pneumatic tires

Abstract

Pneumatic tires, including: a tread section (1) extending in a circumferential direction of the tire and having a ring shape; a pair of sidewall sections (2) arranged on opposite sides of the running surface section (1); and a pair of bead sections (3) arranged towards the inside of the sidewall sections (2) in the tire radial direction; wherein a sound-absorbing element (6) is attached via an adhesive layer (5) to an inner surface (4) of the tread section (1) along the tire circumferential direction; a hardness x (N / 314 cm 2 ) of the sound-absorbing element (6) and the elongation at break y (%) of the sound-absorbing element (6) satisfy the ratios 130 ≤ y ≤ 500, y ≤ -21x + 2770 and x > 80; wherein the hardness x of the sound-absorbing element (6) is measured according to method D according to JIS-K6400; a number of cells of the sound-absorbing element (6) is from 30 cells / 25 mm to 80 cells / 25 mm; the adhesive layer (5) comprises a double-sided adhesive tape, and the adhesive layer (5) has a total thickness of 10 µm to 150 µm.

Description

Technical area

[0001] The present invention relates to a pneumatic tire, and more particularly, to a pneumatic tire capable of preventing separation or breakage of a sound absorbing member under high load and low temperature and achieving a sound absorbing effect via the sound absorbing member during high-speed running. State of the art

[0002] Cavity resonance, caused by air vibration in a tire cavity, is a cause of tire noise. Cavity resonance occurs when a tire tread portion that comes into contact with a road surface during vehicle travel vibrates due to the unevenness of the road surface, and the vibration causes the air in the tire cavity to vibrate. Since sound in a certain frequency band of cavity resonance is perceived as noise, it is important to reduce the sound pressure level (noise level) in that frequency band and reduce cavity resonance.

[0003] A known technique for reducing noise caused by such cavity resonance involves attaching a sound-absorbing member made of a porous material such as sponge to an inner surface of a tread portion on a tire inner surface using an elastic band (see, for example, Patent Document 1). However, in a case where the sound-absorbing member is attached with the elastic band, the elastic band may be deformed during high-speed driving.

[0004] Another known method involving the direct adhesion and attachment of a sound-absorbing member to a tire inner surface has been proposed (see, for example, Patent Document 2). However, in a case where the sound-absorbing member attached to the tire inner surface has low elasticity, the sound-absorbing member may not follow the deformation of the tire under high load or at low temperatures. This leads to significant separation or breakage of the sound-absorbing member. Furthermore, in a case where the sound-absorbing member attached to the tire inner surface has high elasticity, the sound-absorbing member is deformed with compression set during high-speed driving and thus may not sufficiently provide a sound-absorbing effect.

[0005] The prior art includes JP 4281874 B2, JP 5267288 B2, EP 1 876 038 A1, EP 1 950 057 A1, EP 1 577 123 A1 and DE 10 2010 029 081 A1. Brief description of the inventionTechnical problem

[0006] An object of the present invention is to provide a pneumatic tire that can prevent separation or breakage of a sound absorbing member under high load or at low temperatures and achieve a sound absorbing effect via the sound absorbing member during high-speed running. Solution to the problem

[0007] To perform the task described above, a pneumatic tire includes: a tread portion extending in a tire circumferential direction and having a ring shape; a pair of sidewall portions disposed on opposite sides of the tread portion; and a pair of bead portions arranged toward the inside of the sidewall portions in the tire radial direction; wherein a sound-absorbing member is attached via an adhesive layer to an inner surface of the tread portion along the tire circumferential direction, and a hardness x (N / 314 cm 2 ) of the sound-absorbing member and the elongation at break y (%) of the sound-absorbing member satisfy the relationships 130 ≤ y ≤ 500, y ≤ -21x + 2770 and x > 80, wherein the hardness x of the sound-absorbing member is measured according to Method D of JIS-K6400, a number of cells of the sound-absorbing member is from 30 cells / 25 mm to 80 cells / 25 mm, the adhesive layer comprises a double-sided adhesive tape, and the adhesive layer has a total thickness of 10 µm to 150 µm. Advantageous effects of the invention

[0008] A pneumatic tire according to an embodiment of the present invention includes a tread portion extending in the tire circumferential direction and having a ring shape; a pair of sidewall portions disposed on opposite sides of the tread portion; and a pair of bead portions disposed toward the inside of the sidewall portions in the tire radial direction; wherein a sound absorbing member is fixed via an adhesive layer to an inner surface of the tread portion along the tire circumferential direction and has a hardness x (N / 314 cm 2) of the sound-absorbing member and the elongation at break y (%) of the sound-absorbing member satisfy the relationships 130 ≤ y ≤ 500, y ≤ -21x + 2770, and x > 80. This ensures that the sound-absorbing effect of the sound-absorbing member is sufficiently ensured during high-speed driving and prevents separation and breakage of the sound-absorbing member under high load or at low temperatures.

[0009] In one embodiment of the present invention, the sound-absorbing member preferably has a density of 10 kg / m 3 up to 30 kg / m 3 up, and According to the invention, the number of cells of the sound-absorbing member ranges from 30 cells / 25 mm to 80 cells / 25 mm. This allows the sound-absorbing member to have a low density and reduced weight, resulting in a reduction in rolling resistance. Furthermore, the number of cells of the sound-absorbing member is appropriately determined, allowing the formation of fine air bubbles. This ensures a sufficient sound-absorbing effect of the sound-absorbing member.

[0010] In one embodiment of the present invention, the sound-absorbing member preferably has a volume of 10% to 30% of a tire cavity volume. Thus, the sound-absorbing effect of the sound-absorbing member can be sufficiently ensured, resulting in improved noise reduction.

[0011] In one embodiment of the present invention, the sound-absorbing member preferably includes a single strip-shaped body with a rectangular cross-sectional shape, and the strip-shaped body constituting the sound-absorbing member is arranged spanning a tire equator. When the single sound-absorbing member is arranged on the tire inner surface, separation or breakage of the sound-absorbing member under high load or at low temperatures can be effectively prevented.

[0012] In one embodiment of the present invention, the pneumatic tire further includes a central land portion disposed on the tread portion on a tire equator and extending continuously around the tread portion around an entire tire circumference; and wherein the sound-absorbing member includes a first strip-shaped body and a second strip-shaped body each having a rectangular cross-sectional shape; the first strip-shaped body constituting the sound-absorbing member is arranged on one side in a tire transverse direction with respect to a position which is 40% of a width of the central land portion, from an end portion of the central land portion on one side in the tire transverse direction toward the other side in the tire transverse direction; The second strip-shaped body constituting the sound-absorbing member is arranged on the other side in the tire transverse direction with respect to a position that is 40% of the width of the central land portion, from an end portion of the central land portion on the other side in the tire transverse direction to the one side in the tire transverse direction; and The first strip-shaped body constituting the sound-absorbing member and the second strip-shaped body constituting the sound-absorbing member are separated from each other by 60% or more of the width of the central land portion. When a plurality of sound-absorbing members are arranged on the tire inner surface, it is necessary to arrange the sound-absorbing member near a region corresponding to a shoulder portion. Accordingly, the sound-absorbing member arranged in the region may not sufficiently ensure high-speed durability.By disposing a plurality of sound-absorbing members on the tire inner surface as described above, heat buildup during high-speed driving can be effectively inhibited and high-speed durability can be increased. Furthermore, noise performance and high-speed durability can be improved in a well-balanced manner.

[0013] In one embodiment of the present invention, the adhesive layer includes a double-sided adhesive tape, and the adhesive layer has a total thickness of 10 µm to 150 µm. Accordingly, the conformability to deformation during molding can be ensured.

[0014] In one embodiment of the present invention, the sound-absorbing member preferably includes a recessed portion in at least one portion in the tire circumferential direction. Thus, the tire can withstand expansion due to inflation of the tire or shear stress of an adhesion surface due to contact and rolling of the tire for a long period of time.

[0015] In one embodiment of the present invention, the hardness of the sound-absorbing member, the elongation at break of the sound-absorbing member, the density of the sound-absorbing member, and the number of cells of the sound-absorbing member are measured according to JIS-K6400. Method D is used according to the present invention to test the hardness of the sound-absorbing member. Note that the dimensions and void volume of the tire are measured in a state where the tire is mounted on a regular rim and inflated to normal internal pressure. Specifically, the void volume of the tire is the volume of a void portion formed between the tire and the rim in the above-described state."Regular rim" is a rim defined by a standard for each tire according to a system of standards that includes standards on which tires are based. It refers to a "standard rim" in the case of JATMA, a "design rim" in the case of TRA, and a "measuring rim" in the case of ETRTO. However, if the tire is an original equipment tire, the volume of the cavity section is calculated using an original wheel on which the tire is mounted."Normal air pressure" is an air pressure defined by standards for each tire according to a system of standards that includes standards on which tires are based. It refers to a "maximum air pressure" in the case of JATMA, to the maximum value in the "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" table in the case of TRA, and to the "INFLATION PRESSURE" in the case of ETRTO. However, the air pressure marked on the vehicle is used if the tire is an original equipment tire. Brief description of the drawings Fig. 1 is a meridian cross-sectional view illustrating a pneumatic tire according to an embodiment of the present invention. Fig.2 is a cross-sectional view taken along an equator line of a pneumatic tire according to an embodiment of the present invention. Fig. 3 is a graph showing the relationship between a hardness x (N / 314 cm 2 ) and an elongation at break y (%) in a sound absorbing member used in a pneumatic tire according to an embodiment of the present invention. Fig. 4 is a meridian cross-sectional view illustrating a pneumatic tire according to a modified example of an embodiment of the present invention. Description of embodiments

[0016] Configurations of embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Fig. 1 and Fig. 2 illustrate a pneumatic tire according to an embodiment of the present invention. In Fig.1, the reference symbol CL denotes the tire equator.

[0017] As in Fig. 1 and Fig. 2, the pneumatic tire according to the present embodiment includes an annular tread portion 1 extending in the tire circumferential direction, a pair of sidewall portions 2 arranged on opposite sides of the tread portion 1, and a pair of bead portions 3 arranged toward the inside of the sidewall portions 2 in the tire radial direction.

[0018] At least one carcass layer 10 is disposed between the pair of bead portions 3, 3. The carcass layer 10 includes carcass cords arranged in the tire radial direction, and organic fiber cords are preferably used as the carcass cords. The carcass layer 10 is turned upward from the inside to the outside of the tire around a bead core 11 disposed in each of the bead portions 3. A bead filler 12 having a triangular cross-sectional shape is disposed on the outer peripheral side of each of the bead cores 11. Furthermore, an inner liner layer 13 is disposed in a region between the pair of bead portions 3, 3 on a tire inner surface.

[0019] Belt layers 14 are embedded on the outer peripheral side of the carcass layer 10 in the tread portion 1. The belt layers 14 each include a plurality of reinforcing cords inclined with respect to the tire circumferential direction, with the reinforcing cords of the different layers arranged crosswise. In the belt layers 14, the inclination angle of the reinforcing cords with respect to the tire circumferential direction is in a range of, for example, 10° to 40°. Preferably, steel cords are used as the reinforcing cords of the belt layers 14. In order to improve high-speed durability, at least one belt cover layer 15 formed by arranging reinforcing cords at an angle of 5° or less with respect to the tire circumferential direction is arranged on the outer peripheral side of the belt layers 14.As the reinforcing cords of the belt cover layer 15, organic fiber cords made of nylon, aramid or the like are preferably used.

[0020] It should be noted that the tire internal structure described above is a typical example of a pneumatic tire and the pneumatic tire is not limited to this.

[0021] In the pneumatic tire described above, as shown in Fig. 1 and Fig.2, a sound-absorbing member 6 is attached via an adhesive layer 5 to a region of the tire inner surface 4 corresponding to the tread portion 1 and extends along the tire circumferential direction. The adhesive layer 5 comprises a double-sided adhesive tape. The sound-absorbing member 6 is made of a porous material with open cells and has predetermined sound absorption properties based on the porous structure. Preferably, polyurethane foam is used as the porous material of the sound-absorbing member 6. Desirably, the sound-absorbing member 6 does not contain a water repellent. In the Fig. 1, the sound absorbing member 6 includes a single strip-shaped body 6A having a rectangular cross-sectional shape.

[0022] In the present invention, a hardness × (N / 314 cm 2) of the sound absorbing member 6 and the elongation at break y (%) of the sound absorbing member satisfy the relationships 130 ≤ y ≤ 500, y ≤ -21x + 2770 and x > 80. In particular, it is preferable to satisfy the relationships 80 < x ≤ 120, 140 ≤ y ≤ 490 and / or y ≤ -21x + 2700, and more preferably to satisfy the relationships 80 < x ≤ 100, 150 ≤ y ≤ 480 and / or y ≤ -21x + 2600. The hardness x and the elongation at break y of the sound-absorbing member 6 are the hardness and the elongation at break measured under standard conditions (temperature 23 °C, relative humidity 50%).

[0023] In particular, an area S of the hatched section, which is in Fig. 3 illustrates the range of physical properties of the sound-absorbing member 6 used in the pneumatic tire according to an embodiment of the present invention. In Fig.3, if the hardness x of the sound-absorbing member 6 exceeds the upper limit specified by the ratio formulas described above, the deformation of the tire when bearing a load cannot be followed, and thus the sound-absorbing member 6 is likely to separate. If the hardness is 80 N / 314 cm 2 or less, the sound-absorbing member 6 will be deformed with compression set during high-speed driving and cannot sufficiently provide a sound-absorbing effect. Furthermore, if the elongation at break y of the sound-absorbing member 6 is less than 130%, the sound-absorbing member 6 is likely to be easily broken when the tire is severely deformed, and in particular, the tendency to break is significant at low temperatures.

[0024] The pneumatic tire mentioned has a configuration in which the sound-absorbing element 6 is adhered to the area of ​​the tire inner surface 4 corresponding to the tread portion 1, the sound-absorbing member 6 having the hardness x (with N / 314 cm 2 ) and the elongation at break y (%) of the sound-absorbing member 6, the relationships 130 ≤ y ≤ 500, y ≤ -21x + 2770, and x > 80 are satisfied. Thus, the sound-absorbing member 6 can sufficiently ensure the sound-absorbing effect during high-speed driving, and separation or breakage of the sound-absorbing member 6 under high load or at low temperatures can be prevented.

[0025] The above-mentioned pneumatic tire preferably has a configuration in which the density of the sound absorbing member 6 is 10 kg / m 3 up to 30 kg / m 3and the number of cells of the sound-absorbing member 6 according to the invention is from 30 cells / 25 mm to 80 cells / 25 mm. The density of the sound-absorbing member 6 is set as such to impart a low density to the sound-absorbing member 6 and reduce the weight. This leads to a reduction in rolling resistance. In addition, the number of cells of the sound-absorbing member 6 is appropriately set so that fine air bubbles can be formed and the sound-absorbing effect of the sound-absorbing member 6 can be sufficiently ensured.

[0026] The volume of the sound-absorbing member 6 is preferably from 10% to 30% of the volume (cavity volume) of a cavity portion 7 formed between the tire and a rim R. Furthermore, the width of the sound-absorbing member 6 is preferably from 30% to 90% of the ground contact width of the tire. In this way, the sound-absorbing effect of the sound-absorbing member 6 can be sufficiently ensured, resulting in an improvement in quietness. If the volume of the sound-absorbing member 6 is less than 10% of the cavity volume of the tire, the sound-absorbing effect cannot be adequately achieved. Furthermore, if the volume of the sound-absorbing member 6 is more than 30% of the cavity volume of the tire, the noise reduction effect reaches a plateau due to cavity resonance. As a result, the noise reduction effect cannot be further achieved.

[0027] As in Fig.As illustrated in FIG. 2, the sound-absorbing member 6 preferably includes a recessed portion 8 in at least one portion in the tire circumferential direction. The recessed portion 8 is a portion where the sound-absorbing member 6 is not present along the tire circumference. The recessed portion 8 is provided in the sound-absorbing member 6. This allows expansion due to inflation of the tire or shear stress of an adhesion surface due to contact and rolling to be endured for a long period of time, and shear stress on the adhesion surface of the sound-absorbing member 6 to be effectively reduced. One recessed portion 8 or three to five recessed portions 8 may be provided along the tire circumference.In other words, when two recessed portions 8 are provided along the tire circumference, the tire uniformity deteriorates significantly due to mass unbalance, and when six or more recessed portions 8 are provided along the tire circumference, the production cost increases significantly.

[0028] Note that in a case where two or more recessed portions 8 are provided along the tire circumference, the sound-absorbing member 6 is divided into portions in the tire circumferential direction. However, even in such a case, the divided portions of the sound-absorbing member 6 are bonded together with another layered member such as the adhesive layer 5 made of double-sided tape, for example. Thus, the sound-absorbing member 6 can be treated as a single-piece member and easily attached to the tire inner surface 4.

[0029] The pneumatic tire according to the present invention has a configuration in which the adhesive layer 5 is made of double-sided adhesive, and the total thickness of the adhesive layer 5 is from 10 μm to 150 μm. By configuring the adhesive layer 5 as described above, the followability with respect to deformation during molding can be ensured. If the total thickness of the adhesive layer 5 is less than 10 μm, the strength of the double-sided adhesive tape is insufficient, and the adhesion to the sound-absorbing member 6 cannot be sufficiently ensured. If the total thickness of the adhesive layer 5 is more than 150 μm, heat dissipation during high-speed running is inhibited. Thus, the high-speed durability is liable to deteriorate.

[0030] Fig.4 illustrates a pneumatic tire according to a modified example of an embodiment of the present invention. As in Fig. As illustrated in Figure 4, two or more circumferential grooves 20 extending in the tire circumferential direction are formed in the tread portion 1. One or more land portions 21 are defined by the circumferential grooves 20 between two circumferential grooves 20 adjacent in the tire transverse direction, and two (one on each side in the tire transverse direction) shoulder land portions 22 are defined on the outer sides in the tire transverse direction by the circumferential grooves 20 located outermost in the tire transverse direction. The land portion 21 must include a central land portion 21c located on the tire equator CL and extending continuously around the entire circumference of the tire.

[0031] Here closes in the Fig.1, the sound-absorbing member 6 includes a single strip-shaped body 6A having a rectangular cross-sectional shape, and the strip-shaped body 6A constituting the sound-absorbing member 6 is arranged spanning the tire equator CL. In contrast, in the embodiment shown in Fig.4, the sound-absorbing member 6 includes a first strip-shaped body 6A and a second strip-shaped body 6B, each having a rectangular cross-sectional shape. The first strip-shaped body 6A constituting the sound-absorbing member 6 is arranged on one side in the tire transverse direction with respect to a position that is 40% of a width W of the central land portion 21c, from an end portion of the central land portion 21c on one side in the tire transverse direction toward the other side in the tire transverse direction. The second strip-shaped body 6B constituting the sound-absorbing member 6 is arranged on the other side in the tire transverse direction with respect to a position that is 40% of the width W of the central land portion 21c, from an end portion of the central land portion 21c on the other side in the tire transverse direction toward the one side in the tire transverse direction.In addition, a separation distance D between the first strip-shaped body 6A and the second strip-shaped body 6B is set to be 60% or more of the width W of the central land portion 21c. In addition, an overlap amount L of the strip-shaped bodies 6A, 6B and the central land portion 21c (the sum of an overlap amount L1 of the first strip-shaped body 6A and an overlap amount L2 of the second strip-shaped body 6B) is set to be 40% or less of the width W of the central land portion 21c.

[0032] As described above, in the case where the pair of sound-absorbing members 6 including the first strip-shaped body 6A and the second strip-shaped body 6B are mounted, the pair of sound-absorbing members 6 are arranged separately from each other so that heat is most easily generated in the tread portion 1, and the sound-absorbing members 6 are directly mounted at a position away from the inner surface side of the central land portion 21c where heat buildup is likely to occur; heat buildup during high-speed running can be effectively inhibited, and high-speed durability can be improved. In addition, the noise performance and high-speed durability can be improved in a well-balanced manner.

[0033] The first strip-shaped body 6A or the second strip-shaped body 6B is arranged on one side or the other side in the tire transverse direction with respect to the position that is 40% of the width W of the central land portion 21c, from one end portion or the other end portion of the central land portion 21c in the tire transverse direction to the other side or the one side in the tire transverse direction. Note that such a structure includes the case where the end portion of the first strip-shaped body 6A or the end portion of the second strip-shaped body 6B on the inner side in the tire transverse direction coincides with a position that is 40% of the width W of the central land portion 21c from one end or the other end of the central land portion 21c in the tire transverse direction to the other side or the one side in the tire transverse direction. Example

[0034] Pneumatic tires according to Comparative Examples 1 to 8 and Examples 1 to 8 were manufactured. The pneumatic tires have a tire size of 275 / 35ZR20 and include an annular tread portion extending in the tire circumferential direction, a pair of sidewall portions arranged on opposite sides of the tread portion, a pair of bead portions arranged toward the inside of the sidewall portions in the tire radial direction, and a sound-absorbing member attached to the inner surface of the tread portion via an adhesive layer. The physical properties were measured as shown in Tables 1 and 2 for the hardness of the sound-absorbing member (N / 314 cm). 2 ), the elongation at break of the sound-absorbing member (%), the density of the sound-absorbing member (kg / m 3 ), and the number of cells of the sound-absorbing member (cells / 25 mm).

[0035] High-speed camber angle durability, load resistance, and low-temperature durability were evaluated for each of the test tires according to the following test procedures. The results are also shown in Tables 1 and 2. In addition, Fig. 3 The physical properties of the sound absorbing members attached to the tires of Examples 1 to 8 are each indicated by round marks, and the physical properties of the sound absorbing members attached to the tires of Comparative Examples 1 to 8 are indicated by triangular marks.

[0036] High speed stability with camber angle: Each test tire was mounted on a wheel with a rim size of 20x9 J, and a driving test was conducted using a drum testing machine under the following conditions: Driving speed of 330 km / h, air pressure of 290 kPa, load of 6 kN, negative camber angle of -3°, and driving distance of 400 km. After the test, the sound-absorbing member was visually confirmed to determine whether it was subjected to compression set deformation.

[0037] Resistance under load: Each test tire was mounted on a wheel with a rim size of 20x9 1 / 2 J, and a driving test was conducted using a drum testing machine under the following conditions: Driving speed of 81 km / h, air pressure of 160 kPa, load of 8.5 kN, and driving distance of 6480 km. After the test, it was visually confirmed whether the sound-absorbing member was separated from the adhesive surface.

[0038] Low temperature resistance: Each test tire was mounted on a wheel with a rim size of 20x9 1 / 2 J, and a driving test was conducted using a drum testing machine under the following conditions: Temperature of -20°C, driving speed of 81 km / h, air pressure of 160 kPa, load of 5 kN, and driving distance of 6,480 km. After the test, a visual check was performed to determine whether the sound-absorbing element had broken.

[0040] [Table 1-I] Comparison example 1 Comparison example 2 Comparison example 3 Comparison example 4 Hardness of the sound-absorbing member (N / 314 cm 2 ) 80 80 130 75 Elongation at break of the sound-absorbing member (%) 120 130 130 350 Density of the sound-absorbing element (kq / m 3 ) 25 25 25 25 Number of cells of the sound-absorbing element (cells / 25 mm) 50 50 50 50 High speed stability with camber angle Deformed Deformed Not deformed Deformed Durability under load No separation No separation separation No separation Low temperature resistance Broken Not broken (no external damage) Not broken (no external damage) Not broken (no external damage) [Table 1-II] Comparison example 5 Comparison example 6 Comparison example 7 Comparison example 8 Hardness of the sound-absorbing member (N / 314 cm 2 ) 80 110 120 100 Elongation at break of the sound-absorbing member (%) 500 500 300 520 Density of the sound-absorbing element (kq / m 3 ) 25 25 25 25 Number of cells of the sound-absorbing element (cells / 25 mm) 50 50 50 50 High speed stability with camber angle Deformed Not deformed Not deformed Not deformed Durability under load No separation separation separation No separation Low temperature resistance Not broken (no external damage) Not broken (no external damage) Not broken (no external damage) Not broken (no external damage)

[0041] [Table 2] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Hardness of the sound-absorbing member (N / 314 cm 2 ) 85 85 90 125 90 95 100 115 Elongation at break of the sound-absorbing member (%) 130 500 130 130 480 200 350 150 Density of the sound-absorbing element (kq / m 3 ) 25 25 25 25 25 25 25 25 Number of cells of the sound-absorbing element (cells / 25 mm) 50 50 50 50 50 50 50 50 High speed stability with camber angle Not deformed Not deformed Not deformed Not deformed Not deformed Not deformed Not deformed Not deformed Durability under load No separation No separation No separation No separation No separation No separation No separation No separation Low temperature resistance Not broken (no external damage) Not broken (no external damage) Not broken (no external damage) Not broken (no external damage) Not broken (no external damage) Not broken (no external damage) Not broken (no external damage) Not broken (no external damage)

[0039] As can be seen from Tables 1 and 2, the high-speed camber angle durability and the low-temperature durability of the pneumatic tires of Examples 1 to 8 were improved compared to Comparative Example 1. Compared to Comparative Example 3, the load durability of the pneumatic tires of Examples 1 to 8 was improved.

[0040] In Comparative Examples 2, 4, and 5, since the hardness of the sound-absorbing member was set low, the deformation of the sound-absorbing member was confirmed in the high-speed camber angle durability test. In Comparative Examples 6 and 7, the hardness of the sound-absorbing member was set greater than the upper limit specified by the relational formulas for the hardness of the sound-absorbing member and the elongation at break of the sound-absorbing member according to an embodiment of the present invention. Thus, the separation of the sound-absorbing member was confirmed in the load durability test. In Comparative Example 8, the elongation at break of the sound-absorbing member is greater than the upper limit of the elongation at break of the sound-absorbing member according to an embodiment of the present invention, and thus it is difficult to practically manufacture tires. List of reference symbols 1 tread section 2 side wall section 3 bead section 4 Tire inner surface 5 Adhesive layer 6 Sound-absorbing element 6A, 6B Strip-shaped body 7 Cavity section 8 Recessed section 20 circumferential groove 21 footbridge section 21c Central bridge section CL Tire Equator R rim

Claims

[1] Pneumatic tyres comprising: a tread portion (1) extending in a tire circumferential direction and having a ring shape; a pair of sidewall portions (2) arranged on opposite sides of the tread portion (1); and a pair of bead portions (3) arranged towards the inside of the sidewall portions (2) in the tire radial direction; wherein a sound-absorbing member (6) is attached to an inner surface (4) of the tread portion (1) along the tire circumferential direction via an adhesive layer (5); a hardness x (N / 314 cm 2 ) of the sound-absorbing member (6) and the elongation at break y (%) of the sound-absorbing member (6) satisfy the relationships 130 ≤ y ≤ 500, y ≤ -21x + 2770 and x > 80; wherein the hardness x of the sound-absorbing member (6) is measured according to method D of JIS-K6400; a number of cells of the sound-absorbing member (6) is from 30 cells / 25 mm to 80 cells / 25 mm; the adhesive layer (5) comprises a double-sided adhesive tape, and the adhesive layer (5) has a total thickness of 10 µm to 150 µm. [2] A pneumatic tire according to claim 1, wherein the sound absorbing member (6) has a density of 10 kg / m 3 up to 30 kg / m 3 has. [3] A pneumatic tire according to claim 1 or 2, wherein the sound absorbing member (6) has a volume of 10% to 30% of a cavity volume of the tire. [4] A pneumatic tire according to any one of claims 1 to 3, wherein the sound absorbing member (6) comprises a single strip-shaped body (6A) having a rectangular cross-sectional shape, and the strip-shaped body (6A) constituting the sound absorbing member (6) is arranged spanning a tire equator (CL). [5] A pneumatic tire according to any one of claims 1 to 3, further comprising a central land portion (21c) formed on the Tread portion (1) is arranged on a tire equator (CL) and extends continuously around the entire tire circumference around the tread portion (1); and wherein the sound-absorbing member (6) comprises a first strip-shaped body (6A) and a second strip-shaped body (6B), each having a rectangular cross-sectional shape; the first strip-shaped body (6A) constituting the sound-absorbing member (6) is arranged on one side in a tire transverse direction with respect to a position which is 40% of a width of the central land portion (21c), from an end portion of the central land portion (21c) on one side in the tire transverse direction toward the other side in the tire transverse direction; the second strip-shaped body (6B) constituting the sound-absorbing member (6) is arranged on the other side in the tire transverse direction with respect to a position which is 40% of the width of the central land portion (21c), from an end portion of the central land portion (21c) on the other side in the tire transverse direction toward the one side in the tire transverse direction; and the first strip-shaped body (6A) constituting the sound-absorbing member (6) and the second strip-shaped body (6B) constituting the sound-absorbing member (6) are separated from each other by 60% or more of the width of the central web portion (21c). [6] A pneumatic tire according to any one of claims 1 to 5, wherein the sound absorbing member (6) includes a recessed portion (8) in at least one portion in the tire circumferential direction.

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