JP6417274B2 - Radial tires for construction vehicles - Google Patents

Description

  The present invention relates to a radial tire for construction vehicles.

  Conventionally, construction vehicle radial tires mounted on large vehicles used in mines, construction sites, and the like are used under heavy load conditions, poor road surfaces, and severe traction conditions.

  For this reason, various measures for suppressing failures occurring in the radial tire for construction vehicles are being promoted.

  For example, Patent Document 1 discloses a configuration in which a belt reinforcing layer is added to suppress separation that occurs at the end of the belt layer in the tread width direction as one of the failures that occur in a radial tire for construction vehicles. ing.

JP-A-9-193607

  Incidentally, one of the failures that occur in a radial tire for construction vehicles is a crack (hereinafter referred to as an inner liner crack) that occurs in a shoulder portion of an inner liner provided on the inner surface of the tire.

  This inner liner crack occurs as follows. Specifically, when the outer surface of the tread portion of the tire contacts the road surface, the outer surface of the tread portion deforms along the road surface. At this time, since the inner liner also deforms along the road surface in the same manner as the deformation of the outer surface of the tread portion, a circumferential strain that distorts in the tire circumferential direction is generated in the inner liner, and the inner liner crack is caused by the circumferential strain. Occur.

  In addition, the circumferential strain of the inner liner tends to increase as the difference between the radius of the outer surface of the tread portion in the tire radial direction and the radius of the inner liner in the tire radial direction (hereinafter referred to as a radial difference) increases. is there. This is because the inner liner also deforms substantially parallel to the road surface in the same manner as the deformation of the outer surface of the tread portion, and therefore, if the above-mentioned radius difference is large, the amount of deformation of the inner liner in the tire circumferential direction increases. is there.

  Therefore, in radial tires for construction vehicles, where the gauge thickness of the tread portion is larger than that for passenger car tires and truck and bus tires, the radial difference described above is large, so a large circumferential strain is generated in the shoulder portion of the inner liner. As a result, there is a problem that the inner liner is easily cracked.

  Although the technique disclosed in Patent Document 1 can suppress failure occurring in the belt layer of the radial tire for construction vehicles, it cannot sufficiently suppress the inner liner crack as described above. For this reason, the countermeasure for improving durability by suppressing an inner liner crack was desired.

  This invention is made | formed in view of the said problem, and it aims at providing the radial tire for construction vehicles which can improve durability by suppressing an inner liner crack.

  A feature of the present invention is that the tread includes a carcass layer extending in a toroidal shape from a tread portion to a pair of bead portions via a pair of sidewall portions, and an inner liner disposed on an inner peripheral side of the carcass layer, When the end normal that passes through the tread end that is the outer end in the tread width direction of the outer surface of the section and is orthogonal to the carcass layer is defined, the length between the tread end and the carcass layer along the end normal is 100 mm. A radial tire for a construction vehicle as described above, wherein the carcass layer includes a width direction extending portion in which a carcass cord constituting the carcass layer extends in a tread width direction, and the carcass cord in a tread width direction. An inclined extending portion extending in a direction inclined with respect to the tread portion, and a tread portion extending outwardly from the tire equatorial plane on the outer surface of the tread portion. When the 3/8 normal that passes through a position separated by 3/8 times the head width and is orthogonal to the carcass layer is defined, the inclined extension portion is at least the 3/8 normal and the end normal The main point is that it is arranged between the two.

  Another feature of the present invention relates to the above feature and is summarized in that an angle formed between the extending direction of the inclined extending portion and the tread width direction is within a range of 10 to 40 °.

  Another feature of the present invention is related to the above feature, wherein a lug groove extending from the tread end toward the inner side in the tread width direction is formed in the tread portion, and the tire diameter of the lug groove is at the tread end. The gist of the depth in the direction is 100 mm or more.

  Another feature of the present invention relates to the above feature, wherein a reinforcing inner pad is provided between the carcass layer and the inner liner, and the reinforcing inner pad has at least the 3/8 normal line. The gist is to be disposed between the end normal and the end normal.

  According to the radial tire for construction vehicles which concerns on this invention, the radial tire for construction vehicles which can improve durability can be provided by suppressing an inner liner crack.

FIG. 1 is a cross-sectional perspective view of a radial tire for construction vehicles according to the first embodiment. FIG. 2 is a cross-sectional view along the tread width direction and the tire radial direction of the radial tire for construction vehicles according to the first embodiment. FIG. 3 is a developed plan view for explaining the carcass layer of the radial tire for construction vehicles according to the first embodiment. FIG. 4 is a partially enlarged cross-sectional view in the tread width direction and the tire radial direction of the radial tire for construction vehicles according to the first embodiment. FIG. 5 is an explanatory diagram for explaining a deformation when the radial tire for a construction vehicle contacts the road surface. FIG. 6 is a partial cross-sectional view in the tread width direction and the tire radial direction of a radial tire for construction vehicles according to a modification of the first embodiment. FIG. 7 is a graph showing the results of the comparative evaluation.

[First Embodiment]
A radial tire for construction vehicles according to a first embodiment of the present invention will be described with reference to the drawings.

(1) Outline of Construction Tire Radial Tire 1 FIG. 1 is a cross-sectional perspective view of a construction vehicle radial tire 1 according to the first embodiment. FIG. 2 is a cross-sectional view of the radial tire 1 for construction vehicles according to the first embodiment along the tread width direction Tw and the tire radial direction Td.

  As shown in FIGS. 1 and 2, the radial tire 1 for construction vehicles according to the present embodiment is connected to the tread portion 10 that contacts the road surface and the tread portion 10, and is located on the inner side in the tire radial direction Td from the tread portion 10. The side wall portion 20 includes a side wall portion 20 and a bead portion 30 that is connected to the side wall portion 20 and is located inside the tire radial direction Td from the side wall portion 20.

  The construction vehicle radial tire 1 is disposed on the inner side in the tire radial direction Td of the carcass layer 50 and the carcass layer 50 extending in a toroid shape from the tread portion 10 to the pair of bead portions 30 via the pair of sidewall portions 20. An inner liner 60.

  When the radial tire 1 for construction vehicles defines an end normal L1 that passes through the tread end TE that is the outer end in the tread width direction Tw of the outer surface 11 of the tread portion 10 and is orthogonal to the carcass layer 50, the end normal The length between the tread end TE and the carcass layer 50 along L1 is 100 mm or more. Specifically, as shown in FIG. 2, in the cross section of the tread width direction Tw and the tire radial direction Td, the end normal L1 that passes through the position Pe on the tread end TE and is orthogonal to the position Pei on the outer surface of the carcass layer 50. Is defined, the distance between the position Pe on the tread edge TE and the position Pei on the outer surface of the carcass layer 50 along the end normal L1 is 100 mm or more.

  Here, in the present embodiment, the tread end TE refers to the outer surface 11 of the tread portion 10 in a reference state in which the radial tire 1 for a construction vehicle is assembled to a normal rim, a normal internal pressure is applied, and a no-load state is set. Is located at the boundary between the outer surface 11 of the tread portion 10 and the outer surface 21 of the sidewall portion 20.

  “Regular rim” refers to the standard rim specified in the following standards according to the tire size, and “Regular internal pressure” refers to the maximum single wheel at the applicable size described in the following standards. Air pressure corresponding to load capacity. The standard is an industrial standard that is effective in the region where tires are produced or used. For example, in Japan, it is “JATMA YEAR BOOK” of “Japan Automobile Tire Association”, and “THE TIRE AND RIM ASSOCATION INC” in the United States. "YEAR BOOK" in Europe, and "STANDARD MANUAL" in "The European Tire and Rim Technical Organization" in Europe.

  Moreover, in this embodiment, the tread part 10 has the shoulder part 10S. The shoulder portion 10S of the tread portion 10 is located on the outer surface 11 of the tread portion 10 with respect to a position Ps that is 3/8 times the tread width W outward from the tire equatorial plane CL in the tread width direction Tw. The site | part of the tread width direction Tw outer side is shown. The tread width W is a length in the tread width direction Tw between the tread ends TE and TE located on both sides of the tread portion 10.

  The carcass layer 50 forms a skeleton of the construction vehicle radial tire 1 and includes a plurality of carcass cords 500 (see FIG. 3) arranged along the radial direction of the construction vehicle radial tire 1.

  The carcass layer 50 includes a carcass body 51 that is locked to a bead core 40 embedded in a pair of bead portions 30, and a carcass folded portion 52 that extends from the carcass body 51 and is folded around the bead core 40.

  The inner liner 60 is disposed on the inner peripheral side of the carcass layer 50. Note that the inner peripheral side is the inside of the tire radial direction Td in the tread portion 10, and the inside of the tread width direction Tw in the sidewall portion 20 and the bead portion 30. The inner peripheral side may be paraphrased as the inner side in the thickness direction of the carcass layer 50.

  The inner liner 60 is made of a rubber member and functions as a gas barrier layer on the inner surface of the tire. The end of the inner liner 60 on the inner side in the tire radial direction Td may terminate outside the bead core 40 on the outer side in the tire radial direction Td, or may extend to the bead toe.

  In the present embodiment, the inner liner 60 has a shoulder portion 60S. A shoulder portion 60S of the inner liner 60 passes through a position Ps separated by 3/8 times the tread width W from the tire equatorial plane CL to the outside in the tread width direction Tw, and a 3/8 normal line L2 orthogonal to the carcass layer 50; The part between the end normal L1 is shown. The 3/8 normal line L2 is orthogonal to the carcass layer 50 at a position Psi on the outer surface of the carcass layer 50.

  The belt layer 70 is provided outside the carcass layer 50 in the tire radial direction Td. The belt layer 70 is a cross belt composed of a plurality of belts 71, and each belt 71 has a plurality of belt cords (not shown). In the example of FIG. 2, the belt layer 70 is composed of six belts 71.

  For example, in the belt layer 70, the belt cords of the first and second belts 71 from the inner side in the tire radial direction extend at an angle of 0 ° to 10 ° with respect to the tire circumferential direction. The belt cords of the third and fourth layer belts 71 are inclined at an angle of 10 ° to 20 ° with respect to the tire circumferential direction, and the belts of the fifth and sixth layer belts 71 from the inner side in the tire radial direction. The cord extends at an angle of 20 ° to 30 ° with respect to the tire circumferential direction. The number of belts 71 and the direction in which the belt cord extends are not limited to this.

(2) Configuration of Carcass Layer Next, the configuration of the carcass layer 50 according to the present embodiment will be specifically described. As shown in FIG. 2, in the radial tire 1 for construction vehicles according to the present embodiment, the carcass layer 50 includes a width direction extending portion in which a carcass cord 500 constituting the carcass layer 50 extends along the tread width direction Tw. 510 and an inclined extending portion 520 extending in a direction in which the carcass cord 500 is inclined with respect to the tread width direction Tw.

  The inclined extending portion 520 is disposed between the extending portions 510 and 510 in the width direction. Further, the inclined extending portion 520 is disposed at the next position in the tire radial direction Td.

  Specifically, as illustrated in FIG. 2, the inclined extending portion 520 has a maximum tread width when the tread maximum width position Pm of the carcass layer 50 is defined in a cross section along the tread width direction Tw and the tire radial direction Td. The position Pm and the tread end TE are disposed on the outer side in the tire radial direction Td with respect to the position Ph having a length Dm / 2 that is ½ times the length Dm in the tire radial direction Td.

  Here, FIG. 3 shows a developed plan view for explaining the carcass layer 50 of the radial tire 1 for construction vehicles according to the first embodiment. Moreover, since the radial tire 1 for construction vehicles which concerns on this embodiment is a structure symmetrical with respect to the tire equatorial plane CL, in FIG. 3, only one side is shown on the basis of the tire equatorial plane CL, and the other side is abbreviate | omitted. doing.

  In the present embodiment, the inclined extending portion 520 is disposed between the 3/8 normal line L2 and the end normal line L1. Specifically, the end 521 inside the tread width direction Tw of the inclined extending portion 520 is located at the position Psi on the 3/8 normal line L2, and the end 522 outside the tread width direction Tw of the inclined extending portion 520. Is located at a position Pei on the end normal L1.

  Note that the inclined extending portion 520 only needs to be disposed between at least the 3/8 normal line L2 and the end normal line L1. Therefore, the end 521 of the inclined extension 520 may not necessarily be located on the 3/8 normal line L2, and the end 522 of the inclined extension 520 may not be located on the end normal L1. For example, the end 521 of the inclined extension 520 may be located on the inner side in the tread width direction Tw than the position Psi on the 3/8 normal L2. Further, the end portion 522 of the inclined extending portion 520 may be disposed at any position between the position Pei and the position Ph. That is, the end portion 522 of the inclined extending portion 520 is located in the range from the position Ph to the inner side of the tread width direction Tw (or the outer side of the tire radial direction Td).

  Further, the angle θ formed by the extending direction of the inclined extending portion 520 and the tread width direction Tw may be less than 10 °. In addition, it is preferable that angle (theta) which the extending direction of the inclination extension part 520 and the tread width direction Tw make is in the range of 10-40 degrees.

(3) Structure of lug groove formed in tread part Next, the structure of the lug groove 15 will be described. FIG. 4 shows a partially enlarged cross-sectional view in the tread width direction Tw and the tire radial direction Td of the radial tire 1 for construction vehicles according to the present embodiment. The tread portion 10 according to the present embodiment is formed with a lug groove 15 extending from the tread end TE toward the inside of the tread width direction Tw.

  As shown in FIG. 4, in the present embodiment, the depth Dp of the lug groove 15 in the tire radial direction Td is 100 mm or more at the tread end TE. The depth of the lug groove 15 is the length along the tire radial direction Td from the outer surface 11 to the bottom surface 15a of the lug groove 15. The depth Dp of the lug groove 15 is 150 mm or less.

  Here, the depth Dp of the lug groove 15 is a depth of a position where a tread wear indicator (not shown) is provided in the lug groove 15. That is, the depth Dp of the lug groove 15 is the length along the tire radial direction Td from the outer surface 11 to the groove bottom near the tread wear indicator.

  In the present embodiment, the case where the lug groove 15 extending in the tread width direction Tw is formed will be described as an example. However, the tread portion 10 has a rib groove (circumferential groove) extending in the tire circumferential direction Tc. May be formed.

(4) Action / Effect In the radial tire 1 for construction vehicles according to the present embodiment, the carcass layer 50 includes a width direction extending portion 510 and an inclined extending portion 520. The inclined extending portion 520 is disposed across the 3/8 normal line L2 and the end normal line L1.

  Here, FIG. 5 shows a conceptual diagram when the radial tire for construction vehicles contacts the road surface. As shown in FIG. 5, the inner liner 60 is deformed along the road surface at the time of tire contact, so that circumferential distortion occurs in the inner liner 60. In particular, in a radial tire for a construction vehicle having a large gauge thickness, the radial difference between the outer surface 11 of the tread portion 10 and the inner liner 60 is large, so that the circumferential strain of the inner liner 60 increases. In addition, since the shoulder portion 60S of the inner liner 60 is a portion where the radius difference increases, the circumferential distortion at the time of tire contact occurs more greatly in the inner liner 60.

  In the radial tire 1 for a construction vehicle according to the present embodiment, the inclined extending portion 520 in which the carcass cord 500 is inclined is disposed across the 3/8 normal line L2 and the end normal line L1. The inclined extending portion 520 suppresses deformation of the inner liner 60 in the tire circumferential direction Tc. That is, since the circumferential distortion generated in the shoulder portion 60S of the inner liner 60 can be suppressed, the occurrence of inner liner cracking can be suppressed and the durability can be improved. Moreover, since the shoulder part 60S of the inner liner 60 becomes a starting point of the inner liner crack, the inner liner crack can be suppressed from the initial stage by suppressing this.

  Moreover, it is preferable that angle (theta) which the extending direction of the inclination extension part 520 and the tread width direction Tw make is in the range of 10-40 degrees. When the angle θ is 10 ° or more, the circumferential distortion can be more reliably suppressed. On the other hand, when the angle θ is 40 ° or less, rubber separation between the carcass cords 500 adjacent to each other can be suppressed. Further, when the angle θ is 40 ° or less, uneven wear of the shoulder portion 10S due to deformation in the tread width direction Tw (buckling deformation) during cornering can be suppressed.

  In the present embodiment, the depth Dp of the lug groove 15 at the tread end TE is 100 mm or more. Here, when the depth Dp of the lug groove 15 at the tread end TE is 100 mm or more, the force that pushes up the inner liner 60 in the tire radial direction Td by the land portions formed on both sides of the lug groove 15 at the time of tire contact. Will increase. For this reason, the circumferential distortion may increase as the protruding portion 60X (see FIG. 5) in which the inner liner 60 protrudes inside the tire radial direction Td is generated.

  In the radial tire 1 for a construction vehicle having such a configuration, the inclined extending portion 520 obtained by inclining the carcass cord 500 is disposed across the 3/8 normal line L2 and the end normal line L1, so that the inner liner 60 The circumferential distortion in the shoulder portion 60S can be more effectively suppressed. That is, the radial tire 1 for construction vehicles according to the present embodiment can exhibit the effect of suppressing inner liner cracking more when the depth of the lug groove 15 at the tread end TE is 100 mm or more.

  In addition, as a technique for suppressing inner liner cracking, a technique of adding a belt reinforcing layer as in the prior art may be considered. However, since the addition of the belt reinforcing layer may cause an increase in cost due to the addition of the member, the method of adding a new member is not desirable.

  On the other hand, if the radial tire 1 for construction vehicles according to the present embodiment, the inner liner crack can be suppressed only by configuring the inclined extension portion 520 in the carcass cord 500 without adding any members. It is also useful from the viewpoint of suppressing improvement.

(5) Modified Example Next, a radial tire 1 for construction vehicles according to a modified example of the first embodiment will be described with reference to the drawings. FIG. 6 is a partial cross-sectional view of the radial tire 1 for construction vehicles according to the present embodiment in the tread width direction Tw and the tire radial direction Td. In addition, since the radial tire 1 for construction vehicles which concerns on this embodiment is a structure symmetrical with the tire equatorial plane CL as a boundary, in FIG. 6, only one side is shown on the basis of the tire equatorial plane CL, and the other side is abbreviate | omitted. doing.

  As shown in FIG. 6, the radial tire 1 for construction vehicles according to the present embodiment is provided with a reinforcing inner pad 300 between the carcass layer 50 and the inner liner 60. The reinforcing inner pad 300 is disposed along the inner side of the carcass layer 50 in the tread width direction Tw. In the present embodiment, the cross-sectional shape of the reinforcing inner pad 300 along the tread width direction Tw and the tire radial direction Td is a crescent shape, but is not limited thereto.

  In the present embodiment, the maximum thickness of the reinforcing inner pad 300 is 0.5 to 2.0% of the tread width W in the cross section along the tread width direction Tw and the tire radial direction Td. If this is less than 0.5%, the effect of providing such an inner pad cannot be obtained, and if it exceeds 2.0%, the rigidity becomes too high and the load burden rate on the tread portion 10 increases. For this reason, there is a possibility that failure may occur in the tread portion 10.

  Further, the reinforcing inner pad 300 according to the present embodiment is disposed over at least the 3/8 normal line L2 and the end normal line L1.

  Specifically, one end 301 inside the tread width direction Tw of the reinforcing inner pad 300 is positioned inside the tread width direction Tw from the 3/8 normal line L2. The other end 302 outside the tread width direction Tw of the reinforcing inner pad 300 is located outside the end normal L1 in the tread width direction Tw. The other end 302 of the reinforcing inner pad 300 may be located inside the tire radial direction Td from the maximum tread width position Pm of the carcass layer 50.

  As described above, when the reinforcing inner pad 300 is provided on the construction vehicle radial tire 1, the thickness of the outer surface 11 of the tread portion 10 and the inner liner 60 in the tire radial direction Td increases. The radius in the circumferential direction Tc is reduced. As described above, when the radius of the inner liner 60 is reduced, the circumferential strain of the inner liner 60 is increased when the tire is in contact with the ground, so that the inner liner crack is more likely to occur.

  In particular, when the reinforcing inner pad 300 is provided between the 3/8 normal line L2 and the end normal line L1, the radius of the shoulder part 60S of the inner liner 60 becomes small. There is a risk that inner liner cracks are more likely to occur.

  According to the radial tire 1 for construction vehicles according to the present embodiment, the carcass cord 500 is inclined even when the reinforcing inner pad 300 is provided between the 3/8 normal line L2 and the end normal line L1. By disposing the inclined extended portion 520 that extends over the 3/8 normal line L2 and the end normal line L1, the circumferential distortion in the shoulder portion 60S of the inner liner 60 can be more effectively suppressed. That is, the radial tire 1 for construction vehicles according to the present embodiment can further exhibit the effect of suppressing inner liner cracking when the reinforcing inner pad 300 is provided.

[Comparison evaluation]
Next, in order to further clarify the effect of the present invention, a comparative evaluation performed using pneumatic tires according to the following conventional examples and examples will be described. Specifically, (1) an evaluation method and (2) an evaluation result will be described. In addition, this invention is not limited at all by these examples.

(1) Evaluation method A test was performed using a plurality of types of radial tires for construction vehicles, and the circumferential strain generated in the tire circumferential direction Tc was evaluated. First, a radial tire for a construction vehicle according to a conventional example was modeled by a finite element method (hereinafter referred to as a conventional example), and a radial tire for a construction vehicle according to Examples 1 to 9 was modeled by a finite element method. (Hereinafter shown as Examples 1 to 9) were prepared.

  Here, as the conventional example, a carcass layer having no inclined extending portion is used. That is, the one having an angle θ of 0 ° with respect to the tread width direction Tw of the inclined extending portion was used.

  On the other hand, Examples 1 to 9 used the radial tire 1 for construction vehicles according to the first embodiment described above. That is, Examples 1 to 9 used the one having the inclined extending portion 520. The angle θ of each of the inclined extending portions 520 of Examples 1 to 9 is shown in Table 1 below.

  Further, in each of the conventional example and Examples 1 to 9, tires having a tire size of 23.5R25 (ORR tire) were used. The conventional example and Examples 1 to 9 are the same except for the above-described configuration.

  Further, each of the conventional example and Examples 1 to 9 was assembled to a normal rim (29.00J / 6.0), a normal internal pressure was applied, and a state where a normal load was applied was simulated. “Regular load” refers to the maximum load (maximum load capacity) of a single wheel in the applicable size of the above-mentioned standard.

  Then, the circumferential strain generated in each tire circumferential direction Tc was measured. Specifically, the circumferential distortion generated at the intersection of the end normal L1 and the inner liner was measured.

(2) Evaluation Results The evaluation results of the conventional example and Examples 1 to 9 will be described with reference to FIG. Note that the data shown in FIG. 7 and Table 1 are all the same data.

  Moreover, in FIG. 7 and Table 1, the circumferential distortion is indicated by an index value with the result of the conventional example as a reference (100), and the smaller the index value is, the smaller the circumferential distortion is. . In FIG. 7, the result of the conventional example is indicated by D0, and the results of Examples 1 to 9 are indicated by D1 to D9, respectively.

図７及び表１に示すように、従来例及び実施例１乃至９のそれぞれを比較すると、実施例１乃至９は、従来例に係る建設車両用ラジアルタイヤに比べて、周方向歪が抑制されていることがわかる。

As shown in FIG. 7 and Table 1, when comparing the conventional example and Examples 1 to 9, each of Examples 1 to 9 has less circumferential distortion compared to the radial tire for a construction vehicle according to the conventional example. You can see that

  As described above, according to the radial tire for construction vehicles according to this embodiment, it was proved that the inner liner cracking can be suppressed and the durability can be improved by suppressing the circumferential strain.

[Other Embodiments]
Next, other embodiments of the present invention will be described. In the above-described embodiment, the tread end TE is the end of the outer surface 11 of the tread portion 10 on the outer side in the tread width direction Tw. For example, when the boundary between the outer surface 11 of the tread portion 10 and the outer surface 21 of the sidewall portion 20 has a chamfered shape by forming an inclined surface (tapered surface) instead of a corner portion, the tread end TE is The end of the inclined surface inside the tread width direction Tw may be used. Further, for example, the tread end TE includes a tangent along the outer surface 11 of the tread portion 10 and a tangent along the outer surface 21 of the sidewall portion 20 in a cross section along the tread width direction Tw and the tire radial direction Td. It is good also as a point where.

  In the embodiment described above, the construction vehicle radial tire 1 has a symmetric configuration with respect to the tire equator plane CL, but the inclined extending portion 520 may be asymmetric.

  As described above, the present invention naturally includes various embodiments that are not described herein. Various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiments. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

DESCRIPTION OF SYMBOLS 1 ... Radial tire for construction vehicles 10 ... Tread part 11 ... Outer surface 15 ... Lug groove 20 ... Side wall part 30 ... Bead part 40 ... Bead core 50 ... Carcass layer 60 ... Inner liner 70 ... Belt layer 300 ... Reinforcement inner pad 500 ... carcass cord 510 ... width direction extension part 520 ... inclined extension part TE ... tread end W ... tread width L1 ... end normal L2 ... 3/8 normal L2

Claims (7)

A carcass layer extending in a toroidal shape over a pair of bead portions from a tread portion via a pair of sidewall portions, and an inner liner disposed on the inner peripheral side of the carcass layer,
The length between the tread end and the carcass layer along the end normal when passing through the tread end which is the outer end in the tread width direction of the outer surface of the tread portion and defining an end normal perpendicular to the carcass layer Is a radial tire for construction vehicles having a length of 100 mm or more,
The carcass layer includes a width direction extending portion in which a carcass cord constituting the carcass layer extends along a tread width direction, and an inclined extension in which the carcass cord extends in a direction inclined with respect to the tread width direction. A one-layer structure including a portion,
When the outer surface of the tread part defines a 3/8 normal line passing through a position away from the tire equator surface by 3/8 times the tread width outward in the tread width direction and orthogonal to the carcass layer, the inclined extension The radial tire for a construction vehicle is characterized in that the portion is disposed at least between the 3/8 normal and the end normal. 2. The radial tire for construction vehicles according to claim 1, wherein an angle formed by an extending direction of the inclined extending portion and a tread width direction is within a range of 10 to 40 °. A lug groove extending from the tread end toward the inner side in the tread width direction is formed in the tread portion,
The radial tire for construction vehicles according to claim 1 or 2, wherein the depth of the lug groove in the tire radial direction at the tread end is 100 mm or more. A reinforcing inner pad is provided between the carcass layer and the inner liner,
The radial tire for construction vehicles according to any one of claims 1 to 3, wherein the reinforcing inner pad is disposed at least between the 3/8 normal line and the end normal line. A belt layer provided on the outer side in the tire radial direction of the carcass layer;
The belt angle of the first and second layers from the inner side in the tire radial direction of the belt layer is 0 to 10 ° with respect to the tire circumferential direction, and the third and fourth belt angles from the inner side in the tire radial direction are It is 10 to 20 ° with respect to the tire circumferential direction, and the belt angles of the fifth and sixth layers from the inside in the tire radial direction are 20 to 30 ° with respect to the tire circumferential direction.
The radial tire for construction vehicles according to any one of claims 1 to 4 characterized by things. In the cross section along the tread width direction and the tire radial direction, the inclined extending portion has a length in the tire radial direction between the maximum tread width position and the tread end when the maximum tread width position of the carcass layer is defined. It is arranged on the outer side in the tire radial direction than a position having a length that is 1/2 times the length.
The radial tire for construction vehicles according to any one of claims 1 to 5 characterized by things. The maximum thickness of the reinforcing inner pad is 0.5 to 2.0% of the tread width.
The radial tire for construction vehicles according to claim 4 characterized by things.

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