Truck tire with decoupling feature and slit extending therefrom

Abstract

A heavy truck tire is provided that has an inner surface, a shoulder rib, and a sacrificial rib positioned outboard from the shoulder rib in the lateral direction. A decoupling feature is between the shoulder rib and the sacrificial rib and extends in the radial direction. The decoupling feature has a decoupling feature bottom that is a portion of the decoupling feature that is closest to the central axis in the radial direction. A slit extends from the decoupling feature outboard in the lateral direction. The tire does not have a void present that is between the slit and the inner surface in the radial direction and that has a common position in the lateral direction as the slit.

Description

TRUCK TIRE WITH DECOUPLING FEATURE AND SLIT EXTENDING THEREFROMFIELD OF THE INVENTION

[0001] The subject matter of the present invention relates to a truck tire with a sacrificial rib and a slit for redirecting damage done to the sacrificial rib. More particularly, the present application involves a heavy truck tire with a slit that extends from the decoupling feature outboard in the lateral direction to control the direction of tearing of the sacrificial rib.BACKGROUND OF THE INVENTION

[0002] Manufacturers of heavy commercial vehicle tires have made progress in developing tire architectures and tire materials that causes an increase in the wear resistance of tire treads and the reduction of the rolling resistance of tires while at the same time improving their level of grip and resistance to road hazard. Irregular tread wear is a great concern for heavy commercial vehicle tires as it can progressively induce tire vibrations that become sensed by the driver through the steering wheel. It can also make for a poor looking wear pattern. Both of these undesired effects often lead to the tire being removed from service at an early stage of its wear life. Generally, the more the tire is put through a slow-wearing usage, the more irregular wear is affecting the removal mileage. This is why resistance to irregular wear is of paramount importance for truck tires in the so-called long haul steer usage.

[0003] It is known to include structural features in tires to fight irregular wear. For example, a sacrificial rib can be incorporated into the tread architecture to delay the onset of irregular wear. The sacrificial rib may function by providing a negative tangential force in the contact patch while being decoupled from the shoulder rib but still able to provide some lateral support and increase in lateral rigidity in the shoulder rib. The sacrificial rib is outboard of the shoulder rib and offset in the radial direction so as to be closer to the central axis of the tire than the shoulder rib. A narrow decoupling groove, usually 1.5 millimeters or less in width, separates the shoulder rib and the sacrificial rib. One drawback to this design is its susceptibility to aggression damage, specifically cracks that can develop at the bottom of the decoupling groove which may lead to early removal and customer dissatisfaction. This cracking can lead to tearing of the sacrificial rib that may be severe enough to require removal of the tire from service and may render the tire not repairableand / or retreadable. These cracks start at the decoupling groove bottom and propagate downward into the under-tread, and in more severe cases extend downward into the sidewall between the reinforcement ply and the flank.

[0004] Attempts have been made to improve the robustness of this decoupling groove to alleviate aggression damage. These modifications include undulations to make the decoupling groove more interlocking, inward curvature at the bottom of the decoupling groove, and the addition of a teardrop at the bottom of the decoupling groove. Further geometric changes to prevent the formation of a crack can involve an enlarged radii at the decoupling groove bottom or by making the sacrificial rib wider and more robust. Materials that resist tearing can also be utilized, and they can be placed at the decoupling groove bottom to help prevent the formation of a crack. However, these modifications have been generally unsuccessful in the mitigation of crack initiation and subsequent propagation at and from the bottom of the sacrificial groove. Although mechanisms are known for improving irregular wear, there remains room for variation and improvement within the art.BRIEF DESCRIPTION OF THE DRAWINGS

[0005] 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:

[0006] Fig. l is a perspective view of a heavy truck tire.

[0007] Fig. 2 is a cross-sectional front view of a portion of a tire in which a crack extends in the radial direction into the sidewall.

[0008] Fig. 3 is a cross-sectional front view of a portion of a tire with a slit that directs a crack in the lateral direction.

[0009] Fig. 4 is a cross-sectional front detailed view of a decoupling feature and slit in accordance with one exemplary embodiment.

[0010] Fig. 5 is an up-close cross-sectional front detailed view of a decoupling feature and slit in accordance with Fig. 4.

[0011] Fig. 6 is a cross-sectional front detailed view of a slit spaced from the decoupling feature bottom in accordance with another exemplary embodiment.

[0012] Fig. 7 is a perspective view of a portion of the tire that shows the slit in perspective view in accordance with one embodiment.

[0013] Fig. 8 is a perspective view of a portion of the tire that shows the slit in perspective view as having a sinusoidal wave shape.

[0014] Fig. 9 is a perspective view of a portion of the tire that shows the slit in perspective view as having a saw-tooth shape.

[0015] Fig. 10 is a perspective view of a portion of the tire that shows the slit in perspective view as having a square wave shape.

[0016] Fig. 11 is a cross-sectional front detailed view of a portion of the tire that has a notch.

[0017] The use of identical or similar reference numerals in different figures denotes identical or similar features.DETAILED DESCRIPTION OF THE INVENTION

[0018] Reference will now be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, and not meant as a limitation of the invention. For example, features illustrated or described as part of one embodiment can be used with another embodiment to yield still a third embodiment. It is intended that the present invention include these and other modifications and variations.

[0019] The present invention provides for a heavy truck tire 10 tread that includes a shoulder rib 30 and a sacrificial rib 62. The sacrificial rib 62 is decoupled from the shoulder rib 30 via a decoupling feature 50 that could be a decoupling groove 50. A slit 70 extends from the decoupling feature 50 and is provided in order to control cracking that may occur in the sacrificial rib 62. In this regard, the slit 70 is arranged so that if cracking occurs it occurs at the slit 70 and is directed by the slit 70 in a desired direction into the sacrificial rib 70. For example, the slit 70 may direct cracking that could occur in a lateral direction 28 so that the crack 68 avoids the undertread or sidewall of the tire 10. The slit 70 redirects the propagation of the tear in a way that would allow for continued use of the tire 10, and to enable retreadability when the tire 10 is worn out. While redirecting this crack 68, the function and effectiveness of the sacrificial rib 62 is not reduced by the presence of the slit 70.

[0020] Fig. 1 shows a tire 10 that is a heavy duty truck tire 10. In this regard, the tire 10 is not designed for nor used with a car, motorcycle, or light truck (payload capacity less than 4,000 pounds), but is instead designed for and used with heavy duty trucks such as 18wheelers, garbage trucks, or box trucks. The tire 10 may be a steer tire, a drive tire, a trailer tire, or an all position tire. The tire 10 can be a free rolling tire on a truck, such as a “pusher” or “tag” axle that is successive of the steer tires on a truck but are free rolling. The tire 10 is not limited to any particular position on the truck or trailer. The tire 10 includes a carcass 76 onto which a tread is disposed. The central axis 14 of the tire 10 extends through the center of the carcass 76, and the lateral direction 28, which can be called the width or axial direction 28, of the tire 10 is parallel to the central axis 14. The radial direction 24 of the tire 10 can be referred to as the thickness direction 24 and is perpendicular to the central axis 14. The tread is located farther from the central axis 14 in the radial direction 24 than the carcass 76. The tread extends all the way around the carcass 76 in the circumferential direction 26 of the tire 10 and circles the central axis 14 three hundred and sixty degrees. The circumferential direction 26 can also be referred to as the longitudinal direction 26 of the tread.

[0021] The tread in Fig. 1 features four ribs that are separated by three circumferential grooves that extend in the circumferential direction 26 completely about the tire 10, and also includes a pair of sacrificial ribs 62, 64 that are located outboard on the tread in the lateral direction 28. The four ribs can be classified as two intermediate ribs 32, 46, and two shoulder ribs 30, 44. The two intermediate ribs 32, 46 are separated from one another via a center groove 40 that is located in the center of the tire 10 in the lateral direction 28. The first intermediate rib 32 is separated from the first shoulder rib 30 by the first shoulder groove 34, and the second intermediate rib 46 is separated from the second shoulder rib 44 by the second shoulder groove 48. Although four ribs are shown, any number of ribs can be present in other exemplary embodiments. The ribs can each be made up of a number of tread blocks that can have various shapes, sizes, and configurations. The inclusion of these architectural features gives the tread different performance properties in use. The tire 10 can be a brand new tire with the carcass 76 and tread formed at the same time with both being brand new. Alternatively, the tread may be provided as a retread band that is newly formed and then subsequently attached to an existing, used carcass 76 through a retread process.

[0022] Different designs of the tire 10 from that shown in Fig. 1 is shown in Figs. 2 and 3. The tread in these designs include five ribs 30, 32, 42, 44, 46 that are separated by four circumferential grooves 34, 56, 58, 48 that extend in the circumferential direction 26 and all of these features extend completely 360 degrees around the central axis 14. The shoulderribs 30, 44 are the ribs of the tread that are farthest outboard in the lateral direction 28 except for the two sacrificial ribs 62, 64 that are even further outboard and are at the edges of the rolling tread width of the tread. The ribs 30, 32, 42, 44, 46, 62, 64 can each be made up of a number of tread blocks that can have various shapes, sizes, and configurations. Although five ribs, four longitudinal grooves, and two sacrificial ribs 62, 64 are shown, any number of ribs and grooves can be present in other exemplary embodiments. The sacrificial ribs 62, 64 may have an outer radius less than that of the adjacent shoulder ribs 30, 44 and are within the rolling tread width when the tire 10 is new, and contact the ground when the tire 10 is new and may also contact the ground when the tire 10 wears. The decoupling features 50, 60 can be grooves or sipes, which are grooves that are 2 millimeters in width or less. The decoupling features 50, 60 may have widths less than 2 millimeters, and in other arrangements can have widths that are 2 millimeters or greater.

[0023] A radial centerline 22 of the tire 10 is located at the center of the tread in the lateral direction 28. The center rib 42 is located in the center of the tread such that the radial centerline 22 is located in the center rib 42. The inboard and outboard orientations as described herein are with reference to this centerline 22 in which an inboard orientation means something is located towards the centerline 22 in the lateral direction 28, and in which an outboard orientation means that something is located farther away from the centerline 22 in the lateral direction 28. Intermediate ribs 32, 46 are located outboard from the center rib 42 in the lateral direction 28. The first intermediate rib 32 and the center rib 42 define a first center rib groove 56, and the second intermediate rib 46 and center rib 42 define a second center rib groove 58. The first shoulder rib 30 is located adjacent to and outboard from the first intermediate rib 32, and these two ribs 30, 32 define a first shoulder groove 34 therebetween. The second shoulder rib 44 is adjacent to and outboard from the second intermediate rib 46 and these two ribs 44, 46 define a second shoulder groove 48 therebetween. The grooves 34, 48, 56 and 58 are open grooves.

[0024] The tire 10 has a crown 20 that engages the road surface, and a pair of sidewalls 12, 100 that extend from the crown 20 in the radial direction 24 and are separated from one another on opposite sides of the tire 10 in the lateral direction 28. A first bead 18 is located at the end of the first sidewall 12, and a second bead 102 is located at the end of the second sidewall 100 in the radial direction 24. The first bead 18 includes a bead core that is made up of a steel rod 108 and padding gum 104, and the second bead 102 likewise has a bead core made up of padding gum 106 and a steel rod 110. The bead cores with the rod 108,110 function to hold the tire 10 onto the rim and maintain its strength to withstand internal stresses from inflation on the rim to prevent slipping. The steel rods 108, 110 are surrounded by padding gum 104, 106 and in some instances may be completely surrounded on all sides by the padding gum 104, 106. Surrounding the bead cores are wrapping tissue that can be made of nylon in some embodiments. The wrapping tissue wraps around the padding gum 104, 106 to isolate the components 104, 106, 108, 110 from other elements of the tire 10 such as the reinforcement ply 78 and fillers.

[0025] The beads 18, 102 also include bead filler 92, 94 that are made of rubber and are located within the beads 18, 102 and also extend into the adjacent sidewalls 12, 100. The bead filler 92, 94 engage the wrapping tissue around the padding gum 104, 106 and engage the reinforcement ply 78 and anti-abrasive strips 96, 98. The anti-abrasive strips 96, 98 are on the outside of the beads 18, 102 and are designed to engage the rim. The tire 10 includes a tissue designated as a reinforcement ply 78 that is located within the first bead 18 and extends through the first sidewall 12 and crown 20 and into the second sidewall 100 and into the second bead 102. The reinforcement ply 78 wraps around the first bead core and has a portion that can be called a return casing ply that is embedded within the bead filler 92. The opposite end of the reinforcement ply 78 likewise wraps around the padding gum 106 and steel rod 110 in the second bead 102 and terminates within the bead filler 94. The reinforcement ply 78 provides strength and flexibility to the tire 10, and it is the supporting structure for the inflation pressure which carries the load of the tire 10. The reinforcement ply 78 is a composite material that includes metal cords and a rubber mix. The reinforcement ply 78 in the direction of its cords is stiffer than the padding gum 104, 106.

[0026] Another element of the tire 10 that extends from the first bead 18 to the second bead 102 is an inner liner 82 that is inside of the first bead 18 and forms a portion of the exterior of the first bead 18 and extends to the sidewall 12. The inner liner 82 then extends across the entire inner side of the crown 20 in the lateral direction 28 before extending into and forming the inner side of the second sidewall 100 and a part of the exterior surface of the second bead 102. The inner liner 82 in the second bead 102 is arranged in a similar mirror-image manner to its presence in the first bead 18. The inner liner 82 is made of a material that is fluid tight so that fluid between the tire 10 and rim is maintained therein for purposes of maintaining inflation pressure of the tire 10. The inner liner 82 controls air retention, has low temperature cracking resistance, and has good flex fatigue resistance.The inner liner 82 can be made of a single layer or may be multi-layered. The inner liner 82 forms the inward exterior surface of the sidewalls 12 and 100.

[0027] The first sidewall 12 includes a flank 88 made of rubber that forms all of, or at least a portion of, the outward exterior surface of the first sidewall 12. The flank 88 may be located only in the first sidewall 12, or may be in both the first sidewall 12 and the first bead 18, or may be in both the first sidewall 12 and the crown 20. In some embodiments, the flank 88 may be in the crown 20, first sidewall 12, and also the first bead 18. The flank 88 does not extend across the crown 20 to the second sidewall 100. The second sidewall 100 includes a flank 90 that makes up all or a portion of the outboard exterior surface of the second sidewall 100 and can be located just in the second sidewall 100, or can have portions in the crown 20 and / or second bead 102. The flank 90 does not extend to the first sidewall 12 and can be configured in the same manners as previously discussed with respect to the flank 88.

[0028] Another component of the tire 10 is a tread wall 84 that is located at the axial end of the tread and extends from it and into engagement with the flank 88. The tread wall 84 is made of a different rubber composition than the flank 88 and forms a portion of the exterior surface 54 of the tire 10. The tread wall 84 is in the crown 20 and extends into the first sidewall 12. The tread wall 86 is on the opposite end of the tread in the lateral direction 28 and engages the flank 90 and may be a mirror image and configured the same as the tread wall 84 as discussed.

[0029] Included within the crown 20 is a cushion layer 80 that is located on top of the reinforcement ply 78 in the crown 20 and provides a flat surface onto which the belt layers 66 can be disposed. The cushion layer 80 is made of rubber and engages the reinforcement ply 78, the belt layers 66, the belt edge layer 112, and the belt edge layer 114. The belt layers 66 are within the crown 20 and are made up of a first belt 116, a second belt 118, and a third belt 120. Although the belt layers 66 are shown as including three belts 116, 118, and 120, any number of belts in the belt layer 66 can be present in other embodiments. The belts 116, 118, 120 provide reinforcement in the crown 20 for improved wear and cornering power, and allow the tire 10 to maintain its shape. Belt edge layers 112 and 114 act as wedges between the belt layers 66 and the ribs 30, 44, 62, 64 to dampen stresses and are present for endurance performance of the tire 10.

[0030] A pair of sacrificial ribs 62, 64 are on opposite ends of the tread in the lateral direction 28 and are provided to protect the shoulder ribs 30, 44 during use of the tire 10and will normally wear faster than the shoulder ribs 30, 44 so that the shoulder ribs 30, 44 are not subjected to irregular wear during use. The height of the shoulder ribs 30, 44 at the outboard edge of the shoulder ribs 30, 44 in the radial direction 24 is greater than the height of the sacrificial ribs 62, 64 in the radial direction 24. The first shoulder rib 30 has a first shoulder rib upper surface 36 that is the portion of the first shoulder rib 30 that engages the road. The first sacrificial rib 62 has a sacrificial rib upper surface 38 that steps down from the shoulder rib upper surface 36 such that the sacrificial rib upper surface 38 is located closer to the central axis 14 in the radial direction 24 than the shoulder rib upper surface 36 is located to the central axis 14 in the radial direction 24. It is to be understood that this is just one embodiment, and that in other embodiments the sacrificial rib upper surface 38 does not step down from the shoulder rib upper surface 36 such that these two surfaces 36, 38 are at the same distance in the radial direction 24 to the central axis 14. The decoupling feature 50 extends into the tread and terminates at a decoupling feature bottom 52 that is the portion of the decoupling feature 50 that is closest to the central axis 14 in the radial direction 24.

[0031] With reference in particular to Fig. 2, through use of the tire 10, the sacrificial rib 62 and / or other portions of the tire 10 may flex or otherwise deform so that a crack 68 develops in the decoupling feature 50. Typically, this crack 68 originates in the decoupling feature 50 at the decoupling feature bottom 52, the direction the crack 68 propagates from the decoupling feature bottom 52 may be in various directions. In Fig. 2, the crack 68 begins at the decoupling feature bottom 52 and extends therefrom inwards towards the central axis 14 in the radial direction 24 and outboard in the lateral direction 28. The crack 68 extends through the belt edge layer 112 and then out of the crown 20 and into the first sidewall 12. The crack 68 extends between the flank 88 and the reinforcement ply 78 and terminates at a point within the first sidewall 12. When the carcass 76 is damaged in an area such as within the first sidewall 12, or when certain tissues of the tire 10 are damaged such as the belt edge layer 112, the tire 10 may not be able to be retreaded. In most cases this damage is not repairable and the tire 10 cannot be retreaded.

[0032] Fig. 3 shows the same tire 10 as the tire 10 in Fig. 2, but with a slit 70 that extends from the decoupling feature 50. The slit 70 is a void that in contiguous with the decoupling feature 50 and extends therefrom outboard in the lateral direction 28 for a shorter distance than the distance the decoupling feature 50 extends in the radial direction 24. The slit 70 is located at the decoupling feature bottom 52 and extends primarily in the lateral direction28 such that it narrows in the radial direction 24 at further outboard points. In other embodiments, the slit 70 is of constant thickness in the radial direction 24 and does not narrow in the radial direction 24 upon extension in the lateral direction 28. This slit 70 forms a weak point in the decoupling feature 50 such that if a crack develops in the decoupling feature 50, it will start at the slit 70. The slit 70 is positioned and oriented to in turn cause the crack 68 that forms to propagate in a designed for direction. Here, the crack 68 extends outboard in the lateral direction 28 and does not have much or any extension in the radial direction 24. This extension of the crack 68 may cause it to go outboard into the tread wall 84, or may cause it to move to a position between the tread wall 84 and the first sacrificial rib 62, or may cause it to simply remain completely in the sacrificial rib 62 upon exiting to the exterior surface 54. The crack 68 may extend completely 360 degrees around the tire 10 in the circumferential direction 26, or may be limited to some degree of extension around the tire 10 that is less than 360 degrees. The crack 68 may be so severe that it causes all or a portion of the first sacrificial rib 62 to fall off. However, since the crack 68 does not damage the sidewall 12, or portions of the undertread layer such as the belt edge layer 112, or the belt 66, the tire 10 can have its tread removed and can be retreaded. The slit 70 thus does not stop cracking that may develop in the decoupling feature 50 in association with a first sacrificial rib 62, but it may allow one to control the direction the crack 68 propagates upon origination of the crack 68. This control may then in turn allow for the damage to be contained to portions of the tire 10 that can be removed for retreading purposes and can extend the life of the tire 10. The slit 70 thus does not prevent the formation of the crack 68, and in some embodiments may cause the crack 68 to develop more readily, but the slit 70 does redirect the damage instead of reducing the problem so that the tire 10 can be retreaded and continued to be used.

[0033] The second decoupling feature 60 also has a slit 71 that can be arranged in a similar manner to the first slit 70 to control the direction of cracking that could develop at the second decoupling feature 60. However, in the embodiment in Fig. 3, cracking has not yet begun in the decoupling feature 60. The tire 10 includes an inner surface 16 that is an exterior surface of the tire 10 that is for the most part hidden from view when the tire 10 is mounted and running. The inner surface 16 includes the inner liner 82, and some but not all of the anti-abrasive strips 96, 98. The remaining exterior surface of the tire 10 is identified as the exterior surface 54 which includes the remaining parts of the anti-abrasivestrips 96, 98, the flanks 88, 90, the tread walls 84, 86, and the various ribs 62, 30, 32, 42, 46, 44, 64 and other portions of the tread of the tire 10.

[0034] The tire 10 is arranged so that a void is not present inward from the slit 70, 71 in the radial direction 24. The term void means an opening within the tire 10 that can either be open to the exterior surface 16, 54 of the tire 10, or an opening that is completely contained within the tire 10 and not in communication with an exterior surface 16, 54. A void within the tire 10 would have some material of the tire 10 either directly outward or directly inward from the void in the radial direction 24. The slit 70 is provided in the tire 10 so that there is no void present between the inner surface 16 and the slit 70 in the radial direction 24 that shares a common position in the lateral direction 28 with the slit 70. Likewise, there is no void present between the inner surface 16 and the slit 71 in the radial direction 24 that shares a common position in the lateral direction 28 with the slit 71. The slits 70, 71 therefore have solid material of the tire 10 directly inward from them in the radial direction 24 until the exterior surface of the tire 10 which in the Fig. 3 embodiment is the inner surface 16.

[0035] Fig. 4 is a cross-sectional close-up view of a section of the tire 10 that includes the slit 70. A dimension of the decoupling feature 50 is identified as hsrand is the height of the sacrificial rib 62 as defined as being the length in the radial direction 24 from the decoupling feature bottom 52 to the sacrificial rib upper surface 38 at the intersection of the sacrificial rib upper surface 38 and the decoupling feature 50. The width of the base of the sacrificial rib 62 is denoted as Wsr and is the distance in the lateral direction 28 from the decoupling feature bottom 52 to the exterior surface 54. The portion of the decoupling feature bottom 52 that is to be measured to can be the portion that is the same position in the lateral direction 28 as is the most outboard part of the decoupling feature 50, that is the part of the decoupling feature 50 that is most outboard in the lateral direction 28 at the decoupling feature bottom 52.

[0036] Fig. 5 is another up-close cross-sectional view of a portion of the tread 10 that includes the slit 70 and denotes additional geometrical measurements of the slit 70. The slit 70 has a slit bottom 72 that extends from the decoupling feature bottom 52. The slit bottom 72 and the decoupling feature bottom 52 are at the same position in the radial direction 24. The slit bottom 72 extends only in the lateral direction 28 and does not have a component of extension in the radial direction 24. In other embodiments, the slit bottom 72 may in fact have a component of extension in the radial direction 24 in addition to acomponent in the lateral direction 28. The slit top 74 is the portion of the slit 70 that has the most radially outward engagement position with the decoupling feature 50. The slit top 74 extends outboard in the lateral direction 28 and inward in the radial direction 24. In other arrangements, the slit top 74 has not component of extension in the radial direction 24, or may have a component of extension downward in the radial direction 24 upon extension outboard in the lateral direction 28. The slit top 74 and the slit bottom 72 terminate at a slit tip 124 that extends only in the radial direction 24 and not in the lateral direction 28. In yet other arrangements, the slit tip 124 is arranged in other manners such as a point, a radius, a blunt edge, or any other arrangement besides just a linear extension in the radial direction 24 with no component of extension in the lateral direction 28.

[0037] The slit tip 124 has a thickness / height which is the length of extension of the slit tip 124 from the slit top 74 to the slit bottom 72. This distance is denoted as ttip, and in some embodiments ttip < 2 millimeters. In other embodiments, the ttip is from 0.1-0.5 millimeters, from 0.5-1.0 millimeters, from 1-2 millimeters, from 2-3 millimeters, from 3- 4 millimeters, or less than 4.1 millimeters. The slit 70 is also oriented at an angle a relative to the lateral direction 28. To determine the angle a, a mid-plane 122 is first denoted as being a line that extends half way between the slit bottom 72 and the slit top 74 and is angled with respect to these elements 72, 74 to be oriented at a half way angle between these elements 72, 74. A lateral line 128 is drawn through the mid-plane 122 and intersects the mid-plane 122 in the decoupling feature 50. The slit 70 may be oriented so that angle a is a negative angle or is a positive angle. The slit 70 shown in Fig. 5 has a negative angle a which is extension of the slit 70 in the radial direction 24 towards the central axis 14. A positive angle a is extension of the slit 70 away from the central axis 14 in the radial direction 24. In different embodiments angle a is from -45° to +60°, from -35° to +50°, from -25° to +40°, from -10° to +30°, from 0° to 20°, from 10° to 15°, 0°, 5°, or -5°.

[0038] Another dimension noted in Fig. 5 is Wsiit which is the width of the slit 70 in the lateral direction 28 that is the length the slit 70 extends from the decoupling feature 50 in the lateral direction 28. The length Wsiit is the maximum length of extension of the slit 70 from the decoupling feature 50 and is measured from no farther inboard in the lateral direction 28 than the engagement point between the slit 70 and the decoupling feature 50 that is closest to the sacrificial rib upper surface 38 in the radial direction 24. In some embodiments the slit 70 can be dimensioned via the relationship 0.5 millimeters < Wsiit < 0.5 * Wsr. The slit 70 may be arranged relative to the decoupling feature 50 so that thefarthest point of extension of the slit 70 into the tread in the radial direction 24 from the sacrificial rib upper surface 38 is the same as the farthest point of extension of the decoupling feature bottom 52. In some embodiments, the slit 70 extends with a negative angle a so that the slit 70 extends from the decoupling feature bottom 52 farther into the tread so as to be closer to the central axis 14 in the radial direction 24.

[0039] With reference now to Fig. 6, the slit 70 is positioned relative to the decoupling feature 50 so that it is not in engagement with or at the decoupling feature bottom 52. Instead, the slit 70 has a dimension hsiit that is the height of the slit 70 relative to the decoupling feature bottom 52 in the radial direction 24. The closest point of engagement between the slit 70 and the decoupling feature 50 to the decoupling feature bottom 52 is the first measurement point from which hsiit is measured. The second measurement point is the decoupling feature bottom 52, and the height hsiit is the distance from the decoupling feature bottom 52 to the aforementioned point of the slit 70 / decoupling feature 50 engagement in the radial direction 24. The slit 70 can be moved upwards from the decoupling feature bottom 52, but not too far up to be close to the sacrificial rib upper surface 38. In some embodiments, the position of the slit 70 can be placed so that 0 < hsiit < 0.5 * hsr such that the slit 70 is at the midpoint or closer to the decoupling feature bottom 52 relative to the height of the slit 70 in the radial direction 24. The slit 70 in Fig. 6 has a negative angle a such that it has a component of extension towards the central axis 14 upon extension from the decoupling feature 50. In other embodiments, the slit 70 can be arranged so that 0 < hsiit < 0.4 * hsr, or so that 0 < hsiit < 0.25 * hsr, or so that 0 < hsiit < 0.1 * hsr.

[0040] With reference now to Fig. 7, the slit 70 is shown as extending from the decoupling feature bottom 52 and as having the same shape and amount of outboard extension in the lateral direction 28. The slit 70 may be consistently sized and shaped 360 degrees completely around the central axis 14. In this regard, the slit 70 maintains the same shape and maintains the same size upon complete revolution 360 degrees in the circumferential direction 26 about the central axis 14. Fig. 8 shows an alternative arrangement in which the slit 70 has a sinusoidal shape upon extension completely 360 degrees around the central axis 14 in the circumferential direction 26. In this regard, the Wsiit varies in a sinusoidal fashion upon complete revolution of the slit 70 about the central axis 14. However, the Wsiit is never reduced to 0 at any point, but instead always remains spaced some distance from the decoupling feature 50 even when the sinusoidal wave is at its smallest point. Since the Wsiit varies depending upon the particular position of the slit70 in the circumferential direction 26, an average width wavgslit is calculated for slits 70 that have a varying Wsiit. The dimension Wavgsiit is the average of the maximum extension of the slit 70 from the decoupling feature 50 in the lateral direction 28 taken every 1 millimeter along the decoupling feature 50 in the circumferential direction 26. Once the Wavg slit is calculated, this term can be substituted for the term Wsiit in the relationships / equations above to govern the size and spacing of the slit 70. With respect to any embodiment that does not have a consistent Wsiit completely around the circumference of the tire 10, the property wavgslit can be calculated and substituted for the Wsiit in any of the relationships / equations herein. Still further, once wavgslit is calculated, the additional relationship of 0.5 millimeters < Wavg siit < 0.5 * Wsr can be used to determine the size of the slit 70 in the lateral direction 28.

[0041] The slit 70 can be variously shaped in other embodiments of the tire 10. Fig. 9 shows the slit 70 as having a saw tooth shape upon extension in the lateral direction 28 from the decoupling feature 50. At its smallest point of extension, the slit 70 may have zero extension in the lateral direction 28 from the decoupling feature 50 and is thus discontinuous at various points in the circumferential direction 26. Due to the saw tooth shape, the wavgslit can be calculated as previously described, and the relationships previously discussed with reference to Fig. 8 in using the Wavg siit can be utilized with the saw tooth configuration of Fig. 9. The slit 70 may extend completely 360 degrees about the central axis 14 in the circumferential direction 26.

[0042] Another arrangement of the slit 70 is shown with reference to Fig. 10 in which the slit 70 has a square wave shape. The slit 70 is discontinuous in the circumferential direction 26, and the length of discontinuity in the circumferential direction 26 is the same as the amount of circumferential length of the slit 70 at the next square wave. In other versions, the circumferential length of the slit 70 is greater or less than the circumferential length of the discontinuity between the slits 70. As such the amount of the slit 70 and the discontinuity of the slit 70 are the same magnitude in the circumferential direction 26 and alternate from one another completely about the central axis 360 degrees in the circumferential direction 26. The wavgslit can be calculated and utilized in the same way as previously discussed with reference back to the Fig. 8 embodiment. Various embodiments of the tire 10 exist in which the slit 70 can have any shape around the tire 10 that involves a variation of the Wsiit.

[0043] Fig. 11 is an alternative exemplary embodiment in which the slit 70 is configured as described above with respect to the Fig. 5 embodiment. The tread includes a notch 126 that is a cavity that extends into the exterior surface 54. The notch 126 can be located so as to extend into the sacrificial rib 62, some other portion of the tread, and / or into the sidewall 12. The notch 126 may be positioned in the radial direction 24 so that it shares a common position in the radial direction 24 with the slit 70. The notch 126 is present to act as a target for the crack 68 as it develops from the slit 70 and extends into the sacrificial rib 62 in the lateral direction 28. In this regard, the crack 68 will begin at the slit 70 and extend in the lateral direction 28 until it engages the notch 126. The notch 126 may thus help keep the crack 68 in a lateral extension orientation instead of having a radial orientation of extension into lower components of the tread or into the sidewall 12. In some embodiments, a crack may likewise develop at the notch 126 and this crack could move inboard in the lateral direction 28 until it engages the slit 70 or the crack 68 extending from the slit 70. The notch 126 may thus function as a weak point in the tread which allows the crack 68 to develop in a manner that compliments the position of the notch 126 at the base of the sacrificial rib 62 so that the crack 68 extends in a desired direction. The slit 70 behaves likes a pre-existing crack such that if the sacrificial rib 62 becomes heavily solicited it will already have an orientation set up for crack 68 propagation towards the exterior surface 54 in the lateral direction 28.

[0044] Although the slit 70 is described as being associated with the first sacrificial rib 62, the first sidewall 12, the first decoupling feature 50, and the first shoulder rib 30, it is to be understood that this is for sake of convenience in description. The tire 10 may also include a second slit 71 that is associated with a second sacrificial rib 64, a second sidewall 100, a second decoupling feature 60, and a second shoulder rib 44. The second slit 71 and its associated elements can be arranged in the same manner as previously described with the first slit 70 and its associated elements, and a repeat of this information is not necessary.

[0045] While the present subject matter has been described in detail with respect to specific embodiments and methods thereof, it will be appreciated that those skilled in the art, upon attaining an understanding of the foregoing may readily produce alterations to, variations of, and equivalents to such embodiments. Accordingly, the scope of the present disclosure is by way of example rather than by way of limitation, and the subject disclosure does not preclude inclusion of such modifications, variations and / or additions to the present subject matter as would be apparent.

Claims

CLAIMSWhat is claimed is:

1. A heavy truck tire, comprising: a circumferential direction that extends about a central axis, a lateral direction that extends parallel to the central axis, and a radial direction that is perpendicular to the central axis; an inner surface that extends from a crown to a pair of sidewalls and then to a pair of beads; a shoulder rib having a shoulder rib upper surface; a sacrificial rib having a sacrificial rib upper surface, wherein the sacrificial rib is located outboard from the shoulder rib in the lateral direction; a decoupling feature that is between the shoulder rib and the sacrificial rib and that extends in the radial direction, wherein the decoupling feature has a decoupling feature bottom that is a portion of the decoupling feature that is closest to the central axis in the radial direction; a slit that extends from the decoupling feature outboard in the lateral direction, wherein the tire does not have a void present that is between the slit and the inner surface in the radial direction and that has a common position in the lateral direction as the slit.

2. The tire as set forth in claim 1, wherein the decoupling feature is a groove.

3. The tire as set forth in claim 1 or 2, wherein the slit has a slit bottom that is a portion of the slit that is located closest to the central axis in the radial direction, wherein the slit bottom and the decoupling feature bottom are located the same distance to the central axis in the radial direction.

4. The tire as set forth in claim 1 or 2, wherein the slit has a slit bottom that engages the decoupling feature bottom, wherein the slit has a slit top that engages the decoupling feature at a location in the radial direction that is farther from the central axis in the radial direction than is the decoupling feature bottom to the central axis in the radial direction.

5. The tire as set forth in claim 4, wherein the slit has a mid-plane that is located between the slit top and the slit bottom, wherein the mid-plane is oriented relative to thelateral direction at angle a that is from -45° to +60°, wherein a negative angle a is an extension of the slit from the decoupling feature in a direction towards the central axis in the radial direction, and wherein a positive angle a is an extension of the slit from the decoupling feature in a direction away from the central axis in the radial direction.

6. The tire as set forth in claim 1 or 2, wherein the sacrificial rib has a height hsr that is a distance in the radial direction from the decoupling feature bottom to the sacrificial rib upper surface at the decoupling feature; wherein the slit has a height position hsiit that is a distance in the radial direction from the decoupling feature bottom to a point where the slit engages the decoupling feature that is closest to the decoupling feature bottom; and wherein 0 < hsiit < 0.5 * hsr.

7. The tire as set forth in any one of claims 1-6, wherein the slit has a width Wsiit that is the maximum distance of extension of the slit from the decoupling feature in the lateral direction; wherein the sacrificial rib has a base width Wsr that is a distance in the lateral direction from the decoupling feature bottom across the sacrificial rib to an exterior surface of the tire; wherein 0.5 millimeters < Wsiit < 0.5 * Wsr.

8. The tire as set forth in any one of claims 1-7, wherein the slit has a slit bottom that engages the decoupling feature, wherein the slit has a slit top that engages the decoupling feature, wherein the slit has a slit tip that extends from the slit bottom to the slit top, wherein ttip is a length of the slit tip from the slit bottom to the slit top at the farthest outboard position of the slit bottom and the slit top in the lateral direction, and wherein ttip < 2 millimeters.

9. The tire as set forth in claims 1 or 2, wherein the slit has an average width Wavg slit that is the average of the maximum extension of the slit from the decoupling feature in the lateral direction taken every 1 millimeter along the decoupling feature in the circumferential direction;wherein the sacrificial rib has a base width Wsr that is a distance in the lateral direction from the decoupling feature bottom across the sacrificial rib to an exterior surface of the tire; wherein 0.5 millimeters < Wavgsiit < 0.5 * Wsr.

10. The tire as set forth in any one of claims 1 -9, wherein the slit extends continuously 360° about the central axis in the circumferential direction.

11. The tire as set forth in claim 10, wherein the slit has a sinusoidal shape.

12. The tire as set forth in any one of claims 1-9, wherein the slit is discontinuous upon extension about the central axis such that the slit does not extend continuously 360° about the central axis in the circumferential direction.

13. The tire as set forth in claim 12, wherein the slit has a square wave shape or a saw-toothed shape.

14. The tire as set forth in any one of claims 1-13, further comprising a notch in an exterior surface of the tire located at a same position in the radial direction as the slit, wherein the sacrificial rib is located between the notch and the slit in the lateral direction.

15. The tire as set forth in any one of claims 1-14, wherein the sacrificial rib upper surface is located closer to the central axis in the radial direction than the shoulder rib upper surface is located to the central axis in the radial direction;

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