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 inwards from the sidewall sections (2) in the tire radial direction; wherein a sound-absorbing element (6) is attached via an adhesive layer (5a) to an inner surface (4) of the tread section (1) along the tire circumferential direction and, the adhesive layer (5a) comprises a solid adhesive (30) without enclosing a base material (31); wherein the adhesive layer (5a) has an average thickness of 0.40 mm to 5.00 mm.

Description

Technical area

[0001] The present invention relates to a pneumatic tire, and more particularly to a pneumatic tire capable of preventing deterioration of high-speed durability. 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 includes 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 by means of an elastic band (see, for example, JP 4281874 B2). However, in a case where the sound-absorbing member is attached with the elastic band, the elastic band may be deformed when traveling at high speeds.

[0004] Another known method of directly adhering and fixing a sound absorbing member to a tire inner surface has been proposed (see, for example, JP 5267288 B2). As in Fig.As illustrated in FIG. 6, when an adhesive layer 5b formed of pressure-sensitive adhesives 30 and a base material 31, which is a supporting body supporting the pressure-sensitive adhesives 30, are used to directly adhere a sound-absorbing member 6 to a tire inner surface 4, the presence of the base material 31 inhibits the heat dissipation of the tire, and the base material 31 itself generates heat. Thus, high-speed durability may deteriorate.

[0005] The prior art also includes the documents US 2009 / 0038726 A1, EP 1 967 391 A2, EP 1 745 947 A2 and EP 2 433 786 A2. Brief description of the inventionTechnical problem

[0006] An object of the present invention is to provide a pneumatic tire which can prevent the deterioration of high speed durability. 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 inwardly 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 the adhesive layer includes a solid pressure-sensitive adhesive without including a base material, the adhesive layer having an average thickness of 0.40 mm to 5.00 mm. Advantageous effects of the invention

[0008] As a result of careful research on a pneumatic tire with a sound-absorbing member attached to a tire inner surface via an adhesive layer, the present inventors discovered that the adhesive strength is sufficient because the adhesive layer is ensured by using the adhesive layer made of a pressure-sensitive adhesive without a base material, and deterioration of high-speed durability can be effectively prevented. As just described, the inventors achieved the present invention.

[0009] The pneumatic tire 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 inward from the sidewall portions in the tire radial direction. A sound-absorbing member is adhered to an inner surface of the tread portion along the tire circumferential direction via an adhesive layer. The adhesive layer comprises a solid pressure-sensitive adhesive without including a base material, and the adhesive layer has an average thickness of 0.40 mm to 5.00 mm. Thus, heat dissipation of the tire is not inhibited by the adhesive layer, and the adhesive layer itself does not generate heat. Accordingly, deterioration of high-speed durability can be prevented.

[0010] The average thickness of the adhesive layer of 0.40 mm to 5.00 mm allows the adhesive layer to follow the unevenness of the tire's inner surface and ensure a sufficient adhesion area.

[0011] In one embodiment of the present invention, the adhesive layer preferably has a peel adhesion strength of 5 N / 20 mm or more. Thus, the attachment strength of the sound-absorbing member can be well maintained, and the sound-absorbing member can be prevented from peeling off. The peel adhesion strength of the adhesive layer is measured according to JIS-Z0237. In other words, a PET film with a thickness of 25 µm is applied to a double-sided pressure-sensitive adhesive sheet, and thus the double-sided pressure-sensitive adhesive sheet is covered with the PET film. Test pieces are prepared by cutting the covered adhesive sheet into 20 mm x 200 mm squares.The removable cover is peeled off from each of the test pieces, and the exposed adhesive surface is applied as an attached body to a stainless steel sheet (SUS304, BA grade) by rolling a 2 kg roller back and forth over it. After the test piece is kept in an environment at a temperature of 23 °C and a relative humidity of 50% for 30 minutes, the test piece is peeled at 180 °C and a tensile speed of 300 mm / minute under the environment at a temperature of 23 °C and a relative humidity of 50% using a tensile tester according to JIS-Z0237, thus measuring the peel adhesion strength with respect to the SUS sheet.

[0012] In one embodiment of the present invention, the sound-absorbing member preferably has a volume of 10% to 30% of a tire's cavity volume. Thus, the sound-absorbing effect of the sound-absorbing member can be sufficiently ensured, resulting in an improvement in quietness. The cavity volume of the tire is the volume of the cavity portion formed between the tire and the rim in a state where the tire is mounted on a regular rim and inflated to the normal internal pressure. "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, and 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 internal 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, and 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, if the tire is an original equipment tire, the air pressure marked on the vehicle is used.

[0013] 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, deterioration of high-speed durability can be effectively prevented.

[0014] 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 that 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 toward 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 this region may not sufficiently ensure high-speed durability. By arranging the 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, the noise performance and high-speed durability can be improved in a well-balanced manner.

[0015] 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. 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 cross-sectional view of a tread portion of a pneumatic tire according to an embodiment of the present invention. Fig.4 is a graph showing, in a case where an adhesive layer is provided on a tire inner surface, the relationship between a thickness (mm) of the adhesive layer and a temperature (°C) of the tire inner surface at the time of tire failure. Fig. 5 is a meridian cross-sectional view illustrating a pneumatic tire according to a modified example of an embodiment of the present invention. Fig. 6 is a cross-sectional view of a tread portion of a prior art pneumatic tire having a sound absorbing member attached to a tire inner surface. 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 inwardly in the tire radial direction from the sidewall portions 2.

[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 5a is preferably provided on the entire surface of the sound-absorbing member 6. 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. In the embodiment shown in Fig. 1, the sound absorbing member 6 includes a single strip-shaped body 6A having a rectangular cross-sectional shape.

[0022] The adhesive layer 5a is a double-sided adhesive tape with a high adhesive strength. As in Fig.As illustrated in Fig. 3, the adhesive layer 5a is made of a solid pressure-sensitive adhesive 30 without including a base material 31. The adhesive layer 5a does not include a base material 31, and thus the overall thickness can be reduced. The pressure-sensitive adhesive 30 is not particularly limited; however, for example, any of an acrylic-based pressure-sensitive adhesive, a silicone-based pressure-sensitive adhesive, and a rubber-based pressure-sensitive adhesive can be used as the pressure-sensitive adhesive 30. In particular, an acrylic-based pressure-sensitive adhesive or a silicone-based pressure-sensitive adhesive is desirable as the pressure-sensitive adhesive 30. The acrylic-based pressure-sensitive adhesives have excellent heat resistance and are thus suitable for improving high-speed durability. The silicone-based pressure-sensitive adhesive has no temperature dependence of adhesion and has excellent adhesiveness with the sound-absorbing member 6.

[0023] Fig.Figure 4 shows, in a case where an adhesive layer is provided on a tire inner surface, the relationship between a thickness (mm) of the adhesive layer and a temperature (°C) of the tire inner surface at the time of tire failure. Fig. The results given in Figure 4 are tire inner surface temperatures measured at the time of tire failure in a case where the tires were run on a drum testing machine with either only the adhesive layer 5a made of the pressure-sensitive adhesive 30 without enclosing the sound-absorbing member 6 attached to the tire inner surface 4, or the adhesive layer 5b formed of the adhesives 30 layered on both surfaces of the enclosed base material 31, until the tires failed. In Fig. 4 are a case where the adhesive layer 5a is provided which does not include the base material 31 (A in Fig.4), a case where the adhesive layer 5b is provided enclosing the base material 31 (B in Fig. 4), and for comparison, a case where no adhesive layer is provided (C in Fig. 4). At this time, the total thickness of the adhesive layer 5b is 0.40 mm, and specifically, the thickness of each of the layers of the pressure-sensitive adhesives 30 is 0.05 mm (two layers being 0.10 mm), and the thickness of the base material 31 is 0.30 mm.

[0024] As from Fig.As can be seen from Fig. 4, in the case of the adhesive layer 5a, regardless of the thickness (0.05 mm to 0.40 mm), the temperature of the tire inner surface is the same as the temperature of the tire inner surface in the case of the adhesive layer not provided. In contrast, in the case of the adhesive layer 5b, the temperature of the tire inner surface is higher compared to the case of the adhesive layer 5a. In other words, the pressure-sensitive adhesive 30 itself hardly generates heat and does not affect the temperature rise of the tire inner surface at the time of tire failure. In addition, the base material 31 itself generates heat and affects the temperature rise of the tire inner surface.

[0025] In the aforementioned pneumatic tire, the sound-absorbing member 6 is attached to the inner surface of the tread portion 1 along the tire circumferential direction via the adhesive layer 5a, and the adhesive layer 5a is composed of the solid pressure-sensitive adhesive 30 without enclosing the base material 31. Thus, the heat release of the tire is not disturbed, and the adhesive layer 5a itself does not generate heat. As a result, deterioration of high-speed durability can be prevented.

[0026] The aforementioned pneumatic tire has a configuration in which the average thickness g of the adhesive layer 5a is 0.40 mm to 5.00 mm. The average thickness g of the adhesive layer 5a is appropriately adjusted as just described, and thus the adhesive layer 5a can follow the unevenness of the tire inner surface 4 and ensure a sufficient adhesion area. If the average thickness g of the adhesive layer 5a is less than 0.05 mm, the sound-absorbing member 6 is easily separated at the time of load resistance. If the average thickness g of the adhesive layer 5a is greater than 5.00 mm, the weight of the adhesive layer 5a is large, so the rolling resistance is likely to deteriorate. In addition, the average thickness g of the adhesive layer 5a is in the range of 1.00 mm to 5.00 mm, and thus the tire puncture sealing properties can be achieved.

[0027] The peeling bond strength of the adhesive layer 5a is preferably 5 N / 20 mm or more. The upper limit of the peeling bond strength is preferably 100 N / 20 mm or less. The peeling bond strength of the adhesive layer 5a is appropriately adjusted as just described, and thus the attachment strength of the sound-absorbing member 6 can be well maintained. Furthermore, the sound-absorbing member 6 can be prevented from peeling off.

[0028] The volume of the sound-absorbing member 6 of the aforementioned pneumatic tire 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 tire's ground contact width. Thus, the sound-absorbing effect of the sound-absorbing member 6 can be sufficiently ensured, resulting in improved noise reduction. If the volume of the sound-absorbing member 6 is less than 10% of the tire's cavity volume, the sound-absorbing effect cannot be adequately achieved. Furthermore, if the volume of the sound-absorbing member 6 is more than 30% of the tire's cavity volume, the noise reduction effect due to cavity resonance reaches a plateau.As a result, the noise reduction effect can no longer be achieved.

[0029] 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.

[0030] 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 5a made of double-sided tape. Thus, the sound-absorbing member 6 can be treated as a single-piece member and easily attached to the tire inner surface 4.

[0031] Fig.5 illustrates a pneumatic tire according to a modified example of an embodiment of the present invention. As in Fig. As illustrated in Figure 5, 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.

[0032] 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.5, 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 the 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.

[0033] 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.

[0034] 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

[0035] Pneumatic tires according to Examples 1 to 6 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 inward from the sidewall portions in the tire radial direction, and a sound-absorbing member attached to the inner surface of the tread portion along the tire circumferential direction via an adhesive layer, the adhesive layer being formed of a solid pressure-sensitive adhesive without including a base material. In Examples 1 to 6, the thickness (mm) of the adhesive layer was set as shown in Table 1.

[0036] For comparison, a tire according to a prior art example was manufactured in which a sound-absorbing member was not attached to a tire inner surface. Furthermore, a tire according to a comparative example was manufactured with the same structure as in Example 1, except that adhesive layers were laminated on both sides of a base material.

[0037] High-speed durability, load endurance, rolling resistance, and puncture sealing properties were evaluated for each of the test tires according to the following test procedures. The results are also presented in Table 1. Durability at high speed:

[0038] Each of the test tires was mounted on a wheel with a rim size of 20x9 1 / 2 J. Under a condition where a load of 85% of the maximum load capacity defined by JATMA was applied, a running test was conducted on the tire using a drum tester under the condition of an air pressure of 360 kPa. Specifically, an initial speed of 250 km / h was used, and the speed was increased by 10 km / h every 10 minutes. The tires were driven until failure, and the reaching step (speed) was measured. The larger the reaching step (speed), the higher the high-speed durability. Load resistance:

[0039] Each of the test tires was mounted on a wheel with a 20x9 1 / 2 J rim, and a running test was conducted on the tire using a drum tester under the following conditions: running speed of 81 km / h, air pressure of 350 kPa, and running time of 240 hours. After testing, the presence of separation of the sound-absorbing member on the contact surface was visually confirmed. Rolling resistance:

[0040] Each of the test tires was mounted on a wheel with a rim size of 20x9 1 / 2 J and inflated to an air pressure of 230 kPa. Rolling resistance was measured according to ISO 28580 using a drum tester with a drum diameter of 1707 mm. The evaluation results are presented using reciprocals of the measured values ​​and index values, with the comparative evaluation value assigned to 100. Higher index values ​​indicate lower rolling resistance. Note that if the index value is "98" or higher, the state-of-the-art rolling resistance level is maintained. Tire puncture sealing properties:

[0041] A puncture hole was formed in the tread portion of each test tire, and the tires were inflated with air to a tire pressure of 250 kPa under standard conditions (temperature 23°C, relative humidity 50%). The air pressure was then measured, and it was confirmed whether any air leakage occurred. [Table 1] Example of the state of the art Comparison example Example 1 (not according to the invention) Example 2 (not according to the invention) Example 3 Example 4 Example 5 Example 6 (not according to the invention) Presence of the sound-absorbing member No Yes Yes Yes Yes Yes Yes Yes Presence of base material in the adhesive layer - Yes No No No No No No Adhesive layer thickness (mm) - 0,04 0,04 0,05 0,40 1,00 5,00 6,00 High speed stability (km / h) 360 340 350 350 350 350 350 350 Load resistance - separation separation No separation No separation No separation No separation No separation Rolling resistance - 100 100 100 100 100 98 97 Tire puncture sealing properties - Air leakage Yes Air leakage Yes Air leakage Yes Air leakage Yes Air leakage No Air leakage No Air leakage No

[0042] As can be seen from Table 1, the high speed durability was improved in Examples 1 to 6 compared to Comparative Example.

[0043] Specifically, in Examples 2 to 6, where the adhesive layer thickness was set to 0.05 mm or more, the load resistance was also improved. Furthermore, in Examples 1 to 5, where the adhesive layer thickness was set to 5.00 mm or less, the rolling resistance was maintained at a level similar to that of the comparative example. Furthermore, in Examples 4 to 6, where the adhesive layer thickness was set in the range of 1.00 mm to 6.00 mm, the tire exhibited puncture sealing properties. List of reference symbols 1 tread section 2 side wall section 3 bead section 4 Tire inner surface 5a, 5b 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 30 pressure sensitive adhesives 31 Base material 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 inwardly of the sidewall portions (2) in the tire radial direction; wherein a sound-absorbing member (6) is attached via an adhesive layer (5a) to an inner surface (4) of the tread portion (1) along the tire circumferential direction and, the adhesive layer (5a) comprises a solid pressure-sensitive adhesive (30) without including a base material (31); wherein the adhesive layer (5a) has an average thickness of 0.40 mm to 5.00 mm. [2] A pneumatic tire according to claim 1, wherein the adhesive layer (5a) has a peel adhesive strength of 5 N / 20 mm or more. [3] A pneumatic tire according to any one of claims 1 to 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) forming 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) disposed on the tread portion (1) on a tire equator (CL) and extending continuously around the tread portion (1) around an entire tire circumference; 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), the position being 40% of the width 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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