JP2010195204A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire excellent in bad road traveling property. <P>SOLUTION: In the pneumatic tire including lug grooves 6 opened in a side wall surface 5 on a tread surface 1, groove width of the lug groove 6 is gradually increased from an inner position in a tire width direction than an opening end on a side wall surface 5 side toward the opening end on the side wall surface 5 side, and a projection part 7 extending in the extending direction of the lug groove 6 is arranged in a groove bottom of the lug groove 6. The projection part 7 has a branch part 7a branched to a plurality of parts at an inner position in a tire width direction than a ground-contact end in a tire width direction and extending over the ground-contact end in the width direction in tire front view. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a pneumatic tire provided with a lug groove opened on a sidewall surface on a tread surface, and more particularly to a pneumatic tire intended for traveling on a rough road.

  Pneumatic tires (so-called off-road tires) intended for rough road travel not only on flat and unpaved roads, but also on rough roads including muddy areas. I am considering. In particular, when traveling in a muddy area, there are many situations in which a pneumatic tire is buried and it is difficult to change the course due to the tire itself. If it is difficult to change the course, if the driver cannot travel on the driving line intended by the driver, he / she goes to a more unfavorable road surface area, and in the worst case, the tire is buried in mud and cannot travel. It will cause a so-called stack to fall.

  Here, in the following Patent Document 1, in a pneumatic tire having a lug groove, the lug groove is filled with mud when traveling on a muddy ground by forming a protrusion on the groove bottom of the lug groove. Techniques for preventing this have been proposed. Further, in Patent Document 2 below, in a pneumatic tire having a lug groove, the surface of the bottom of the lug groove is covered with a mud adhesion preventing layer made of a low hardness elastic body layer, and the surface of the mud adhesion preventing layer is predetermined. By arranging a plurality of substantially linear grooves with a predetermined interval in the longitudinal direction of the lug groove, the phenomenon that the lug groove is filled with mud when traveling in a muddy area is prevented. Technology has been proposed. However, these technologies do not sufficiently eliminate the mud filled in the lug grooves, and the traction performance on the tread surface is not sufficiently exhibited. For this reason, in the pneumatic tires described in Patent Documents 1 and 2 below, the rough road running tendency tends to deteriorate.

  Further, in Patent Document 3 below, in a pneumatic tire having a block pattern in which a plurality of blocks are formed on the surface of the tire, the tire is provided with a lateral groove that opens at a tire width direction grounding end, and a groove bottom of the lateral groove is provided in the lateral groove direction. A protrusion extending along the tire, the protrusion having a starting point closer to the center side than the ground contact end in front of the tire, and having an end point beyond the ground contact end and beyond the ground contact end. A pneumatic tire is described. In such a pneumatic tire, mud clogging of the lug groove in the muddy area is effectively suppressed, and the traction performance on the tread surface is improved. However, it has been found that such a pneumatic tire has room for further improvement in terms of eliminating the mud filled in the lug grooves.

  Further, in Patent Document 4 below, a plurality of protrusions having a height of 5 mm or more are arranged at intervals in the circumferential direction on the buttress portion, and the circumferential length of the surface of the protrusion and the length in the tire radial direction are There is described a pneumatic radial tire that is longer than the height of the protrusion, increases in area from the surface to the bottom of the protrusion, and has an area of the bottom surface of the protrusion that is twice or more the surface area of the protrusion. Such a pneumatic tire is excellent in traction performance on the sidewall surface, but it has been found that there is room for further improvement in terms of rough road running performance when considering the exclusion of mud filled in the lug groove. It was.

Japanese Utility Model Publication No. 60-118502 JP-A-10-230708 JP 2008-49751 A JP 2004-291936 A

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a pneumatic tire excellent in rough road running performance.

  The above object can be achieved by the present invention as described below. That is, the pneumatic tire of the present invention is a pneumatic tire provided with a lug groove that opens in a sidewall surface on a tread surface, wherein the lug groove is located on the side of the sidewall surface side from the opening end in the tire width direction. The groove width is gradually increased toward the wall surface side opening end, and the groove bottom of the lug groove is provided with a protrusion extending along the extending direction of the lug groove, and the protrusion is the front of the tire. In view, it is characterized by having a branching portion that branches into a plurality of positions at the inner side in the tire width direction than the ground contact end in the tire width direction and extends beyond the ground contact end in the tire width direction.

  In the pneumatic tire described above, when traveling on a rough road, the lug groove is filled with mud, so that the arranged ridges vibrate due to the load resistance of the mud. Here, in the pneumatic tire described above, the protruding portion has a branch portion that branches into a plurality of positions at the inner side in the tire width direction from the tire width direction ground end in a front view of the tire and extends beyond the tire width direction ground end. Therefore, the vibration amount of the ridge when receiving the load resistance of mud is amplified. As a result, in the pneumatic tire, the mud filled in the lug groove when traveling on a rough road is quickly and easily eliminated by the vibration of the ridge, and the traction performance by the lag groove and the ridge is effective. The traction performance is effectively demonstrated on the tread surface even when driving on rough roads. As a result, the pneumatic tire according to the present invention has excellent rough road running performance.

  In the pneumatic tire, it is preferable that the plurality of branch portions have different protrusion heights. According to such a configuration, when receiving the load resistance of mud, the vibration amount of the ridge is further amplified. As a result, the pneumatic tire having such a configuration effectively exhibits the traction performance on the tread surface even when traveling on a rough road, and has a better road running ability.

  In the pneumatic tire described above, a lug groove width direction of the branch portion and a lug groove wall on a side adjacent to the branch portion in a cross section including a tire width direction grounding end and orthogonal to the extending direction of the lug groove When the interval is T1 and the interval between the plurality of branch portions in the lug groove width direction is T2, it is preferable that T1 ≦ T2. According to this configuration, the mud adhered to the wall surface of the lug groove is particularly easily peeled off by the vibration of the branch portion when receiving the load resistance of the mud. As a result, in the pneumatic tire having such a configuration, the mud filled in the lug groove is more quickly and easily removed when traveling on a rough road, and the traction performance is achieved on the tread surface even when traveling on a rough road. Is effectively demonstrated. As a result, the pneumatic tire having such a configuration has further excellent rough road running performance.

  In the pneumatic tire described above, the ridge portion located on the outer side in the tire width direction from the ground end in the tire width direction is more prominent than the ridge portion located on the inner side in the tire width direction from the ground end in the tire width direction. It is preferable that the strip height is high. According to such a configuration, the amount of vibration of the ridge when traveling on a rough road is further amplified. Thereby, the mud filled in the lug groove when traveling on a rough road is further quickly and easily removed. As a result, according to this configuration, the bad road running performance of the pneumatic tire is further improved.

  In the pneumatic tire, the sidewall surface is provided with a raised portion, and the protruding portion is provided continuously to the raised portion beyond the sidewall surface side opening end of the lug groove. It is preferable.

  When driving on rough roads, pneumatic tires may be buried, and not only the tread surface but also the sidewall surface may be grounded. Here, in the pneumatic tire having the above-described configuration, since the raised portion is disposed on the sidewall surface, the traction performance is effectively exhibited on the sidewall surface even when traveling on a rough road. In particular, when changing the course of the vehicle, the wall surface of the tire itself can be scraped by the raised portion and become an element that is caught on the wall surface of the tire, so that the handling performance is improved in the pneumatic tire having the above configuration.

  Further, in the pneumatic tire having the above-described configuration, the protruding portion is continuously provided to the raised portion beyond the side wall surface side opening end of the lug groove. As described above, in the pneumatic tire having the above-described configuration, the traction performance is effectively exhibited by the raised portion disposed on the sidewall surface when traveling on a rough road. Vibrates under load resistance such as mud. Here, in the pneumatic tire having the above-described configuration, since the ridges and the ridges are continuously provided, the ridges vibrate when traveling on a rough road in conjunction with the ridges. Thus, in the pneumatic tire having the above-described configuration, the mud filled in the lug groove when traveling on a rough road is quickly and easily eliminated by the vibration of the ridge, and the traction performance by the lag groove and the ridge is improved. Effectively demonstrated. For this reason, in the pneumatic tire having the above-described configuration, the traction performance is effectively exhibited on the tread surface even when traveling on a rough road. As a result of the traction performance being effectively exhibited on the sidewall surface and the tread surface, the pneumatic tire having the above-described configuration has particularly excellent rough road running performance.

  In the pneumatic tire described above, it is preferable that the raised portion extends continuously in the circumferential direction. When the bulging portion extends continuously in the circumferential direction, the driving force is surely ensured by the bulging portion when traveling on a rough road, and the course can be easily changed. As a result, according to this configuration, the bad road running performance of the pneumatic tire is further improved. In addition, according to such a configuration, the bulging portion continuously extending in the circumferential direction contacts the ground when traveling on a rough road, so that the contact pressure is dispersed, so that the tire's flotation performance (tire settlement prevention performance) is achieved. improves.

An example of a front view of a pneumatic tire according to the present invention An example of the principal part perspective view containing the cross section of the pneumatic tire which concerns on this invention A-A 'arrow sectional view of FIG. B-B 'arrow sectional view of FIG. The other example of the principal part perspective view containing the cross section of the pneumatic tire which concerns on this invention The other example of the principal part perspective view containing the cross section of the pneumatic tire which concerns on this invention Front view of a pneumatic tire according to Comparative Example 1

  Hereinafter, embodiments of the present invention will be described. FIG. 1 is an example of a front view of a pneumatic tire according to the present invention. 2 is an example of a perspective view of a main part including a cross section of the pneumatic tire according to the present invention, FIG. 3 is a cross-sectional view taken along the line AA ′ of FIG. 2, and FIG. -B 'arrow sectional drawing. In the figure, “WD” means the tire width direction, and “PD” means the tire circumferential direction.

  As shown in FIG. 2, the pneumatic tire of the present embodiment includes a pair of bead cores 2, a carcass 3 that is wound around the bead core 2 to form a toroidal shape, and a belt layer 4 that is disposed on the outer side in the tire radial direction of the crown portion of the carcass 3. Prepare. The tread surface 1 includes lug grooves 6 that extend substantially in the tire width direction and open to the sidewall surfaces 5.

  As shown in FIG. 1 and FIG. 2, in the pneumatic tire according to the present invention, the groove width is gradually increased from the inner side position P <b> 1 in the tire width direction with respect to the sidewall surface side opening end S toward the sidewall surface side opening end S. Lug grooves 6 are provided on the tread surface 1. The lug groove 6 is provided with a protrusion 7 at the groove bottom starting from the tire width direction inner side than the tire width direction grounding end T and extending along the extending direction of the lug groove 6. The ridge 7 has a branch portion 7a that branches into a plurality at the tire width direction inner side position P2 from the tire width direction grounding end T and extends beyond the tire width direction grounding end T in the tire front view. In this embodiment, the example which has the two branch parts 7a extended beyond the tire width direction grounding end T as the protrusion part 7 is shown.

  As shown in FIG. 3, in the front view of the tire, when the width of the protrusion 7 located on the inner side in the tire width direction from P2 is W1, and the width of the lug groove 6 is W, 1/10 × W ≦ W1 It is preferable that ≦ 1/4 × W. Further, in the front view of the tire, when the height of the protrusion 7 located on the inner side in the tire width direction from P2 is H1, and the groove depth of the lug groove 6 is H, 1/3 × H ≦ H1 ≦ It is preferable to set to 1/6 × H. Within such a range, by setting the ridge width and the ridge height of the ridge portion 7 located on the inner side in the tire width direction from P2, the mud filled in the lug groove 6 when traveling on a rough road is more Eliminate quickly and easily. Although it does not specifically limit as a cross-sectional shape of the protrusion part 7, The rectangular shape shown in FIG. 3 is mentioned. In the present invention, the groove width W of the lug groove 6 on the inner side in the tire width direction from P1 is 20 to 30 mm, and the circumferential interval of the lug grooves 6 is 50 to 70 mm.

  Further, in the front view of the tire, the relationship between the ridge width W1 and the ridge height H1 of the ridge 7 positioned on the inner side in the tire width direction from P2 is 0.7 ≦ W1 / H1 ≦ 1.5. Is preferred. If W1 / H1 is outside this range, the protrusion 7 may not vibrate sufficiently in the mud filled in the lug groove 6.

  Like the pneumatic tire of this embodiment, the ridge 7 branches into two at the tire width direction inner side position P2 from the tire width direction ground end T in the tire front view, and the tire width direction ground end T When it has the branch part 7a extended beyond, the vibration amount of the protrusion part 7 at the time of receiving the load resistance of mud is amplified. As a result, the mud filled in the lug grooves 6 during rough road travel is quickly and easily eliminated by the vibration of the ridges 7, and the traction performance by the lag grooves 6 and the ridges 7 is effectively exhibited. Even when traveling on a rough road, the traction performance is effectively exhibited on the tread surface 1.

  As shown in FIG. 4, in the present embodiment, in the cross section including the tire width direction grounding end T and orthogonal to the extending direction of the lug groove 6 (the cross section taken along the line BB ′ in FIG. 2) 7a and the lug groove width interval between the branching portion 7a and the adjacent lug groove wall is T1, and the interval between the lug groove width directions of the two branching portions 7a is T2, T1 ≦ T2 is doing. In this case, especially the mud adhered to the lug groove wall surface side is easily peeled off by the vibration of the branch portion 7a when receiving the load resistance of the mud. Here, T1 and T2 mean the distance in the lug groove width direction measured at the depth position in the lug groove depth direction of the branch portion 7a. In the present embodiment, as shown in FIG. 4, the protrusion heights H2 of the two branch portions 7a are set to be the same, and the protrusion widths are also set to be the same. In consideration of the exclusion of mud filled in the lug groove 6 when traveling on a rough road, the ridge width W2 of the branching portion 7a and the groove width W ′ of the lug groove 6 in the cross section orthogonal to the extending direction of the lug groove 6 Is preferably 1/10 × W ′ ≦ W2 ≦ 1/4 × W ′, and the protrusion height H2 of the branching portion 7a and the lug groove 6 in the cross section orthogonal to the extending direction of the lug groove 6 are satisfied. The groove depth H ′ is preferably 1/3 × H ′ ≦ H2 ≦ 1/6 × H ′.

  Here, in the present invention, the reason why the exclusion property of the mud filled in the lug groove 6 is improved will be described in detail. When the tire rotates, the lug groove 6 and the ridge 7 cut the soil wall to obtain a catching effect and generate a propulsive force. At this time, mud is compressed and filled in the lug groove 6, and the protruding portion 7 is deformed like “behind” toward the rear side in the tire rotation direction. In this state, when the ridge portion 7 having the branching portion 7a extending beyond the tire width direction grounding end T is exposed, the mud that has “bent” the ridge portion 7 is caused by the tire rotational force. Since the load acting on the protruding portion 7 disappears due to further peeling, the protruding portion 7 restores its own shape. At this time, the protrusion 7 in the lug groove 6 is also deformed together, causing the mud filled in the lug groove 6 to “squeeze” from the inside of the lug groove 6 and partially peeled from the inner wall surface of the lug groove 6. The mud becomes the core, and the surrounding mud is caught by the stickiness of the mud, and peels off with the surrounding mud while expanding the peeling range. In the present invention, since the ridge 7 has a plurality of branch portions 7a extending beyond the tire width direction grounding end T, the ridge portion 7 is formed in the lug groove 6 as compared with the case where the ridge portion 7 does not have the branch portion 7a. The filled mud is easily peeled off. As a result, the exclusion property of the mud filled in the lug groove 6 is improved.

  In the present embodiment, the ridge height of the ridge portion 7 is different between the tire width direction inner side and the tire width direction outer side, with the tire width direction ground contact end T as a boundary. Specifically, the ridge 7 positioned on the outer side in the tire width direction from the ground contact end T in the tire width direction is compared with the ridge 7 located on the inner side in the tire width direction from the ground contact end T in the tire width. The ridge height is high. In particular, in the present embodiment, the ridge height of the ridge portion 7 is gradually increased toward the outer side in the tire width direction with the tire width direction ground contact end T as a boundary. According to such a configuration, the amount of vibration of the protrusion 7 is further amplified when traveling on a rough road. Thereby, the mud filled in the lug groove 6 at the time of rough road traveling is more quickly and easily removed. As a result, according to this configuration, the bad road running performance of the pneumatic tire is further improved. In particular, the ridge portion 7 located on the outer side in the tire width direction from the tire width direction grounding end T has a ridge width larger than the ridge portion 7 located on the inner side in the tire width direction from the tire width direction grounding end T. When it is formed widely, it is preferable because the amount of vibration of the ridge 7 is particularly amplified when traveling on a rough road.

[Other Embodiments]
(1) In the above-described embodiment, the example in which the protrusion height H2 of the two branch portions 7a is set to be the same is shown. However, in the present invention, the protrusion heights of the plurality of branch portions 7a may be different from each other. According to such a configuration, when receiving the load resistance of mud, the vibration amount of the ridge 7 is further amplified. As a result, the pneumatic tire having such a configuration effectively exhibits traction performance on the tread surface 1 even when traveling on a rough road, and has a better rough road running performance. In order to appropriately amplify the vibration amount of the ridge 7, the branch height of the higher branch 7a is 1.3 to 2.0 times the height of the ridge of the lower branch 7a. It is preferable that More specifically, for example, when the protrusion height of the lower branch portion 7a is 4 mm, and the branch height of the higher branch portion 7a is 6 to 8 mm, the vibration amount of the protrusion portion 7 Can be particularly amplified.

  (2) As shown in FIG. 5, in the present invention, the protruding portion 8 is provided on the sidewall surface 5 and extends beyond the sidewall surface side opening end S of the lug groove 6. You may connect 7a and the protruding part 8 continuously. In this case, as a result of the traction performance being effectively exhibited on the sidewall surface 5 and the tread surface 1, the pneumatic tire having the above configuration has particularly excellent rough road running performance. In addition, when changing the course of the vehicle, the heel wall of the tire itself can be scraped by the raised portion 8 and become an element that is caught on the heel wall, so that the handling performance is improved in the pneumatic tire having the above configuration.

  In order for the traction performance to be effectively exhibited on the sidewall surface 5, the height of the raised portion 8 is preferably 3 mm or more. Although it does not specifically limit as a surface shape of the protruding part 8, For example, as shown in FIG. In the present embodiment, the raised portions 8 are disposed at intervals at substantially the same circumferential position as the tire circumferential direction position corresponding to the sidewall surface side opening end S of the lug groove 6. In order to improve the traction performance on the sidewall surface 5, the interval in the tire circumferential direction between the adjacent raised portions 8 is preferably 10 mm to 30 mm. Moreover, when the surface shape of the protruding part 8 is a rectangular shape, it is preferable that the circumferential direction length of the protruding part 8 is 30-40 mm.

  When the branching portion 7a of the ridge 7 is connected to the raised portion 8, the continuous portion is restrained by the raised portion 8. However, stress is easily concentrated on the continuous portion by this restraining force. There are concerns about the occurrence of cracks. Therefore, in order to alleviate the stress concentration at the continuous portion, it is preferable that the continuous portion between the protruding portion 7 and the raised portion 8 is formed gently. Moreover, it is preferable that the protrusion height H <b> 2 of the branching portion 7 a in the cross section orthogonal to the extending direction of the lug groove 6 is not less than half of the protruding height of the protruding portion 8. In this case, the catching effect (traction performance) of the branched portion 7a itself protruding from the sidewall surface 5 is further improved. In addition, when the branch portion 7a is connected to the raised portion 8, the rigidity of the branch portion 7a itself is ensured, and thereby vibrations are transmitted to the ridge portion 7 disposed in the lug groove 6. Therefore, it is possible to promote exclusion of the mud filled in the lug groove 6. On the other hand, if H2 is less than half of the raised height of the raised portion 8, the rigidity of the branched portion 7 a is increased on the sidewall surface 5. The amount of vibration transmitted to the provided branching portion 7a is reduced. In addition, since the catching effect of the branch part 7a itself is small, the effect of connecting the branch part 7a and the raised part 8 of the ridge part 7 may not be sufficiently exhibited.

  In order to improve the traction performance on the side wall surface 5 and to improve the elimination of the mud filled in the lug groove 6, the arrangement position of the tire radial direction outer end of the raised portion 8 on the side wall surface 5 Is preferably located on the outer side in the tire radial direction than the maximum width position in the tire width direction of the pneumatic tire.

  (3) As shown in FIG. 6, in the present invention, the protruding portion 8 that continuously extends in the circumferential direction is disposed on the sidewall surface 5, and extends beyond the sidewall surface side opening end S of the lug groove 6. You may connect the branch part 7a and the protruding part 8 of the protrusion part 7 continuously. When the raised portion 8 extends continuously in the circumferential direction, the driving force is reliably ensured by the raised portion 8 when traveling on a rough road, and the course can be easily changed. As a result, according to this configuration, the bad road running performance of the pneumatic tire is further improved. In addition, according to such a configuration, the raised portion 8 that continuously extends in the circumferential direction contacts the ground when traveling on a rough road, so that the contact pressure is dispersed, so that the tire floatation performance (tire settlement prevention performance). Will improve.

  Hereinafter, examples and the like specifically showing the configuration and effects of the present invention will be described. In addition, each performance evaluation of the tire was performed as follows.

(1) Rough road performance Tires (tire size LT265 / 75R16; standard rim mounted, set to TRA standard internal pressure) are mounted on a 4-wheel-pick Pickup vehicle, and the feeling of traveling on muddy ground by three panelists Evaluation was performed. The evaluation is indicated by an index when the conventional product (Comparative Example 1) is set to 100, and the larger the value, the better the rough road running performance.

(2) Traction performance A tire (tire size LT265 / 75R16; standard rim mounted, set to TRA standard internal pressure) is mounted on a 4-wheel-pick Pickup vehicle, and a fixed load of 200 kg is applied on the bed. Acceleration evaluation during traveling on a muddy road 200 m was carried out, and the arrival time was measured. The evaluation is indicated by an index when the conventional product (Comparative Example 1) is set to 100, and the larger the value, the better the traction performance.

(3) Exclusion of mud After finishing the traction performance evaluation, the tire was run on a paved road surface at a low constant speed for 100 mm, and after cleaning the tire side part and the rim part, each tire weight was measured. The evaluation is indicated by an index when the conventional product (Comparative Example 1) is set to 100, and the larger the numerical value, the better the mud excretion.

(4) Handling performance (steerability)
Tires (tire size LT265 / 75R16; standard rim mounted, TRA standard internal pressure set) are mounted on a 4-wheel-pick Pickup vehicle, and a soft road surface (tire The rim part is not buried in the road surface, but the side wall surface 5 runs on a closed / oval (elliptical) course formed on the road surface to the extent that it is buried in the road surface. The panel was evaluated by three panelists using the escape performance when entering the cage and escaped as the handling performance. The evaluation is indicated by an index when the conventional product (Comparative Example 1) is set to 100, and the larger the value, the better the handling performance.

(5) Floatability Tires (tire size LT265 / 75R16; standard rim mounted, set to TRA standard internal pressure) mounted on a 4-wheel-pick Pickup vehicle, with a fixed load of 200 kg on the bed Run on a closed / oval (elliptical) course formed on an excessively soft road surface (a road surface in which approximately half of the rim of the tire is buried in the road surface), and three panelists will evaluate the feeling of driving performance Carried out. The evaluation is indicated by an index when the conventional product (Comparative Example 1) is set to 100, and the larger the value, the better the handling performance.

Comparative Example 1
As shown in FIG. 7, when viewed from the front of the tire, the sidewall surface side opening end S of the lug groove 6 has a starting point on the inner side in the tire width direction from the tire width direction grounding end T and beyond the tire width direction grounding end T. A pneumatic tire in which a ridge 7 ′ having an end point on the inner side in the tire width direction is disposed on the groove bottom of the lug groove 6 ′ (the groove width W of the lug groove 6 ′ = 25 mm, the groove depth of the lug groove 6 ′) H = 15 mm, the protrusion width W2 of the protrusion 7 ′ = 3 mm, and the protrusion height H2 = 3 mm of the protrusion 7 ′). Table 1 shows the results of the above evaluation using such a pneumatic tire.

Example 1
A pneumatic tire having the configuration shown in FIGS. 1 to 4 (the groove width W = 25 mm of the lug groove 6 on the inner side in the tire width direction than P1, the groove depth H = 15 mm of the lug groove 6, and the sidewall surface side opening end) The groove width of the lug groove 6 at S is 32 mm, the protrusion width W1 = 3 mm of the protrusion 7 located on the inner side in the tire width direction than P2, the protrusion height H1 = 3 mm, the tire width direction grounding end T, and the lug In the cross section orthogonal to the extending direction of the groove 6, the protrusion height H2 of the branch portion 7a = 3 mm, the protrusion width W2 = 3 mm, the lug groove width direction interval T1, and the lug groove width direction interval T2 between the two branch portions 7a. Both were manufactured 6 mm (T1 = T2). Table 1 shows the results of the above evaluation using such a pneumatic tire.

Example 2
As shown in FIG. 5, a protruding portion 8 (a height of the protruding portion 8 of 5 mm) is arranged on the sidewall surface 5 and the protruding portion 7 extends beyond the sidewall surface side opening end S of the lug groove 6. A pneumatic tire having the same configuration as that of Example 1 was manufactured except that the portion 7a and the raised portion 8 were continuously provided. Table 1 shows the results of the above performance evaluations using such tires.

Example 3
As shown in FIG. 5, a pneumatic tire having the same configuration as that of Example 2 was manufactured except that the protruding portion 8 continuously extended in the circumferential direction. Table 1 shows the results of the above performance evaluations using such tires.

  From the results of Table 1, the pneumatic tires of Example 1 and Example 2 have significantly improved rough road running performance as compared with the pneumatic tire of Comparative Example 1, and in addition, traction performance, mud exclusion, handling It can be seen that both performance and floatability are improved. In the pneumatic tire of Example 2, the protruding portion 8 is disposed on the sidewall surface 5, and the protruding portion 7 a and the protruding portion 7 a that extends beyond the sidewall surface side opening end S of the lug groove 6 are raised. It can be seen that the traction performance and the removal of mud are particularly improved from the fact that the section 8 is continuously provided. Furthermore, in the pneumatic tire of Example 3, it is found that the floatability is particularly improved by arranging the raised portions 8 continuously extending in the circumferential direction on the sidewall surface 5.

1: tread surface 5: sidewall surface 6: lug groove 7: ridge 7a: branching portion 8: raised portion

Claims (6)

In a pneumatic tire provided with a lug groove opening in a sidewall surface on a tread surface,
The groove width is gradually increased from the position in the tire width direction to the sidewall surface side opening end from the sidewall surface side opening end toward the sidewall surface side opening end, and the groove bottom of the lug groove is an extension of the lug groove. A ridge extending along the direction of movement is provided,
The protruding portion has a branch portion that branches into a plurality of positions at the inner side in the tire width direction from the ground contact end in the tire width direction when viewed from the front of the tire and extends beyond the ground contact end in the tire width direction. tire.   The pneumatic tire according to claim 1, wherein the plurality of branch portions have different protrusion heights. In the cross section including the tire width direction grounding end and perpendicular to the extending direction of the lug groove,
T1 ≦ T2 where T1 is the distance in the lug groove width direction between the branch part and the lug groove wall adjacent to the branch part, and T2 is the distance in the lug groove width direction between the plurality of branch parts. The pneumatic tire according to claim 1 or 2.   The ridge portion positioned on the outer side in the tire width direction with respect to the tire width direction ground end is formed with a higher ridge height than the ridge portion positioned on the inner side in the tire width direction with respect to the tire width direction ground end. The pneumatic tire according to any one of claims 1 to 3.   5. The side wall surface is provided with a raised portion, and the ridge portion is connected to the raised portion beyond the side wall surface side opening end of the lug groove. The pneumatic tire according to any one of the above.   The pneumatic tire according to claim 5, wherein the raised portion extends continuously in the circumferential direction.

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