Patent Description:
The documents <CIT> and <CIT> disclose treads for heavy truck tires.

Manufacturers of heavy commercial vehicle tires have made progress in developing tire architectures and tire materials that increase the wear resistance of tire treads and reduce the rolling resistance of tires while at the same time improving their level of grip and resistance to road hazards. 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 a slow-wearing usage, the more irregular wear is affecting the removal mileage. This is why resistance to irregular wear is of paramount importance for truck tires in the so-called long haul steer usage.

It is known to include structural features in tires to fight irregular wear. For example, a sacrificial rib can be incorporated into the tread architecture to delay the onset of irregular wear. However, this feature is sensitive to curbing aggression and its use may not be practical outside of North American long haul applications. Other sculptural features that can combat irregular wear include microsipes and inclined microsipes. These are small grooves that extend generally in the lateral, width direction of the tire. Unfortunately, these features are unusable in severe usage applications due to aggression concerns. Aggression on tires is a concern in growing or emerging markets that feature roadways that subject the tire to more severe usage that functions to tear up and wear down the tread at a higher rate than roads that are smoother and in better condition.

Stone ejectors are sculptural features of tires that are located in grooves of the tread that function to remove stones from the grooves and prevent stones from drilling into the belts and carcass of the tire. The stone ejectors are blocks of rubber at the bottom of the grooves and generally do not extend all the way to the upper surface of the tread, at least not when the tire is new. The stone ejectors work by flexing or compressing in and out of the contact patch as the tire rotates in order to push stones present within the groove out of the groove. However, stone ejectors do not function to decrease abnormal wear in tires. As such, there remains room for variation and improvement within the art.

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

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.

The present invention provides for an inclined stone ejector <NUM> that provides a coupling force that reduces or eliminates irregular wear. This coupling force is produced by including an inclined upper surface <NUM> on the stone ejector <NUM> that is oriented in the direction of rotation of the tire <NUM>. As the tire <NUM> enters the contact patch, the stone ejector <NUM> creates a coupling force x/z that mimics forces generated by other, less robust sculptural features such as sacrificial ribs, micro sipes, and inclined micro sipes. In this regard, x is the forward/rolling component, and z is the vertical component of force. Although described as having an inclined upper surface <NUM>, the upper surface <NUM> in some arrangements need not be inclined, or continuously inclined, but need only have a portion closer to its back edge <NUM> that is higher, thicker than a portion closer to its front edge <NUM>.

<FIG> shows a tire <NUM> that is a heavy duty truck tire <NUM>. In this regard, the tire <NUM> is not designed for nor used with a car, motorcycle, or light truck (payload capacity less than <NUM>,<NUM> pounds), but is instead designed for and used with heavy duty trucks such as <NUM> wheelers, garbage trucks, or box trucks. The tire <NUM> may be a steer tire, a drive tire, a trailer tire, or an all position tire. The tire <NUM> includes a carcass <NUM> onto which a tread <NUM> is disposed thereon. The central axis <NUM> of the tire <NUM> extends through the center of the carcass <NUM>, and the axial direction <NUM> of the tire <NUM> is parallel to the central axis <NUM>. The axial direction <NUM> can also be referred to and known as the inboard/outboard direction <NUM>. The radial direction <NUM> of the tire <NUM> is perpendicular to the central axis <NUM>, and the tread <NUM> is located farther from the central axis <NUM> in the radial direction <NUM> than the carcass <NUM>. The tread <NUM> extends all the way around the carcass <NUM> in the circumferential direction <NUM> of the tire <NUM> and circles the central axis <NUM><NUM> degrees.

The tread <NUM> features five ribs that are separated by four longitudinal grooves that extend in the circumferential direction <NUM>. The ribs and grooves may extend completely around the tire <NUM> in the circumferential direction <NUM>. The five ribs can be classified as a central rib, two intermediate ribs, and two shoulder ribs. In <FIG>, only one of the intermediate ribs <NUM> is labeled, and this intermediate rib <NUM> is located next to the only labeled shoulder rib <NUM>. A longitudinal groove <NUM> separates the intermediate rib <NUM> from the shoulder rib <NUM>. The shoulder rib <NUM> may be a sacrificial rib in some embodiments. Although five ribs and four grooves are shown in the illustrated embodiment, any number of ribs can be present in other exemplary embodiments. The ribs can each be made up of a number of tread blocks that can have various shapes, sizes, and configurations. The inclusion of these architectural features gives the tread <NUM> different performance properties in use. The tread <NUM> may include certain structural features that can reduce abnormal wear. One such structural feature shown with reference to <FIG> may be directional sipes that extend across the tread blocks of the ribs in the axial direction <NUM>.

Stone ejectors <NUM> are located in the groove <NUM> between the intermediate rib <NUM> and the shoulder rib <NUM>. The stone ejectors <NUM> extend along the entire length of the groove <NUM> in the circumferential direction <NUM> and thus extend <NUM> degrees around the central axis <NUM>. The stone ejectors <NUM> are spaced from one another in the circumferential direction <NUM> and are likewise spaced from the ribs <NUM>, <NUM> in the axial direction <NUM>. However, in other arrangements, the stone ejectors <NUM> may engage the intermediate rib <NUM>, and/or the shoulder rib <NUM>. The tire <NUM> also includes another groove located adjacent the other shoulder rib and stone ejectors <NUM> are likewise present within this other groove. The grooves between the center rib and the intermediate ribs do not include stone ejectors <NUM>. However, in other embodiments they may be present within these grooves as well.

Although described in connection with a tire <NUM>, the tread <NUM> having the stone ejectors <NUM> may alternatively be provided as a retread band <NUM> that may be subsequently attached to a carcass <NUM> through a retread process. An example of a retread band <NUM> is illustrated in <FIG> that has five ribs and four grooves that span across the tread <NUM> in the axial direction <NUM> which is the inboard/outboard direction <NUM> of the tread <NUM>. Stone ejectors <NUM> are located in the grooves between the shoulder ribs and the intermediate ribs. One of the intermediate ribs <NUM> is labeled and it along with the adjacent labeled shoulder rib <NUM> partially defines the labeled groove <NUM>. The labeled groove <NUM> is further defined at its bottom by the tread <NUM> and is open at its top. The retread band <NUM> is directional in that it has a specified rolling direction <NUM> in which at least the stone ejectors <NUM> are oriented. There may or may not be other directional features on the tread <NUM> that likewise cause the retread band <NUM> to be directional above and beyond just the stone ejectors <NUM>.

The stone ejectors <NUM> are arranged so that their front sides <NUM> are oriented towards the direction of the rolling direction <NUM>, and so that their oppositely disposed back sides <NUM> are oriented away from the rolling direction <NUM>. The stone ejectors <NUM> have an outboard side <NUM> that directly faces the shoulder rib <NUM>, and an inboard side <NUM> that directly faces the intermediate rib <NUM>. The upper surface <NUM> of the stone ejectors <NUM> are visible and are inclined relative to the bottom <NUM> of the grooves <NUM>, although this cannot be easily distinguished in <FIG>. The stone ejectors <NUM> are spaced from the shoulder rib <NUM> and the intermediate rib <NUM> and are free from contact with both of these ribs <NUM>, <NUM>. In other arrangements, the stone ejector <NUM> may engage the intermediate rib <NUM> and/or the shoulder rib <NUM>. The shoulder rib <NUM> may be a sacrificial rib in certain embodiments. Further, although shown as being between the intermediate ribs and the shoulder ribs, the stone ejectors <NUM> could likewise or alternatively be within any other groove or grooves of the tread <NUM>, such as the grooves formed between the center rib and the adjacent intermediate ribs. The retread band <NUM> with the tread <NUM> may be of any length and width and can be crafted for tires <NUM> of varying sizes.

<FIG> illustrate a stone ejector <NUM> in accordance with one exemplary embodiment that features an inclined upper surface <NUM>. As shown in <FIG>, the stone ejector <NUM> extends upwards from the bottom <NUM> of the groove <NUM>. The tread <NUM> is new tread and the stone ejector <NUM> extends upwards in the radial direction <NUM> to a point that is below the extension of the shoulder rib <NUM> in the radial direction <NUM>. When the tire <NUM> rotates, the stone ejector <NUM> will not engage the ground <NUM> as it is below the upper surfaces of the shoulder ribs <NUM> and intermediate ribs <NUM>. The stone ejector <NUM> in such instances will not impact the problem of abnormal wear. Once the tread <NUM> begins to wear down the upper surfaces of the intermediate rib <NUM> and the shoulder rib <NUM> will erode in the radial direction <NUM> and the upper surface <NUM> of the stone ejector <NUM> will contact the ground <NUM> and will begin to impact and reduce the problem of abnormal wear.

The base of the stone ejector <NUM> has fillets that join the bottom <NUM> of the groove <NUM> formed by the tread <NUM>. The fillets need not be present in other embodiments. The stone ejector <NUM> has a front side <NUM> that is angled relative to the radial direction <NUM>. The front side <NUM> extends at an angle <NUM> to the radial direction <NUM> such that the front side <NUM> extends from the bottom <NUM> to the upper surface <NUM> at an angle <NUM>. Angle <NUM> is an obtuse angle and may be various degrees in different versions of the stone ejector <NUM>. For example, angle <NUM> can be from <NUM>-<NUM> degrees, from <NUM>-<NUM> degrees, from <NUM>-<NUM> degrees, from <NUM>-<NUM> degrees, or up to <NUM> degrees in accordance with different exemplary embodiments. In other embodiments, the angle <NUM> may be <NUM> degrees. Although described as being an obtuse angle <NUM>, in other versions of the stone ejector <NUM>, angle <NUM> can be an acute angle or a right angle. The front side <NUM> is a flat surface. The stone ejector <NUM> has a back surface <NUM> that is likewise flat and that extends outward in the radial direction <NUM> from the bottom <NUM>. The back surface <NUM> is oriented at a ninety degree angle to the bottom <NUM>. The rolling direction <NUM> is illustrated in <FIG> and is the direction the tire <NUM> rotates. In this regard, the front side <NUM> is before the back side <NUM> such that the front side <NUM> will enter the contact patch before the back side <NUM> when the tire <NUM> rotates.

The upper surface <NUM> of the stone ejector <NUM> extends at different distances from the bottom <NUM> in the radial direction <NUM>. In particular, a first location <NUM> on the upper surface <NUM> is located closer to the back side <NUM> than a second location <NUM> on the upper surface. In turn, the second location <NUM> is located closer to the front side <NUM> than the first location <NUM> is to the front side <NUM>. The first location <NUM> is located farther from the bottom <NUM> in the radial direction <NUM> than the second location <NUM>. In this regard, the upper surface <NUM> at the first location <NUM> is farther from the bottom <NUM> than is the upper surface <NUM> at the second location <NUM>. The front edge <NUM> of the upper surface <NUM> engages the front side <NUM>, and the back edge <NUM> of the upper surface <NUM> engages the back side <NUM>. The first location <NUM> is located at the back edge <NUM>, and the second location <NUM> is located at the front edge <NUM>. However, in other arrangements, the first and second locations <NUM>, <NUM> need not be at the front and back edges <NUM>, <NUM>. The upper surface <NUM> is continuously inclined from the front edge <NUM> to the back edge <NUM> so that at all points closer to the back edge <NUM> are farther from the bottom <NUM> in the radial direction <NUM> than points closer to the front edge <NUM>. The first location <NUM> at the back edge <NUM> may be <NUM> millimeter farther from the bottom <NUM> in the radial direction <NUM> than the second location <NUM> at the back edge <NUM> is to the bottom <NUM> in the radial direction <NUM>.

In other versions, the upper surface <NUM> need not be continuously inclined all the way from the front edge <NUM> to the back edge <NUM>, but could have some portions located closer to the back side <NUM> closer to the bottom <NUM> in the radial direction <NUM> than portions closer to the front side <NUM>. However, the upper surface <NUM> will still have somewhere a first location <NUM> closer to the back side <NUM>, and a second location <NUM> closer to the front side <NUM>, where the distance in the radial direction <NUM> from the bottom <NUM> to the upper surface <NUM> is longer to the first location <NUM> than to the second location <NUM>. The upper surface <NUM> when inclined can be any amount of inclination, so long as it is greater than zero degrees and not a flat surface parallel to the bottom <NUM>.

It is to be understood that the drawings in <FIG>, <FIG> show the bottom <NUM> being flat. The tread <NUM> could be a retread and thus in fact have a flat bottom <NUM>. Alternatively, the tread <NUM> can be in a tire <NUM> which is a round object. The bottom <NUM> may be curved as well, and the stone ejector <NUM> can also exhibit some amount of curvature due to the roundness of the tire <NUM>. However, the figures illustrate the bottom <NUM> and the stone ejectors <NUM> being flat without this curvature for sake of clarity in the description.

With reference now to <FIG> and <FIG>, the stone ejector <NUM> has an inboard side <NUM> that directly faces the intermediate rib <NUM>, and an outboard side <NUM> that directly faces the shoulder rib <NUM>. The direct facing means that no other component is located between the two facing components. The inboard side <NUM> is a flat surface and is inclined in the axial direction <NUM>. Similarly, the outboard side <NUM> is also a flat surface inclined in the axial direction <NUM> an identical magnitude as the inboard side <NUM>. The outboard side <NUM> is free from engagement with the shoulder rib <NUM>, and the inboard side <NUM> is free from engagement with the intermediate rib <NUM>. The back side <NUM> extends a longer distance in the axial direction <NUM> than does the front side <NUM> so that the back side <NUM> is wider than the front side <NUM>. In this regard, the inboard side <NUM> extends in the inboard direction upon its extension from the front side <NUM> to the back side <NUM>. The outboard side <NUM> extends in the outboard direction <NUM> upon its extension from the front side <NUM> to the back side <NUM>. Although shown as being symmetrical relative to the front and back sides <NUM>, <NUM>, the inboard and outboard sides <NUM>, <NUM> may be asymmetrical in other embodiments. It is to be understood that <FIG> show only a single one of the stone ejectors <NUM>, and only portions of the intermediate rib <NUM> and the shoulder rib <NUM> and that the tread <NUM> can include multiple ones of the stone ejectors <NUM> and other sections of the tread <NUM>. Other figures in the drawings likewise only disclose portions of the tread <NUM> and not all of the tread <NUM>.

<FIG> is a side view of a pair of sequential stone ejectors <NUM> of the tread <NUM>. They are both shaped and sized the same as one another and have front sides <NUM> and back sides <NUM> that extend outwards in the radial direction <NUM> at ninety degree angles to the bottom <NUM>. The upper surfaces <NUM> are both organized so that they are continuously inclined with first locations <NUM> at the back edges <NUM> farther from the bottom <NUM> than second locations <NUM> located at the front edges <NUM>. The stone ejectors <NUM> are spaced from one another along the bottom <NUM> so that they do not contact one another, and directly face one another. The upper surfaces <NUM> of all of the stone ejectors <NUM> of the entire tire <NUM> can all be arranged with higher first locations <NUM> than second locations <NUM>.

<FIG> shows a pair of sequential stone ejectors <NUM> arranged in the same manner as one another. The upper surface <NUM> of the stone ejector <NUM> has a concave shape that extends all the way from the front edge <NUM> to the back edge <NUM>. The first location <NUM> is located at the back edge <NUM> and extends a farther distance in the radial direction <NUM> from the bottom <NUM> than does the second location <NUM> located at the front edge <NUM>. The upper surface <NUM> could be convex in other arrangements of the stone ejector <NUM>. The back side <NUM> is angled relative to the bottom <NUM> so that it does not extend at a ninety degree angle to the bottom <NUM>. Here, the back side <NUM> is oriented at an angle <NUM> to the bottom <NUM> and is an obtuse angle such that the back side <NUM> extends from the back edge <NUM> to the bottom <NUM> in a direction away from the rolling direction <NUM>. Angle <NUM> may be from <NUM>-<NUM> degrees, from <NUM>-<NUM> degrees, from <NUM>-<NUM> degrees, from <NUM>-<NUM> degrees, or up to <NUM> degrees in accordance with various exemplary embodiments. As can be seen the two stone ejectors <NUM> in <FIG> have angles <NUM> that are of different magnitudes so that the back sides <NUM> are oriented at different inclinations to the bottom <NUM>. However, the angles <NUM> could be the same in other arrangements so that all of the stone ejectors <NUM> are identical to one another.

<FIG> shows another embodiment of the stone ejector <NUM> that again has a front side <NUM> and a back side <NUM> that extend ninety degrees to the bottom <NUM>. The upper surface <NUM> has a first location <NUM> that is closer to the back side <NUM> than a second location <NUM>. The second location <NUM> is closer to the front side <NUM> than the first location <NUM>. The upper surface <NUM> at the first location <NUM> extends a farther distance from the bottom <NUM> in the radial direction <NUM> than does the upper surface <NUM> at the second location <NUM>. The first location <NUM> is spaced from the back edge <NUM> in the rolling direction <NUM> and is not located at the back edge <NUM>. Likewise, the second location <NUM> is spaced from the front edge <NUM> in the rolling direction <NUM> and is not located at the front edge <NUM>. It is to be understood that the first and second locations <NUM>, <NUM> need not be located at the front and back edges <NUM>, <NUM>. The upper surface <NUM> is stepped in that it is arranged as a series of four steps from the front edge <NUM> to the back edge <NUM>. In other embodiments, any number of steps may be used such as two steps, three steps, from <NUM>-<NUM> steps, or up to <NUM> steps. The steps extend different distances from the bottom <NUM> in the radial direction <NUM>. The steps are arranged so that they continuously increase in distance from the bottom <NUM> in the radial direction <NUM> upon extension from the front edge <NUM> to the back edge <NUM>.

The upper surface <NUM> can be arranged in various embodiments so that it does not move closer towards the bottom <NUM> in the radial direction <NUM> at any point or points upon extension from the front edge <NUM> to the back edge <NUM>. Although the upper surface <NUM> may have the same distance from the bottom <NUM> in the radial direction <NUM> at different locations in the rolling direction <NUM>, for instance all of the points on the upper surface <NUM> at a single step are at different locations in the rolling direction <NUM> but are all the same distance in the radial direction <NUM>, nowhere does the upper surface <NUM> move closer to the bottom <NUM> upon extension of the upper surface <NUM> from the front side <NUM> to the back side <NUM>. In other embodiments of the stone ejector <NUM>, the upper surface <NUM> may in fact move closer to the bottom <NUM> at certain points in the direction of extension from the front edge <NUM> to the back edge <NUM>. The stone ejector <NUM> is arranged so that its upper surface <NUM> has a portion that extends to the upper surface of the shoulder rib <NUM> in the radial direction <NUM> so that they are located at the same distance in the radial direction <NUM>. The stone ejector <NUM> may therefore engage the ground <NUM> along with the shoulder rib <NUM> when the tire <NUM> is new. However, other embodiments show the upper surface <NUM> even at its highest point still lower than the upper surface of the shoulder rib <NUM> in the radial direction <NUM> and this distance may be up to <NUM> millimeters, or greater than <NUM> millimeters in accordance with different exemplary embodiments.

The stone ejector <NUM> in <FIG> has a flat front side <NUM> and a flat back side <NUM> that extend upwards in the radial direction <NUM> at ninety degree angles to the bottom <NUM>. The upper surface <NUM> is inclined and flat along its entire length from the front edge <NUM> to the back edge <NUM>. The front side <NUM> and the back side <NUM> extend the same width as one another in the axial direction <NUM>. The inboard side <NUM> is flat and is parallel to the side of the intermediate rib <NUM> that partially defines the groove <NUM>. The outboard side <NUM> is flat and is parallel to the side of the shoulder rib <NUM> that defines the groove <NUM>. The inboard and outboard sides <NUM>, <NUM> are parallel with one another and are of the same lengths as one another in the rolling direction <NUM>.

<FIG> show another exemplary embodiment of the stone ejector <NUM> that protects against abnormal tread <NUM> wear. The stone ejector <NUM> has a Y-shaped configuration with the wider portion located rearward in the rolling direction <NUM> and the more narrow portion located forward in the rolling direction <NUM>. The stone ejector <NUM> is spaced from the shoulder rib <NUM> and the intermediate rib <NUM> and is not in engagement therewith. The stone ejector <NUM> has an inboard prong <NUM> that defines a portion of the back edge <NUM>, and an outboard prong <NUM> that defines a different portion of the back edge <NUM>. The outboard prong <NUM> is outboard from the inboard prong <NUM> in the outboard direction <NUM> of the tire <NUM>. The inboard and outboard prongs <NUM>, <NUM> may be shaped and sized identical to one another and a void can be located between them at the centerline of the stone ejector <NUM>. The forward portion of the stone ejector <NUM> features a single prong <NUM> that is located at the midpoint of the stone ejector <NUM> in the axial direction <NUM>. The stone ejector <NUM> reaches its most narrow point in the axial direction <NUM> at the single prong <NUM>, and the front edge <NUM> is located at the single prong <NUM>. With reference in particular to <FIG>, the upper surface <NUM> is convex in shape continuously from the front edge <NUM> to the back edge <NUM>. The first location <NUM> is farther from the bottom <NUM> in the radial direction <NUM> than the second location <NUM>, and the locations <NUM>, <NUM> are spaced from the edges <NUM>, <NUM>. The upper surface <NUM> continuously increases from the front edge <NUM> to the back edge <NUM> in the radial direction <NUM>. This increase may be at the same rate, or at a different rate, but at no point in its extension rearward in the rolling direction <NUM> does the upper surface <NUM> move towards the bottom <NUM> in the radial direction <NUM>. The inboard side <NUM> and the outboard side <NUM> have concave shapes. At the inboard and outboard prongs <NUM>, <NUM> the sides <NUM> and <NUM> transition to convex shapes. In other embodiments of the stone ejector <NUM>, the inboard and outboard sides <NUM>, <NUM> are concave along their entire lengths from the front side <NUM> to the back side <NUM>.

The embodiment of the stone ejector <NUM> in <FIG> is Y-shaped, and this is but one example of the various shapes the stone ejector <NUM> can take. In other arrangements, the stone ejector <NUM> can be X-shaped, circular in shape, triangular in shape, or can be variously shaped. It is to be understood that the shapes of the stone ejectors <NUM> illustrated and described in the present application are only examples and that others are possible in accordance with other exemplary embodiments of the tread <NUM>.

With reference now to <FIG>, a cross-section view of portions of a tread <NUM> and carcass <NUM> are shown that illustrate another exemplary embodiment of the tire <NUM>. The stone ejector <NUM> is made up of a material that is different than the material making up an undertread layer <NUM> of the tire <NUM>. The carcass <NUM> is below this undertread layer <NUM> and includes belts and may be made of a different material than the undertread layer <NUM> and the stone ejector <NUM>. The stone ejector <NUM> is made of a different material than the shoulder rib <NUM>, and is made of a different material than the intermediate rib <NUM>. In some instances, the intermediate rib <NUM> and the shoulder rib <NUM> can be made of the same material as one another. The stone ejector <NUM> has a different hysteresis value than the ribs <NUM>, <NUM> and a different hysteresis value than the undertread layer <NUM>. In particular, the stone ejector <NUM> has a higher hysteresis value than the shoulder rib <NUM>, the intermediate rib <NUM>, and the undertread layer <NUM>.

Hysteresis can be measured by the tan(δ) value of the rubber making up the layer/component. The loss factor "tan(δ)" is a dynamic property of the rubber compound. It is measured on a viscosity analyzer (Metravib VA4000) according to Standard ASTM D5992-<NUM>. The response of a test specimen consisting of two cylindrical pellets each <NUM> millimeters 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 layer 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 <NUM>, at a temperature of <NUM>° C. The sweep covers amplitude of deformation from <NUM>% to <NUM>% peak to peak (on the outbound cycle) then from <NUM>% to <NUM>% peak to peak (on the return cycle). The results that are used here are the loss factor tan(δ) and the complex dynamic shear modulus. The complex dynamic shear modulus is denoted "G*<NUM>" in reference to the <NUM>% strain applied during the test. During the outbound cycle, the maximum value of tanδ that is observed is denoted "max tan(δ)".

In some embodiments, the max tan(δ) of the shoulder rib <NUM> and the intermediate rib <NUM> may be from <NUM>-<NUM>, and the max tan(δ) of the stone ejector <NUM> may be from <NUM>-<NUM>, in which the max tan(δ) of the stone ejector <NUM> is higher than the max tan(δ) of the ribs <NUM>, <NUM>. In certain embodiments the max tan(δ) of the undertread layer <NUM> is from <NUM>-<NUM> and the max tan(δ) of the stone ejector <NUM> is higher than the undertread layer and is greater than <NUM> and less than <NUM>. In certain embodiments, the max tan(δ) of the undertread layer <NUM> is the same as the max tan(δ) of the ribs <NUM>, <NUM>, and this max tan(δ) is less than the max tan(δ) of the stone ejector <NUM>. The max tan(δ) of the stone ejector <NUM> can be the same as, greater than, or less than the max tan(δ) of the undertread layer <NUM>, the shoulder rib <NUM>, the intermediate rib <NUM>, carcass <NUM>, or any other portion of the tire <NUM>, and the material making up the stone ejector <NUM> may be the same as or different from the material making up the undertread layer <NUM>, shoulder rib <NUM>, intermediate rib <NUM>, carcass <NUM> or any other portion of the tire <NUM>. The max tan(δ) of the stone ejector <NUM> may be any value in accordance with various exemplary embodiments. The undertread layer <NUM> may have the same max tan(δ) as the ribs <NUM>, <NUM> in certain embodiments.

The complex shear modulus for <NUM>% strain (G*<NUM>) at <NUM>, referred to herein as G*<NUM>, may be selected so that the G*<NUM> of the stone ejector <NUM> is greater than the G*<NUM> of the intermediate rib <NUM> and the G*<NUM> of the shoulder rib <NUM>. The G*<NUM> of the stone ejector <NUM> can be greater than the G*<NUM> of the undertread layer <NUM>. In this regard, the G*<NUM> can be used to gauge the rigidity of the material, and the stone ejector <NUM> may be selected so that it is more rigid than the shoulder rib <NUM>, the undertread layer <NUM>, and the intermediate rib <NUM>. In other embodiments, the G*<NUM> of the stone ejector <NUM> may be the same as that of the shoulder rib <NUM>, the undertread layer <NUM>, or the intermediate rib <NUM>. In some embodiments, the G*<NUM> of the stone ejector <NUM>, the undertread layer <NUM>, the intermediate rib <NUM>, and the shoulder rib <NUM> are from <NUM>-<NUM> MPa, with the stone ejector <NUM> being the highest or tied for the highest among these components. The G*<NUM> of the stone ejector <NUM> may be any number in other exemplary embodiments.

The stone ejector <NUM> may be provided with a high G*<NUM> and thus a greater rigidity than other tread <NUM> components because a more rigid stone ejector <NUM> may generate greater x/z coupling and function to better reduce abnormal wear. The higher G*<NUM> with the stone ejector <NUM> may also provide a better wear speed differential so that the stone ejector <NUM> wears slower than the rest of the useful tread <NUM> such as the shoulder rib <NUM> and the intermediate rib <NUM>. Although described as having a greater max tan(δ) and G*<NUM>, it is to be understood that one or both of these values of the stone ejector <NUM> may be the same as or less than those of the other components of the tire <NUM> such as the shoulder rib <NUM>, the intermediate rib <NUM>, the undertread layer <NUM>, and the carcass <NUM>.

The length, width, and height of the stone ejector <NUM> can be varied in order to achieve different performance properties. Also, the degree of slope of the upper surface <NUM> can be varied to again achieve different performance characteristics of the stone ejector <NUM>. The material that changes hysteresis and/or G*<NUM> of the stone ejector <NUM> versus other components of the tread <NUM> can be present in order to enhance these effects, or may not be present in accordance with different exemplary embodiments. The upper surface <NUM> having the different elevations generates forces in the contact patch of the tire <NUM> to fight irregular wear, and the presence of the stone ejector <NUM> still maintains the original intent of stone ejectors in preventing stone damage to the tire <NUM>. Since the orientation of the upper surface <NUM> allows for the minimization of abnormal wear, the tire <NUM> that has the stone ejectors <NUM> of the present disclosure are all directional tires <NUM>. The G*<NUM> of the stone ejector <NUM> can be the same as, greater than, or less than the G*<NUM> of the undertread layer <NUM>, the shoulder rib <NUM>, the intermediate rib <NUM>, the carcass <NUM>, or any other portion of the tire <NUM>. The G*<NUM> of the undertread layer <NUM> may be the same as the G*<NUM> of the shoulder rib <NUM> and the intermediate rib <NUM> in certain exemplary embodiments. The material making up the stone ejector <NUM> may be the same as or different from the material making up the shoulder rib <NUM>, intermediate rib <NUM>, undertread layer <NUM>, carcass <NUM>, or any other portion of the tire <NUM>.

The heel to toe aspect of the upper surface <NUM> generates a coupling force that in turn results in better irregular wear resistance. The stone ejector <NUM> engaging the ground <NUM> is illustrated with reference to <FIG> that shows the stone ejector <NUM> deformed in the contact patch and the entire upper surface <NUM> engaging the ground <NUM>. The rolling direction <NUM> is the direction the entire tire <NUM> is moving, but it is to be understood that different parts of the tire <NUM> move in different directions when rolling. For example, the stone ejector <NUM> illustrated in <FIG> is in fact moving in a direction opposite to the rolling direction <NUM> due to it being on the bottom of the tire <NUM> contacting the ground <NUM>. The front side <NUM> and the back side <NUM> are curved in shape upon engaging the ground <NUM> and being subjected to driving and weight forces. The orientation of the upper surface <NUM> as previously discussed presents a generally inclined surface to the ground <NUM> resulting in x and z force components to be generated on the stone ejector <NUM>. The driving force is applied to the adjacent shoulder rib <NUM> and this applied driving force to this rib <NUM> results in a decrease in abnormal wear of the shoulder rib <NUM>. The stone ejector <NUM> could be used to prolong the coupling effect that currently degrades linearly with tread <NUM> wear. The tire <NUM> may initially get its directionality from other structural features such as micro sipes, and may remain protected even when these structural features have lost their effectiveness from tread <NUM> wear as the stone ejectors <NUM> can begin to contribute to abnormal wear minimization or elimination. The stone ejectors <NUM> protect against aggression by preventing stones from drilling into the tread <NUM>, and the upper surface <NUM> orientation protects from irregular wear.

Claim 1:
A tread (<NUM>) for a heavy truck tire (<NUM>), said tread being directional in that it has a specified rolling direction (<NUM>), said tread comprising:
a longitudinal groove (<NUM>) that has a bottom (<NUM>); and
a stone ejector (<NUM>) located within the groove (<NUM>) that extends upwards from the groove bottom (<NUM>), wherein the stone ejector (<NUM>) has a front side (<NUM>) and a back side (<NUM>), wherein the stone ejector (<NUM>) has an upper surface (<NUM>) that extends at different distances upwards at different locations on the upper surface (<NUM>) such that a first location (<NUM>) on the upper surface (<NUM>) is located closer to the back side (<NUM>) and extends a longer distance upwards than a second location (<NUM>) on the upper surface (<NUM>) that is located closer to the front side (<NUM>), wherein the front side (<NUM>) is oriented towards the direction of the rolling direction (<NUM>) and wherein the back side (<NUM>) is oriented away from the rolling direction (<NUM>);
characterized in that the tread (<NUM>) further comprises:
a successive stone ejector (<NUM>) immediately successive to the stone ejector (<NUM>) in a circumferential direction (<NUM>) with a space present between the stone ejector (<NUM>) and the successive stone ejector (<NUM>), wherein the successive stone ejector (<NUM>) is shaped the same as the stone ejector (<NUM>) and has a successive stone ejector back side (<NUM>) that extends a longer distance upwards than a successive stone ejector front side (<NUM>) such that the successive stone ejector (<NUM>) is oriented the same as the stone ejector (<NUM>) in the circumferential direction (<NUM>).