WO2025136643A1

WO2025136643A1 - Truck tire having higher hysteresis in shoulder rib than in center rib

Info

Publication number: WO2025136643A1
Application number: PCT/US2024/058259
Authority: WO
Inventors: Tyler SITES; Stefan Voss; Alexandra SNYDER
Original assignee: Compagnie Generale des Etablissements Michelin SCA
Current assignee: Compagnie Generale des Etablissements Michelin SCA
Priority date: 2023-12-18
Filing date: 2024-12-03
Publication date: 2025-06-26
Anticipated expiration: 2026-06-18

Abstract

A heavy truck tire (10) is provided that has a first shoulder rib (44) made of a first material (40) that is located outward from a third material (60) in a radial direction. A first intermediate rib (46) and the first shoulder rib (44) define a first shoulder groove (48) that has an outboard side wall (52) that extends deeper into the tread in the radial direction than does the first material (40) of the first shoulder rib (44). A center rib (42) is present and is made of a second material (50) located outward from the third material (60) in the radial direction. A first max tan(6) of the first material (40) is greater than a second max tan(6) of the second material (50). The first max tan(6) is from 0.15 - 0.20, the second max tan(6) is from 0.05 - 0.15, and the third max tan(6) is from 0.05 - 0.15.

Description

TRUCK TIRE HAVING HIGHER HYSTERESIS IN SHOULDER RIB THAN IN

CENTER RIB

FIELD OF THE INVENTION

[0001] The subject matter of the present invention relates to a truck tire that has a tread design that reduces tire rolling resistance while maintaining desired irregular wear performance. More particularly, the present application involves a tread that features shoulder ribs that have higher hysteresis to protect against irregular wear in areas of the tread more prone to irregular wear, and has a center rib that has lower hysteresis to minimize rolling resistance in areas of the tire that are not as sensitive to irregular wear.

BACKGROUND OF THE INVENTION

[0002] Manufacturers of heavy commercial vehicle tires have made huge progress in developing tire architectures and tire materials that allow them to increase the wear resistance of tire treads and reduce rolling resistance while at the same time improving their level of grip and resistance to road hazards. One issue that challenges heavy commercial vehicle tires is irregular tread wear. Irregular tread wear (also called “uneven wear” or “abnormal 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 slow-wearing usage, the more irregular wear affects the removal mileage.

[0003] Tires that have good irregular wear resistance distinguish themselves with consumers because they are more likely to remain on the road and have higher removal mileage. Such tires should perform well with expected performance characteristics such as rolling resistance, yet they should do so without compromising other performance characteristics such as wear and irregular wear. The present disclosure seeks to offer such a heavy commercial vehicle tire.

BRIEF DESCRIPTION OF THE DRAWINGS

[0004] 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: [0005] Fig. 1 is a perspective view of a heavy truck tire in accordance with one exemplary embodiment.

[0006] Fig. 2 is a top view of a portion of a tread in accordance with another exemplary embodiment.

[0007] Fig. 3 is a cross-sectional view of a tire in accordance with another exemplary embodiment in which the first shoulder rib and the first intermediate rib have materials with different hysteresis.

[0008] Fig. 4 is a cross-sectional view of the tire in accordance with another exemplary embodiment in which a static discharge element is in the center rib.

[0009] Fig. 5 is a cross-sectional view of the tread in accordance with another exemplary embodiment in which the first shoulder rib and the first intermediate rib have a material with the same hysteresis.

[0010] The use of identical or similar reference numerals in different figures denotes identical or similar features.

DETAILED DESCRIPTION OF THE INVENTION

[0011] 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.

[0012] The present invention provides for a heavy duty truck tire 10 design that provides a compromise between irregular wear and rolling resistance. The area of the tread 16 most sensitive to irregular wear is the shoulder area, so the design places materials that are more hysteretic in the shoulder area to minimize, reduce, or eliminate irregular wear in this area. The other areas of the tread 16 that are not as prone to irregular wear, such as the center of the tread 16, are provided with less hysteretic material so that these areas have better rolling resistance characteristics to result in an overall tire 10 that likewise has better rolling resistance performance. The intermediate areas of the tread 16, those areas between the shoulder and center areas, may include higher hysteretic mixes to reduce irregular wear in these areas. In other embodiments, the intermediate areas of the tread 16 are provide with lower hysteretic mixes so that rolling resistance performance in this area is improved to result in an overall improvement in tire 10 rolling resistance.

[0013] 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 18 wheelers, garbage trucks, fire trucks, school busses, 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 includes a casing/carcass 76 onto which a tread 16 is disposed thereon. The central axis 14 of the tire 10 extends through the center of the carcass 76, and the lateral/axial direction 28 of the tire 10 is parallel to the central axis 14. The radial direction 24, which is also known as the thickness direction 24, of the tire 10 is perpendicular to the central axis 14, and the tread 16 is located farther from the central axis 14 in the thickness direction 24 than the carcass 76. The tread 16 extends all the way around the carcass 76 in the circumferential direction 26 of the tire 10 and circles the central axis 360 degrees.

[0014] The tread 16 features five ribs 30, 32, 42, 44, 46 that are separated by four longitudinal 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 shoulder ribs 30, 44 are the ribs of the tread 16 that are farthest outboard in the axial direction 28 and are at the edges of the rolling tread width of the tread 16. The ribs 30, 32, 42, 44, 46 can each be made up of a number of tread blocks 60 that can have various shapes, sizes, and configurations. Although five ribs and four longitudinal grooves are shown, any number of ribs and grooves can be present in other exemplary embodiments. Another embodiment of the tread 16 is shown with reference to Fig. 2 in which again five ribs 30, 32, 42, 44, 46 are present along with four longitudinal grooves 34, 56, 58, 48, however these elements are configured differently from those shown in the Fig. 1 embodiment. The ribs 30, 32, 42, 44, 46 do not have blocks in them, and the shoulder ribs 30, 44 are not the two most exterior features of the tread 16 in the lateral direction 28. A first sacrificial rib 62 is located adjacent the first shoulder rib 30, and a second sacrificial rib 64 is located adj acent the second shoulder rib 44 and these sacrificial ribs 62, 64 are the tread 16 elements located at the edges of the tread 16 in the lateral direction 28. The first sacrificial rib 62 is separated from the first shoulder rib 30 by a first space 124, and the second sacrificial rib 64 is separated from the second shoulder rib 44 by a second space 126. The spaces 124, 126 may have a width that is less than 2 millimeters, but in other embodiments the widths of the spaces 124, 126 are 2 millimeters or greater.

[0015] 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.

[0016] The tread 16 includes micro sipes 122 that are blind and extend from the grooves 34, 56, 58, 48, and from the first and second spaces 124, 126 to reduce stress singularities that may occur at the rib edges of these features. The micro sipes 122 have widths that are less than 2 millimeters and extend only a short distance into the ribs 30, 32, 42, 46, 44. There are no micro sipes 122 in the sacrificial ribs. The local compressive nature of the micro sipes 122 help distribute/absorb this stress resulting in less probability for the tread 16 to initiate irregular wear when compared to ribs 30, 32, 42, 46, 44 with no micro sipes 122.

[0017] The micro sipes 122 are oriented at a zero degree angle to the lateral direction 28 and can be described as directional micro sipes. The non-zero angle may be from 2-85 degrees. The directionality of the micro sipe 122 is oriented so that they are angled towards the forward rolling direction of the tire 10.

[0018] A radial centerline 22 of the tire 10 is located at the center of the tread 16 in the lateral direction 28. The center rib 42 is located in the center of the tread 16 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. [0019] Fig. 3 is a cross-sectional view of a tire 10 in accordance with another exemplary embodiment that shows features of the tire 10 that will now be discussed. The tire 10 has a crown portion that engages the road surface, and a pair of sidewalls 12, 100 that extend from the crown 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 steel rods 108, 110 are shown as a single piece and have a rectangular cross-sectional shape. This single piece can actually be many rods arranged together in the shape of a rectangle. 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. The wrapping tissue may have a stiffness of 14 MPa and can be made of a rubber mix and textile which in some instances can be a nylon ply, the padding gum 104, 106 can be a rubber mix and may have a stiffness of 28 MPa, and the steel rods 108, 110 can be made of steel or aluminum and can have a stiffness of 30,000,000 MPa in some embodiments.

[0020] 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 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. [0021] 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 in the axial 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 mirrorimage 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.

[0022] 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. In some embodiments, the flank 88 may be in the crown, first sidewall 12, and also the first bead 18. The flank 88 does not extend across the crown 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 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.

[0023] Another component of the tire 10 is a tread wall 84 that is located at the axial end of the tread 16 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 of the tire 10. The tread wall 84 is in the crown and extends into the first sidewall 12. The tread wall 86 is on the opposite end of the tread 16 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. The tread walls 84, 86 are made of a different material than the third material 60 and have a hysteresis different than that of the third material 60.

[0024] Included within the crown is a cushion layer 80 that is located on top of the reinforcement ply 32 in the crown 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 32, the belt layers 66, the belt edge layer 112, and the belt edge layer 114. The belt layers 66 are within the crown 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 for improved wear and cornering power. The steel belts 116, 118, 120 allow the tire 10 to maintain its shape. Belt edge layers 112 and 114 act as wedges between the belt layers 66 and the third material 60 to dampen stresses and are present for endurance performance of the tire 10. The first belt 116 is the farthest of the belt layers 66 from the central axis 14 in the radial direction 24 and engages the third material 60 and the second belt 118 and is free from engagement with the cushion layer 80 and the belt edge layers 112, 114. The first belt 116 extends across the center of the tire 10 to the other side in the axial direction 28.

[0025] The second belt 118 engages and is located inward in the radial direction 24 from the first belt 116. The second belt 118 engages the belt edge layers 112, 114 and is outward from them in the radial direction 24. The second belt 118 also engages the third belt 120 and is free from engagement with the cushion layer 80. The third belt 120 engages and is outward from the cushion layer 80 in the radial direction 24. The third belt 120 is under the belt edge layers 112, 114 in the radial direction 24 and engages these layers 112, 114. The second and third belts 118, 120 are free from engagement with the first, second and third materials 40, 50, 60.

[0026] The crown includes the plurality of ribs 30, 32, 42, 46, 44 that define on their outer radial surface the outer surface 20 of the tread 16 that is the portion of the tread 16 that engages the ground during use of the tire 10. The first shoulder groove 34 defined between the first shoulder rib 30 and the first intermediate rib 32 is made of an outboard sidewall 36 and an inboard sidewall 38. The line of demarcation between the two sidewalls 36, 38 is the center of the first shoulder groove 34 as positioned in the lateral direction 28 so that the outboard sidewall 36 is the outer half of the groove 34, and the inboard sidewall 38 is the inboard side of the groove 34. The second shoulder grove 48 is similarly made up of an outboard sidewall 52 that is the outboard half of the second shoulder groove 48, and an inboard side wall 54 that is the inboard half of the second shoulder groove 48 in the lateral direction 28.

[0027] A static discharge element 72 is present within the tire 10 and functions as a pathway for static electricity built up in the vehicle to be discharged through the tire 10 and into the ground. Portions of the beads 18, 102 and the sidewalls 12, 100 may be electrically conductive so that electricity has a path into the crown portion of the tire 10. However, the third material 60 may not be electrically conductive so that electricity could build up within the tire 10 and not be discharged as the third material 60 may act as an insulator or may not allow for good electrical conduction. The static discharge element 72 is an electrically conductive element and engages on one radial end the second belt 118 of the belt layers 66 and on the other radial end the bottom of the first material 40. The static discharge element 72 is embedded within the third material 60, and this third material 60 may not be a good conductor of electricity. Electricity that travels to the belt layers 66 can then flow through the static discharge element 72 to the first material 40 which may be a good conductor of electricity so that the electricity can then flow from the static discharge element 72 into the first material 40 and then into the ground. In this embodiment, the static discharge element 72 is not on the exterior of the tire 10 and is completely contained within the inside of the tire 10 and is not visible. The static discharge element 72 may extend completely 360 degrees around the central axis 14 in the circumferential direction 26, or the static discharge element 72 may extend less than the entire 360 degrees about the central axis 14.

[0028] The crown includes an undertread layer that makes up a portion of the tread 16 and is likewise located below the tread 16 in the radial direction 24 and is in engagement with both the tread 16 and the belt layers 66. The undertread layer extends along the majority of the entire crown in the axial direction 28. The undertread layer may be made of a material that minimize heat generation from the tread 16 and steel belts in the belt layers 66. The undertread layer can also function as an oil migration barrier, provide desirable tack, and have low hysteresis. However, these properties can be eliminated or modified in various tires 10 as desired.

[0029] Hysteresis can be measured by the tan(6) value of the rubber of a particular spot of the tire 10. The loss factor “tan(6)” is a dynamic property of the rubber compound. It is measured on a viscosity analyzer (Metravib VA4000) according to Standard ASTM D5992-96. As used herein, the exact testing method Standard ASTM D5992-96 that can be used is the 2018 version. The response of a test specimen consisting of two cylindrical pellets each 2 mm thick and one centimeter in diameter is recorded (the test specimen is made from samples taken from a tire mid-way up the height of the zone concerned as close as possible to the region of the equatorial plane in a region that is thick enough to be able to form the test specimen), the specimen being subjected to simple alternating sinusoidal shear loadings at a frequency of 10 Hz, at a temperature of 60° C. The sweep covers amplitude of deformation from 0.1% to 25% peak to peak (on the outbound cycle) then from 25% to 1% peak to peak (on the return cycle). The results that are used here are the loss factor tan(6) and the complex dynamic shear modulus. The complex dynamic shear modulus is denoted “G*25” in reference to the 25% strain applied during the test. During the outbound cycle, the maximum value of tan(6) that is observed is denoted “max tan(6)”.The complex dynamic shear modulus for 25% strain (G*25) at 60°C, referred to herein as G*25, is likewise obtained during this test to further characterize the properties of the rubber being provided in the tire 10.

[0030] The first material 40 is located in the first and second shoulder ribs 30 and 44 and is the portion of these ribs 30, 44 that form the outer surface 20 and engage the ground during use. The first material 40 has a higher hysteresis than the second material 50 and is not the same as the third material 60 and in some instances can be higher than the third material 60. The max tan(6) is an indicator of the hysteresis such that a material with a higher max tan(6) has a higher hysteresis than a material with a lower max tan(6). The max tan(6) of the first material 40 may be 0.18. In accordance with certain exemplary embodiments, the max tan(6) of the first material 40 may be from 0.15-0.20, from 0.15- 0.16, from 0.15-0.17, from 0.15-0.18, from 0.15-0.19, from 0.16-0.20, from 0.17-0.20, from 0.18-0.20, from 0.19-0.20, from 0.16-0.19, from 0.16-0.18, from 0.16-0.17, from 0.17-0.19, from 0.18-0.19, 0.16, 0.17, 0.19, or 0.20. As used herein, when listing a range of numbers, the range includes the upper and lower boundary numbers of the range as well. In some embodiments, the G*25 of the first material 40 is 1.83 MPa. In other embodiments, the G*25 of the first material 40 is from 1.6-2.0 MPa, from 1.6-1.9 MPa, from 1.6 -1.8 MPa, from 1.6 -1.7 MPa, from 1.9 - 2.0 MPa, from 1.8-2.0 MPa, from 1.7-2.0 MPa, from 1.7-1.8 MPa, 1.6 MPa, 1.7 MPa, 1.8 MPa, 1.9 MPa, 2.0 MPa, 1.65 MPa, 1.75 MPa, 1.85 MPa, or 1.95 MPa.

[0031] The second material 50 is located in the center rib 42, first intermediate rib 32, and second intermediate rib 46 and is the portion of these ribs 42, 32, 46 that form the outer surface 20 and engage the ground during use. The second material 50 has a hysteresis that is not the same as the third material 60. The max tan(6) of the second material 50 may be 0.11. In accordance with certain exemplary embodiments, the max tan(6) of the second material 50 may be from 0.05-0.15, from 0.05-0.14, from 0.05-0.13, from 0.05-0.12, from 0.05-0.11, from 0.05-0.10, from 0.05-0.09, from 0.05-0.08, from 0.05-0.07, from 0.05-0.06, from 0.06-0.15, from 0.07-0.15, from 0.08-0.15, from 0.09-0.15, from 0.10-0.15, from 0.11-0.15, from 0.12-0.15, from 0.13-0.15, from 0.14-0.15, from 0.07-0.14, from 0.07-0.13, from 0.07-0.12, from 0.07-0.11, from 0.07-0.10, from 0.07-0.09, from 0.07-0.08, from 0.08-0.14, from 0.09-0.14, from 0.10-0.14, from 0.11-0.14, from 0.12-0.14, from 0.13-0.14, from 0.08-0.13, from 0.08-0.12, from 0.08-0.11, from 0.08-0.10, from 0.08-0.09, from 0.09-0.13, from 0.10-0.13, from 0.11-0.13, from 0.12-0.13, from 0.09-0.12, from 0.09-0.11, from 0.09-0.10, from 0.10-0.12, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.12, 0.13, 0.14 or 0.15. [0032] In some embodiments, the G*25 of the second material 50 is 1.85 MPa. In other embodiments, the G*25 of the second material 50 is from 1.6-2.0 MPa, from 1.6-1.9 MPa, from 1.6 -1.8 MPa, from 1.6 -1.7 MPa, from 1.9 - 2.0 MPa, from 1.8-2.0 MPa, from 1.7- 2.0 MPa, from 1.7-1.8 MPa, 1.6 MPa, 1.7 MPa, 1.8 MPa, 1.9 MPa, 2.0 MPa, 1.65 MPa, 1.75 MPa, 1.85 MPa, or 1.95 MPa.

[0033] The third material 60 is located in all of the ribs 30, 32, 42, 44, 46 but is not the outward portion of these ribs in the radial direction 24 and does not engage the ground when the tire 10 is new. The third material also makes up the sacrificial ribs 62, 64 and the undertread of the tire 10. The max tan(6) of the third material 60 may be 0.10. In accordance with certain exemplary embodiments, the max tan(6) of the third material 60 may be from 0.05-0.15, from 0.05-0.14, from 0.05-0.13, from 0.05-0.12, from 0.05-0.11, from 0.05-0.10, from 0.05-0.09, from 0.05-0.08, from 0.05-0.07, from 0.05-0.06, from 0.06-0.15, from 0.07-0.15, from 0.08-0.15, from 0.09-0.15, from 0.10-0.15, from 0.11-0.15, from 0.12-0.15, from 0.13-0.15, from 0.14-0.15, from 0.07-0.14, from 0.07-0.13, from 0.07-0.12, from 0.07-0.11, from 0.07-0.10, from 0.07-0.09, from 0.07-0.08, from 0.08-0.14, from 0.09-0.14, from 0.10-0.14, from 0.11-0.14, from 0.12-0.14, from 0.13-0.14, from 0.08-0.13, from 0.08-0.12, from 0.08-0.11, from 0.08-0.10, from 0.08-0.09, from 0.09-0.13, from 0.10-0.13, from 0.11-0.13, from 0.12-0.13, from 0.09-0.12, from 0.09-0.11, from 0.09-0.10, from 0.10-0.12, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.12, 0.13, 0.14 or 0.15.

[0034] In some embodiments, the G*25 of the third material 60 is 1.51 MPa. In other embodiments, the G*25 of the third material 60 is from 1.0-1.75 MPa, from 1.0-1.7 MPa, from 1.0 -1.6 MPa, from 1.0 -1.5 MPa, from 1.0 - 1.4 MPa, from 1.0-1.3 MPa, from 1.0-

1.2 MPa, from 1.0-1.1 MPa, from 1.1-1.75 MPa, from 1.2-1.75 MPa, from 1.3-1.75 MPa, from 1.4-1.75MPa, from 1.5-1.75 MPa, from 1.6-1.75 MPa, from 1.7-1.75 MPa, from 1.1- 1.7 MPa, from 1.1-1.6 MPa, from 1.1-1.5 MPa, from 1.1-1.4 MPa, from 1.1-1.3 MPa, from 1.1-1.2 MPa, from 1.2- 1.7 MPa, from 1.3-1.7 MPa, from 1.4- 1.7 MPa, from 1.5-1.7 MPa, from 1.6-1.7 MPa, from 1.2-1.6 MPa, from 1.2-1.5 MPa, from 1.2-1.4 MPa, from 1.2-1.3 Mpa, from 1.3-1.6 MPa, from 1.4-1.6MPa, from 1.5- 1.6 MPa, from 1.3-1.5 MPa, from 1.3- 1.4 MPa, 1.0 MPa, 1.1 MPa, 1.2 MPa, 1.3 MPa, 1.4 MPa, 1.5 MPa, 1.6 MPa, 1.7 MPa or 1.75 MPa.

[0035] The static discharge element 72 can be made of rubber in some embodiments and its hysteresis can be different or the same as the hysteresis of the first, second and third materials 40, 50, 60. The max tan(6) of the static discharge element 72 can be 0.15. In accordance with certain exemplary embodiments, the max tan(6) of the static discharge element 72 may be from 0.05-0.17, from 0.05-0.16, from 0.05-0.15, from 0.05-0.14, from 0.05-0.13, from 0.05-0.12, from 0.05-0.11, from 0.05-0.10, from 0.05-0.09, from 0.05-0.08, from 0.05-0.07, from 0.05-0.06, from 0.06-0.17, from 0.06-0.16, from 0.06-0.15, from 0.06-0.14, from 0.06-0.13, from 0.06-0.12, from 0.06-0.11, from 0.06-0.10, from 0.06-0.09, from 0.06-0.08, from 0.06-0.07, from 0.07-0.16, from 0.08-0.16, from 0.09-0.16, from 0.10-0.16, from 0.11-0.16, from 0.12-0.16, from 0.13-0.16, from 0.14-0.16, from 0.15-0.16, from 0.07-0.15, from 0.08-0.15, from 0.09-0.15, from 0.10-0.15, from 0.11-0.15, from 0.12-0.15, from 0.13-0.15, from 0.14-0.15, from 0.07-0.14, from 0.07-0.13, from 0.07-0.12, from 0.07-0.11, from 0.07-0.10, from 0.07-0.09, from 0.07-0.08, from 0.08-0.14, from 0.09-0.14, from 0.10-0.14, from 0.11-0.14, from 0.12-0.14, from 0.13-0.14, from 0.08-0.13, from 0.08-0.12, from 0.08-0.11, from 0.08-0.10, from 0.08-0.09, from 0.09-0.13, from 0.10-0.13, from 0.11-0.13, from 0.12-0.13, from 0.09-0.12, from 0.09-0.11, from 0.09-0.10, from 0.10-0.12, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10, 0.12, 0.13, 0.14, 0.16 or 0.17.

[0036] In some embodiments, the G*25 of the static discharge element 72 is 1.39 MPa. In other embodiments, the G*25 of the static discharge element 72 is from 1.0-1.75 MPa, from 1.0-1.7 MPa, from 1.0 -1.6 MPa, from 1.0 -1.5 MPa, from 1.0 - 1.4 MPa, from 1.0-

1.3 MPa, from 1.0-1.2 MPa, from 1.0-1.1 MPa, from 1.1-1.75 MPa, from 1.2-1.75 MPa, from 1.3-1.75 MPa, from 1.4-1.75MPa, from 1.5-1.75 MPa, from 1.6-1.75 MPa, from 1.7- 1.75 MPa, from 1.1-1.7 MPa, from 1.1-1.6 MPa, from 1.1-1.5 MPa, from 1.1-1.4 MPa, from 1.1-1.3 MPa, from 1.1-1.2 MPa, from 1.2-1.7 MPa, from 1.3-1.7 MPa, from 1.4-1.7 MPa, from 1.5-1.7 MPa, from 1.6-1.7 MPa, from 1.2-1.6 MPa, from 1.2-1.5 MPa, from 1.2-1.4 MPa, from 1.2-1.3 Mpa, from 1.3-1.6 MPa, from 1.4-1.6MPa, from 1.5-1.6 MPa, from 1.3-1.5 MPa, from 1.3-1.4 MPa, 1.0 MPa, 1.1 MPa, 1.2 MPa, 1.3 MPa, 1.4 MPa, 1.5 MPa, 1.6 MPa, 1.7 MPa or 1.75 MPa.

[0037] The first material 40 and the third material 60 make up the first and second shoulder ribs 30 and 44 with the boundary between these two materials 40, 60 being located at the first and second spaces 124, 126 and at the first and second shoulder grooves 34, 48. These boundaries are located at the outboard sidewall 36 and at the outboard sidewall 52 and do not extend to the very bottom of the grooves 34, 48 so that the grooves 34, 48 and spaces 124, 126 extend a greater depth in the radial direction 24 than does the first material 40 in the radial direction 24. The second material 50 forms a boundary with the third material 60 that is located at the same distance into the tread 16 in the radial direction 24 as is the boundary between the first and third materials 40, 60. This boundary is located at the inboard sidewall 38, inboard sidewall 54, and at both of the sidewalls of both of the center rib grooves 56, 58. The grooves 34, 56 and 58 extend a greater distance into the tread 16 in the radial direction 24 than does the extension of the second material 50 into the tread 16 in the radial direction 24. The hysteresis as measured by the max tan(6) number is greater with the first material 40 than the second material 50 so that the tread 16 exhibits less irregular wear at shoulder areas that are sensitive to irregular wear, while at the same time exhibiting better rolling resistance in center and intermediate areas of the tread 16 that are not as sensitive to irregular wear.

[0038] Another embodiment of the tire 10 is shown with reference to Fig. 4 that includes many similar features as previously discussed with respect to Fig. 3 so that they need not be repeated. The one difference between the Fig. 3 and Fig. 4 embodiments resides in the placement of the static discharge element 72 within the tire 10. In Fig. 4, the static discharge element 72 extends from the belt layers 66 to the outer surface 20 and forms a portion of the outer surface 20. In particular, the static discharge element 72 engages on its most radially inward end the first belt 116 and its radially outward end forms a portion of the outer surface 20. The static discharge element 72 is located at the radial centerline 22 and engages both the second material 50 and the third material 60 and is free from engagement with the first material 40. The static discharge element 72 is located in center rib 42 and has high electrical conductivity so that electricity that builds up in the vehicle can be channeled into the belt layers 66 and discharged from the belt layers 66 through the static discharge element 72 and into the ground directly therefrom.

[0039] Fig. 5 shows another embodiment of the tire 10 that is similar to that previously discussed with reference back to Fig. 3, and a repeat of this information is not necessary. The difference in the Fig. 5 embodiment is that the second material 50 located in the first and second intermediate ribs 32 and 46 is replaced by the first material 40. This embodiment may likewise reduce irregular wear in the intermediate ribs 32, 46 due to the higher hysteretic first material 40 so that these ribs 32, 46 are less likely to experience irregular wear. To improve the compromise between irregular wear and rolling resistance the less hysteretic second material 50 mix is present within the center rib 42. The embodiments disclosed show a pair of shoulder ribs 30, 44 and a single center rib 42 between two intermediate ribs 32 and 46. However it is to be understood that if an even number of ribs are present within the tread 16 in other embodiments, two center ribs 42 will be present. Still further, additional exemplary embodiments exist in which there are more than two intermediate ribs 32, 46 and that any number of intermediate ribs 32, 46 can be included within the tread 16 in other versions of the tire 10. In all versions, the center rib or ribs 42 will include the second material 50 and the two shoulder ribs 30, 44 will include the first material 40 with the intermediate ribs 32, 46 including either the first material 40 or second material 50 or both the first and second materials 40, 50. In some embodiments, each one of the ribs 30, 44, 42, 32, 46 include either the first material 40 or the second material 50 and do not include both the first and second materials 40, 50, while in yet other arrangements ribs are present within the tread 16 that are not sacrificial ribs 62, 64 and that do not include either the first material 40 or the second material 50. Also, although shown as extending the same distance into the tread 16 in the radial direction 24, the first and second materials 40, 50 may extend distances different from one another into the tread 16 in the radial direction 24.

[0040] The max tan(6) of the first material 40 is greater than the max tan(6) of the second material 50 to improve the compromise between irregular wear and rolling resistance. The second material 50 with lower hysteresis reduces the overall tire 10 rolling resistance by being placed into less sensitive irregular wear areas of the tread 16. In some embodiments the first material 40 is 30% or greater in hysteresis than the second material 50. In this regard, if the max tan(6) of the first material 40 is 0.18 and the max tan(6) of the second material 50 is 0.11 then to calculate how much greater of a percentage (P) the first material 40 is than the second material 50 can be calculated as follows:

[0041] (0.18P) + 0.11 = 0.18

[0042] (0.18P) = 0.07

[0043] P = 38.8 %

[0044] The first, second and third materials 40, 50, 60 can be layered into the tire 10 using a coextrusion process. A tread design in which layers of different material are incorporated into the tire can be seen with reference to United States Patent No. 11,254,166 entitled “Methods and Apparatuses for Assembling Tire Components” which is owned by the assignee of the present application and is incorporated by reference herein in its entirety for all purposes. In the present arrangement, the third material 60 is outboard from both the first and second materials 40, 50 in the axial direction 28, and is inboard from them in the radial direction 24. The third material 60 may be present within all of the ribs 30, 32, 42, 44, 46, and the third max tan (6) is different than the first max tan(6) and the second max tan(6). The higher and lower hysteresis of the first, second and third materials 40, 50, 60 is imparted based upon the material making up the materials 40, 50, 60 such as the rubber, silica, carbon black, sulfur, or other fillers, and is not higher or lower based upon belts or other components causing the layer to be a tissue. The max tan(6) of the materials 40, 50, 60 result from the tread 16 mix, and does not result from the tread 16 being a tissue.

[0045] The tire 10 can be an original equipment manufactured tire that is produced and goes onto a new vehicle. The tire 10 may also be a retreaded tire in which a used casing 76 is fitted with a new tread 16. The tread 16 may thus be provided as a retread band, or as a tire 10. The tread 16 allows for the provision of steer and trailer tires 10 that do not incorporate sacrificial ribs 62, 64.

[0046] 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

CLAIMS What is claimed is:

1. A tread for a heavy truck tire, comprising: a first shoulder rib made of a first material and a third material, wherein the first material is located outward from the third material in a radial direction; a first intermediate rib made partially of the third material such that the third material is not located at a most radially outward point of the first intermediate rib, wherein the first intermediate rib and the first shoulder rib define a first shoulder groove that has an outboard side wall made of both the first material and the third material such that the first shoulder groove extends deeper into the tread in the radial direction than does the first material of the first shoulder rib; a center rib made of a second material and the third material, wherein the second material is located outward from the third material in the radial direction; a second shoulder rib made of the first material and the third material, wherein the first material is located outward from the third material in the radial direction; a second intermediate rib made partially of the third material such that the third material is not located at a most radially outward point of the second intermediate rib, wherein the second intermediate rib and the second shoulder rib define a second shoulder groove that has an outboard side wall of the second shoulder groove made of both the first material and the third material such that the second shoulder groove extends deeper into the tread in the radial direction than does the first material of the second shoulder rib; wherein a first max tan(6) of the first material is greater than a second max tan(6) of the second material; wherein a third max tan(6) of the third material is not the same as the first max tan(6), and wherein the third max tan(6) is not the same as the second max tan(6); wherein the first max tan(6) is from 0.15 - 0.20; wherein the second max tan(6) is from 0.05 - 0.15; and wherein the third max tan(6) is from 0.05 - 0.15.

2. The tread as set forth in claim 1, wherein the second max tan(6) is from 0.10 - 0.15.

3. The tread as set forth in claim 1 or 2, wherein the first intermediate rib is made of the second material and the third material such that the second material is located outward from the third material in the radial direction; wherein the first shoulder groove has an inboard side wall made of both the second material and the third material such that the first shoulder groove extends deeper into the tread in the radial direction than does the second material of the first intermediate rib; wherein the second intermediate rib is made of the second material and the third material such that the second material is located outward from the third material in the radial direction; and wherein the second shoulder groove has an inboard side wall made of both the second material and the third material such that the second shoulder groove extends deeper into the tread in the radial direction than does the second material of the second intermediate rib.

4. The tread as set forth in claim 1 or 2, wherein the first intermediate rib is made of the first material and the third material such that the first material is located outward from the third material in the radial direction; wherein the first shoulder groove has an inboard side wall made of both the first material and the third material such that the first shoulder groove extends deeper into the tread in the radial direction than does the first material of the first intermediate rib; wherein the second intermediate rib is made of the first material and the third material such that the first material is located outward from the third material in the radial direction; and wherein the second shoulder groove has an inboard side wall made of both the first material and the third material such that the second shoulder groove extends deeper into the tread in the radial direction than does the first material of the second intermediate rib.

5. The tread as set forth in any one of claims 1 - 4, wherein the second and third materials of the center rib partially define a first center rib groove, and wherein the second and third materials of the center rib partially define a second center rib groove; wherein the first center rib groove extends deeper into the tread in the radial direction than does second material of the center rib; and wherein the second center rib groove extends deeper into the tread in the radial direction than does the second material of the center rib.

6. The tread as set forth in any one of claims 1-5, further comprising: a first sacrificial rib that is made of the third material, wherein the first sacrificial rib is located outboard in an axial direction from the first shoulder rib; a second sacrificial rib that is made of the third material, wherein the second sacrificial rib is located outboard in the axial direction from the second shoulder rib.

7. The tread as set forth in any one of claim 1-6, further comprising: belt layers located inward from the first shoulder rib, the first intermediate rib, the center rib, the second shoulder rib, and the second intermediate rib in the radial direction; a first sidewall; a first bead that engages the first sidewall and is located inward in the radial direction from the first sidewall; a second sidewall; a second bead that engages the second sidewall and is located inward in the radial direction from the second sidewall; and a static discharge element through which electrical charge travels, wherein the static discharge element engages the third material and engages at least one of the layers of the belt layers.

8. The tread as set forth in claim 7, wherein the static discharge element is located in the first shoulder rib and engages the first material and does not extend to an outer surface of the tread.

9. The tread as set forth in claim 7, wherein the static discharge element is located in the center rib and engages the second material and extends to an outer surface of the tread.

10. The tread as set forth in claim 8 or 9, wherein the static discharge element has a complex shear modulus for 25% strain (G*25) at 60°C that is from 1.0 MPa to 1.75 MPa; wherein the static discharge element has a max tan(6) is from 0.05 - 0.17.

11. The tread as set forth in claim 10, wherein the static discharge element has a complex shear modulus for 25% strain (G*25) at 60°C that is 1.39 MPa; wherein the static discharge element has a max tan(6) that is 0.15.

12. The tread as set forth in any one of claims 1-11, wherein: the first material has a complex shear modulus for 25% strain (G*25) at 60°C that is from 1.6 MPa to 2.0 MPa; the second material has a complex shear modulus for 25% strain (G*25) at 60°C that is from 1.6 MPa to 2.0 MPa; and the third material has a complex shear modulus for 25% strain (G*25) at 60°C that is from 1.0 MPa to 1.75 MPa.

13. The tread as set forth in claim 12, wherein the first material has a complex shear modulus for 25% strain (G*25) at 60°C that is 1.83 MPa; wherein the second material has a complex shear modulus for 25% strain (G*25) at 60°C that is 1.85 MPa; and wherein the third material has a complex shear modulus for 25% strain (G*25) at 60°C that is 1.51 MPa.

14. The tread as set forth in any one of claims 1-13, wherein the first max tan(6) is 0.18; the second max tan(6) is 0.11; and the third max tan(6) is 0.10.

15. The tread as set forth in any one of the preceding claims, wherein the tread is a retread band.

16. The tread as set forth in any one of the preceding claims, wherein the first max tan(6) is 30% or greater than the second max tan(6).