Patent Publication Number: US-2019184769-A1

Title: Pneumatic tire and pneumatic tire and rim assembly

Description:
BACKGROUND ART 
     Field of the Disclosure 
     The present disclosure relates to a pneumatic tire, and a tire and rim assembly capable of reducing road noise. 
     Description of the Related Art 
     A road noise is known as one of the tire noises. A primary cause of the road noise is resonance vibrations of air generated in the tire cavity. To reduce such resonance vibrations of air, the following Patent document 1 has proposed a pneumatic tire which includes a tread portion provided with a sponge member on a tread inner surface. 
     However, further reduction in road noise generated by tires has been required in view of recent quiet vehicles. 
     Patent Document 1 
     Japanese Patent No. 3622957 
     SUMMARY OF THE DISCLOSURE 
     In view of the above problems in the conventional art, the present disclosure has a primary object to provide a pneumatic tire, and a tire and rim assembly capable of reducing road noise further. 
     According to one aspect of the disclosure, a pneumatic tire includes a tread portion having a tread inner surface provided with a noise damper. The noise damper includes sponge members arranged in a tire circumferential direction. Each sponge member includes an inner surface facing radially inwardly, wherein the inner surface of each sponge member includes protrusions protruding radially inward and recesses recessed radially outward, and the protrusions and the recesses are arranged alternately. 
     In another aspect of the disclosure, the tread portion may further include a belt layer, wherein an axial width of each sponge member may be in a range of from 19% to 90% of an axial width of the belt layer. 
     In another aspect of the disclosure, a maximum thickness of each sponge member may be in a range of from 10 to 25 mm. 
     In another aspect of the disclosure, the sponge members may be arranged at regular intervals in the tire circumferential direction. 
     In another aspect of the disclosure, in each sponge member, differences in height between the protrusions and the recesses may be equal to or more than 5 mm. 
     In another aspect of the disclosure, in each sponge member, the protrusions and the recesses may be arranged alternately in the tire circumferential direction. 
     In another aspect of the disclosure, in each sponge member, the protrusions may be continuous over an entire axial width of the sponge member at a constant height. 
     In another aspect of the disclosure, in each sponge member, the recesses may be continuous over an entire axial width of the sponge member at a constant height. 
     In another aspect of the disclosure, in each sponge member, an arrangement pitch of the protrusions is greater than an axial width of the sponge member. 
     In another aspect of the disclosure, in each sponge member, at least one of edges of the sponge member in the tire circumferential direction may be formed as one of the recesses. 
     In another aspect of the disclosure, a pneumatic tire and rim assembly includes the pneumatic tire as mentioned above and a rim on which the pneumatic tire is mounted, wherein total volume of the sponge members is in a range of from 0.9% to 12.8% of a tire cavity volume enclosed by the pneumatic tire and the rim. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross-sectional view of a tire/rim assembly in accordance with an embodiment of the disclosure; 
         FIG. 2  is a cross-sectional view of a pneumatic tire under a standard state; 
         FIG. 3  is a perspective view of a sponge member, 
         FIG. 4  is a circumference sectional view of the tire/rim assembly along the tire equator C; 
         FIGS. 5A and 5B  are perspective views of sponge members in accordance with other embodiments; 
         FIG. 6  is a perspective view of another embodiment of the sponge member; 
         FIGS. 7A and 7B  are perspective views of sponge members of examples; and 
         FIG. 8  is a perspective view of a sponge member of a comparative example. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     An embodiment of the present disclosure will be explained below with reference to the accompanying drawings. 
       FIG. 1  illustrates a cross-sectional view of a tire/rim assembly (hereinafter, simply referred to as “assembly”) T in accordance with an embodiment of the disclosure. As illustrated in  FIG. 1 , the assembly T includes a rim R and a pneumatic tire (hereinafter, simply referred to as “tire”)  1  which is mounted on the rim R. In this embodiment, as a preferred embodiment, a passenger car tire in which quiet is strongly required is illustrated. Note that the present disclosure may be embodied as different kinds of tires  1 , e.g., directed to motorcycle, light truck, heavy-weight vehicle and the like. 
     The assembly T forms a tire cavity Ta enclosed by the rim R and the tire  1  when the tire  1  is mounted on the rim R. 
     The rim R according to the embodiment includes an annular rim main body Ra on which two bead portions  4  of the tire  1  are mounted, and a circular disc Rb for fixing the rim main body Ra to an axle, and the rim R is configured to be a standard rim having a conventional structure. 
     As used herein, the standard rim is a wheel rim officially approved for each tire by standards organizations on which the tire  1  is based, wherein the standard rim is the “standard rim” specified in JATMA, the “Design Rim” in TRA, and the “Measuring Rim” in ETRTO, for example. 
       FIG. 2  illustrates a cross-sectional view of the tire  1  under a standard state. As illustrated in  FIG. 2 , the tire  1  according to the embodiment has a tubeless structure which includes a tread portion  2 , axially spaced two sidewall portions  3  extending radially inward from both the respective both ends of the tread portions, and two bead portions  4  each positioned radially inward of each sidewall portion  3 . 
     As used herein, the standard state is such that the tire  1  is mounted on the standard rim (the rim R) with a standard pressure but is loaded with no tire load. Unless otherwise noted, dimensions of respective portions of the tire  1  are values measured under the standard state. 
     As used herein, the standard pressure is a standard pressure officially approved for each tire by standards organizations on which the tire  1  is based, wherein the standard pressure is the “maximum air pressure” in JATMA, the maximum pressure given in the “tire Load Limits at Various Cold Inflation Pressures” table in TRA, and the “Inflation Pressure” in ETRTO, for example. 
     In this embodiment, the tire  1  includes a carcass  6  extending between bead cores  5  each disposed in a respective one of the bead portions  4  through the tread portion  2  and the sidewall portions  3 , and a belt layer  7  disposed radially outside the carcass  6 . 
     The carcass  6  includes at least one carcass ply  6 A (one ply in the embodiment). The carcass ply  6 A includes carcass cords embedded in a topping rubber, wherein the carcass cords are oriented at angles of from 75 to 90 degrees with respect to the tire equator C, for example. 
     The belt layer  7  is disposed radially outside the carcass  6  within the tread portion  2 . The belt layer  7  includes at least two, in this embodiment, two belt plies  7 A and  7 B arranged in the tire radial direction. The belt plies  7 A and  7 B, for example, each includes belt cords embedded in a topping rubber. Note that a conventional band layer may be disposed radially outside the belt layer  7 . 
     An axial width Wa of the belt layer  7  is not particularly limited, but is preferably in a range of from 60% to 110% of the tread width TW. 
     The tread width TW is the axial distance between tread edges Te. The tread edges Te are defined as axially outermost edges of the ground contacting patch of the tread portion  2  which occurs under a standard loaded condition. The standard loaded condition is such that the tire  1  is mounted on the standard rim R with the standard pressure and is loaded with a standard tire load when the camber angle of the tire is zero. 
     As used herein, the standard tire load is a tire load officially approved for each tire by standards organizations in which the tire  1  is based, wherein the standard tire load is the “maximum load capacity” in JATMA, the maximum value given in the above-mentioned table in TRA, the “Load Capacity” in ETRTO, for example. 
     The tire  1  according to the embodiment includes a noise damper  10  provided on a tread inner surface  2 a of the tread portion  2 . The noise damper  10 , in this embodiment, is configured to includes a plurality of sponge members  11  arranged in the tire circumferential direction. 
     In this embodiment, each sponge member  11  has a porus structure which, for example, includes a so-called sponge made of foamed rubber or plastic, and an integrated member in which synthetic fibers, plant fibers or animal fibers are interwinded. 
     Here, the porous structure includes not only an open-cell but also closed-cell. Such sponge members  11  can absorb sound energy generated in the tire cavity Ta effectively to suppress resonance vibrations of air, thus reducing road noise. Further, since each sponge member  11  is easy to deform, e.g., compression, bending and the like, mounting property of the tire  1  onto the rim can be ensured. For the sponge members  11 , for example, open-cell type spongy member such as ether polyurethane sponge, or ester polyurethane sponge can suitably be employed. 
       FIG. 3  illustrates a perspective view of one sponge member  11 . As illustrated in  FIG. 3 , each sponge member  11  includes an inner surface  11   a  facing radially inward and an outer surface  11   b  facing radially outward (i.e., an opposite direction to the inner surface  11   a ). The outer surface  11   b,  in this embodiment, is fixed to the tread inner surface  2   a  of the tread portion  2  using a synthetic rubber adhesive, for example. 
     In this embodiment, the inner surface  11   a  includes protrusions  12  protruding radially inward and recesses  13  recessed radially outward, and the protrusions  12  and the recesses  13  are arranged alternately. In the tire  1  according to the embodiment, since the plurality of sponge members  11  each of which has the protrusions  12  and the recesses  13  alternately is arranged in the tire circumferential direction, road noise can further be reduced. This sound absorbing effect is synergistic effect which is brought about a combination of an increase of surface area of the inner surface  11   a  of each sponge member  11  by the protrusions  12  and the recesses  13 , and an arrangement of the sponge members  11  arranged in the tire circumferential direction. 
     The inner surface  11   a,  in this embodiment, is provided with the protrusions  12  and the recesses  13  which are arranged alternately in the tire circumferential direction. Since the tire  1  is supposed to rotate around the tire axis Co (shown in  FIG. 1 ), the air in the tire cavity Ta mainly flows along the tire circumferential direction. Thus, the protrusions  12  and the recesses  13  which are alternately in the tire circumferential direction can absorb resonance vibrations of air effectively, resulting in reducing road noise further. The inner surface  11   a,  in this embodiment, two protrusions  12  are provided. 
     In each sponge member  11 , the protrusions  12  according to the embodiment are continuous over the entire axial width W 1  of the sponge member  11  at a constant height h 1 . Further, in each sponge member  11 , the recesses  13  are continuous over the entire axial width W 1  of the sponge member  11  at a constant height h 2 . Such protrusions  12  and recesses  13  can absorb resonance vibrations effectively further. 
     In each sponge member  11  according to the embodiment, the inner surface  11   a  includes a flat surface portion  15  extending along (e.g. parallel with) the tread inner surface  2   a  and the protrusions  12  protruding radially inward from the flat surface portion  15 , and thus the flat surface portion  15  forms the recesses  13 . 
     In this embodiment, the protrusions  12 , in a tire circumferential sectional view, has a trapezoidal shape tapering toward radially inwardly. Such protrusions  12  can exhibit better sound absorbing effect while suppressing an increase in mass of the sponge member  11 . Note that the protrusions  12  are not particularly limited to such an aspect, but can be modified in various shapes, e.g., a triangular shape tapering toward radially inwardly (not illustrated), rectangular shape, wavy shape, and circular shape in the tire circumferential sectional view. 
     In each sponge member  11 , at least one of edges  11   e  in the tire circumferential direction of the sponge member  11  is preferably formed as one of the recesses  13 . When the one edge  11   e  is formed as one of the recesses  13 , the edge  11   e  forms one recess surface and an end surface  16  connecting the recess surface and the tread inner surface  2   a.  Thus, in comparison with the edge  11   e  being formed as a protrusion  12 , for example, surface area of the edge  11   e  becomes larger, improving absorbing resonance vibration effectively. Further, when the at least one edge  11   e  is formed as a recess  13 , the at least one edge  11   e  of the sponge member  11  can be fixed to the tread inner surface  2   a  strongly, resulting in reducing road noise for a long term. In view of the above, both edges  11   e  in the tire circumferential direction of the sponge member  11  is preferably formed as recesses  13 . 
     Preferably, in each sponge member  11 , an arrangement pitch p 1  of the protrusions  12  is greater than the axial width W 1  of the sponge member  11 . Thus, surface area of the inner surface  11   a  increases, resulting in suppressing resonance vibrations of air generated in the tire cavity further. 
     Preferably, an axial width W 1  of each sponge member  11  is in a range of from 19% to 90% of the axial width Wa of the belt layer  7 . When the axial width W 1  of each sponge member  11  is less than 19% of the axial width Wa of the belt layer  7 , it may be difficult to suppress resonance vibrations of air generated in the tire cavity. When the axial width W 1  of each sponge member  11  is greater than 190% of the axial width Wa of the belt layer  7 , it may be difficult to expect improving sound absorbing effect. More preferably, the axial width W 1  of each sponge member  11  is in a range of from 40% to 70% of the axial width Wa of the belt layer  7 . 
     In the same point of view, a maximum thickness (t) of each sponge members  11  is in a range of from 10 to 25 mm. In this embodiment, the maximum thickness (t) of each sponge member  11  corresponds to the heights h 1  of the protrusions  12 . 
     In each sponge member  11 , the difference in height (h 1 -h 2 ) between adjacent protrusion  12  and recess  13  is preferably equal to or more than 5 mm. Thus, the effect that increases surface area of the inner surface  11  a can be ensured, resulting in suppressing road noise effectively. Preferably, the difference in height (h 1 -h 2 ) is equal to or less than 20 mm, in order to suppress crack of the sponge members  11  due to vibration or rotation of the tire  1 . 
     Preferably, a circumferential length L 1  of each sponge member  11  is equal to or more than 50 mm in order to further suppress resonance vibrations of air. The upper limit of the length L 1  of each sponge member  11  may be given according to the number of sponge members  11 . 
     Preferably, the sponge members  11  have specific gravity of from 0.005 to 0.06, more preferably 0.010 to 0.05, yet further preferably 0.016 to 0.05, still further preferably 0.016 to 0.035 in order to further suppress resonance vibrations of air. 
       FIG. 4  illustrates a circumferential sectional view of the assembly T at the tire equator C. As illustrated in  FIG. 4 , the sponge member  11  are preferably arranged in the tire circumferential direction at regular intervals P so that a circumferential gap is provided between adjacent sponge members  11 . In this embodiment, a circumferential length of the gap is shorter than the circumferential length L 1  of each sponge member  11 . This structure can suppress resonance vibrations of air further. When the sponge members  11  are arranged in such a manner, uniformity of the tire  1  can be maintained better, vibration of the tire  1  upon traveling can be suppressed. The sponge members  11 , in this embodiment, are arranged in the entire tire circumferential region at the regular pitches P. 
     Preferably, total volume Va of the sponge members  11  is in a range of from 0.9% to 12.8% of a tire cavity volume V of the tire cavity Ta. Setting the total volume Va of the sponge members  11  being equal to or more than 0.9% of the tire cavity volume V, a sufficient reduction in road noise can be obtained. Setting the total volume Va of the sponge members  11  being equal to or less than 12.8% of the tire cavity volume V, excessive increase in mass of the tire  1  as well as unbalance of mass can be suppressed. 
     As used herein, the total volume Va of the sponge members  11  means the apparent entire volume of the sponge members  11  including inside bubbles. Further, the tire cavity volume V is defined under the standard state by the following approximate equation (1): 
       V= A ×{( Di−Dr )/2+ Dr}×pi    (1)
 
     where “A” represents a cross sectional area of the tire cavity Ta of the assembly T which is not provided with sponge members  11 , and which is measured using a CT scanning, “Di” represents the maximum outer diameter of the tire cavity Ta as shown in  FIG. 1 , “Dr” represents the rim diameter, and “pi” represents circular constant. 
       FIGS. 5A and 5B  illustrate perspective view of the sponge members  11  according to other embodiments. In this embodiment as illustrated in  FIG. 5A , the inner surface  11   a  of each sponge member  11  includes a flat surface portion  15  extending along (e.g. parallel with) the tread inner surface  2   a,  and recesses  13  recessed radially outwardly from the flat surface  15 . Thus, the flat surface portion  15  forms a top surface of each protrusion  12 . In this embodiment, the recesses  13 , in the tire circumferential sectional view, each has a bottom having a circular shape. Further, both circumferential edges  11   e  of each sponge member  11  are configured as recesses  13 . Note that the recesses  13  are not limited to such an aspect, but may be modified in various shapes, e.g., a triangular shape tapering toward radially inwardly (not illustrated), rectangular shape, and wavy shape in the tire circumferential sectional view. 
     In the embodiment as illustrated in  FIG. 5B , in the tire circumferential sectional view, the protrusions  12  each are configured as a triangular shape tapering toward radially inwardly and the recesses  13  each are configured as a triangular shape tapering toward radially outwardly. That is, the sponge member  11  according to the embodiment is configured using only inclined surfaces with respect to the tire radial direction without having the flat surface portion extending along (e.g. parallel with) the tread inner surface  2   a.    
       FIG. 6  illustrates a perspective view of one sponge member  11  according to yet another embodiment of the disclosure. As illustrated in  FIG. 6 , each sponge member  11  according to the embodiment includes the inner surface  11   a  which includes a standard flat surface portion  15  extending along (e.g. parallel with) the tread inner surface  2   a,  protrusions  12  each protruding radially inwardly from the standard flat surface portion  15 , and recesses  13  recessed radially outwardly from the standard flat surface portion  15 . In this embodiment, each of the protrusions  12  and the recesses  13  is configured as a rectangular shape in the tire circumferential sectional view. The circumferential both edges  11   e  of the sponge member  11  are configured as recesses  13 , for example. Note that the protrusions  12  and the recesses  13  are not particularly limited to such an aspect, but can be modified in various aspects, e.g., a triangular shape, and a trapezoidal shape in the tire circumferential sectional view. Preferably, at a circumferential cross-sectional view of each sponge member  11 , shapes of protrusions  12  are the same as the shapes of recesses  13 . 
     While the particularly preferable embodiments of the heavy-duty pneumatic tire  1  in accordance with the present disclosure have been described in detail, the present disclosure is not limited to the illustrated embodiments but can be modified and carried out in various aspects. 
     EXAMPLE 
     Tires of 215/55R17 having a basic structure as shown in  FIG. 2  were manufactured by way of trial based on the specification in Table 1. Then, noise performance and vibration property of each test tire was tested. The common specification of each test tire and the test method are as follows:
         specific gravity of sponge members: 0.031   sponge member material: ester polyurethane sponge (MARUSUZU CO., LTD., product No. E16)   tire cavity volume V: 33.8 cm 3      axial width Wa of belt layer: 178 mm       

     Note that in Table 1, “A” represents that the sponge members are arranged at regular pitches in the entire circumference of the tire, and “B” represents that the sponge members are arranged at regular pitches in the half circumference of the tire. 
     Noise Performance Test: 
     Each test tire was made to run on a drum tester under the following condition and the tire noise was measured by a microphone:
         rim: 17×7.5 J,   inner pressure: 240 kPa,   tire load: 4.6 kN, and   speed: 60 km/hr.       

     Then, the peak of the sound pressure level around 205 Hz, which corresponds to resonance vibrations of air generated in the tire cavity of the tire noise, was analyzed. In Table 1, the results are shown as reduced values in the sound level (db(A)) when compared with the sound level of a tire which does not include any sponge members. The larger the value, the better. 
     Vibration Property Test: 
     Each set of four test tires of Examples 2 and 11 was installed to a vehicle of 2000 cc displacement under the following condition:
         rim: 17×7.5 J, and   inner pressure: 240 kPa.       

     Then, a test driver drove the vehicle on a dry asphalt test course at about 100 km/hr to evaluate the degree of vibration by his sense. 
     
       
         
           
               
               
               
               
               
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
             
            
               
                   
                 Ref. 1 
                 Ref. 2 
                 Ref. 3 
                 Ex. 1 
                 Ex. 2 
                 Ex. 3 
                 Ex. 4 
               
               
                   
               
               
                 Sponge member shapes 
                 rectangular 
                 FIG. 8 
                 rectangular 
                 FIG. 3 
                 FIG. 3 
                 FIG. 3 
                 FIG. 3 
               
               
                   
                 parallelepiped 
                   
                 parallelepiped 
                   
                   
                   
                   
               
               
                 Number of sponge members 
                 1 
                 1 
                 1 
                 12 
                 8 
                 4 
                 2 
               
               
                 Protrusion heights h1 (mm) 
                 15 
                 25 
                 15 
                 25 
                 25 
                 25 
                 25 
               
               
                 (h1 + h2)/2 (mm) 
                 — 
                 15 
                 — 
                 15 
                 15 
                 15 
                 15 
               
               
                 Sponge member widths W1 (mm) 
                 100 
                 100 
                 10 
                 100 
                 100 
                 100 
                 100 
               
               
                 Sponge member lengths L1 (mm) 
                 1950 
                 1950 
                 1950 
                 100 
                 100 
                 100 
                 100 
               
               
                 Total volume Va of sponge 
                 2925 
                 2925 
                 292.5 
                 1800 
                 1200 
                 600 
                 300 
               
               
                 members (mm 3 ) 
                   
                   
                   
                   
                   
                   
                   
               
               
                 Ratio Va/V (%) 
                 8.6 
                 8.6 
                 0.9 
                 5.3 
                 3.5 
                 1.8 
                 0.9 
               
               
                 Ratio W1/Wa (%) 
                 56 
                 56 
                 6 
                 56 
                 56 
                 56 
                 56 
               
               
                 Layout of sponge members 
                 — 
                 — 
                 — 
                 A 
                 A 
                 A 
                 A 
               
               
                 Total mass of sponge members (g) 
                 91 
                 91 
                 9 
                 56 
                 37 
                 19 
                 9 
               
               
                 Noise performance [db(A)] 
                 3.1 
                 4 
                 0.4 
                 6 
                 3.1 
                 2 
                 1 
               
               
                 Vibration property 
                 — 
                 — 
                 — 
                 — 
                 small 
                 — 
                 — 
               
               
                   
               
               
                   
                 Ex. 5 
                 Ex. 6 
                 Ex. 7 
                 Ex. 8 
                 Ex. 9 
                 Ex. 10 
                 Ex. 11 
               
               
                   
               
               
                 Sponge member shapes 
                 FIG. 3 
                 FIG. 3 
                 FIG. 3 
                 FIG. 3 
                 FIG. 7A 
                 FIG. 7B 
                 FIG. 3 
               
               
                 Number of sponge members 
                 18 
                 18 
                 4 
                 4 
                 4 
                 4 
                 8 
               
               
                 Protrusion heights h1 (mm) 
                 25 
                 25 
                 25 
                 25 
                 25 
                 25 
                 25 
               
               
                 (h1 + h2)/2 (mm) 
                 15 
                 15 
                 15 
                 15 
                 15 
                 15 
                 15 
               
               
                 Sponge member widths W1 (mm) 
                 160 
                 190 
                 178 
                 160 
                 50 
                 33.3 
                 100 
               
               
                 Sponge member lengths L1 (mm) 
                 100 
                 100 
                 100 
                 100 
                 200 
                 300 
                 100 
               
               
                 Total volume Va of sponge 
                 4320 
                 5130 
                 1068 
                 960 
                 600 
                 600 
                 1200 
               
               
                 members (mm 3 ) 
                   
                   
                   
                   
                   
                   
                   
               
               
                 Ratio Va/V (%) 
                 12.8 
                 15.2 
                 3.2 
                 2.8 
                 1.8 
                 1.8 
                 3.5 
               
               
                 Ratio W1/Wa (%) 
                 90 
                 107 
                 100 
                 90 
                 28 
                 19 
                 56 
               
               
                 Layout of sponge members 
                 A 
                 A 
                 A 
                 A 
                 A 
                 A 
                 B 
               
               
                 Total mass of sponge members (g) 
                 134 
                 159 
                 33 
                 30 
                 19 
                 19 
                 37 
               
               
                 Noise performance [db(A)] 
                 9.5 
                 9.7 
                 2.8 
                 2.7 
                 1.8 
                 1.3 
                 2.9 
               
               
                 Vibration property 
                 — 
                 — 
                 — 
                 — 
                 — 
                 — 
                 large 
               
               
                   
               
            
           
         
       
     
     From the test results, as to noise performance, Ex. 1 is better than the References. In particular, Ex. 1 shows better noise performance than References  1  and  2  even though the total mass of the sponge members is small. The inventors have concluded that this result relies on that the protrusions and the recesses on the inner surface are arranged alternately in the tire circumferential direction with regular pitches. Ex. 2 shows the same noise performance as Ref.  1  even though the total mass of the sponge members is smaller than that of Ref.  1 . As to Ex. 4, it is confirmed that when the total volume of the sponge members is 0.9% the tire cavity volume, the noise performance improves. Further, it is confirmed that although Ex. 4 has the same total mass of the sponge members as Ref.  3 , it improves noise performance. 
     In comparison with Ex. 5 and Ex. 6, it is confirmed that the effect of improvement in noise performance in response to increasing of the total mass of the sponge members might reach the peak when the total volume of the sponge members to the tire cavity volume exceeds 12.8%. In comparison with Ex. 2 and Ex. 11, it is confirmed that when the sponge members are arranged in the entire tire circumferential region at the regular pitches, vibration property, as well as noise performance, can be improved in comparison to one in which the sponge members are arranged in the half tire circumferential region at the regular pitches.