tire

Abstract

To provide a tire having a smooth pattern which allows a residual tread gauge to be easily grasped.SOLUTION: A tire 10 has a smooth pattern which does not substantially include grooves on a tread surface 11 of a tread part 1 comprising tread rubber 1a. In the tire 10, on a side part outer surface 21 of the tire 10, a plurality of ridges 30 extends in a tire circumferential direction by projecting from the side part outer surface 21, and is provided by being spaced apart from each other in a tire radial direction, in order to confirm a residual tread gauge until the tread rubber 1a reaches a wear limit.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a tire. [Background technology]

[0002] Conventionally, tires for construction and mining vehicles, such as tires for road haul dumps used in underground mines and tunnel construction sites, have sometimes used a tread pattern with no grooves on the tread surface, known as a smooth pattern, primarily to improve wear life. For such smooth-pattern tires, the remaining groove depth cannot be determined by measuring the groove depth with a wear indicator at the bottom of the groove or a depth gauge, as is the case with ordinary tires with grooves. Therefore, various means have been considered and are being used to determine the amount of wear of the tread rubber (and ultimately, the remaining tread gauge until the tread rubber reaches its wear limit) (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 11-254914 Summary of the Invention [Problem to be solved by the invention]

[0004] Here, one method for determining the remaining tread gauge until the wear limit of a smooth pattern tire is to make narrow slits extending to the outer surface of the side at the tread edge at several points around the tire, and insert a depth gauge into the slit from the tread surface to measure the remaining depth of the slit to determine the remaining tread gauge until the wear limit. However, in the case of tires for road haul dumps, for example, underground tunnels, which are the main work sites, are dark, and if a break or chip occurs near the shoulder of a tire with a slit, it can easily be confused with the slit. For these reasons, it can be difficult to see the position of the slit where the depth gauge should be inserted, and as a result, it can be difficult to easily determine the remaining tread gauge until the wear limit.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a tire having a smooth pattern that allows the remaining tread gauge to be easily grasped. [Means for solving the problem]

[0006] The tire of the present invention is A tire having a smooth pattern with substantially no grooves on the tread surface of the tread portion including the tread rubber, The tire is characterized in that a plurality of ridges are provided on the outer surface of the side portion, protruding from the outer surface of the side portion and extending in the tire circumferential direction, spaced apart in the tire radial direction, for checking the remaining tread gauge until the tread rubber reaches its wear limit. The tire of the present invention has a smooth pattern that allows the remaining tread gauge to be easily grasped.

[0007] In the tire of the present invention, It is preferable that a numerical value corresponding to the remaining tread gauge is displayed at a position on the outer surface of the side portion corresponding to each of the plurality of ridges. In this case, the remaining tread gauge can be more easily grasped.

[0008] In the tire of the present invention, Of the plurality of ridges, the ridge located at the innermost position in the tire radial direction is preferably provided at a position in the tire radial direction that corresponds to a wear limit position that is a wear limit of the tread rubber. In this case, the remaining tread gauge until the wear limit is reached can be more accurately determined.

[0009] In the tire of the present invention, The plurality of ridges preferably includes three ridges, the distance between adjacent ridges in the tire radial direction being 25% of the remaining tread gauge of the tire when new. In this case, the remaining tread gauge until the wear limit is reached can be grasped more accurately in stages.

[0010] In the tire of the present invention, A slit may further be provided, extending from the tread surface to the outer surface of the side portion, for inserting a depth gauge from the tread surface to measure the depth and thereby checking the remaining tread gauge. In this case, the remaining tread gauge can be grasped more accurately. [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a tire having a smooth pattern that allows the remaining tread gauge to be easily grasped. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a partial perspective view schematically showing a tire according to an embodiment of the present invention as viewed obliquely from above on the left side. [Figure 2] FIG. 2 is a partial side view showing a part of the tire of FIG. 1 as viewed from the side of the tire. [Figure 3] 2. FIG. 3 is a partial cross-sectional view in the tire width direction showing a part of the tire of FIG. 1 in a reference state, taken along line XX of FIG. [Figure 4] 3 is a cross-sectional view showing the ridge of FIG. 2 taken along line YY of FIG. 2. DETAILED DESCRIPTION OF THE INVENTION

[0013] The tire according to the present invention can be suitably used for any type of tire having a smooth pattern, and can be suitably used for tires for construction and mining vehicles such as road haul dump tires used for excavating, transporting, and loading rocks and minerals in underground mines and tunnel construction sites, and tire for wheel loaders used in open pits above ground in mines, tires for industrial vehicles such as tire for reach stackers and container handlers used for moving and stacking transport containers at ports and cargo transshipment bases, and also tires for track-running vehicles used in subways, monorails, new transportation systems, etc.

[0014] Hereinafter, embodiments of a tire according to the present invention will be described with reference to the drawings. However, the drawings are schematic, and dimensions and the ratios between dimensions may differ from those in reality. The same reference numerals are used to designate common members and parts in the drawings. In some drawings, the tire width direction is indicated by the symbol "WD," the tire radial direction is indicated by the symbol "RD," and the tire circumferential direction is indicated by the symbol "CD."

[0015] Figures 1 to 3 are drawings for explaining a tire 10 according to one embodiment of the present invention. Figure 1 is a partial perspective view schematically showing a tire according to one embodiment of the present invention as viewed from diagonally above left, Figure 2 is a partial side view showing a part of the tire of Figure 1 as viewed from the side of the tire, and Figure 3 is a partial cross-sectional view in the tire width direction showing a part of the tire of Figure 1 in a reference state as a cross-section taken along line XX of Figure 2. The tire 10 of the present embodiment may be configured as any type of tire.

[0016] Unless otherwise specified, the positional relationship and dimensions of each element are measured in the standard condition, with the tire mounted on the applicable rim, inflated to the specified internal pressure, and no load applied. In this specification, "tread surface" refers to the outer peripheral surface of the tire that comes into contact with the road surface when the tire is mounted on an applicable rim, inflated to the specified internal pressure, and subjected to the maximum load, and "tread edge" refers to the edge of the tread surface in the tire width direction. In addition, in this specification, the side closer to the tire cavity is referred to as the "inner side" of the tire, and the side farther from the tire cavity is referred to as the "outer side" of the tire.

[0017] In this specification, the term "applicable rim" refers to the standard rim (Measuring Rim in the ETRTO Standards Manual and Design Rim in the TRA Year Book) for the applicable size, which is an industrial standard valid in the region where the tire is produced and used, and which is described or will be described in the future, such as the JATMA Year Book of the Japan Automobile Tire Manufacturers Association (JATMA) in Japan, the European Tyre and Rim Technical Organization (ETRTO) Standards Manual in Europe, and the Tire and Rim Association, Inc. (TRA) Year Book in the United States. However, for sizes not described in these industrial standards, it refers to a rim with a width corresponding to the bead width of a pneumatic tire. "Applicable rim" includes not only current sizes but also sizes that will be described in the aforementioned industrial standards in the future. An example of a "size to be described in the future" is the size described as "FUTURE DEVELOPMENTS" in the 2013 edition of the ETRTO Standards.

[0018] In this specification, "specified internal pressure" refers to the air pressure (maximum air pressure) corresponding to the maximum load capacity of a single wheel for the applicable size and ply rating as set forth in the aforementioned industrial standards, such as the JATMA Yearbook, or, in the case of a size not set forth in the aforementioned industrial standards, refers to the air pressure (maximum air pressure) corresponding to the maximum load capacity specified for each vehicle on which the tire is to be mounted. Furthermore, in this specification, "maximum load" refers to the load corresponding to the maximum load capacity of the tire for the applicable size as set forth in the aforementioned industrial standards, or, in the case of a size not set forth in the aforementioned industrial standards, the load corresponding to the maximum load capacity specified for each vehicle on which the tire is to be mounted.

[0019] Furthermore, in this specification, "wear limit" refers to the state of the tread rubber's wear limit, determined by the tire manufacturer, beyond which the tire cannot be used, and "wear limit position" refers to the radial position of the tread surface when the tire is at its wear limit. The wear limit does not necessarily have to be a state that could actually be the wear limit, such as one in which the belt of the tread portion is exposed; for example, for greater safety, the wear limit may be determined to be a state in which the tread surface is slightly radially outward of the tread surface position when in that state. Furthermore, in this specification, the term "remaining tread gauge" refers to the maximum radial thickness of the tread rubber remaining before the wear limit is reached. In other words, the remaining tread gauge is the value obtained by subtracting the amount of wear in the tire radial direction from the maximum radial thickness of the tread rubber of a new tire.

[0020] As shown in FIGS. 1 and 3, a tire 10 of this embodiment has a tread portion 1 constituting a radially outer portion of the tire 10, and side portions 2 constituting both widthwise outer portions of the tire 10. The tread portion 1 and the side portions 2 partially overlap at both widthwise outer portions of the tread portion 1 and at both widthwise outer portions of the side portions 2. Therefore, a side portion outer surface 21, which will be described later, also includes the outer surfaces of both widthwise outer portions of the tread portion 1 on the tire widthwise outer sides. As shown in FIG. 3, the tire 10 has a carcass 5 extending between both bead portions (not shown) and made up of one or more carcass layers, and a belt 6 arranged radially outward of a crown portion of the carcass 5 and made up of one or more belt layers (five layers indicated by reference numerals 6a to 6e in the illustrated example). A tread rubber 1a is provided radially outward of the belt 6 in the tread portion 1 of the tire 10. In this embodiment, the internal configuration of the tire 10 is the same as the internal configuration of a general tire, as described above. However, the internal configuration of the tire 10 is not particularly limited to this. The internal configuration of the tire 10 may be any desired configuration.

[0021] 1 and 3, the tire 10 of this embodiment is a so-called smooth pattern tire that has substantially no grooves on the tread surface 11 of the tread portion 1 including the tread rubber 1a. That is, the tire 10 has substantially no grooves for drainage or the like on the tread surface 11 except for slits 40 for checking the remaining tread gauge, which will be described later. Because the tread pattern of the tire 10 is a smooth pattern, sufficient volume and tread rigidity of the tread rubber 1a can be ensured, thereby obtaining a sufficient wear life, etc.

[0022] As shown in Figures 1 to 3, in this embodiment, tire 10 has an outer surface 21 of a side portion 2 of tire 10 (hereinafter referred to as the "side portion outer surface"), on which multiple (three in this embodiment) ridges 30 (31 to 33) are provided, spaced apart in the tire radial direction, protruding outward in the tire width direction from the side portion outer surface 21 and extending in the tire circumferential direction. Here, the ridge 30 "extending in the tire circumferential direction" does not necessarily mean that the ridge 30 extends continuously around the entire circumference of the tire, but only needs to extend over at least a portion of the circumference of the tire. For example, the ridge 30 may extend so as to be continuous in the tire circumferential direction except for one location on the circumference of the tire where the slit 40 is provided, as in this embodiment (FIGS. 1 to 3), or may extend in a manner that is divided into a plurality of locations (e.g., two locations) around the tire so as to be discontinuous in the tire circumferential direction. However, from the viewpoint of allowing the user of the tire 10 to adequately see the ridges 30 and easily check the remaining tread gauge, it is preferable that each of the multiple ridges 30 extend over a range of 50% or more of the total circumferential length of the tire at the radial position of each side outer surface 21, more preferably over a range of 75% or more, even more preferably over a range of 90% or more, and most preferably over the entire circumference. In this embodiment, the ridges 30 (31 to 33) extend along the tire circumferential direction (that is, in a direction parallel to the tire circumferential direction).

[0023] In this embodiment, the ridges 30 (31 to 33) are used to check the remaining tread gauge until the tread rubber 1a reaches the aforementioned wear limit. More specifically, in this embodiment, the multiple ridges 30 (31 to 33) are each provided at a relatively outer position in the tire radial direction on the side portion outer surface 21, i.e., within a tire radial direction range on the side portion outer surface 21 equivalent to at least the tire radial direction range where the tread portion 1 exists (i.e., the tire radial direction range between the tire radially outermost position on the tire outer surface and the tire radially outermost position on the tire inner surface) in order to check the remaining tread gauge. Even more specifically, in this embodiment, the multiple ridges 30 (31 to 33) are each provided at a tire radial direction position that should indicate the remaining tread gauge (for example, as shown in FIG. 2, 0%, 25%, 50%, etc., respectively, relative to the remaining tread gauge Dn of the tire 10 when new, as will be described later).

[0024] 1 to 3 show only the plurality of ridges 30 provided on the side portion 2 (and thus the side portion outer surface 21) of the tire half portion on one side in the tire width direction. However, the side portion 2 (and thus the side portion outer surface 21) of the tire half portion on the other side in the tire width direction may or may not be similarly provided with the plurality of ridges 30. However, taking into consideration the possibility that the tire 10 may be removed from the wheel during use to check its wear state, or that the tire 10 may be mounted on a vehicle with the mounting directions on the vehicle of one side and the other side in the tire width direction reversed (in other words, with the front and back (serial side and anti-serial side) of the tire 10 reversed), it is preferable that the side portion 2 (and thus the side portion outer surface 21) of the tire half portion on the other side in the tire width direction also be similarly provided with the plurality of ridges 30. In this case, the plurality of ridges 30 on one side and the other side in the tire width direction may have the same configuration (shape, arrangement, etc.) or may have different configurations.

[0025] As described above, according to this embodiment, the tire 10 is a tire having a smooth pattern, and a plurality of ridges 30 (31 to 33) are provided on the side outer surface 21 of the tire 10, protruding from the side outer surface 21 and extending in the tire circumferential direction, spaced apart from one another in the tire radial direction, for checking the remaining tread gauge until the tread rubber 1a reaches its wear limit. Therefore, according to this embodiment, the plurality of ridges 30 function as indicators that can be used to check the wear state, and it is possible to easily grasp, for example visually, which of the plurality of ridges 30 arranged spaced apart in the tire radial direction the position of the tread surface 11 of the tire 10 in use has reached or exceeded, and thus the approximate remaining tread gauge can be easily checked. Furthermore, according to this embodiment, the multiple ridges 30 for checking the remaining tread gauge extend in the circumferential direction of the tire. Therefore, compared to, for example, a case where slits for inserting depth gauges are provided at the tread ends in several locations around the tire to measure the remaining tread gauge, even if a chip or break occurs at the tread end, the remaining tread gauge can be checked using the ridges 30 at other locations around the tire. As described above, the tire of this embodiment has a smooth pattern that allows the remaining tread gauge to be easily grasped. Furthermore, according to this embodiment, the multiple ridges 30 for checking the remaining tread gauge protrude from the outer surface 21 of the side portion and extend in the circumferential direction of the tire. Therefore, compared to, for example, a case where a groove extending in the circumferential direction of the tire for checking the remaining tread gauge is provided on the outer surface of the side portion, there is no risk of groove bottom cracks and, in turn, separation failure between the tread rubber and the belt due to the progression of the groove bottom cracks, and the durability of the tire can be maintained.

[0026] In this embodiment, as shown in FIG. 2, it is preferable that numerical values ​​(digits) corresponding to the remaining tread gauge are displayed at positions on the side outer surface 21 corresponding to each of the plurality of ridges 30 (31 to 33). More specifically, in this embodiment, as shown in FIG. 2, a numerical value corresponding to the remaining tread gauge, i.e., in the illustrated example, a numerical value (in the illustrated example, "50" indicating 50%, "25" indicating 25%, and "0" indicating 0%) indicating the percentage of the remaining tread gauge at the time of use of the tire 10, which is intended to grasp the wear state relative to the remaining tread gauge when the tire 10 is new, is displayed at a position corresponding to each of the multiple ridges 30 (31-33), i.e., in the illustrated example, at the same tire radial position as each of the multiple ridges 30 (31-33) (more specifically, at a tire radial position that at least partially overlaps with the tire radial area occupied by each of the multiple ridges 30 (31-33)). However, the "numerical value corresponding to the remaining tread gauge" does not have to be as shown in the above example. For example, the numerical value corresponding to the remaining tread gauge may be a numerical value expressed as a percentage of the amount of wear in the tire radial direction, calculated by subtracting the remaining tread gauge when the tire's wear state is determined from the remaining tread gauge when the tire was new, with the wear limit being 100% (for example, if the remaining tread gauge is 0%, it is 100%, and if the remaining tread gauge is 25%, it is 75%).In addition, the above-mentioned "positions corresponding to each of the multiple ridges" do not have to be as in the above example, and may be, for example, positions in the tire radial vicinity of each of the multiple ridges 30 (31-33) where the corresponding ridge can be recognized. The numerical value may be displayed by, for example, forming it to protrude from the outer surface 21 of the side portion using a tire manufacturing mold, similar to a logo mark or the like that is normally displayed on the side portion 2 of the tire 10, or may be displayed by printing on the outer surface 21 of the side portion. Furthermore, the numerical values ​​(digits) may be displayed in a color other than black (for example, red) to improve visibility. Numerical values ​​corresponding to the remaining tread gauge are displayed at positions corresponding to each of the multiple ridges 30 (31-33) on the side outer surface 21, so that the wear condition of the tire 10 and therefore the approximate remaining tread gauge can be visually confirmed at a glance, and therefore the remaining tread gauge can be more easily understood.

[0027] In this embodiment, as shown in Figure 3, among the multiple ridges 30 (31 to 33), it is preferable that the ridge 33 located at the innermost position in the tire radial direction is provided at a tire radial position corresponding to the wear limit position, which is the wear limit of the tread rubber 1a. More specifically, in this embodiment, as shown in FIG. 3, the wear limit position WL (shown in FIG. 3 by a virtual line extending along the tire width direction), which is the wear limit of the tread rubber 1a, is set to the tire radial position of the outermost belt layer 6e in the tire radial direction among the multiple belt layers (more precisely, the portion of the thickness direction center line of the belt layer 6e that is the outermost in the tire radial direction), and the ridge 33 that is located innermost in the tire radial direction among the multiple ridges 30 (31 to 33) is provided at the tire radial position corresponding to the wear limit position. In this embodiment, more specifically, the ridge 33 is positioned so that the tire radially outer end 33eo of the tire radially innermost ridge 33 (more precisely, the top surface 33ts of the ridge 33 (see Figure 4)) coincides with the wear limit position WL, but the ridge 33 may be positioned so that any portion of the top surface 33ts of the ridge 33, including the tire radial center 33c and the tire radially inner end 33ei of the ridge 33 (more precisely, the top surface 33ts of the ridge 33), coincides with the wear limit position WL. By locating the ridge 33 located radially innermost in the tire at a position in the tire radial direction that corresponds to the wear limit position WL, the remaining tread gauge until the wear limit is reached can be grasped more accurately compared to, for example, a case where the entire innermost ridge 33 is located below or above the wear limit position WL, away from the wear limit position WL.

[0028] 1 to 3, the plurality of ridges 30 preferably includes three ridges, including a ridge 33 located at the innermost position in the tire radial direction, which is located at a tire radial position corresponding to the wear limit position WL, such that the tire radial distance between adjacent ridges in the tire radial direction is 25% of the remaining tread gauge of the tire 10 when new. That is, in the present embodiment, the plurality of ridges 30 includes only three ridges 31, 32, and 33, as shown in FIG. 2. In addition, a tire radial distance D12 between the ridge 31 located at the outermost position in the tire radial direction and the ridge 32 adjacent to the ridge 31 on the inner side in the tire radial direction, and a tire radial distance D23 between the ridge 32 and the ridge 33 located at the innermost position in the tire radial direction and adjacent to the ridge 32 on the inner side in the tire radial direction, are the same, and both are 25% of the remaining tread gauge Dn of the tire 10 when new. The distance between each ridge is measured based on the widthwise center (and therefore the tire radial center) 30c (31c to 33c) of each ridge 30 (31 to 33) (more precisely, the top surface of each ridge 31 to 33). By configuring the plurality of ridges 30 from the three ridges 31 to 33 as described above, the user of the tire 10 can know that, for example, when the radial position of the tread surface 11 on at least the side outer surface 21 of the tire 10 reaches the radially outermost ridge 31 during use of the tire 10, the remaining tread gauge has decreased to 50% of that when the tire 10 was new, and when the radial position of the tread surface 11 reaches the ridge 32 adjacent to the ridge 31 on the radially inner side of the tire, the remaining tread gauge has decreased to 25% of that when the tire 10 was new. In other words, by configuring the plurality of ridges 30 from the three ridges 31 to 33 as described above, the remaining tread gauge until it reaches the wear limit can be grasped stepwise more accurately, and thus can be effectively utilized for, for example, managing the wear state of the tire 10. 2, in this embodiment, a numerical value (digit) "50" indicating 50%, "25" indicating 25%, and "0" indicating 0%, which are the ratios of the remaining tread gauge to the remaining tread gauge Dn of the new tire 10, are displayed in order at positions corresponding to each of the plurality of ridges 31 to 33. Therefore, according to this embodiment, the remaining tread gauge can be grasped more accurately in stages and more easily at a glance.

[0029] 1 to 3, the tire 10 may further be provided with a slit 40 that extends from the tread surface 11 to the side outer surface 21 (i.e., includes the tread edge TE and opens to the tread surface 11 and the side outer surface 21), and that allows a depth gauge to be inserted from the tread surface 11 to measure the depth, thereby confirming the remaining tread gauge. In this case, it becomes possible to measure the specific remaining depth of the slit 40, and therefore the specific remaining tread gauge, during the wear of the tire 10. Therefore, by using the slit 40 in combination with a plurality of ridges 30 that allow a more general remaining tread gauge to be confirmed, the remaining tread gauge can be more accurately determined.

[0030] The tire radial position of the slit bottom (i.e., the tire radial inner end) 40ei of the slit 40 on the side outer surface 21 is not particularly limited, but from the viewpoint of making it easier to understand the remaining tread gauge, it is preferable to set it at a tire radial position corresponding to the wear limit position WL. 1 to 3 show only one slit 40 provided around the tire 10, the slit 40 may be provided at multiple locations (for example, two locations) around the tire. For example, when the slits 40 are provided at two locations around the tire (i.e., two slits around the tire), the slits 40 may be provided at positions facing each other around the tire (i.e., positions spaced 180° apart from each other in terms of central angle) from the viewpoint of ease of grasping the remaining tread gauge. 1 to 3 show only the slits 40 provided in the half portion of the tire on one side in the tire width direction, but the half portion of the tire on the other side in the tire width direction may or may not be provided with a similar slit 40. However, considering that the tire 10 may be removed from the wheel during use to check its wear state, or that the tire 10 may be mounted on a vehicle with the mounting directions on the vehicle of one side and the other side in the tire width direction reversed (in other words, the tire 10 is mounted on a vehicle with the front and back (serial side and anti-serial side) reversed), it is preferable that the half portion of the tire on the other side in the tire width direction also be provided with a similar slit 40. In this case, the slits 40 on one side and the other side in the tire width direction may have the same configuration (shape, arrangement, etc.) or may have different configurations. Furthermore, for example, when slits 40 are provided at two locations around the circumference of each of the tire halves on one side and the other side in the tire width direction (i.e., two on each of both halves), from the standpoint of ease of grasping the remaining tread gauge and rigidity balance near the tread ends on both sides, the slits 40 may be provided, for example, in each half so that two slits 40 are located 180° apart from each other at the central angle, and between each half, the slits 40 may be positioned out of phase so that they are located 90° apart from each other at the central angle.

[0031] Next, a preferred configuration of the ridge 30 will be described with reference to FIG. Fig. 4 is a cross-sectional view of the ridge in Fig. 2 taken along line YY in Fig. 2. Fig. 4 shows the cross-sectional shape of the ridge 33, which is the innermost ridge in the tire radial direction, as a typical example of the multiple ridges 31 to 33. The cross-sectional shape of the ridge 33 will be described below, but the cross-sectional shapes of the other ridges 31 and 32 are similar to those described below. The cross-sectional shapes of the ridges 31 and 32 may be the same as or different from the cross-sectional shape of the ridge 33. In this embodiment, the cross-sectional shapes of the multiple ridges 31 to 33 are the same as each other.

[0032] The height H of the ridge 33 from the side outer surface 21 is not particularly limited, but is preferably 0.8 to 1.2 mm from the viewpoint of ridge visibility (i.e., ease of visually confirming the presence and position of the ridge) and suppressing an increase in rubber volume. The width W of the top surface 33ts of the ridge 33 is not particularly limited either, but is preferably 2 to 6 mm, more preferably 3 to 5 mm, from the viewpoint of the visibility of the ridge and its functionality as an indicator. 4, the connection portion between the radially outer side surface 33so of the ridge 33 and the side portion outer surface 21 and the connection portion between the radially inner side surface 33si of the ridge 33 and the side portion outer surface 21 are formed in an arc shape with a curvature radius R1 and a curvature radius R2, respectively, thereby suppressing stress concentration at the base of the ridge and thereby suppressing chipping or breakage of the ridge. From the viewpoint of effectively suppressing chipping or breakage of the ridge, it is preferable that the curvature radii R1 and R2 be greater than 0.3 mm. 4, the radially outer end 33eo and the radially inner end 33ei of the top surface 33ts of the ridge 33 are angular in cross section, which makes the ends clearly stand out and improves the visibility of the ridge and its functionality as an indicator. However, the ends may also be rounded. 4, the angle on the inner side of the ridge 33 formed between the top surface 33ts of the ridge 33 at the tire radially outer end 33eo of the top surface 33ts and the tire radially outer side surface 33so, and the angle on the inner side of the ridge 33 formed between the top surface 33ts of the ridge 33 at the tire radially inner end 33ei of the top surface 33ts of the ridge 33 and the tire radially inner side surface 33si are both greater than 90°, thereby preventing the ridge from chipping or breaking. However, both angles may be less than 90°.

[0033] The ridges 30 (31 to 33) can be formed to protrude from the outer surface 21 of the side portion using a tire manufacturing mold, for example, in the same manner as logo marks or the like that are normally displayed on the side portion 2 of the tire 10. Furthermore, in order to improve visibility, at least the top surface or the entire outer surface of the ridge 30 (31 to 33) may be colored in a color other than black (for example, red).

[0034] The foregoing describes exemplary embodiments of the present invention, and various modifications can be made without departing from the scope of the claims. [Industrial Applicability]

[0035] The tire according to the present invention can be suitably used for any type of tire having a smooth pattern, and can be suitably used for tires for construction and mining vehicles such as tires for road haul dumps and tire for wheel loaders, tires for industrial vehicles such as tires for reach stackers and container handlers, and also tires for track-running vehicles. [Explanation of symbols]

[0036] 1: tread portion, 1a: tread rubber, 2: side portion, 5: carcass, 6: belt, 6a to 6e: belt layer, 10: tire; 11: tread surface; 21: outer surface of side portion; 30, 31 to 33: Ridge; 30c, 31c to 33c: Center of ridge top surface; 33ei: Tire radially inner end of ridge top surface; 33eo: Tire radially outer end of ridge top surface; 33si: Tire radially inner side surface of ridge; 33so: Tire radially outer side surface of ridge; 33ts: Ridge top surface; 40: slit, 40ei: tire radial direction inner end of the slit, CD: tire circumferential direction, D12, D23: tire radial distance, Dn: remaining tread gauge when tire is new, H: ridge height, R1, R2: curvature radius, RD: tire radial direction, TE: tread edge, W: width of ridge top surface, WD: tire width direction, WL: wear limit position

Claims

1. A tire having a smooth pattern with substantially no grooves on the tread surface of the tread portion including the tread rubber, a plurality of ridges are provided on an outer surface of a side portion of the tire, protruding from the outer surface of the side portion and extending in a tire circumferential direction, the ridges being spaced apart in a tire radial direction for checking a remaining tread gauge until the tread rubber reaches a wear limit; a numerical value corresponding to the remaining tread gauge is displayed at a position on the outer surface of the side portion corresponding to each of the plurality of ridges, A slit is further provided, extending from the tread surface to the outer surface of the side portion, for inserting a depth gauge from the tread surface to measure the depth and thereby confirming the remaining tread gauge, A tire, characterized in that the numerical value is disposed between the ridge and the slit in the tire circumferential direction.

2. The tire according to claim 1 , wherein the ridge located radially innermost among the plurality of ridges is provided at a radial position corresponding to a wear limit position of tread rubber.

3. 3. The tire according to claim 2, wherein the plurality of ridges are three ridges, and the tire radial distance between adjacent ridges is 25% of the remaining tread gauge of the tire when new.

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