阅读说明：本技术 重型卡车轮胎胎面和具有不对称泪滴沟槽的重型卡车轮胎 (Heavy truck tire tread and heavy truck tire with asymmetric tear drop grooves ) 是由 V·阿巴罗廷 于 2019-05-10 设计创作，主要内容包括：提供了一种重型卡车轮胎定向型胎面,其在纵向方向上具有两个连续的不对称沟槽(14),该不对称沟槽在侧向方向上共享至少一些与胎面边缘的相同偏移。两个不对称沟槽(14)中的每个都具有本体(28)和泪滴(30)。沟槽(14)的底部的表面具有沿底部的整个表面不是相同的曲率半径。沟槽的几何结构抵抗裂纹萌生和传播,并由等式R-(A.B.avg)>1.4 x R-(ref)控制,其中,R-(A.B.avg)是沟槽的底部的特定部分的平均半径,并且R-(ref)是沟槽的底部的参考半径。(A heavy truck tire directional tread is provided having two continuous asymmetric grooves (14) in the longitudinal direction that share at least some of the same offset from the tread edge in the lateral direction. Each of the two asymmetric channels (14) has a body (28) and a tear drop (30). The surface of the bottom of the groove (14) has a radius of curvature that is not the same along the entire surface of the bottom. The geometry of the trench resists crack initiation and propagation and is governed by equation R A.B.avg >1.4 x R ref Control wherein R A.B.avg Is the average radius of a particular portion of the bottom of the trench, and R ref Is the reference radius of the bottom of the trench.)

1. Heavy truck tire directional tire tread having a longitudinal direction, a lateral direction and a thickness direction and a rolling direction in the longitudinal direction, comprising:

a tread edge;

two consecutive asymmetric grooves in the longitudinal direction sharing at least some of the same offsets from the tread edge in the lateral direction, wherein each of the two asymmetric grooves is arranged with:

a body; and

a tear drop at a bottom end of the body, wherein the tear drop has a forward tangent line L1 and a rearward tangent line L2, wherein one of the forward tangent line and the rearward tangent line extends in the thickness direction, wherein the forward tangent line L1 is parallel to the rearward tangent line, wherein the forward tangent line L1 extends through a left tangent point, and wherein the rearward tangent line L2 extends through a right tangent point, wherein an equator is a straight line extending through the left tangent point and the right tangent point, wherein a bottom of the tear drop is a portion of the tear drop bounded by the equator and closer to a center of the tire than a remaining top of the tear drop on the opposite side of the equator that is farther from the center of the tire; wherein the bottom portion has a surface whose radius of curvature is not the same along the entire surface of the bottom portion;

wherein S is an area bounded by the equator and the surface of the bottom, and wherein a reference radius R_refThe calculation is as follows:

wherein line L3 is perpendicular to the thickness direction and extends through tangent point A at the surface of the base;

wherein tangent point B is located at the surface of the base in a direction opposite the rolling direction relative to tangent point A, and line L4 extends through tangent point B and is oriented at a 45 degree angle to the thickness direction;

wherein line L5 extends through tangent point a and tangent point B;

wherein d is_maxIs the maximum distance between line L5 and the surface of the bottom measured perpendicular to line L5;

wherein d is_A.B.Is the linear distance from tangent point a to tangent point B along line L5;

wherein the average radius R between tangent point A and tangent point B_A.B.avgThe calculation is as follows:

wherein R is_A.B.avg>1.4 x R_ref。

2. The tread of claim 1, wherein the tear drop has an elliptical cross-sectional shape.

3. The tread of claim 1 or 2, wherein the tread has a tread surface, and wherein the body has a top end at the tread surface, wherein the top end of the body and the bottom end of the body are spaced from each other in the thickness direction and are not spaced from each other in the longitudinal direction.

4. The tread of claim 1 or 2, wherein the tread has a tread surface, and wherein the body has a top end at the tread surface, wherein the top end of the body and the bottom end of the body are spaced from each other in the thickness direction and are spaced from each other in the longitudinal direction.

5. The tread of any of claims 1-4, wherein the tread has a shoulder rib defined at least in part by the tread edge, and wherein each of the two consecutive asymmetric grooves is located in the shoulder rib.

6. The tread of any of claims 1-5, wherein the two consecutive asymmetric grooves have a same offset from the tread edge in the lateral direction.

7. The tread of any of claims 1-6, wherein the two consecutive asymmetric grooves are immediately adjacent in the longitudinal direction such that no groove and no groove are located between the two consecutive asymmetric grooves in the longitudinal direction at the same offset from the tread edge all shared by the two consecutive asymmetric grooves.

8. The tread of any of claims 1-6, wherein at least one symmetric groove is located between the two consecutive asymmetric grooves in the longitudinal direction at least some of the same offsets from the tread edge shared by the two consecutive asymmetric grooves.

9. The tread of claim 8, wherein three symmetric grooves are located between two consecutive asymmetric grooves in the longitudinal direction at least some of the same offsets from the tread edge shared by the two consecutive asymmetric grooves.

10. The tread of any of claims 1-5, wherein a groove is located between two consecutive asymmetric grooves in the longitudinal direction at least some of the same offsets from the tread edge shared by the two consecutive asymmetric grooves.

11. A heavy truck tire comprising the tread of any of the preceding claims.

Technical Field

The present invention generally relates to tire treads and tires. More particularly, the present invention relates to tire treads and tires most suitable for the drive axles of heavy trucks, such as tractors used in tractor-semi-trailer combinations or stand-alone straight trucks, having a continuous asymmetric tear drop groove (side) with a geometry that resists crack initiation and propagation.

Background

The tire tread generally extends around the outer circumference of the tire to serve as an intermediary between the tire and the surface over which the tire travels (the operating surface). Contact between the tire tread and the operating surface occurs along the footprint of the tire. The tire tread provides grip that may be generated during tire acceleration, braking, and/or cornering to resist tire slip. The tire tread may also include tread features, such as ribs, lugs, grooves, and grooves, each of which may help provide target tire performance when the tire is operating under certain conditions. One problem with tires, and particularly the treads of drive tires, is the tradeoff between traction, rolling resistance, and wear/abnormal wear.

It is known that the addition of grooves in tire ribs can improve wear rate and improve traction, but the presence of grooves can also increase the risk of cracking, typically at the bottom of the grooves. The trench may be provided as a tear drop trench having an enlarged, generally circular cross-sectional shape at the bottom to address cracking at the trench bottom. The circular cross-sectional shape increases the radius of the trench bottom, thereby reducing stress concentration at the bottom to minimize crack initiation.

It is known for the shoulder of a drive axle tire to include a tear drop groove. For these grooves, a large small tear drop is required to reduce cracking due to the large amount of torque applied to the tire. However, such large diameter drops can create other problems in the shoulder, such as undesirable compression of the edge of the block in the shoulder due to the undercut formed by the large diameter drops. Such undercutting may cause abnormal wear of the tire. Accordingly, there remains room for variation and improvement in the art.

Drawings

A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which:

FIG. 1 is a perspective view of a heavy truck tire.

FIG. 2 is a front view of a portion of a tread including asymmetric grooves.

Fig. 3A is a cross-sectional view taken along line 3A-3A of fig. 2.

FIG. 3B is a detailed view of circle 3B of FIG. 3A.

FIG. 4 is a front view of a portion of a tread including asymmetric grooves according to another exemplary embodiment.

Fig. 5A is a cross-sectional view taken along line 5A-5A of fig. 4.

FIG. 5B is a detailed view of circle 5B of FIG. 5A.

Fig. 6 is a cross-sectional view of an asymmetric groove with an elliptical tear drop.

Fig. 7 is a cross-sectional view of a continuous asymmetric trench separated by a groove.

The same or similar reference numbers are used in the drawings to refer to the same or similar features.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings. These examples are provided as illustrations of the invention.

The present invention provides a tread 12 having a teardrop groove 14 with an asymmetric shape. The tear drop 30 of the trench 14 is asymmetric in shape such that the bottom surface 44 of the trench 14 does not have a radius of curvature 50 that is the same throughout its length. Bottom surface 44 is configured such that average radius R between tangent points A and B_A.B.avgSpecific reference radius R_ref1.4 times larger. This arrangement results in an asymmetric gutter 14 in which the radius of curvature 50 of tear drop 30 is greater in longitudinal direction 16 behind the midpoint of bottom surface 44 generally away from rolling direction 22. Providing a compound having R_refAnd R_A.B.avgThe ratio of (a) of tear drop(s) 30 is such that the geometry of the tear drop(s) 30 may function to reduce or eliminate crack initiation and propagation that would otherwise be more likely to occur at this generally rearward portion of the tear drop(s) 30 based on the manner in which torque is applied to the tread 12.

Fig. 1 shows a tire 10, which is a heavy truck tire 10. In this regard, the tire 10 is not designed for use with an automobile, motorcycle, or light truck (payload capacity less than 4000 pounds), but is instead designed for and used with a heavy truck such as an 18-wheel vehicle, a garbage truck, or a van truck. The tire 10 may be a steering tire, a drive tire, a trailer tire, or an all-position tire. The tire 10 includes a casing 68 upon which the tread 12 is disposed. The central axis 72 of the tire 10 extends through the center of the casing 68, and the lateral (in this case axial) direction 18 of the tire 10 is parallel to the central axis 72. The radial direction 20 of the tire 10, which may be referred to as the thickness direction 20, is perpendicular to the central axis 72, and the tread 12 is positioned farther from the central axis 72 in the radial direction 20 than the casing 68. The tread 12 extends completely around the casing 68 in the circumferential direction 16 of the tire 10, also referred to as the longitudinal direction 16, and 360 degrees around the central axis 72.

The tread 12 has five ribs separated by four longitudinal grooves extending in the circumferential direction 16. The five fins may be classified as a center fin, two middle fins, and two shoulder fins. However, any number of ribs may be present in other exemplary embodiments, or none, and five ribs are present in only some embodiments. One of the shoulder ribs 60 is specifically identified and is bounded on one side in the lateral direction 18 by the circumferential groove 74 and on the opposite side by the tread edge 24. The ribs may each be constructed of a number of tread blocks that may have various shapes, sizes, and configurations. The inclusion of these structural features imparts different performance characteristics to the tread 12 in use. The tread 12 may include certain structural features that may enhance traction or wear rates. One such structural feature illustrated with reference to fig. 1 may be a groove 14 extending in a lateral direction 18 across the tread block of the rib. The particular groove 14 indicated in fig. 1 is in one of the intermediate ribs. The tread 12 has a first tread edge 24 and an oppositely disposed second tread edge in the lateral direction 18. The rolling tread width of the tread 12 extends from one edge 24 to the other and is the portion of the tread 12 designed to engage the ground when the tire 10 is new before any tread 12 has worn.

FIG. 2 illustrates a portion of a front portion of the tread 12 according to an exemplary embodiment. The tread 12 is a directional tread designed to roll primarily in one direction. The rolling direction 22 is the direction in which the tread 12 is designed to roll in the longitudinal direction 16, which may be the forward direction of the vehicle, as opposed to the rearward, reverse direction of the vehicle. The asymmetric grooves 14 are arranged in response to the rolling direction 22. The tread 12 with asymmetric grooves 14 in all exemplary embodiments may be provided as part of a new tire 10 or may be provided as a retread band attached to a used casing 68. The asymmetric grooves 14 are arranged such that they are continuous. The asymmetric groove 14 is continuous with the second asymmetric groove 70 in the longitudinal direction 16. The grooves 14, 70 share at least some common offset 26 in the lateral direction 18 with the tread edge 24. In this regard, the asymmetric grooves 14, 70 are continuous in the longitudinal direction 16 and have at least some common portions that are co-located in the lateral direction 18.

Fig. 3A is a cross-sectional view taken along line 3A-3A of fig. 2 showing the cross-sectional shape of the asymmetric groove 14, 70. The asymmetric trenches 14, 70 are identical to each other, but need not be identical in other embodiments. The groove 14 has a body 28 with a top end 58 located at the tread surface 56 of the tread 12. The end opposite the top end 58 is the bottom end 32 of the body 28, and the tear drop 30 extends from the bottom end 32 in the thickness direction 20 toward the center 46 of the tire 10. Body 28 extends from tear drop 30 to tread surface 56 at an oblique angle such that bottom end 32 is not in the same location in longitudinal direction 16 as top end 58. In other embodiments, the body 14 may be angled in the opposite direction relative to the rolling direction 22, or may not be angled at all in various arrangements of the tread 12.

Referring also to fig. 3B, which is a detailed view of tear drop 30 of fig. 3A, the asymmetric shape of tear drop 30 is shown. Tear drop 30 is asymmetric in shape and has a left tangent point 36 and a right tangent point 38. Tangent points 36 and 38 are points located at opposite ends of tear drop 30 along longitudinal direction 16, at the forwardmost and rearwardmost extremities of tear drop 30. A forward tangent line L1 extends through left tangent point 36 and a rearward tangent line L2 extends through right tangent point 38. At least one of the tangent lines L1 and L2 extends in the thickness direction 20. In other embodiments, both tangents L1 and L2 extend in the thickness direction. The two tangent lines L1 and L2 are parallel to each other. Two tangent lines L1 and L2 join tear drop 30 at the aforementioned front and rear ends of tear drop 30 in longitudinal direction 16.

The equator 40 is a line defined as a straight line extending through the left and right tangency points 36, 38. The equator 40 divides the tear drop 30 into a base 42 and a top 48. Bottom 42 of tear drop 30 has a bottom surface 44. The bottom portion 42 is the portion of the tear drop 30 on the side of the equator 40 that is near the center 46 of the tire 10 or deeper within the tread 12 in the thickness direction 20. The top portion 48 of the tear drop 30 is the portion of the tear drop 30 bounded by the equator 40 that is closer to the tread surface 56 than the bottom portion 42 in the thickness direction 20. The top portion 48 engages the body 28 at the bottom end 32. With respect to the top 48 and bottom 42 of the tear drop 30, the equator 40 separates the two portions 48 and 42 and the top 48 is closer to the tread surface 56 in the thickness direction 20 than the bottom 42 is to the tread surface 56.

The bottom surface 44 of the bottom 42 is curved and does not have the same radius of curvature 50 along the entire bottom surface 44. The curvature of bottom surface 44 is generally concave. The radius of curvature 50 of the bottom surface 44 is different at least two different locations. The bottom surface 44 may be arranged such that there are many different radii of curvature 50, for example from 5-10, from 11-15, or theoretically up to an infinite number of different radii of curvature 50 along the entire bottom surface 44. Tear drop 30 can be described as being asymmetrically shaped in that bottom surface 44 has at least two different radii of curvature 50 such that radii of curvature 50 of bottom surface 44 are not the same along the entire bottom surface 44. Area S is the area of a cross-section of tear drop 30 bounded by equator 40 and bottom surface 44. Any technique known in the art may be used to calculate the cross-sectional area S.

The geometry of the tear drop 30 is relative to a reference radius R_refAnd (4) constructing. Reference radius R_refDefined by the following equation:

reference radius R_refIt can be calculated after obtaining the area S. Reference radius R_refRepresents the average radius of bottom surface 44 and will be used later to define asymmetric groove 14 about average radii a through B R_A.B.avgThe geometry of the values of (a).

Once certain other geometric characteristics of the groove 14 are determined, the average radii A through BR can be calculated_A.B.avg. A line L3 is drawn on the trench 14 and is a line perpendicular to the thickness direction 20. In some embodiments, line L3 extends in longitudinal direction 16. Line L3 is tangent to bottom surface 44. The point at which line L3 is tangent to bottom surface 44 is designated tangent point a. If line L3 forms a line with the tangent of bottom surface 44 instead of a single point, point A is defined as the point at the end of the tangent line closest to right tangent point 38. Line L4 may then be drawn relative to trench 14. Line L4 is oriented at a 45 degree angle to the thickness direction 20. Line L4 at the 45 degree angular orientation is tangent to bottom surface 44 and this tangent point is designated tangent point B, which is a point on bottom surface 44. The tangent points a and B have a relationship such that they are both at the bottom surface 44 and the tangent point a is located forward of the tangent point B in the rolling direction 22. Accordingly, tangent point B is located rearward of tangent point a in roll direction 22, below right tangent point 38 on bottom surface 44 and not at right tangent point 38. If line L4 forms a line with the tangent of bottom surface 44 instead of a single point, point B is defined as the point at the end of the tangent line closest to tangent point A.

Line L5 passes through tangent point a and tangent point B. By establishing this line L5, a value d can be calculated_max. Value d_maxIs the maximum perpendicular distance from line L5 to bottom surface 44. The distance from line L5 to bottom surface 44 is measured as extending from line L5 perpendicular to line L5 to bottom surface 44. The maximum measured distance is designated at d_maxAt the maximum distance. Another value measured to determine the geometry of the trench 14 is d_A.B.Which is the linear distance between tangent point a and tangent point B. The distance between tangent point a and tangent point B is measured along line L5.

The average radius between tangent points A and B is denoted as R_A.B.avgAnd can be calculated using the following equation:

average radius R between calculated tangent points A and B_A.B.avgThen, the design of the trench is such that R_A.B.avgAnd a reference radius r_refThe following relationship between exists and is as follows:

R_A.B.avg>1.4x R_ref。

thus, the groove 30 has an average radius R between the tangent points A and B therein_A.B.avgSpecific reference radius R_refA shape 1.4 times as large. The asymmetry of groove 14 is defined in the portion of tear drop 30 because the radius of curvature 50 of bottom surface 44 is not the same along the entire length of bottom 42, but is different at least in two locations. The tire tread 12 includes a second asymmetric groove 70 that is continuous with the first asymmetric groove 14 in the longitudinal direction 16 such that there is no other groove or groove between the first and second continuous grooves 14 and 70. The second asymmetric trench 70 as shown in fig. 3A has the same cross-sectional configuration as the first asymmetric trench 14 and all of the foregoing features need not be repeated. Thus, the second asymmetric groove 70 may include all of the lines, distances, points, and curvatures described above. The second asymmetric trench 70 may be formed identically to the first asymmetric trench 14, or may be different so long as it has an R as previously described_A.B.avg>1.4x R_refAnd (4) relationship.

The cracking of drive tire 10 under torque at bottom surface 44 of tear drop 30 typically begins off bottom dead center of bottom surface 44. The applicant speculates that the torque acting on the tread 12 causes cracks to develop behind the dead point in a direction opposite to the rolling direction 22, which, if present, may cause cracks to propagate below the leading edge of the block. Thus, the relationship R_A.B.avg>1.4x R_refHave been designed to prevent or minimize such cracking. The bottom surface 44 has a shape that may be located at a location where crack initiation probability is highest. The tread 12 as disclosed herein is directional in nature such that the orientation of the tear drop 30 may be set according to the rolling direction 22 to ensure it is most likely to experience crackingLocation. The design of the asymmetric grooves 14, 70 may allow for the use of smaller tear drops 30 to maintain traction and wear resistance in the event of cracking.

Another embodiment of the tread 12 is described with reference to fig. 4, 5, and 5A. Here again, the asymmetric groove 14 is located within the shoulder rib 60 of the tread 12. The shoulder rib 60 is a rib bounded on one side in the lateral direction 18 by the tread edge 24 and on an opposite side by the circumferential shoulder groove 74. According to various exemplary embodiments, the grooves 14 may be located in the shoulder ribs, the mid-rib ribs, and/or the center rib. Although shown in the shoulder ribs, the asymmetric grooves 14 need not be located exclusively or in other embodiments therein at all. The grooves 14 may be arranged in a directional manner with other tread 12 elements such that the tread 12 is provided as a directional tread 12. The groove 14 extends all the way across the width of the shoulder rib 60 in the lateral direction 18. The tread 12 has a first asymmetric groove 14 and a second asymmetric groove 70 that have the same length in the lateral direction 18 and the same common offset 26. The common offset 26 is the distance shared by the grooves 14 and 70 in the lateral direction 18 from the tread edge 24. This common offset 26 serves to connect the two grooves 14, 70 to each other, in contrast to comparing the first asymmetric groove 14 with some other groove on the tread 12, such as a groove in a central rib or a groove in an opposing shoulder rib. The tread 12 includes three symmetrical grooves 64 located between consecutive asymmetrical grooves 14, 70, which also extend in the lateral direction 18 across the entire width of the shoulder rib 60 and share the same common offset 26 as the grooves 14, 70.

Cross-sectional views of the grooves 14, 70, and 64 are shown in fig. 5A and 5B and are taken through their cross-sectional widths along lines that are angled relative to the longitudinal direction 16 due to the angular orientation of the grooves 14, 70, 64 relative to the longitudinal direction 16. The cross-sectional view of the asymmetric groove 14 shown in fig. 5A and 5B has the body 28 extending only in the thickness direction 20 and not in the longitudinal direction 16, such that the body 28 is not angled, unlike the body 28 shown in fig. 2 and 3. Tear drop 30 may be similar to that previously discussed in other embodimentsIn other embodiments, the relationship R is presented_A.B.avg>1.4x R_ref。

The embodiment of fig. 4, 5A and 5B includes a second, continuous asymmetric trench 70 opposite the first asymmetric trench 14. The arrangement of the second asymmetric grooves 70 may be the same as the arrangement of the first asymmetric grooves 14. Alternatively, the second asymmetric groove 70 may be different from the first asymmetric groove 14, as long as the relationship R is maintained_A.B.avg>1.4x R_ref. The three symmetrical grooves 64 are located between the two asymmetrical grooves 14, 70 in the longitudinal direction 16. However, the asymmetric grooves 14, 70 are still referred to as continuous, since they are two asymmetric grooves 14, 70 that are continuously adjacent to each other in the longitudinal direction 16. The symmetrical grooves 64 have symmetrical tear drops. In this regard, the bottoms of the tear drops of the symmetrical grooves 64 all have the same radius of curvature. However, if the cross-section is a mirror image, the radii of curvature may be different and the grooves 64 may still be symmetrical. In discussing the symmetry of the trench, it may be the case that only the bottom of the tear drop makes it symmetrical or asymmetrical, as the ends of the body may create asymmetry when engaging the top of the tear drop, even if the rest of the tear drop is symmetrical. Thus, the determination of the asymmetry of the trench can be evaluated based on the symmetry or asymmetry of the bottom of the tear drop, as previously described.

FIG. 6 is a cross-sectional view of a tread 12 according to another exemplary embodiment, where two consecutive asymmetric grooves 14, 70 again utilize a relationship R_A.B.avg>1.4x R_refThe setting is performed. The asymmetric channels 14, 70 have an elliptical tear drop 30. The ellipses are oriented such that the relationship R is achieved_A.B.avg>1.4x R_ref. Other embodiments of the present tread 12 exist where R is in two consecutive asymmetric grooves 14, 70 that are not elliptical drops 30_A.B.avg>1.4x R_ref. There are no symmetric grooves 64, grooves 66, or other tread features between two consecutive asymmetric grooves 14, 70 in the longitudinal direction 16. Thus, the shape of the asymmetric grooves 14, 70 is not only elliptical, but also elliptical oriented with respect to the thickness and longitudinal direction 20, 16, such that R as defined_A.B.avg>1.4x R_ref. It should be understood that the shape of tear drop 30 may be elliptical, but need not be elliptical in other embodiments. Any shape of tear drop 30 can be used, so long as the disclosed geometric boundaries are followed to produce R_A.B.avg>1.4x R_refAnd (4) relationship. This relationship can be calculated using the techniques described above and does not require repetition of the information.

FIG. 7 illustrates an embodiment of the tread 12 in which two consecutive asymmetric grooves 14, 70 are present in the tread 12 and again include the relationship R_A.B.avg>1.4x R_ref. This relationship can be calculated using the techniques described above and does not require repetition of the information. The recess 66 is located between the two asymmetric grooves 14, 70 in the longitudinal direction 16.

Provides for calculating R_refAnd R_A.B.avgTo describe R_A.B.avgHow to exceed R_ref1.4 times of example. Here, tear drop 30 has an elliptical shape that defines bottom contour 44 of tear drop 30 and has a dimension of 3.4mm along its longest axis and a dimension of 2.0mm along its shortest axis. The area formula for the ellipse is pi ab, where a is the half-length of the major axis and b is the half-length of the minor axis. According to this formula, the area of the ellipse is 5.34mm². Knowing that equator 40 exactly bisects the ellipse, the area bounded by equator 40 and bottom surface 44 is half the area of the full ellipse, or 2.67mm². Using for R_refThen with reference to the radius R_refThe calculation is 1.30 mm. The orientation of the elliptical tear drop 30 can then be examined and measured to produce d in this particular example_A.B1.95mm and d_max0.09 mm. The average radius R between points A and B is calculated using the equation above_A.B.avgIs 5.33 mm. This value is greater than 1.4x R_ref(5.33mm>1.82mm)。

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For example, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. As already discussed above, a tread or tire according to the invention may also comprise tread halves that differ significantly from each other, as long as each tread half remains within the scope of the invention as defined by the claims. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.