Description:TECHNICAL FIELD
[0001] The present disclosure relates to the technical field of automobile tyres. In particular, the present disclosure relates to reduction of noise due to tyre road interaction. More particularly the present disclosure pertains to an improved pneumatic tyre for vehicles that provides improved noise, vibration, and harshness (NVH) quality, and a method for reducing noise from a tyre.

BACKGROUND
[0002] Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
[0003] The vehicle NVH quality is extensively affected by engine, aerodynamic and tyre-road noise. As the current NVH technology has been able to reduce the engine noise transmission to the cabin by sound insulation materials, and wind noise by having a reduced drag coefficient, the overall cabin noise is now dominated by tyre-road interaction noise.
[0004] A pneumatic tyre (also referred to as tyre, hereinafter) is excited over a range of wide frequencies during the tyre to road interaction. In the lower frequency range, such as below 400Hz, the tyre amplifies the vibration at certain frequencies due to presence of its structural modes. These amplified vibrations propagate through the vehicle structure and generate low-frequency noise inside the vehicle cabin. The low-frequency in-cabin noise is divided into a booming, air cavity and rumble noise respectively.
[0005] In-cabin noise of the vehicle in the low-frequency region of 200 to 250 Hz due to tyre air cavity mode is mostly higher and is tonal in nature, which may irritate the passengers inside the vehicle. Therefore, there is a need to reduce the same to make the vehicle acoustically comfortable.
[0006] Tyre NVH performance is typically controlled by modifying its mass, damping and stiffness. It is commonly done by tuning construction and tread compound of tyres. But the conventional methodology to reduce the noise due to tyre air cavity is not fully effective. One of the common ways to reduce the in-cabin noise due to air cavity mode around 200 to 250 Hz is by introducing polyurethane foam inside the tyre's inner cavity. The foam absorbs the sound produced inside the tyre due to cavity excitation. However, use of foam has its limitations.
[0007] Another way is to form a Helmholtz resonator in the wheel rim by attaching an air chamber therewith. However, this restricts workability of the wheel rim and manufacturability. Filling helium inside the tyre cavity to shift the air cavity mode to higher side is another method to reduce air cavity noise, but is not cost effective.
[0008] Therefore, there is a requirement of an improved methodology for overcoming the problem of air cavity noise in the pneumatic tyres.
[0009] All publications herein are incorporated by reference to the same extent as if each individual publication or patent application were specifically and individually indicated to be incorporated by reference. Where a definition or use of a term in an incorporated reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply.
[0010] In some embodiments, the numbers expressing quantities of ingredients, properties such as concentration, reaction conditions, and so forth, used to describe and claim certain embodiments of the invention are to be understood as being modified in some instances by the term “about.” Accordingly, in some embodiments, the numerical parameters set forth in the written description and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by a particular embodiment. In some embodiments, the numerical parameters should be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of some embodiments of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as practicable. The numerical values presented in some embodiments of the invention may contain certain errors necessarily resulting from the standard deviation found in their respective testing measurements.
[0011] As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.
[0012] The recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g. “such as”) provided with respect to certain embodiments herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.
[0013] Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is herein deemed to contain the group as modified thus fulfilling the written description of all Markush groups used in the appended claims.

OBJECTS OF THE INVENTION
[0014] A general object of the present disclosure is to improve comfort of occupant of a vehicle by improving NVH quality.
[0015] An object of the present disclosure is to reduce noise from tyres of a vehicle to improve comfort level of the occupants of the vehicle.
[0016] An object of the present disclosure is to provide a pneumatic tyre that exhibits reduced noise due to tyre-road interaction.
[0017] Another object of the present disclosure is to provide an improved tyre for noise reduction that does not need any change in manufacturing process of the tyre.
[0018] Yet another object of the present disclosure is to provide a method for reducing air cavity noise from a tyre due to the tyre and road interaction.
[0019] Still another object of the present disclosure is to provide a method for reducing air cavity noise from a tyre that does not require any change in the manufacturing process of the tyre and is simple to implement.
[0020] Still yet another object of the present disclosure is to provide an improved tyre and method of reducing air cavity noise that is cost effective.

SUMMARY
[0021] Aspects of the present disclosure relate to an improved pneumatic tyre and a method for producing a pneumatic tyre with reduced air cavity noise. In particular, the present disclosure provides a methodology for air cavity noise reduction that is cost effective and does not require any changes in the existing processes for manufacturing the tyres.
[0022] In an aspect, the proposed pneumatic tyre with reduced air cavity noise for a vehicle comprises a tread portion, a pair of sidewall portions that extend radially inwardly from two edges of the tread portion, and a pair of bead portions disposed at radially inner edges of the sidewall portions. The pneumatic tyre further comprises a sound absorbing device affixed to an inner surface of the pneumatic tyre at a tread region. The sound absorbing device extends in a circumferential direction of the pneumatic tyre. In an aspect, the sound absorbing device comprises a mesh.
[0023] In an embodiment, the mesh may be made of any of a synthetic and natural polymeric material; preferably the mesh is made of polypropylene.
[0024] In an embodiment, the mesh may be affixed to the inner surface of the pneumatic tyre using an adhesive layer. The adhesive layer may be of any one or a combination of a liquid or semi-liquid adhesive, a double-sided adhesive tape and a puncture proof material.
[0025] In an embodiment, the mesh may cover 30% to 90% of a tread arc width of the pneumatic tyre, preferably the mesh covers 50% to 90% of the tread arc width of the pneumatic tyre.
[0026] In an embodiment, a thickness of the mesh may be 0.1 mm-5 mm; preferably the thickness of the mesh is 0.5 mm to 5 mm.
[0027] In an embodiment, the mesh may comprise an array of voids, and the voids may constitute 30% to 95% of a surface area of the mesh.
[0028] In an embodiment, the voids may be of a polygonal shape.
[0029] In an embodiment, the pneumatic tyre may comprise two or more pieces of the mesh configured as any or a combination of: parallel to each other in the circumferential direction and as segments of the inner surface.
[0030] An aspect of the present disclosure relates to a method for producing a pneumatic tyre with reduced air cavity noise, the method comprising the steps of: (i) providing a pneumatic tyre comprising: a tread portion, a pair of sidewall portions that extent radially inwardly from two edges of the tread portion, and a pair of bead portions disposed at radially inner edges of the sidewall portions; (ii) providing a sound absorbing device that comprises a mesh; (iii) preparing an inner surface of the pneumatic tyre at a tread region of the pneumatic tyre; (iv) applying an adhesive layer to a surface of the mesh; and (v) fixing the mesh with the adhesive to the inner surface at the tread region.
[0031] In an embodiment, the step of providing sound absorbing device may further comprise: providing the mesh made of synthetic or natural polymeric material, preferably made of polypropylene, with a thickness in a range of 0.1 mm-5 mm, preferably in a range of 0.5 mm to 5 mm, and having an array of polygonal shaped voids, the voids constituting 30% to 95% of a surface area of the mesh.
[0032] In an embodiment, the step of preparing the inner surface at the tread region may comprise: removal of curing release agents from the inner surface of the pneumatic tyre.
[0033] In an embodiment, the method may further comprise the step of preforming the mesh to a required size, wherein the preformed mesh may be sized to cover 30% to 90% of a tread arc width of the pneumatic tyre, preferably 50% to 90% of the tread arc width of the pneumatic tyre.
[0034] In an embodiment, the step of applying the adhesive layer to the mesh may further comprise: fixing a double-sided adhesive tape on one side of the preformed mesh.
[0035] In an embodiment, the method may further comprise the step of applying a roller pressure on the mesh fixed to the inner surface.
[0036] Various objects, features, aspects and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like components.

BRIEF DESCRIPTION OF THE DRAWINGS
[0037] The accompanying drawings are included to provide a further understanding of the present disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure.
[0038] FIG. 1 illustrates an exemplary image showing cross section of the disclosed pneumatic tyre configured with a mesh to reduce air cavity noise, in accordance with embodiments of the present disclosure.
[0039] FIG. 2 illustrate exemplary image showing a top view from inside of the pneumatic tyre configured with a mesh to reduce air cavity noise, in accordance with embodiments of the present disclosure.
[0040] FIG. 3 illustrates an exemplary mesh with polygonal voids for reducing air cavity noise in a pneumatic tyre, in accordance with embodiments of the present disclosure.
[0041] FIGs. 4A and 4B illustrate exemplary cross sectional views of the pneumatic tyre showing different configurations of the manner of fixing the mesh to the inner surface, in accordance with embodiments of the present disclosure.
[0042] FIG. 5 illustrates an exemplary flow diagram for the disclosed method for manufacturing a pneumatic tyre with reduced air cavity noise, in accordance with embodiments of the present disclosure.
[0043] FIG. 6A illustrates an exemplary graph showing results of in-cabin noise spectrum measurement in zone of left side of driver of a vehicle fitted with the disclosed tyre and a conventional tyre, in accordance with embodiments of the present disclosure.
[0044] FIG. 6B illustrates an exemplary graph showing results of in-cabin noise measurement in zone right side of co-driver of a vehicle fitted with the disclosed tyre and a conventional tyre, in accordance with embodiments of the present disclosure.
[0045] FIG. 7 illustrates an exemplary graph showing results of spindle vibration measurement on a vehicle fitted with the disclosed tyre and a conventional tyre, in accordance with embodiments of the present disclosure.

DETAILED DESCRIPTION
[0046] The following is a detailed description of embodiments of the disclosure depicted in the accompanying drawings. The embodiments are in such detail as to clearly communicate the disclosure. However, the amount of detail offered is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure as defined by the appended claims.
[0047] Each of the appended claims defines a separate invention, which for infringement purposes is recognized as including equivalents to the various elements or limitations specified in the claims. Depending on the context, all references below to the "invention" may in some cases refer to certain specific embodiments only. In other cases it will be recognized that references to the "invention" will refer to subject matter recited in one or more, but not necessarily all, of the claims.
[0048] Various terms are used herein. To the extent a term used in a claim is not defined, it should be given the broadest definition persons in the pertinent art have given that term as reflected in printed publications and issued patents at the time of filing.
[0049] Embodiments explained herein relate to an improved pneumatic tyre with reduced air cavity noise, and a method for producing a pneumatic tyre with reduced air cavity noise. In an aspect, the air cavity noise reduction is achieved by affixing at least one piece of a mesh on an inner surface of a tread of the pneumatic tyre, such as on an inner liner of the tyre on a portion of the inner liner opposite the tread of the tyre. The mesh can be a non-metallic mesh made of a natural or synthetic polymeric material, such a polypropylene. Voids of the mesh can be of polygonal shape covering 30% to 95% of surface area of the mesh.
[0050] In an embodiment, the mesh can be affixed to the inner surface of a conventional pneumatic tyre by an adhesive with voids of the mesh open on an inner side of the tyre, thereby making the process of air cavity noise reduction easy without affecting the existing manufacturing process of the tyre. The mesh can be one or more pieces, which can be affixed to the inner surface of the tread area in different manners, such as in circumferential direction and as segments of the inner tread arc, covering 50% to 90% of the tread arc width of the tyre, preferably covering 30% to 90% of the tread arc width.
[0051] Referring now to FIGs. 1 and 2, where images of the improved pneumatic tyre having a mesh affixed to an inner surface of the tyre opposite the tread of the tyre, are disclosed, the pneumatic tyre 100 with reduced air cavity noise comprises a conventional tyre 102 with a tread 104 having a tread arc width WT, and an inner surface 106. A mesh 300, used as a sound absorbing device, is affixed to the inner surface 106, such as on an inner liner of the tyre 102, in the region opposite the tread 104 of the tyre 102 (also referred to as tread region of the tyre). The mesh 300, when affixed to the inner surface, can cover at least 50% of the tread arc width WT of the tyre 102. In a preferred embodiment, the mesh 300 can cover 30% to 90%, preferably 50% to 90%, of the tread arc width WT. In another aspect, voids, such as voids 302 shown in FIG. 3, remain open towards inner side of the tyre 102, when the mesh 300 is affixed to the inner surface of the tyre 102.
[0052] FIG. 3 shows details of a mesh 300 used as the sound absorbing device. The mesh 300 can comprise an array of voids, such as voids 302 shown therein. The voids 302 can be of polygonal shape, such as but not limited to a square, rectangle, pentagon, hexagon, octagon, or a combination thereof. In a preferred embodiment, the mesh can have a honeycomb structure. The voids 302 can be configured such that they cover at least 30% of surface of the mesh 300. In a preferred embodiment, the voids 302 can cover 30% to 95% of surface area of the mesh 300. Thickness of the mesh can be in a range of 0.1 mm to 5 mm. In a preferred embodiment, the thickness of the mesh 300 can be in a range of 0.5 mm to 5 mm.
[0053] FIGs. 4A and 4B are cross sectional views of pneumatic tyre 100 showing different ways in which the mesh 300 can be affixed to the inner surface 106 of the tyre 102, wherein FIG. 4A shows a single elongate piece of the mesh 300 affixed to the inner surface 106 opposite the tread 104 of the tyre 102 in a circumferential direction. The mesh 300 is affixed to the inner surface 106 using an adhesive, such as but not limited to, any of a liquid or semi-liquid adhesive, a double-sided adhesive tape and a sealing material, or a combination thereof. While using a double-sided adhesive tape, the adhesive tape, such as adhesive tape 402 shown in FIG. 4A, may be fixed to a surface of the elongate piece of pre-cut mesh 300, and thereafter the combination of the mesh 300 and the tape 402 can be affixed to the inner surface 106. A roller may be applied to the mesh 300 to endure proper bonding of the mesh 300 to the inner surface 106. As can be understood, two ends of the elongate piece of the mesh 300 shall be located adjacent to each other. The size of the pre-cut elongate piece of the mesh 300 may be selected to minimize a gap (not shown here) between the two ends. In a preferred embodiment, the gap between the two ends of the mesh 300 may be less than or equal to a maximum dimension of the voids 302 of the mesh 300. In a further preferred embodiment, there may not be any gap between the adjacently located ends of the mesh 300.
[0054] FIG. 4B shows two elongate pieces of the mesh 300-1 and 300-2 configured parallel to each other on the inner surface in the circumferential direction, each by a corresponding adhesive tape 402-1 and 402-2. Gap ‘G’ (also referred to as axial gap) between circumferential sides of the adjacent pieces of mesh 300-1 and 300-2 (collectively/individually referred to as mesh 300, hereinafter) may be less than or equal to a maximum dimension of the voids 302. In a preferred embodiment, there may not be any axial gap ‘G’ between the circumferential sides of the adjacent pieces of the mesh 300-1 and 300-2.
[0055] In either case, the mesh 300 can cover a width WM, which can be 30% to 90%, preferably 50% to 90%, of the tread arc width WT of the tyre 102.
[0056] It is to be appreciated that, while the exemplary illustration of FIG. 4B shows only two elongate pieces of the mesh 300, it is possible to have more than two pieces affixed adjacent to each other in the manner as explained above.
[0057] It is to be further appreciated that, while the exemplary embodiments of FIGs. 4A and 4B have been explained with reference to elongate pieces of the mesh 300 covering the entire circumferential length of the inner surface 106 of the tyre 102, it is possible that the circumferential length of the inner surface 106 of the tyre 102 is covered by more than one piece of the mesh 300, and accordingly, the pneumatic tyre can have more than two pieces of the mesh 300 affixed to the inner surface as any or a combination of segments of an inner circumference of the tyre opposite the tread 104 and parallel to each other in the circumferential direction.
[0058] FIG. 5 is a flow diagram for the disclosed method for producing a pneumatic tyre with reduced air cavity noise, the method 500 can, at step 502, involve providing a pneumatic tyre, such as tyre 102 shown FIG. 1, comprising: a tread portion, a pair of sidewall portions that extent radially inwardly from two edges of the tread portion, and a pair of bead portions disposed at radially inner edges of the sidewall portions. Step 504 of the method 500 can be to provide a sound absorbing device that comprises a mesh, such as the mesh 300 shown in FIG. 3. Step 506 of the method 500 can be to prepare an inner surface of the tyre 102 at a tread region of the pneumatic tyre 102, such as the inner surface 106 shown in FIG. 1. Step 508 of the method 500 can involve applying an adhesive layer, such as the adhesive layer 402 shown in FIG. 4A, to a surface of the mesh 300; and step 510 of the method 500 can be: fixing the mesh 300 with the adhesive 402 to the inner surface 106 at the tread region.
[0059] In an embodiment, the step 504 of providing sound absorbing device can comprise: providing a mesh 300 made of synthetic or natural polymeric material, preferably made of polypropylene, with a thickness in a range of 0.1 mm-5 mm, preferably in a range of 0.5 mm to 5 mm, and having an array of polygonal shaped voids, such as voids 302 shown in FIG. 3, the voids may constitute 30% to 95% of surface area of the mesh 300.
[0060] In an embodiment, the step 506 of preparing the inner surface 106 opposite the tread 104 can comprise: applying a solvent to the inner surface 106 to remove curing release agents.
[0061] In an embodiment, the method 500 can further comprise the step of pre-forming the mesh 300 to a required size, wherein the preformed mesh can be sized to cover 30% to 90% of a tread arc width, such as tread arc width WT shown in FIG. 1, of the pneumatic tyre 102, preferably 50% to 90% of the tread arc width WT of the pneumatic tyre.
[0062] In an embodiment, the step 508 of applying the adhesive layer 402 to the mesh 300 may comprise: applying a double-sided tape on one side of the pre-formed mesh 300.
[0063] In an embodiment, the method 500 can further comprise the step of applying a roller pressure on the mesh 300 fixed to the inner surface 106 opposite the tread 104 to ensure proper bonding of the mesh with the inner surface.

EXPERIMENTS
[0064] Efficacy of the disclosed methodology of reducing air cavity noise by affixing a mesh on an inner surface opposite the tread of a tyre was validated by measuring in-cabin noise spectrum in zone of on left side of driver and right side of co-driver of a vehicle fitted with a disclosed pneumatic tyre and comparing the result with similar measurements when the vehicle is fitted with a conventional tyre. The tests were done on a specified test track for measuring noise emitted by road vehicles and their tyres as stipulated vide ISO 10844:2014. In-cabin noise measurement was done in accordance with ISO 5128 by keeping microphones near driver ear position using mic holders.
[0065] FIG. 6A is a graph 600 showing results of in-cabin noise spectrum measurement in zone of left side of the driver of a vehicle fitted with the disclosed tyre and a conventional tyre, wherein the plot 602 pertains to measurements taken with tyre without mesh and the plot 604 pertains to measurements taken with tyre affixed with a mesh. As can be seen, there is 3 dB(A) reduction in the peak value of air cavity noise for mesh fitted tyres compared to the conventional tyres in the case of driver left microphone.
[0066] FIG. 6B is a graph 650 showing results of in-cabin noise measurement in zone right side of co-driver of a vehicle fitted with the disclosed tyre and a conventional tyre, wherein the plot 652 pertains to measurements taken with tyre without mesh and the plot 654 pertains to measurements taken with tyre affixed with a mesh. As can be seen, there is nearly 5 dB(A) reduction in the peak value of air cavity noise for mesh fitted tyres compared to regular tyres in the case of a microphone placed in the right side of co-driver of the vehicle.
[0067] Measurements were also done for spindle vibrations in z direction by fixing a tri-axial accelerometer at front suspension spindle.
[0068] FIG. 7 is a graph 700 showing results of spindle vibration measurement on a vehicle fitted with the disclosed tyre and a conventional tyre, wherein the plot 702 pertains to measurements taken with tyre without mesh and the plot 704 pertains to measurements taken with tyre affixed with a mesh. As can be seen, vertical spindle vibration in the 200 to 250 Hz frequency range is reduced in mesh fitted tyres compared to the conventional tyres without any mesh.
[0069] Thus, the present disclosure provides a methodology for reducing air cavity noise that is simple to implement and does not require any changes in the existing process for manufacturing the tyres. The methodology results in a reduction of around 2 ~ 4 dB(A) in peak cavity noise on coarse roads, and around 2 ~ 3 dB(A) on smooth roads, thereby providing a definite advantage, and a cost-effective solution to the problem of air cavity noise in tyres.
[0070] While the foregoing describes various embodiments of the invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof. The scope of the invention is determined by the claims that follow. The invention is not limited to the described embodiments, versions or examples, which are included to enable a person having ordinary skill in the art to make and use the invention when combined with information and knowledge available to the person having ordinary skill in the art.

ADVANTAGES OF THE INVENTION
[0071] The present disclosure helps to improve comfort of occupant of a vehicle by improving NVH quality.
[0072] The present disclosure helps in reducing noise from tyres of a vehicle and improves comfort level of the occupants of the vehicle.
[0073] The present disclosure provides a pneumatic tyre that exhibits reduced noise due to tyre-road interaction.
[0074] The present disclosure provides an improved tyre for noise reduction that does not need any change in manufacturing process of the tyre.
[0075] The present disclosure provides a method for reducing noise from a tyre due to the tyre and road interaction.
[0076] The present disclosure provides a method for reducing noise from a tyre that does not require any change in the manufacturing process of the tyre and is simple to implement.
 
, Claims:1. A pneumatic tyre comprising: a tread portion, a pair of sidewall portions that extend radially inwardly from two edges of the tread portion, and a pair of bead portions disposed at radially inner edges of the sidewall portions; the pneumatic tyre further comprising a sound absorbing device affixed to an inner surface of the pneumatic tyre at a tread region, the sound absorbing device extending in a circumferential direction of the pneumatic tyre, wherein the sound absorbing device comprises a mesh.
2. The pneumatic tyre as claimed in claim 1, wherein the mesh is made of any of a synthetic and natural polymeric material; preferably the mesh is made of polypropylene.
3. The pneumatic tyre as claimed in claim 1, wherein the mesh is affixed to the inner surface of the pneumatic tyre using an adhesive layer, and wherein the adhesive layer is of any one or a combination of a liquid or semi-liquid adhesive, a double-sided adhesive tape and a puncture proof material.
4. The pneumatic tyre as claimed in claim 1, wherein the mesh covers 30% to 90% of a tread arc width of the pneumatic tyre, preferably the mesh covers 50% to 90% of the tread arc width of the pneumatic tyre.
5. The pneumatic tyre as claimed in claim 1, wherein a thickness of the mesh is 0.1 mm-5 mm; preferably the thickness of the mesh is 0.5 mm to 5 mm.
6. The pneumatic tyre as claimed in claim 1, wherein the mesh comprises an array of voids, the voids constituting 30% to 95% of a surface area of the mesh.
7. The pneumatic tyre as claimed in claim 6, wherein the voids are of a polygonal shape.
8. The pneumatic tyre as claimed in claim 1, wherein the pneumatic tyre comprises two or more pieces of the mesh configured as any or a combination of: parallel to each other in the circumferential direction and as segments of the inner surface.
9. A method for producing a pneumatic tyre with reduced air cavity noise, the method comprising the steps of:
providing a pneumatic tyre comprising: a tread portion, a pair of sidewall portions that extent radially inwardly from two edges of the tread portion, and a pair of bead portions disposed at radially inner edges of the sidewall portions;
providing a sound absorbing device that comprises a mesh;
preparing an inner surface of the pneumatic tyre at a tread region of the pneumatic tyre;
applying an adhesive layer to a surface of the mesh; and
fixing the mesh with the adhesive to the inner surface at the tread region.
10. The method as claimed in claim 9, the step of providing sound absorbing device further comprises:
providing the mesh made of synthetic or natural polymeric material, preferably made of polypropylene, with a thickness in a range of 0.1 mm-5 mm, preferably in a range of 0.5 mm to 5 mm, and having an array of polygonal shaped voids, the voids constituting 30% to 95% of a surface area of the mesh.
11. The method as claimed in claim 9, wherein the step of preparing the inner surface at the tread region comprises:
removal of curing release agents from the inner surface of the pneumatic tyre.
12. The method as claimed in claim 9, wherein the method further comprises the step of preforming the mesh to a required size, wherein the preformed mesh are sized to cover 30% to 90% of a tread arc width of the pneumatic tyre, preferably 50% to 90% of the tread arc width of the pneumatic tyre.
13. The method as claimed in claim 9, wherein the step of applying the adhesive layer to the mesh further comprises:
fixing a double-sided adhesive tape on one side of the preformed mesh.
14. The method as claimed in claim 9, the method further comprising the step of applying a roller pressure on the mesh fixed to the inner surface.