Tire and tire tread

Abstract

The present invention relates to a tread and a tire having a tread in which, over a majority of the circumferential length, i) the maximum axial width in the top portion of the tread groove is at least 5% less than the axial width in the bottom portion of the tread groove, ii) the axial width in the bottom portion of the tread groove is at least 5% less than the maximum axial width of the tread groove in the radially intermediate portion of the tread groove, and iii) the maximum axial width in the intermediate portion of the tread groove is in the range of 15% to 50% of the total radial height of the tread groove.

Description

Technical Field

[0001] The present invention relates to a tire tread, such as a truck tire tread. In addition, the present invention relates to a tire comprising a tread. The tire can also be retreaded with the tread. Background Art

[0002] Over the past few decades, tire performance has improved significantly. In particular, in the field of truck tire technology, rolling resistance and tread wear have been successfully improved. As a result, the environmental impact of tires has been reduced and more cost-effective products have been provided. However, there is still a desire to further increase the efficiency of tires, in particular to further reduce rolling resistance and thus reduce energy consumption. At the same time, it is desirable to provide tires with advantageous properties, such as grip, for example wet grip. Despite the progress made in the past few years, there is still room for improvement. Summary of the invention

[0003] In a first aspect, the present invention relates to a tire tread, wherein the tire tread comprises two tread shoulders, the two tread shoulders comprising a first tread shoulder and a second tread shoulder, and a tread center portion axially arranged between the two tread shoulders. The first tread shoulder comprises a first circumferential shoulder rib, and the second tread shoulder comprises a second circumferential shoulder rib, wherein each shoulder rib is defined by a circumferential shoulder groove. The tread center portion comprises at least two adjacent circumferential tread ribs defining a circumferential tread groove. The tread groove has a top portion, a bottom portion, and an intermediate portion radially located between the top portion and the bottom portion. The tread groove has a cross section over most of its circumferential length, in which the maximum axial width in the top portion is at least 5% less than the axial width of the tread groove in the bottom portion, the axial width in the bottom portion being measured at 5% of the total radial height of the tread groove from the bottom of the groove. Furthermore, in said cross section, the axial width of the tread groove in the bottom portion (also measured at 5% of the total radial height of the tread groove from the groove bottom) is at least 5% smaller than the maximum axial width of the tread groove in the middle portion. Furthermore, still in the cross section, the maximum axial width of the tread groove in the middle portion is in the range of 15% to 50% of the total radial height of the tread groove.

[0004] In a second aspect of the invention, the invention relates to a tire comprising a tread, the tread comprising: two tread shoulders, the two tread shoulders comprising a first tread shoulder and a second tread shoulder; and a tread center portion axially arranged between the two tread shoulders. The first tread shoulder comprises a first circumferential shoulder rib, the first circumferential shoulder rib comprising a circumferential row of shoulder tread blocks, and the second tread shoulder comprises a second circumferential shoulder rib, the second circumferential shoulder rib comprising a second circumferential row of shoulder tread blocks, wherein each shoulder rib is defined by a circumferential shoulder groove. The tread center portion comprises at least two adjacent circumferential tread ribs defining a circumferential tread groove. Each circumferential tread rib comprises a circumferential row of center tread blocks separated by lateral grooves. The tread groove has a top portion, a bottom portion and a middle portion radially located between the top portion and the bottom portion. Furthermore, the tread groove has a cross section over most of its circumferential length in which the maximum axial width in the top portion is at least 5% smaller than the axial width in the bottom portion, the axial width of the bottom portion being measured at 5% of the total radial height of the tread groove from the bottom of the tread groove. Furthermore, in this cross section, the axial width in the bottom portion (measured at 5% of the total radial height of the tread groove from the bottom of the tread groove) is at least 5% smaller than the maximum axial width of the tread groove in the middle portion. Furthermore, still in this cross section, the maximum axial width in the middle portion is in the range of 15% to 50% of the total radial height of the tread groove.

[0005] The present invention provides the following technical solutions:

[0006] 1. A tire, comprising:

[0007] A tread having tread grooves extending continuously in a circumferential direction;

[0008] The tread groove has a top portion, a bottom portion and a transition portion between the top portion and the bottom portion.

[0009] Wherein, the maximum axial width of the tread groove in the top portion is 2 mm,

[0010] wherein the tread groove has opposing side walls, and wherein the opposing side walls taper toward each other in a bottom portion,

[0011] The opposite side walls in the transition portion gradually widen away from each other.

[0012] 2. The tire according to claim 1, wherein the bottom portion has a minimum width wb in the range of 1.5-3.5 mm.

[0013] 3. The tire according to claim 1, wherein the groove has a maximum width Wmax in the range of 4 to 9 mm.

[0014] 4. The tire according to claim 1, wherein the groove has a maximum width Wmax in the range of 5 to 7 mm.

[0015] 5. The tire according to claim 1, wherein the groove has a maximum width Wmax in the transition section.

[0016] 6. The tire according to claim 1, wherein the ratio of Wmax to Wb is in the range of 1.5-2.5.

[0017] 7. The tire according to claim 1, wherein the maximum width of the groove is located at a radial height within a range of 40-60% of the total radial height.

[0018] 8. The tire according to claim 1, wherein the maximum width of the groove is located at 50% of the radial height.

[0019] 9. The tire tread according to claim 1, wherein the groove is located on the center line of the tread.

[0020] 10. The tire tread according to claim 1, wherein the maximum axial width of the tread groove is one or more of the following:

[0021] Less than 50% of the maximum axial width of the shoulder groove;

[0022] Greater than 30% of the maximum axial width of the shoulder groove;

[0023] 20% to 45% of the total radial height of one or more of the tread grooves and the shoulder grooves;

[0024] Exists at a radial height in the range of 35% to 65% of the total height of the tread groove measured in the radial direction from the bottom of the tread groove.

[0025] 11. The tire tread of claim 1, wherein the total cross-sectional area of ​​the tread grooves is one or more of the following:

[0026] Less than 35% of the total cross-sectional area of ​​the shoulder groove;

[0027] Greater than 15% of the total cross-sectional area of ​​the shoulder groove.

[0028] 12. The tire tread according to claim 1, wherein the maximum axial width of the top portion of the tread groove is one or more of the following:

[0029] Less than 25% of the maximum axial width of the tread groove;

[0030] Greater than 10% of the maximum axial width of the tread groove;

[0031] Less than 10% of the maximum axial width of the shoulder groove;

[0032] Greater than 3% of the maximum axial width of the shoulder groove.

[0033] 13. The tire tread according to claim 1, wherein the tread shoulder groove has one or more of the following:

[0034] Basically V-shaped;

[0035] having two side walls at relative angles in the range of 75° to 85° with respect to the axial direction;

[0036] A shape that gradually narrows from its radially outermost portion to its radially innermost bottom.

[0037] 14. The tire tread according to claim 1, wherein the tread groove has an amphora-like cross-sectional shape.

[0038] 15. The tire tread according to claim 1, wherein the tread groove has an axial width within a range of 30% to 60% of the maximum axial width of the tread groove at 5% of its total axial height measured from the bottom of the tread groove.

[0039] 16. The tire tread according to claim 1, wherein each sidewall of the tread groove has an inflection point in the middle portion between a radial height of a maximum axial thickness of the tread groove and a radial height of a minimum axial thickness of the tread groove.

[0040] 17. The tire tread according to claim 16, wherein a tangent line fitted in the inflection point of the sidewall has an angle in the range of 25° to 60° with the axial direction.

[0041] 18. A tire comprising the tread according to claim 1.

[0042] 19. The tire according to claim 18, wherein the tire is one or more of the following:

[0043] Truck tires;

[0044] trailer tires;

[0045] 22.5-inch tires;

[0046] Pneumatic tires;

[0047] A tire having three circumferential tread grooves and two circumferential shoulder grooves;

[0048] A tire with four steel-wire reinforced belts;

[0049] A tire retreaded with the tread;

[0050] Tires with steel wire reinforced carcass plies;

[0051] A tire having two bead areas, each bead area comprising a bead, a carcass ply extending between the two bead areas, wherein the carcass ply is radially covered by a reinforcing belt in the crown area of ​​the tire, and the belt is arranged radially below the tread;

[0052] A tread having at least two radially superimposed tread layers, wherein the tread layer that contacts the road during driving defines the bottom and the side walls of the grooves.

[0053] 20. The tire of claim 18, wherein the tire is one of a 22.5 inch truck tire and a 22.5 inch truck trailer tire.

[0054] 21. A tire tread, comprising:

[0055] two tread shoulders, including a first tread shoulder and a second tread shoulder;

[0056] The central part of the tread arranged axially between the two tread shoulders.

[0057] wherein the first tread shoulder comprises a first circumferential shoulder rib and the second tread shoulder comprises a second circumferential shoulder rib, and wherein each shoulder rib is defined by a circumferential shoulder groove,

[0058] wherein the tread center portion includes at least two adjacent circumferential tread ribs defining a circumferential tread groove,

[0059] wherein the tread groove has a top portion, a bottom portion, and a middle portion radially between the top portion and the bottom portion;

[0060] Therein, the tread groove has, over most of its circumferential length, a cross section in which:

[0061] the maximum axial width in the top portion is at least 5% less than the axial width in the bottom portion measured at 5% of the total radial height of the tread groove from the bottom of the tread groove; wherein

[0062] The axial width in the bottom portion, measured at 5% of the total radial height of the tread groove from the bottom of the tread groove, is at least 5% less than the maximum axial width of the tread groove in the middle portion; and wherein

[0063] The maximum axial width of the tread groove in the middle portion is in the range of 15% to 50% of the total radial height of the tread groove.

[0064] 22. The tire tread of claim 21, wherein, in cross-section, the top portion extends over 20% to 40% of the total radial height of the tread groove.

[0065] 23. The tire tread according to claim 21, wherein, in cross section, the bottom portion extends from a height of a maximum axial width of the middle portion to a bottom of the groove.

[0066] 24. The tire tread according to claim 21, wherein, in cross section, the bottom portion has one or more of the following:

[0067] a radial height in the range of 35% to 65% of the total radial height of the tread groove;

[0068] two opposite side walls gradually narrowing along the inner radial direction;

[0069] Two opposing side walls, at least one of which has an angle with the axial direction in the range of 65° to 85°.

[0070] 25. The tire tread of claim 21, wherein, in cross section, the top portion has one or more of the following:

[0071] parallel side walls;

[0072] straight sidewalls;

[0073] Two side walls extending in parallel along a radial direction;

[0074] Constant width along radial height;

[0075] A maximum axial width within the range of 1% to 10% of the total radial height of the tread groove;

[0076] A radially innermost end is at a radial height in the range of 55% to 80% of the total radial height of the tread groove measured in the radial direction from the bottom of the tread groove. BRIEF DESCRIPTION OF THE DRAWINGS

[0077] The present invention will now be described by way of example with reference to the accompanying drawings, in which:

[0078] Figure 1 is a schematic cross-sectional view of a truck tire according to a first preferred embodiment of the present invention;

[0079] Figure 2 is a schematic cross-sectional view of another truck tire according to a second preferred embodiment of the present invention;

[0080] Figure 3a is based on Figure 1 An enlarged cross-sectional view of a (center) tread groove of an embodiment of;

[0081] Figure 3b is based on Figure 1 An enlarged cross-sectional view of a shoulder groove of an embodiment of the present invention;

[0082] Figure 4a is based on Figure 2 An enlarged cross-sectional view of a (center) tread groove of an embodiment of;

[0083] Figure 4b is based on Figure 2 an enlarged cross-sectional view of a shoulder groove of an embodiment of; and

[0084] Figure 5 is a schematic side view of a tire having a tread according to another embodiment of the present invention. DETAILED DESCRIPTION

[0085] In one aspect, the present invention relates to a tire tread, wherein the tire tread comprises two tread shoulders, the two tread shoulders comprising a first tread shoulder and a second tread shoulder, and a tread center portion axially arranged between the two tread shoulders. The first tread shoulder comprises a first circumferential shoulder rib, and the second tread shoulder comprises a second (or another) circumferential shoulder rib, wherein each shoulder rib is defined by a circumferential shoulder groove. The tread center portion comprises at least two adjacent circumferential tread ribs, the circumferential tread ribs defining (between them) a circumferential tread groove. The tread groove has a (radial) top portion, a (radial) bottom portion and an intermediate portion radially located between the top portion and the bottom portion. The tread groove has a cross section over most of its circumferential length, in which the maximum axial width of the top portion is at least 5% (preferably at least 10%) smaller than the axial width of the tread groove of the bottom portion, the axial width of the tread groove of the bottom portion being measured (in the cross section) at 5% of the total radial height of the tread groove from the groove bottom. Furthermore, in the cross section, the axial width of the tread groove of the bottom portion (also measured at 5% of the total radial height of the tread groove from the groove bottom and in the cross section) is at least 5% (preferably at least 10%) smaller than the maximum axial width of the tread groove of the middle portion of the cross section. Furthermore, still in the cross section, the maximum axial width (length) of the tread groove of the middle portion is in the range of 15% to 50% of the total radial height (length) of the tread groove.

[0086] Thus, the tire and / or tread design according to the present invention has a circumferential tread groove having a relatively narrow top portion, a relatively wide middle portion and a again narrow bottom portion over most of its circumferential length. Taking into account the above ranges, the inventors have found that rolling resistance can be reduced early in the tire life, while wet traction can be significantly improved after the tire has further worn and the level of slip resistance has decreased.

[0087] In one embodiment of the invention, in said cross section, the top portion (radially) extends over 20% to 40% (preferably 22% to 40%) of the total radial height of the tread groove. Thus, the relatively narrow top portion extends over a large height of the groove, which helps to provide stiffness and / or reduce rolling resistance to an unworn or new tire tread.

[0088] In another embodiment of the invention, still in said cross section, the bottom portion extends from the height (downwards) of the maximum axial width of the middle portion to the bottom of the groove.

[0089] In yet another embodiment, in the cross section, the bottom portion has one or more of the following:

[0090] a radial height in the range of 35% to 65% (preferably from 40% to 50% or to 49%) of the total radial height of the tread groove;

[0091] two (opposite) side walls that taper along or in the inner radial direction;

[0092] The two side walls, at least one of which makes an angle with the axial direction in the range of 65° to 85°, preferably 70° to 85°. Preferably, the angles and / or orientations of the two side walls are opposite to each other.

[0093] In yet another embodiment, in the cross section, the top portion has one or more of the following:

[0094] (substantially) parallel side walls;

[0095] at least partially straight side walls;

[0096] two side walls extending (substantially) parallel to the radial direction;

[0097] constant (axial) width along radial height;

[0098] a maximum axial width in the range of 1% to 10%, preferably 2% to 5%, of the total radial height of the tread groove; and

[0099] A radially innermost end (e.g., where the two sidewalls are no longer parallel) at a radial height in the range of 55% to 80%, preferably in the range of 60% to 75% of the total radial height of the tread groove, measured in the radial direction from the bottom of the tread groove.

[0100] In another embodiment, in cross-section, the middle portion has an axial width at its radially outermost position that is the same as the axial width of the top portion (e.g., at the radially innermost end of the top portion), and the axial width widens or increases in a radially inward direction to a maximum axial width of the middle portion.

[0101] Preferably, also in cross section, the maximum axial width of the intermediate portion is also the (overall) maximum axial width of the tread groove in the cross section.

[0102] In yet another embodiment, the width of the tread grooves continuously widens or increases in a radially inward direction (starting from a radially outermost position of the intermediate portion) to reach a maximum axial width of the intermediate portion, all within the cross-section.

[0103] In yet another embodiment, and still in cross-section, the bottom portion extends from the radial location of the maximum axial width of the intermediate portion (and / or the tread groove) downwardly to the bottom of the tread groove.

[0104] In another embodiment of the invention, and in cross section, the bottom portion tapers, for example continuously, and / or is straight, preferably over at least 70% of its radial height, from its radially outermost position or radially external position towards the bottom of the groove. In particular, such a feature can support improved demoulding of the tread and / or contribute to limiting undesired accumulation of stones while driving.

[0105] In yet another embodiment, in cross section, the maximum axial width of the tread groove and / or the intermediate portion is or corresponds to one or more of the following:

[0106] Less than 60% (preferably less than 50%) of the maximum axial width of the shoulder groove (e.g. each shoulder groove);

[0107] Greater than 30% of the maximum axial width of the shoulder groove;

[0108] 20% to 50% of the total radial height of one or more of the tread grooves and the shoulder grooves;

[0109] Present at a radial height in the range 35% to 65%, preferably 40% to 60% or even more preferably 45% to 55% of the total height of the tread groove, measured in radial direction from the bottom of the tread groove.

[0110] In one embodiment, one or more ranges mentioned herein for a tread groove apply to each tread groove of the tread. The ranges mentioned herein for a shoulder groove may also apply to each shoulder groove of the tread. In addition, or alternatively, one or more ranges, percentages, and values ​​mentioned herein apply to the cross-section.

[0111] In another embodiment, in said cross section, the total cross-sectional area of ​​the tread grooves is less than 35% of the total cross-sectional area of ​​the shoulder grooves, preferably at the same circumferential position, and / or greater than 15% of the total cross-sectional area of ​​the shoulder grooves, preferably at the same circumferential position.

[0112] In yet another embodiment, the cross section is a plane comprising or spanned by the axial and radial directions of the tire, and / or a plane perpendicular to the circumferential direction.

[0113] In yet another embodiment, in cross-section, the maximum axial width of the top portion of the tread groove (which may be substantially constant, or radially constant along the top portion) has one or more of the following:

[0114] less than 25%, preferably less than 20%, of the maximum axial width of the intermediate portion and / or of the tread groove;

[0115] greater than 5%, preferably greater than 10%, of the maximum axial width of the middle portion and / or of the tread groove;

[0116] Less than 10% of the maximum axial width of the shoulder groove;

[0117] Greater than 3% of the maximum axial width of the shoulder groove;

[0118] Typically, the maximum axial width of the shoulder groove exists at its radially outermost opening.

[0119] In another embodiment, the tread shoulder groove has one or more of the following over a majority of its circumferential length:

[0120] a substantially V-shaped cross-section, or V-shape, wherein, optionally, the bottom of the shoulder groove has a curved shape;

[0121] Two side walls having relative angles in the range of 75° to 85° with respect to the axial direction;

[0122] A shape that gradually narrows from its radially outermost part or radially outermost side to its radially innermost bottom.

[0123] In another embodiment, one or both side walls of the bottom portion extend rectilinearly over at least 70% of the radial height of the bottom portion in cross section.

[0124] In yet another embodiment, in cross section, one or both side walls of the middle portion extend straight over at least 25% of the radial height of the middle portion. Preferably, the angle of such straight portion or segment with the axial direction may be in the range of 25° to 60°, preferably from 30° to 55°.

[0125] In yet another embodiment, in cross section, the tread groove has an amphora-like cross-sectional shape. Optionally, in cross-sectional view, it has a bottleneck portion (i.e., top portion) which is narrower than the area radially below the bottleneck, and widens below the lower end of the bottleneck in a first portion (i.e., middle portion) to reach a maximum width, and a bottom portion below the first portion or middle portion shrinks again toward its radial bottom.

[0126] The present invention and embodiments refer to different types of circumferential ribs or circumferential tread ribs. The term rib or circumferential rib preferably also covers circumferential rows of tread blocks, which are optionally arranged one after another in the circumferential direction. This may apply in particular to shoulder ribs and / or center ribs. In addition, or alternatively, the multiple rows of tread blocks include tread blocks separated by lateral grooves. The lateral grooves may be angled with the axial direction. Such angles are preferably less than 40°, 30° or 20°. The lateral grooves may include sipes, such as zigzag sipes. The angle of the zigzag sipe mentioned herein is determined between the axial direction and the line connecting the two axial outermost ends of the zigzag sipe.

[0127] In yet another embodiment, the tread groove and / or the bottom portion of the tread groove has, at 5% of its total radial height, an axial width in the range of 30% to 60% of the maximum axial width of the tread groove and / or the middle portion of the tread groove, measured from the bottom of the tread groove in cross-section.

[0128] In yet another embodiment, and still in cross section, each sidewall of the tread groove has, in the middle portion, at least one point of inflection between the radial height of the maximum axial thickness and the radial height of the minimum axial thickness of the tread groove in the middle portion.

[0129] In another embodiment, a tangent line cooperating with said inflection point of the side wall has an angle with the axial direction in the range of 25° to 60°, preferably from 30° to 55°.

[0130] In another aspect, the invention relates to a tire comprising such a tread.

[0131] In one embodiment, the tire is selected from one or more of the following: a truck tire; a trailer tire; a 22.5 inch tire; a 24.5 inch tire; a pneumatic tire; a tire having three circumferential tread grooves and two circumferential shoulder grooves; a tire having four steel wire reinforced belt layers; a tire retreaded with a tread; a tire having a steel wire reinforced carcass ply; a tire having two bead areas, each bead area including a bead, a carcass ply extending between the two bead areas, wherein the carcass ply is radially covered by a reinforcing belt layer in the crown area of ​​the tire, and / or wherein the belt layer is arranged radially below the tread; a multi-layer tread having at least two radially superimposed tread (e.g., tread crown) layers, wherein the tread layer (e.g., tread crown layer) that contacts the road during driving defines or forms the bottom and / or sidewalls of the groove.

[0132] In another embodiment, the tire is one of a 22.5 inch truck tire, a 24.5 inch truck tire, a 22.5 inch truck trailer tire, and a 24.5 inch truck trailer tire.

[0133] In a second aspect, the invention relates to a tire having a tread, the tread comprising two tread shoulders, the two tread shoulders comprising a first tread shoulder and a second tread shoulder, and a tread center portion axially arranged between the two tread shoulders. The first tread shoulder comprises a first circumferential shoulder rib comprising a circumferential row of shoulder tread blocks, and the second tread shoulder comprises a second circumferential shoulder rib comprising a second circumferential row of shoulder tread blocks, wherein each shoulder rib is defined by a circumferential shoulder groove. The tread center portion comprises at least two adjacent circumferential tread ribs defining a circumferential tread groove. Each circumferential tread rib comprises a circumferential row of center tread blocks separated by lateral grooves. The tread groove has a top portion, a bottom portion and a middle portion radially located between the top portion and the bottom portion. In addition, the tread groove has a cross section over most of its circumferential length in which the maximum axial width in the top portion is at least 5% smaller than the axial width in the bottom portion, the axial width in the bottom portion being measured at 5% of the total radial height of the tread groove from the bottom of the tread groove (in the cross section). In addition, in the cross section, the axial width in the bottom portion measured at 5% of the total radial height of the tread groove from the bottom of the tread groove is at least 5% smaller than the maximum axial width of the tread groove in the middle portion of the cross section. In addition, still in the cross section, the maximum axial width in the middle portion is in the range of 15% to 50% of the total radial height of the tread groove.

[0134] In one embodiment, the tread has two, three or four circumferential central ribs and two circumferential shoulder ribs. Preferably, the tread has three circumferential central ribs.

[0135] In another embodiment, the majority of the lateral grooves comprise lateral sipes, preferably comprising a zigzag shape.

[0136] In yet another embodiment, the majority of the lateral grooves comprise a lateral cutout at each of the two axially outer ends of the lateral groove and / or at each adjacent tread block.

[0137] In yet another embodiment, in the circumferential row of central tread blocks of two axially outer (or outermost and / or opposite) central ribs, circumferentially adjacent tread blocks are separated by sipes having a zigzag shape. Optionally, every other sipe having a zigzag shape extends to the radially outermost surface of the adjacent tread block, and the remaining sipes having a zigzag shape of the central tread blocks of the same row extend from their radially inner bottom to a radial position at least 10% or 20% (and optionally at most 70%) below the radially outermost surface of the adjacent tread block. Optionally, at a position radially above said radial position, the corresponding lateral groove is circumferentially wider than the zigzag shape and / or is linear.

[0138] In another embodiment, in the central tread blocks of the circumferential row that intersects the equatorial plane of the tire, all of the tread blocks are separated by lateral zigzag sipes.

[0139] In yet another embodiment, the tire includes circumferential tread grooves axially divided by the equatorial plane of the tire.

[0140] Figure 1 A schematic cross-section of a tire 1 according to a preferred embodiment of the present invention is shown. The tire 1 has a tread 10, an inner liner 13, a belt structure 11 including four belt layers, a carcass ply 9, two sidewalls 2 and two bead areas 3 including a bead filler apex 5 and a bead 4. The example tire 1 is suitable for being mounted on a rim of a vehicle (e.g., a truck), for example. The carcass ply 9 includes a pair of axially opposite ends 6, each end 6 being fixed to a respective bead 4. Each axial end 6 of the carcass ply 9 is turned up and around a respective bead 4 to a position sufficient to anchor each axial end 6. The carcass ply 9 may be a rubber ply having a plurality of substantially parallel carcass reinforcement members (e.g., made of metal). The turned-up portion 6 of the carcass ply 9 may be engaged with the axially outer surfaces of the two bead core wrappers 8 and the axially inner surfaces of the two heel reinforcement layers 7. As Figure 1 As shown, the example tread 10 may have four circumferential grooves.

[0141] Still based on Figure 1 In the illustrated embodiment, the tire tread 10 has two axially outer shoulder ribs 40 and three central tread center ribs 50. The shoulder ribs 40 are bounded by one of the shoulder grooves 20. The grooves formed between the central tread ribs 50 are referred to herein as tread grooves 30. Figure 1As can be seen in FIG. 1 , the shoulder groove 20 and the tread groove 30 have different cross-sectional shapes, such as Figure 3a and 3b As described above, the tread ribs 40, 50 may comprise or be formed from a circumferential row of tread blocks.

[0142] An axial direction a, a radial direction r, and a circumferential direction c are indicated in the various figures herein. The axial direction a is parallel to the axis of rotation of the tire, the radial direction r is perpendicular to the axial direction a, and the circumferential direction c is perpendicular to the radial direction and the axial direction. Unless otherwise specified, a reference to one of these directions does not necessarily include a specific orientation.

[0143] FIG3A shows a tread groove 30 between two tread center ribs 50. The tread groove 30 has an overall height h. Along its height h, the groove 30 has three adjacent and / or continuous portions or segments, i.e., having a height h. t The top portion 31 has a height h b and a middle portion 32 directly adjacent and radially disposed between the top portion 31 and the bottom portion 33, wherein the middle portion 32 has a radial height h i The top portion 31 has a width w in this embodiment. t , which in this example is constant in the radial direction. The middle portion 32 has a varying width, with a maximum axial width of w max In particular, the width of the middle portion 32 increases continuously from a radially upper position to a radially lower position. The bottom portion 33 also has a varying width, having an axial width w measured at a radial position of 5% of the total radial height h from the bottom of the tread groove 30. b While the top portion 31 preferably has a constant axial groove width, the axial width of the middle portion 32 of the groove 30 increases until reaching a maximum value at the lower end of its bottom / middle portion 32. From this radial position, the axial width of the groove 30 gradually narrows in its bottom portion 33 toward the bottom of the groove 30. Unless otherwise specified herein, the width of the groove is measured in the axial direction from one sidewall 35 of the groove to the opposite sidewall 36 of the same groove, and / or the height is measured in the radial direction.

[0144] It is noted herein that the cross-section of the groove 30 shown in FIG. 3 applies along a majority of the circumferential length of the groove 30. In particular, the tread 10 and / or the ribs 40, 50 may include lateral grooves, for example, separating adjacent tread blocks. For example, such a cross-section or other circumferential cross-sections shown herein may be present over at least 50% or at least 70% of the circumferential length of the respective circumferential groove. Similarly, such a cross-section may also be present over at least 50% or at least 70% of the circumferential length of the tread block (or, in other words, each tread block) forming the sidewall of the respective groove.

[0145] Still according to the same non-limiting embodiment, the width w t Preferably in the range of 2% to 10%, preferably to 6%, of the total radial height h, and / or less than the maximum axial width w of the middle portion 32 / tread groove 30 max In one example, the width w t It is in the range of 0.5 mm to 2 mm, preferably to 1.5 mm.

[0146] The maximum width w of the groove 30 and / or the middle portion 32 max Preferably in the range of 20% to 45% of the total radial height h, preferably in the range of 20% to 35%, or in the range of 20% to 30%, and / or in the example, in the range of 4mm to 9mm, or preferably in the range of 5mm to 8mm.

[0147] Width b Preferably in w max In one example, the width w is in the range of 30% to 60% of the height h and / or in the range of 6% to 19% of the height h. b It may be in the range of 1.5mm to 4mm, or from 2mm to 3.5mm.

[0148] In this embodiment, the overall height h is optionally in the range of 20 mm to 50 mm (or to 40 mm, or only to 30 mm).

[0149] Height t Preferably in the range of 30% to 40% of the radial height h, and / or 7 mm to 12 mm, preferably from 7 mm to 10 mm.

[0150] Height i Preferably in the range of 10% to 25% of the radial height h, and / or preferably in the range of 2 mm to 7 mm, or 3 mm to 6 mm.

[0151] Height b Preferably, it is in the range of 40% to 55% of the radial height h and / or from 9 mm to 14 mm.

[0152] In the conical bottom portion 33 , the side walls 35 , 36 (and / or their straight portions as described herein) may have an angle β with the axial direction α, which angle β is preferably in the range of 75° to 89°, preferably from 75° to 85°.

[0153] Preferably, the parts or sections of the side walls 35, 36 in the bottom portion 33 may extend straight over at least 70% of their length from a radially outer position to a radially inner position.

[0154] The middle portion 32 preferably has an inflection point between its radial top and radial bottom. At the inflection point, a tangent line cooperating with one of the side walls 35, 36 preferably has an angle α with the axial direction a, which is in the range of 40° to 55°, preferably from 40° to 50°.

[0155] Optionally, one or both of the side walls 35, 36, or sections of the side walls 35, 36, are straight over at least 25% of the radial height of the middle portion 32. The angle α of such straight sections with the axial direction α may be in the range of 40° to 55°, preferably from 40° to 50°.

[0156] Figure 3b An enlarged view of the shoulder groove 20 is shown, and its scale is similar to Figure 3a The (center) tread groove 30 shown in is substantially the same. The total height of the groove 20 is shown as h and corresponds substantially to the height h of the groove 30 in this example. The sidewalls 25, 26 of the shoulder groove 20 taper in the radially inward direction, each sidewall having an absolute angle γ with the axial direction a in the range of 75° to 85°. The width W of the shoulder groove 20 at the (radially outermost) groove opening leading to the (outermost) tread surface is in the range of 50% to 70% (preferably 55% to 65%) of the total radial groove height H, for example, it may be from 12 mm to 16 mm or from 13 mm to 15.5 mm. The width W b It is measured at 5% of the radial height H and may be in the range of 15% to 25% of H, and / or in the range of from 25% to 40% of W, and / or in the range of from 3 mm to 7 mm, preferably in the range of from 4 mm to 6 mm.

[0157] and Figure 3a similar, Figure 4a Shown with Figure 2 Another embodiment of a tread groove 30 ′ of a corresponding design is schematically shown in FIG.

[0158] In particular, according to this embodiment of the present invention, Figure 2A tire 1' is shown, which has a tread 10', the tread 10' having a shoulder rib 40', a (center) tread rib 50', a shoulder groove 20' and a (center) tread groove 30'. The groove design of the tire tread 10' is similar to that according to Figure 1 The groove design of the tread 10 is different.

[0159] Figure 4a It shows that Figure 2 An enlarged view of a groove 30' between two tread grooves 50' of a tire 1' is shown, showing a full groove height h', a top portion 31' of the groove 30' having a height h'. t ', the height of the middle part 32' is h i ', the height of the bottom portion 33' is h b ', the width of the top portion 31' is w t ', the maximum width of the middle part 32' is w max ', and the width of the bottom portion 33' of the groove 30' determined at 5% of the total height h' of the groove 30' is w b '. The side walls 35', 36' (in particular, their straight parts or segments) have an angle β' with the axial direction in the bottom part 33'. Furthermore, in the middle part 32', the side walls 35', 36' (or their straight parts or segments) have an angle α' with the axial direction at the inflection point between the radial inner end of the top part 31' and the radial outer end of the bottom part 33'.

[0160] for Figure 4a In the embodiment, the width w t 'Preferably in the range of 4% to 10% of the total radial height h' and / or less than the maximum axial width w of the middle portion 32' / the entire groove 30' max '. In one example, the width w t 'In the range of 0.5mm to 2mm, preferably to 1.5mm.

[0161] The maximum width w of the groove 30' or the middle portion 32' max Preferably in the range of 20% to 50%, preferably from 30% to 50% of the total radial height h', and / or in the example in the range of 4mm to 9mm, or preferably 5mm to 8mm.

[0162] Width b 'Preferably in w max In one example, the width w is in the range of 30% to 60% of the height h' and / or in the range of 10% to 25%, preferably 15% to 25%, of the height h'. b 'Can be in the range of 1.5mm to 4mm, or in the range of 2mm to 3.5mm.

[0163] The overall height h' is optionally in the range of 10 mm to 30 mm (or from 10 mm to 25 mm or to 20 mm).

[0164] Height t 'Preferably in the range of 15% (or 20%) to 40% (or 30%) of the radial height h', and / or 2mm to 7mm, preferably from 3mm to 6mm.

[0165] Height i Preferably, it is in the range of 20% to 40% of the radial height h' and / or preferably in the range of 4 mm to 6 mm.

[0166] Height b 'Preferably in the range of 35% to 55% of the radial height h', and / or from 4 mm to 8 mm.

[0167] At least one of the side walls 35', 36' (and / or its straight section) tapers in the bottom portion 33', forming an angle β' with the axial direction, which is preferably in the range of 65° to 80°, preferably from 70° or 71° to 79° or 75°.

[0168] The middle section 32' preferably has an inflection point between its radial top and radial bottom. At the inflection point, the side walls 35', 36' preferably have an angle α' with the axial direction a, the angle α' being in the range of 30° to 55°, preferably from 35° to 50°. In addition, or alternatively, the straight sections of the side walls 35', 36' have an angle α' with the axial direction a in the middle section 32', the angle α' being in the range of 30° to 55°, preferably from 35° to 50°.

[0169] Figure 4b An enlarged view of the shoulder groove 20' is shown, and its scale is similar to Figure 4a The (center) tread groove 30' shown in is substantially identical to the (center) tread groove 30' shown in . The total height of the groove 20' is shown as H' and corresponds substantially to the height h' of the tread groove 30' in this example. The sidewalls 25', 26' of the shoulder groove 20' taper in the radially inward direction and have an absolute angle γ' with the axial direction in the range of 75° to 85°. The shoulder groove width at the (radially outermost) groove opening to the (outermost) tread surface is indicated as W' and is in the range of 60% to 80% of the total radial groove height H' and can be, for example, from 9 mm to 14 mm or from 10 mm to 13 mm. The width W b ' is measured at 5% of the radial height H' and may be in the range of 15% to 35% of H', and / or in the range of 25% to 40% of W', and / or in the range of from 3mm to 7mm, preferably in the range of from 4mm to 6mm.

[0170] In general, the treads 10, 10' may have more axial / lateral grooves not depicted herein. They may also have sipes, such as winter / snow sipes and / or zigzag sipes. They may also have additional grooves extending in other directions and / or depths.

[0171] The grooves mentioned herein may generally have two opposite side walls and / or may have opposite side walls extending from the bottom of the groove in a radially outward direction at opposite angles. In particular, the opposite side walls (or parts or segments thereof) may have opposite angles, such that the side walls gradually narrow from a radially outer position to a radially inner position at such opposite angles.

[0172] Unless otherwise stated, the descriptions of groove geometry and / or design herein are presented for a new and / or unworn tire. The groove width and / or cross-sectional shape will (intentionally) change as the tire tread wears.

[0173] Figure 5 A perspective side view of another tire 1″ according to a preferred embodiment of the present invention is shown. The tire 1″ includes a tread 100 having two shoulder ribs 400. Each shoulder rib 400 includes a row of circumferential shoulder tread blocks. In addition, the tire 1″ has a tread center portion, which includes three tread center ribs, including two axially outer center ribs 510 and one axially inner center rib 520, which are arranged along the equatorial plane of the tire (not explicitly shown). Each center rib 510, 520 includes a row of circumferential tread blocks, which are separated by lateral grooves. In particular, the center rib 520 includes tread blocks separated by lateral grooves, which include zigzag sipes 630. The axially outer center rib 510 includes tread blocks, which are also separated by lateral grooves, which include zigzag sipes. However, although the axially outer center rib 510 Every other tread block of is separated from its circumferentially adjacent tread blocks by a groove 620 including a zigzag sipe (similar to groove 630), but the remaining tread blocks thereof are separated by a groove 610 which includes a sipe (particularly a zigzag sipe) only in the radially lower portion of groove 610. In other words, in grooves 620 and 630, the respective zigzag sipes extend to the radially outermost surface of the adjacent tread blocks, whereas in groove 610, the zigzag sipes extend only over a portion of the total radial depth of groove 610. The radial top of groove 610 is wider in the circumferential direction than its zigzag sipe and is substantially linear or straight in the transverse direction.

[0174] According to this embodiment of the invention, the tire 1 ″ further comprises a circumferential tread groove 300 axially separating axially adjacent center ribs 510, 520. In this case, the tire 1 ″ has two such circumferential tread grooves 300. Preferably, these grooves 300 have a cross section over at least 50% of their circumferential length, which cross section has been described in other embodiments herein. In particular, this applies to the cross section between two axially adjacent tread blocks of two axially adjacent tread center ribs 510, 520.

[0175] like Figure 5 As further shown, the lateral grooves 610, 620, 630 have cutouts 710, 720 at their respective axially outer ends. In particular, these cutouts 710, 720 extend in the radial direction to the bottom of the lateral grooves and / or the circumferential grooves. In other words, preferably, one cutout is provided at each of the four corners of the tread block. At the positions where the four corners of the four tread blocks face each other and / or are adjacent, the cutouts of the four adjacent corners together form a radially extending channel, which preferably extends from the radial outer surface of the tread 100 to the bottom of the adjacent lateral grooves.

[0176] Furthermore, the tread 100 has two circumferential shoulder grooves 200 which have a V-shaped cross section over at least 50% of the circumferential length. This applies in particular to the cross section between axially adjacent tread blocks.

[0177] The present invention and / or one or more embodiments thereof provide improved tread designs. In particular, the groove designs disclosed herein can help improve tread stiffness and / or rolling resistance early in the life of the tire. The increased tread stiffness can also help improve tread wear early in the life of the tire. In addition, wet traction can be improved, especially when the tread is partially worn. In other words, when the gaps in the tread features (such as lateral grooves, sipes, etc.) are large, the proposed groove design can help improve tread wear and / or rolling resistance by at least partially increasing the tread stiffness. When the tread features are not so rich, the groove width is increased to improve wear traction and / or drainage. The groove cross-sections proposed herein can also make demolding easier and / or have reduced stone retention performance.

[0178] The above-mentioned aspects, embodiments and features thereof may be combined with each other.

[0179] According to the description provided herein, the present invention can be varied. Although certain representative embodiments and details have been shown for the purpose of illustrating the present invention, it will be appreciated by those skilled in the art that various changes and modifications may be made thereto without departing from the scope of the present invention. Therefore, it should be understood that the specific embodiments described may be varied and these variations will be within the full intended scope of the present invention as defined by the following appended claims.

Claims

1. A tire, comprising: A tread having tread grooves extending continuously in a circumferential direction; The tread groove has a top portion, a bottom portion and a transition portion between the top portion and the bottom portion. Wherein, the maximum axial width of the tread groove in the top portion is 2 mm, wherein the tread groove has opposing side walls, and wherein the opposing side walls taper toward each other in a bottom portion, The opposite side walls in the transition portion gradually widen away from each other.

2. The tire according to claim 1, wherein the bottom portion has a minimum width wb in the range of 1.5-3.5 mm. 3 . The tire according to claim 1 , wherein the grooves have a maximum width Wmax in the range of 4 to 9 mm. 4 . The tire according to claim 1 , wherein the grooves have a maximum width Wmax in the range of 5 to 7 mm. The tire according to claim 1 , wherein the groove has a maximum width Wmax in the transition section.

6. The tire of claim 1, wherein a ratio of Wmax to Wb is in the range of 1.5-2.

5.

7. The tire of claim 1, wherein the maximum width of the groove is located at a radial height in the range of 40-60% of the total radial height.

8. The tire of claim 1, wherein the maximum width of the groove is located at 50% of the radial height.

9. A tire comprising a tread according to claim 1.

10. A tire tread, comprising: two tread shoulders, including a first tread shoulder and a second tread shoulder; The central part of the tread arranged axially between the two tread shoulders. wherein the first tread shoulder comprises a first circumferential shoulder rib and the second tread shoulder comprises a second circumferential shoulder rib, and wherein each shoulder rib is defined by a circumferential shoulder groove, wherein the tread center portion includes at least two adjacent circumferential tread ribs defining a circumferential tread groove, wherein the tread groove has a top portion, a bottom portion, and a middle portion radially between the top portion and the bottom portion; Therein, the tread groove has, over most of its circumferential length, a cross section in which: the maximum axial width in the top portion is at least 5% less than the axial width in the bottom portion measured at 5% of the total radial height of the tread groove from the bottom of the tread groove; wherein The axial width in the bottom portion, measured at 5% of the total radial height of the tread groove from the bottom of the tread groove, is at least 5% less than the maximum axial width of the tread groove in the middle portion; and wherein The maximum axial width of the tread groove in the middle portion is in the range of 15% to 50% of the total radial height of the tread groove.

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