JP2012006449A - Pneumatic tire - Google Patents

Abstract

[PROBLEMS] To improve the mud performance and the cut-proof performance by limiting the shape and arrangement position of the protector.
A pneumatic tire (1) having a protector (9) on at least one outer surface (3b) of a sidewall portion (3). The outer end 10 and the inner end 11 of the protector 9 in the tire radial direction are provided 0.75 to 0.9 times and 0.5 to 0.7 times the tire cross-section height H from the bead base line BL. The protector thickness L is maximized at a position 0.05 to 0.2 times the length H1 of the protector 9 in the tire radial direction from the outer end 10. It includes a thickness changing portion 14 that gradually decreases from the maximum ridge point 13 where the protector thickness L is maximum toward the inside in the tire radial direction. The protector 9 has a concave groove 20 extending in the tire circumferential direction extending from the outer end 18 on the outer side in the tire radial direction from the maximum raised point 13 to the inner end 19 at a position beyond the maximum raised point 13 inward in the tire radial direction. Established.
[Selection] Figure 1

Description

  The present invention relates to a pneumatic tire with improved mud performance and cut resistance.

  For pneumatic tires used on vehicles traveling on rough roads such as four-wheel drive vehicles and trucks, when driving on gravel roads, sharp stones collide with the side wall, and the side wall is cut. May occur. Conventionally, in order to deal with such a problem, for example, as shown in FIG. 5, it has been proposed to provide a protector c that protrudes outward in the tire axial direction on the outer surface b of the sidewall portion a to increase cut resistance. Yes.

  On the other hand, there is an opportunity for such a vehicle to travel in a muddy area. Since a large driving force is required when traveling in such muddy areas, a tire having a large groove volume ratio in the tread portion, for example, a pneumatic tire having a block pattern in which a plurality of blocks are provided in the tread portion is suitable. in use.

  However, in a soft muddy area where the tire sinks greatly into the ground, sufficient driving performance (hereinafter, this performance may be referred to as “mad performance”) is only possible with the driving force provided by the blocks provided in the tread portion. It was difficult to obtain and further improvement was desired. Related technologies include the following.

JP 2003-112505 A Japanese Patent Laid-Open No. 5-294115

  The present invention was devised in view of the above problems, and based on improving the thickness distribution of the protector provided in the sidewall portion and providing the protector with a concave groove, The main purpose is to provide a pneumatic tire capable of improving cut resistance.

  Invention of Claim 1 among this invention is a pneumatic tire which has a protector which consists of a protruding part which protrudes on the outer surface of at least one sidewall part in the tire axial direction and extends in the tire circumferential direction. In a tire meridian cross section including a tire shaft in a normal state in which the rim is assembled and filled with a normal internal pressure, the outer end of the protector in the tire radial direction is 0.75 to the tire cross section height from the bead base line. The inner end of the protector in the tire radial direction is provided at a position 0.5 to 0.7 times the tire cross-section height from the bead base line, and the protector includes: The distance from the outer surface of the virtual side wall smoothly connecting the inner and outer ends of the tire in the radial direction to the outer surface of the protector measured in the normal direction. The protector thickness is maximized at a position 0.05 to 0.20 times the length of the protector in the tire radial direction from the outer end, and the tire radius extends from the maximum raised point at which the protector thickness is maximized. The protector includes a thickness changing portion that gradually decreases inward in the direction, and the protector includes the maximum bulge point inward in the tire radial direction from an outer end portion located on the radially outer side of the maximum bulge point. A concave groove extending to the inner end of the position is spaced apart in the tire circumferential direction.

  According to a second aspect of the present invention, the protector includes an outer wall surface that extends from the maximum bulge point to the outer end and faces outward in the tire radial direction, and an inner wall surface that extends inward in the tire radial direction from the maximum bulge point. The pneumatic tire according to claim 1, wherein the outer end portion of the concave groove opens at the outer wall surface.

  The invention according to claim 3 is the pneumatic tire according to claim 1 or 2, wherein the concave groove extends at an angle of 30 degrees or less with respect to a tire radial direction.

  The invention according to claim 4 is the pneumatic tire according to any one of claims 1 to 3, wherein the groove has a groove depth that gradually decreases from the maximum raised point toward the inside in the tire radial direction.

  According to a fifth aspect of the present invention, the ratio of the groove depth of the concave groove at the maximum bulge point to the protector thickness is smaller than the ratio of the groove depth of the concave groove at the inner end to the protector thickness. The pneumatic tire according to any one of 1 to 4.

  The invention according to claim 6 is the pneumatic tire according to any one of claims 1 to 5, wherein the groove has a groove width at the maximum bulge point that is larger than a groove width at the inner end portion. is there.

  The pneumatic tire of the present invention is provided with a protector including a raised portion that protrudes outward in the tire axial direction and extends in the tire circumferential direction on the outer surface of at least one sidewall portion. The protector has the maximum protector thickness at a position 0.05 to 0.20 times the length of the protector in the tire radial direction from the outer end in the tire radial direction, and the protector thickness is maximized. It includes a thickness changing portion that gradually decreases from the maximum bulge point toward the inside in the tire radial direction.

  Such a protector increases the rubber thickness of the sidewall portion and improves the cut resistance. In particular, in the pneumatic tire of the present invention, the maximum thickness portion of the protector can be provided at a position where cut damage is likely to occur by limiting the position of the protector to a specific range. For this reason, the pneumatic tire of the present invention greatly improves cut resistance. Moreover, excessive increase in the tire weight is suppressed by gradually reducing the thickness of the bead portion side of the protector which is hard to be cut. Moreover, the thickness distribution of the protector as described above enhances the rigidity of the sidewall portion in a well-balanced manner against the thrust force in the radial direction of the tire and suppresses local bending deformation to the side of the sidewall portion. This is useful for enhancing the durability of the sidewall portion and preventing contact with foreign matter.

  Further, the protector is provided with concave grooves extending in the tire circumferential direction extending from the outer end portion on the outer side in the tire radial direction from the maximum raised point to the inner end portion at a position exceeding the maximum raised point on the inner side in the tire radial direction. . Such a ditch | groove can also obtain a driving force also from a sidewall part by diving in mud in a soft mud and shearing mud. Accordingly, the pneumatic performance of the present invention greatly improves the mud performance.

It is sectional drawing of the right half which shows the pneumatic tire of one Embodiment of this invention. It is an enlarged view of the protector of FIG. It is a perspective view of the sidewall part of FIG. (A) thru | or (c) is sectional drawing along the tire circumferential direction of a protector, (a), (c) is a maximum bulge point, (b) is a thing in an inner edge part. It is a perspective view of the side wall part of the conventional pneumatic tire.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view of a pneumatic tire (hereinafter, simply referred to as “tire”) 1 of the present embodiment in a normal state. In this specification, the “normal state” means that the tire is assembled to a normal rim (not shown) and filled with a normal internal pressure and is in an unloaded state, and unless otherwise specified, the dimensions of each part of the tire. Etc. are values measured in this normal state.

  Here, the “regular rim” is a rim defined for each tire in the standard system including the standard on which the tire is based, and is “standard rim” for JATMA, and “for TRA” “Design Rim” or “Measuring Rim” for ETRTO. In addition, the “regular internal pressure” is an air pressure determined by each standard for each tire in the standard system including the standard on which the tire is based. TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES "Maximum value", ETRTO, "INFLATION PRESSURE".

  The pneumatic tire 1 according to the present embodiment is disposed on a carcass 6 that extends from the tread portion 2 through the sidewall portion 3 to the bead core 5 of the bead portion 4, and on the radially outer side of the carcass 6 and inside the tread portion 2. Belt layer 7. The tread portion 2 is provided with a drainage or mud drainage groove 8 as appropriate.

  The carcass 6 includes a main body portion 6a straddling a pair of bead cores 5 and 5 in a toroidal manner, and a folded portion 6b which is continuous from both sides of the main body portion 6a and is folded from the inner side to the outer side in the tire axial direction around the bead core 5. And at least one carcass ply 6A in this embodiment. In the carcass ply 6A, the carcass cord is inclined with respect to the tire equator C direction at an angle of 75 to 90 °, for example. For example, an organic fiber cord or a steel cord is adopted as the carcass cord.

  The belt layer 7 is composed of at least two belt plies 7A and 7B, in the present embodiment, in the tire radial direction, and in the outer two. Each belt ply 7A, 7B has a highly elastic belt cord such as a steel cord inclined at an angle of 15 to 40 ° with respect to the tire equator C. The belt plies 7A and 7B are overlapped so that the belt cords intersect each other.

  A protector 9 is provided on the outer surface 3a of at least one of the sidewall portions 3, and includes a raised portion that protrudes outward in the tire axial direction and extends in the tire circumferential direction. The protector 9 is formed of rubber, and in the present embodiment, forms a ring that is continuous in the tire circumferential direction. Moreover, the protector 9 of this embodiment is provided in the side wall part 3 of both sides, respectively.

  The protector 9 has an outer end 10 in the tire radial direction and an inner end 11 in the tire radial direction. The outer end 3 of the side wall is connected to the outer end 10 of the protector 9, and the inner end 3d of the side wall 3 is connected to the inner end 11 of the protector 9.

  The outer region 3c smoothly extends from the outer end 10 of the protector 9 toward the end of the tread portion 2 with an arc having a radius of curvature R1. The inner region 3d includes an inner region 3d that smoothly extends from the inner end 11 of the protector 9 to the bead portion 4 with an arc having a radius of curvature R2. The protector 9 of the present embodiment is formed so as to protrude from the outer region 3c and the inner region 3d to the outside in the tire axial direction.

  In the present invention, improvements are made such as the position of the protector 9, the distribution of the protector thickness, and the addition of a concave groove. Thereby, in the pneumatic tire 1 of this invention, cut-proof performance and mud performance are improved significantly.

  First, in order to effectively improve the cut resistance, it is necessary that the protector 9 is disposed at a position where it can easily come into contact with foreign matter on the road surface. At the same time, it is important that the protector 9 is disposed at a position where when the tire travels in a muddy area, the protector 9 comes into contact with the mud and obtains a driving force from the protector 9 provided with the concave groove 20. is there.

  The positions as described above were found from the inventors' various actual vehicle running tests. Specifically, as shown in FIGS. 1 and 2, the outer end 10 of the protector 9 in the tire radial direction is 0.75 to 0.9 times the tire cross-section height H from the bead base line BL, and The inner end 11 of the protector 9 in the tire radial direction is provided 0.5 to 0.7 times the tire cross-section height H from the bead base line BL.

  If the height H1 of the outer end 10 of the protector 9 from the bead base line BL exceeds 0.9 times the tire cross-section height H, the outer end 10 of the protector 9 may be on a road surface other than a bad road such as a muddy ground. There is a risk that contact may occur easily, resulting in poor ride comfort and early wear of the protector. On the contrary, if the height H1 is less than 0.75 times the tire cross-section height H, it is not possible to protect a region where cut flaws are likely to occur, and the protector 9 is brought into contact with the mud in the mud during running It becomes difficult to make. From such a viewpoint, the height H1 of the protector 9 is preferably 0.78 times or more, more preferably 0.8 times or more, and preferably 0.88 times or less of the tire cross-section height H. More preferably, 0.86 times or less is desirable.

  Similarly, if the height H2 of the inner end 11 of the protector 9 from the bead base line BL exceeds 0.7 times the tire cross-section height H, the protection area by the protector 9 is reduced, and the cut resistance is sufficiently improved. Is not demonstrated. Conversely, if the height H2 is less than 0.5 times the tire cross-section height H, the protector 9 is provided unnecessarily, leading to an increase in tire weight. From such a viewpoint, the height H2 of the inner end 11 is preferably 0.52 times or more, more preferably 0.54 times or more, and preferably 0.6 times or less of the tire cross-section height H. More preferably, 0.58 times or less is desirable.

  Further, the improvement of the thickness distribution of the protector 9 is shown in an enlarged manner in FIG. First, the protector 9 has a maximum raised point 13 at which the protector thickness L is maximum at a position 0.05 to 0.20 times the length H3 of the protector 9 in the tire radial direction from the outer end 10. In addition, it includes a thickness changing portion 14 that gradually decreases from the maximum raised point 13 toward the inside in the tire radial direction.

  Such a protector 9 effectively increases the thickness at a position where cut flaws are likely to occur frequently, and improves the cut resistance. For this reason, in the pneumatic tire 1 of the present invention, the cut resistance is greatly improved. Further, by gradually reducing the thickness of the protector 9 on the bead portion side where the cut is difficult to occur, an excessive increase in tire weight is suppressed while preventing formation of an excessively rigid step in the sidewall portion 3. Further, the thickness distribution of the protector increases the rigidity of the sidewall portion against the thrust force in the tire radial direction received from the road surface when traveling on a rough road in a well-balanced manner. Suppresses bending deformation. This is useful for enhancing the durability of the sidewall portion and preventing contact with foreign matter.

  Here, the thickness of the protector is a distance from the virtual sidewall outer surface 3b smoothly connecting the inner end 11 and the outer end 10 of the protector 9 to the outer surface of the protector 9 measured in the normal direction. . Further, “smoothly connected” the inner end 11 and the outer end 10 of the protector 9 means that the arc having the radius of curvature R1 of the outer region 3c of the sidewall portion 3 and the sidewall as shown in FIG. This means that the arc having the radius of curvature R2 of the inner region 3d of the portion 3 is joined by a smooth single arc without generating an inflection point.

  As a result of various experiments by the inventors, a raised point length H4 which is a distance in the tire radial direction between the maximum raised point 13 of the protector 9 and the outer end 10 of the protector 9 is 0.05 of the protector length H3. If it is less than double, the rubber volume concentrates on the outer end 10 side of the protector 9 and the cut resistance on the inner end side is lowered, and cracks and chips from the outer end 10 are likely to occur. On the other hand, when the raised point length H4 exceeds 0.2 times the protector length H3, the maximum raised point 13 cannot sufficiently dive in the muddy ground, and improvement of the mud performance cannot be expected. From such a viewpoint, the raised point length H4 is preferably 0.06 times or more, more preferably 0.07 times or more, more preferably 0.15 times or more than the protector length H3 from the outer end 10. It is desirable that it is not more than twice, more preferably not more than 0.10 times.

  Further, the thickness changing portion 14 of the protector 9 of the present embodiment includes an outer wall surface 16 that extends from the maximum ridge point 13 to the outer end 10 and faces outward in the tire radial direction, and extends from the maximum ridge point 13 inward in the tire radial direction. The inner wall surface 17 is partitioned by a step surface 15 that joins the inner end 17t in the tire radial direction of the inner wall surface 17 and the inner end 11 and faces inward in the tire radial direction. The outer wall surface 16 and the step surface 15 are smoothly connected to the outer region 3c and the inner region 3d through small arcs, respectively.

  The protector thickness Lmax at the maximum raised point 13 is preferably 2 mm or more, more preferably 4 mm or more. When the protector thickness Lmax is reduced, the protection effect of the sidewall portion 3 and the driving force in the muddy area are lowered, and thus there is a tendency that improvement in cut resistance and mud performance cannot be expected. On the contrary, when the protector thickness Lmax is increased, the tire weight is liable to increase and the ride comfort is deteriorated. Therefore, the protector thickness Lmax is preferably 15 mm or less, more preferably 12 mm or less.

  Further, as shown in FIG. 3, the protector 9 is provided with concave grooves 20 extending in the tire radial direction so as to be spaced apart in the tire circumferential direction.

  The outer end portion 18 of the recessed groove 20 is located on the outer side in the tire radial direction from the maximum ridge point 13, and is open at the outer wall surface 16 in the present embodiment. Further, the inner end portion 19 of the concave groove 20 is located beyond the maximum ridge point 13 on the inner side in the tire radial direction, and ends in the inner wall surface 17 without opening in the step surface 15 in the present embodiment.

  Such a protector 9 is desirable in that it sinks into the muddy ground and shears mud in the groove 20 to exert a large driving force, thereby improving the mud performance. Further, since the groove 20 extends inward and outward in the tire radial direction including the maximum raised point 13, the rigidity near the maximum raised point 13 can be relaxed, and excessive deterioration of the riding comfort on the paved road surface can be prevented. In particular, since the inner end 19 of the groove 20 is terminated without opening at the stepped surface 15, the circumferential rigidity of the protector 9 is ensured, and the shape can be maintained for a long period of time by preventing chipping. In addition, it can also open by the level | step difference surface 15 from a viewpoint of making tire weight small and a viewpoint which further ensures cord performance.

  The concave groove 20 extends straight from the outer end 18 on the outer side in the tire radial direction to the inner end 19. Preferably, the groove 20 is preferably 30 degrees or less, more preferably 20 degrees or less with respect to the tire radial direction, and the most preferable angle θ extends at 0 degrees. When the angle θ of the concave groove 20 with respect to the tire radial direction becomes large, it is difficult to exert a shearing force in the muddy ground, and there is a tendency that the effect of improving the mud performance cannot be sufficiently expected.

  4A shows the AA cross section of FIG. 2, and FIG. 4B shows the BB cross section of FIG. The concave groove 20 of the present embodiment has a cross section perpendicular to the longitudinal direction formed in an arc shape. However, as shown in FIG. 4C, the cross section may be substantially trapezoidal, or may be a square groove or a triangular groove (not shown).

  The groove width W of the concave groove 20 is preferably 3 mm or more, more preferably 4 mm or more, and preferably 7 mm or less, more preferably 6 mm or less. Further, the depth D of the groove 20 is preferably 1 mm or more, more preferably 1.5 mm or more, and preferably 4 mm or less, more preferably 35 mm or less. If the groove width W is less than 3 mm or the depth D is less than 1 mm, the groove volume becomes small and there is a possibility that sufficient driving force cannot be obtained in a muddy area. Conversely, the groove width W is larger or deeper than 7 mm. When D exceeds 4 mm, the cut resistance of the portion may be lowered.

  Moreover, when the arrangement pitch P of the concave grooves 20 and 20 adjacent to each other in the tire circumferential direction is too small, the rigidity of the protector 9 may be reduced, and the cut resistance may be reduced. Conversely, when the arrangement pitch P is increased. There is a possibility that the improvement effect of the mud performance is lowered. From such a viewpoint, the arrangement pitch P of the concave grooves 20 is preferably 20 mm or more, more preferably 30 mm or more, and preferably 60 mm or less, more preferably 50 mm or less.

  The groove width W, depth D, and arrangement pitch P of the concave groove 20 are all values at the position of the maximum raised point 13. Further, the depth D of the concave groove 20 is measured along the normal direction of the virtual sidewall outer surface 3b, similarly to the thickness of the protector.

  Further, as shown in FIG. 2, the groove length H5, which is the length in the tire radial direction between the outer end 18 and the inner end 19 of the groove 20, is preferably 0.4 of the protector length H3. It is desirable that the ratio be at least twice, more preferably at least 0.5 times, preferably at most 0.8 times, more preferably at most 0.7 times.

  In the present embodiment, the protector thickness L gradually decreases from the maximum ridge point 13 toward the inside in the tire radial direction, and accordingly, the depth D of the concave groove 20 also increases from the maximum ridge point 13 to the tire radius. It gradually decreases inward. Thereby, the rigidity of the protector 9 is made substantially uniform over the length direction, and the cut resistance and the mud performance are exhibited with a good balance.

  Similarly, it is desirable that the width W of the groove 20 gradually decreases from the maximum ridge point 13 toward the inside in the tire radial direction. That is, it is desirable that the groove width Wa at the maximum raised point 13 is formed larger than the groove width Wb at the inner end portion 19. In particular, the ratio Wa / Wb between the groove width Wa and the groove width Wb is preferably 1.1 to 1.4.

  As shown in FIGS. 4A and 4B, the protector 9 has a ratio Da / Lmax between the groove depth Da and the protector thickness Lmax of the groove 20 at the maximum raised point 13. It is formed smaller than the ratio Db / Lb of the depth Db of the concave groove 20 at the inner end 19 and the protector thickness Lb. Such a configuration can enhance the improvement of the mud performance on the inner end portion 19 side where the cut damage is relatively less likely to occur while the cut resistance and the mud performance at the maximum raised point 13 are balanced. In particular, the ratio Db / Lb is preferably 1.1 to 2.0 times the ratio Da / Lmax.

  The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the illustrated embodiments, and can be implemented in various forms.

Pneumatic tires (size: 285 / 60R18) having the basic structure shown in FIG. 1 and having the protectors specified in Table 1 were manufactured and their performance was tested. The common specifications are as follows.
Rim size: 8JJ × 18
Tread width: 206mm
Protector: Continuous in the tire circumferential direction and formed on both sidewalls Protector thickness Lmax at maximum ridge point: 6mm
Length in the tire radial direction from the outer end of the protector to the maximum bulge point H4 / H3: 0.05
Groove length H5: 50mm
Groove width Wb at the inner end of the concave groove: 4 mm (gradual decrease inward in the tire radial direction)
Groove depth D of the concave groove: 3.5 to 2.0 mm (gradual decrease inward in the tire radial direction)
The test method is as follows.

<Cut resistance (pendulum type)>
A pendulum-type sidewall impact test was conducted in which a wedge-shaped blade attached to the weight was provided at the lower end of the pendulum and collided with the sidewall portion of the tire by a free-fall method. Then, the cut-off performance of the sidewall portion was evaluated by determining the fracture energy obtained from the weight of the weight and the drop height. The cutting edge of the blade was a flat body having a tapered cross-section with a circular arc at the tip. A result is displayed by the index | exponent which makes the fracture energy of the comparative example 1 100, and shows that cut resistance is excellent, so that a numerical value is large.

<Cut resistance (actual vehicle evaluation)>
The total number of cut scratches (length x depth) generated on the side wall of a four-wheel drive vehicle with test tires on all wheels. The value was measured. A result is displayed by the index | exponent which makes the reciprocal number of the value of the comparative example 1 100, and it shows that it is excellent in cut-proof performance, so that a numerical value is large.

<Mud performance (traction force)>
Drive the muddy ground with a depth of about 200 mm with the vehicle. The traction limit load was measured. A result is an index | exponent which sets the comparative example 1 to 100, and shows that mud performance is so favorable that a numerical value is large.

<Mud performance (vehicle evaluation)>
The vehicle was run on the muddy ground, and the driving force, braking force, turning ability, etc. were comprehensively evaluated by the driver's sensuality. The result is a 10-point method with Comparative Example 1 as 6, and the larger the value, the better.
The test results are shown in Table 1.

  As a result of the test, it can be confirmed that the tire of the example has improved the mud performance and the cut resistance performance compared to the comparative example.

DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Tread part 3 Side wall part 3a Side wall part 3b Virtual side wall outer surface 6 Carcass 7 Belt layer 9 Protector 10 Outer end 11 Protector inner end 13 Maximum raised point 14 Thickness change part 18 Concave Groove outer end 19 Groove inner end 20 Groove groove BL Bead base line H1 Protector length L Protector thickness

Claims (6)

A pneumatic tire having a protector including a raised portion that protrudes outward in the tire axial direction and extends in the tire circumferential direction on the outer surface of at least one sidewall portion,
In the tire meridian cross section including the tire shaft in a normal state with no load loaded with a normal rim and filled with a normal internal pressure,
The outer end of the protector in the tire radial direction is provided at a position 0.75 to 0.9 times the tire cross-sectional height from the bead base line, and the inner end of the protector in the tire radial direction is a bead base line. From 0.5 to 0.7 times the tire cross-section height,
The protector has a thickness of the protector that is a distance from an outer surface of the virtual sidewall that is smoothly connected between an inner end and an outer end in the tire radial direction to an outer surface of the protector that is measured in the normal direction. It becomes maximum at a position 0.05 to 0.20 times the length of the protector in the tire radial direction from the outer end, and gradually decreases inward in the tire radial direction from the maximum raised point at which the protector thickness becomes maximum. Including the thickness change section,
The protector is provided with concave grooves extending in the tire circumferential direction from an outer end portion located on the outer side in the tire radial direction from the maximum raised point to an inner end portion at a position exceeding the maximum raised point on the inner side in the tire radial direction. Pneumatic tire characterized by being made. The protector comprises an outer wall surface that extends from the maximum bulge point to the outer end and faces outward in the tire radial direction, and an inner wall surface that extends from the maximum bulge point inward in the tire radial direction,
The pneumatic tire according to claim 1, wherein the outer end portion of the concave groove opens at the outer wall surface.   The pneumatic tire according to claim 1, wherein the concave groove extends at an angle of 30 degrees or less with respect to a tire radial direction.   The pneumatic tire according to claim 1, wherein the groove has a groove depth that gradually decreases from the maximum bulge point toward the inside in the tire radial direction.   The ratio of the groove depth of the concave groove and the protector thickness at the maximum bulge point is smaller than the ratio of the groove depth of the concave groove and the protector thickness at the inner end portion. Pneumatic tire.   The pneumatic tire according to claim 1, wherein the groove has a groove width at the maximum bulge point that is larger than a groove width at the inner end.

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