × 0.25 mm steel band with an end count of 23 / 25.4 mm was arranged as the belt layer and two such layers were applied (the belt angle was as shown in Table 1).

[0034] Regarding the belt reinforcement layer, the number of layers in all tires of the examples and the comparison examples was 1.

[0035] With regard to the organic fiber tape forming the belt reinforcement layer, "Ny66" in the tape material listed in Table 1 represents a nylon 66 fiber, and "Aramid / Ny66" represents a hybrid tape made from a para-type aramid fiber and a nylon 66 fiber. Regarding the tape structure, "1,400 dtex / 2" signifies a double-twisted structure obtained by twisting two yarns with a combined nominal fineness of 1,400 dtex. "1,100 dtex / 1 + 940 dtex / 1" signifies a double-twisted structure obtained by twisting a yarn made from an aramid fiber with a combined nominal fineness of 1,100 dtex and a yarn made from a nylon fiber with a combined nominal fineness of 940 dtex.

[0036] The number of twists T in Table 1 represents the number of final twists. Incidentally, in all tapes, the number of initial twists was set to the same number as the number of twists T in Table 1 (the number of final twists). The fiber density ρ for calculating the twist coefficient K was set to ρ = 1.14 g / cm³ for the nylon fiber tape. 3 and for the hybrid tape of a nylon fiber and an aramid fiber at ρ = 1.29 g / cm 3 set.

[0037] The nylon fiber tape of comparison example 1, the nylon fiber tape of examples 1, 3, and 5, and that of comparison examples 2, 3, and 6 differ not only in the number of twists T, but also in the tape treatment conditions. With regard to the drying step, the heat curing step, and the normalization step after immersion in an RFL treatment fluid, in comparison example 1 the dyeing step was carried out at a temperature of 140 °C with a tension of 1.14 N / tape, the heat curing step was carried out at a temperature of 230 °C with a tension of 2.10 N / tape, and the normalization step was carried out at a temperature of 180 °C with a tension of 0.85 N / tape.Meanwhile, in Examples 1, 3, and 5, and the comparison examples 2, 3, and 6, the dyeing step was performed at a temperature of 170 °C with a tension of 1.70 N / ribbon, the heat curing step was performed at a temperature of 235 °C with a tension of 2.30 N / ribbon, and the normalization step was performed at a temperature of 150 °C with a tension of 2.5 N / ribbon. By setting these conditions, the LASE was adjusted and increased by 5%.

[0038] The nylon fiber tape of comparison example 7 differed from the nylon fiber tape of comparison example 2 in that the tension was changed during the normalization step of the immersion treatment using an RFL treatment fluid. Specifically, the tension was set to 1.5 N / tape.

[0039] Using each tire, high-speed durability, actual car steering stability, ride comfort, and wet braking performance were evaluated. Tires with poor high-speed durability results were not included in the actual car test. The results are shown in Table 1. [Table 1] Comparative example 1 Example 1 Example 2 Example 3 Example 4 Example 5 Comparative example 2 Comparative example 3 Comparative example 4 Comparative example 5 Comparative example 6 Comparative example 7 Tape material Ny66 Ny66 Aramid / Ny66 Ny66 Aramid / Ny66 Ny66 Ny66 Ny66 Aramid / Ny66 Aramid / Ny66 Ny66 Ny66 Band structure 1400 dtex / 2 1400 dtex / 2 1100dtex / 1 + 940dtex / 1 1400 dtex / 2 1100dtex / 1 + 940dtex / 1 1400 dtex / 2 1400 dtex / 2 1400 dtex / 2 1100dtex / 1 + 940dtex / 1 1100dtex / 1 + 940dtex / 1 1400 dtex / 2 1400 dtex / 2 Tape fineness (dtex) 2800 2800 2040 2800 2040 2800 2800 2800 2040 2040 2800 2800 Number of twists T (twists / 10cm) 38 27 36 27 52 51 58 18 22 66 27 58 Coefficient of twist K 1883 1338 1432 1338 2068 2528 2874 892 875 2625 1338 2874 Band diameter (mm) 0,67 0,60 0,55 0,60 0,59 0,64 0,65 0,58 0,53 0,62 0,60 0,65 Band strength (N) 220 237 216 237 180 213 205 238 230 148 237 210 LASE 5% (N) 30,0 48,0 73,0 48,0 67,0 37,0 34,0 52,0 83,0 57,0 48,0 32,0 LASE 5% × E (N) 840 1248 2044 1200 2278 1073 1020 1352 2158 2280 1248 960 End count E (bands / 25 mm) 28 26 28 25 34 29 30 26 26 40 26 30 Belt angle (°) 33 33 33 38 33 33 33 33 33 33 41 33 Tire rating Durability at high speed 100 105 108 102 109 103 98 83 85 98 98 98 actual steering stability of the car 100 100 100 100 100 100 100 - - 100 94 100 Driving comfort appropriate good good good good good good - - good appropriate good Braking performance in wet conditions 100 100 100 101 100 100 100 - - 100 99 100

[0040] As shown in Table 1, in examples 1 to 5, compared to the comparison example 1, the durability at high speeds of the tire and the driving comfort were improved, while the actual steering stability of the car and the performance in wet conditions, which were achieved by an increased angle of the belt band, could be maintained.

[0041] In contrast, in comparison example 2, which used a nylon fiber tape with a twist coefficient K of 2.874 (outside the specified range), the number of ends was increased to achieve the desired securing force. Consequently, the cut end portion of the belt reinforcement layer was prone to adhesion failure, and the high-speed tire durability did not improve. In comparison example 3, which used a nylon fiber tape with a twist coefficient K of 892 (outside the specified range), the tape's fatigue resistance was poor, and the high-speed tire durability deteriorated significantly compared to comparison example 1.In comparative example 4, where a hybrid aramid-nylon tape with a twist coefficient K of 875 was used (outside the specified range), the tape's fatigue resistance was poor, and the tire's high-speed durability deteriorated significantly compared to comparative example 1. In comparative example 5, where an aramid-nylon hybrid tape with a twist coefficient K of 2.625 (also outside the specified range) was used, the number of ends was increased to achieve the desired securing force. Consequently, the cut end portion of the belt reinforcement layer was prone to adhesion failure, and the tire's high-speed durability did not improve.In comparative example 6, where the belt angle was 41°, which is outside the prescribed range, the circumferential bonding force of the tire decreased, and the tire's durability at high speeds did not improve. Furthermore, the actual steering stability of the car decreased, and no improvement in ride comfort was observed. In comparative example 7, where the product of LASE 5% and the terminal number E was less than 1000 N, the bonding force decreased, and the tire's durability at high speeds did not improve.

[0042] Some embodiments of the invention have been described above. However, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be carried out in other different ways, and various omissions, substitutions, and modifications can be made to them without departing from the core of the invention. These embodiments, as well as the omissions, substitutions, and modifications thereto, fall within the scope and core of the invention and also within the scope of the claimed invention and its equivalents.

[0043] The embodiments of the invention can be used in a suitable manner for various pneumatic tires, including passenger car tires.

Claims

[1] Pneumatic tire which has: a belt layer (7) obtained by arranging a belt band obliquely with respect to a circumferential direction of the tire on the radially outer side of a carcass layer (4) in a tread portion (3); and a belt reinforcement layer (9) obtained by arranging an organic fiber band along the circumferential direction of the tire on the radially outer side of the belt layer (7); wherein the belt layer (7) is designed such that an angle of the belt band with respect to a circumferential direction of the tire is 31° or more and 37° or less; and wherein the organic fiber tape of the belt reinforcement layer (9) is designed such that, if the number of twists per 10 cm length is T (twists / 10 cm), the fineness is D (dtex) and the fiber density is ρ (g / cm³). 3 ) is a twist coefficient K, which is expressed as T × (D / ρ)1 / 2 is determined to be 900 to 2600 and the product of a load at 5% elongation LASE 5% (N) of the organic fiber tape and a number of ends E (tapes / 25 mm) of the organic fiber tape is 1000 N or more, and where the number of ends E is from 25 to 35 / 25 mm. [2] Pneumatic tire according to claim 1, wherein the organic fiber tape of the belt reinforcement layer (9) is an organic fiber tape obtained by twisting a plurality of nylon yarns together, and wherein the twist coefficient K is 1,100 to 2,600. [3] Pneumatic tire according to claim 1, wherein the organic fiber tape of the belt reinforcement layer (9) is a hybrid tape obtained by twisting a nylon yarn and an aramid yarn, and wherein the twist coefficient K is 900 to 2300. [4] Pneumatic tire according to one of claims 1 to 3, wherein the fineness D of the organic fiber tape of the belt reinforcement layer (9) is 1,000 to 4,000 dtex. [5] Pneumatic tire according to any one of claims 1 to 4, wherein the number of twists T of the organic fiber tape of the belt reinforcement layer (9) is 20 / 10 cm to 60 / 10 cm. [6] Pneumatic tire according to any one of claims 1 to 5, wherein the LASE 5% of the organic fiber tape of the belt reinforcement layer (9) is 30 to 100 N. [7] Pneumatic tire according to any one of claims 1 to 6, wherein the end number E of the organic fiber tape of the belt reinforcement layer (9) is 15 / 25 mm to 50 / 25 mm.

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