Abstract:
Disclosed are several embodiments of a colorized tread marker for a tire, a method of manufacturing the tread markers, as well as a tire incorporating the colorized markers within the tire tread and a method for manufacturing the tire. The tread markers serve as both aesthetic complements to the tires&#39; visual appearance, such as indicia of the source of manufacture, distribution, or point of consumer purchase of the tire, as well as tread wear indicators that notify consumers when a tire is in need of replacement to help ensure the safety of a vehicle&#39;s occupants as well as the public at large.

Description:
RELATED APPLICATION DATA 
       [0001]    This application is a division of and claims priority to pending U.S. patent application Ser. No. 12/265,924, filed Nov. 6, 2008, which claims priority to U.S. provisional application Ser. No. 60/985,969 filed Nov. 6, 2007, each of which is incorporated herein by reference in its entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to tread markers for tires and tires that incorporate such markers. 
       BACKGROUND OF THE INVENTION 
       [0003]    The automobile is the most prevalent form of transportation. As the only point of contact between a speeding automobile and the roadway, pneumatic tires play a critical role in helping to ensure the safety of both a vehicle&#39;s occupants, as well as the safety of others who share common roadways. The tread of a tire is designed to provide traction under a variety of road conditions including wet roadways as well as slush-filled, snow-covered, and icy roadways. When tire tread wears thin, the tractive capacity of the tire is diminished to a point where the tires should be replaced. This occurs through the normal wear of tires, but can also occur, often in an accelerated manner, in the uneven wear of tires which are, for example, out of alignment, out of balance, or over/under inflated. Consequently, preventive maintenance by vehicle owners, such as keeping the tires in alignment, balanced, and properly inflated, can extend the tire&#39;s useful life while protecting a vehicle&#39;s occupants and others. 
         [0004]    Even though tires are so critical to people&#39;s safety, the condition of tires on an automobile is often overlooked by the busy owner. This is because tire tread is homogeneously colored and looks, at a glance, the same—day in and day out. This is compounded by the fact that tire makes and models, for the most part, look the same across the tire-making industry. Consequently, tires are commodity items in the mind of the consumer. 
         [0005]    What is needed is a tire that elevates the status of this critically important component of the automobile by grasping consumers&#39; attention while providing consumer value through the incorporation of tread wear indicators within the tire&#39;s tread. What is needed is a visually attractive tire whose tread contains an eye-catching logo, icon, trademark, or indicia of the source of manufacture, distribution, or point of consumer purchase while providing a continuous visual indication of the tire&#39;s wear status so that the consumer is able to discern, at a glance, the level of performance and safety he or she can expect from his or her tires. Furthermore, it would be of benefit to visually ascertain tire tread wear from a distance, not only when the vehicle is stationary, but also when it is moving, and to achieve these objectives in a cost effective, practical manner. 
         [0006]    The present disclosure solves many of the disadvantages associated with existing tires by providing insertable tread markers, tires containing insertable tread markers, as well as methods of making the tread markers and tires incorporating them. It will be appreciated that the disclosure may disclose more than one invention. The inventions are pointed out with particularity in the claims annexed hereto and forming a part hereof. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0007]    The inventions generally relate to tread markers that are inserted into the tread of a tire, methods of making the tread markers, tires that incorporate the tread markers, and methods of manufacturing the tires. The tread markers may be multicolored to provide a visual indication of the level of wear at a particular location in the tire. A change in color of the tread marker, as viewed by a consumer as a tire&#39;s tread wears, may particularly indicate when a tire is approaching the end of its effective life, has reached the end of its effective life, or it may indicate a percentage of the tire&#39;s life expended or remaining. In addition, the marker may be used to indicate an end of a warrantee, or an end of a certain level of safety for a particular type of road condition, such as wet or icy or snowy roadways, for example. The tread markers may also display a popular icon or symbol, or provide indicia of the source of manufacture, distribution, or point of purchase of the tire, e.g., by including a logo, trademark, or other indicia of source. Preferably, multiple tread markers are located in the tread, both radially around the circumference of the tire, as well as in a direction parallel to the tire&#39;s axis, between the two shoulders of a tire. 
         [0008]    A first embodiment of the tread marker comprises a top portion having a first color, and a bottom portion having a second color, where the marker is adapted to be mounted in a blind hole in the tire tread at a predetermined depth, where the first color substantially matches a color of the tire tread, and where the second color is configured to provide an indication that the tire has reached a tire replacement time. 
         [0009]    A second embodiment of the tread marker comprises a body having an axis, a top surface, and a bottom surface, where the body comprises a multicomponent stack along the axis, where each component includes a color different from adjacent components. 
         [0010]    A third embodiment of the tread marker comprises a rod-shaped polymeric body having an axis, a top surface and a bottom surface; a first wear region within the marker having a first color and located axially from the outer surface to an interface that is perpendicular to the axis, where the first wear region provides an indication of a percentage of tread life expended as the marker wears from the top surface to the interface, and a second wear region having a second color and located below the interface, where the second wear region provides a visual indication that a tire replacement time has been reached. 
         [0011]    A fourth embodiment of the tread marker comprises a rod-shaped polymeric body having an axis, a top surface and a bottom surface; a first wear region within the marker having a first color and located axially from the outer surface to an interface that is perpendicular to the axis, where the first wear region includes a popular icon or symbol or indicia of source of manufacture, distribution, or point of purchase, and a second wear region having a second color and located below the interface, where the second wear region provides a visual indication that a tire replacement time has been reached. 
         [0012]    A fifth embodiment of the tread marker comprises a rod-shaped polymeric body having an axis, a top surface and a bottom surface; a first wear region within the marker having a first color and located axially from the outer surface to an interface that is perpendicular to the axis, where the first wear region provides a popular icon or symbol, or indicia of source of manufacture, distribution, or point of purchase, as well as a visual indication of a percentage of tread life expended, as the marker wears toward the interface, and a second wear region located below the interface having a second color, where the second wear region provides a visual indication that a tire replacement time has been reached. 
         [0013]    One advantage of the present apparatus is that it provides consumers with an eye-catching indication of the wear status of his or her tires, to notify him or her that a tire is in need of maintenance, or that the end of the tire&#39;s effective life is approaching or has passed. 
         [0014]    Another advantage of one embodiment is that it elevates the status of the tire from that of an ignored commodity to one where consumers are able to differentiate one brand from another and choose the brand that provides an inherent level of safety by providing an instantaneous indication of tread wear, and indicating in a visually obvious manner when the effective lifetime of the tire is over. 
         [0015]    The inventions are pointed out with particularity in the claims annexed hereto and forming a part hereof. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]      FIG. 1  is a side view of a tire having a section removed so as to provide a section view of the tread of the tire having visually indicating tread markers in accordance with the invention. 
           [0017]      FIG. 2  is an enlarged section view of a portion of  FIG. 1 . 
           [0018]      FIG. 3  is an end view of the tire of  FIG. 1 , showing an exemplary placement of visually indicating tread markers in the tread of the tire. 
           [0019]      FIGS. 4A-B  are two isometric views of a first embodiment of a tread marker. 
           [0020]      FIG. 4C  is an exploded view of the first embodiment of a tread marker. 
           [0021]      FIGS. 5A-C  are lateral sectional views of the first embodiment of a tread marker. 
           [0022]      FIG. 5D  is a longitudinal cross section of the first embodiment of a tread marker. 
           [0023]      FIGS. 6A-C  are sectional views of a second embodiment of a tread marker. 
           [0024]      FIG. 6D  is a longitudinal cross section of the second embodiment of a tread marker. 
           [0025]      FIGS. 7A-C  are sectional views of a third embodiment of a tread marker. 
           [0026]      FIG. 7D  is a longitudinal cross section of the third embodiment of a tread marker. 
           [0027]      FIGS. 8A-C  are a top view, a side view, and a lateral sectional view of a fourth embodiment of a tread marker. 
           [0028]      FIGS. 9A-B  are a top and a side view of a fifth embodiment of a tread marker. 
           [0029]      FIGS. 10A-B  are a top and a side view including partial sectional views to show an embodiment of an interface between two annular components of the fifth embodiment of a tread marker. 
           [0030]      FIG. 11A-F  shows exemplary arrangements of tread markers in a tire tread which yield visually attractive tread marker patterns both when a vehicle having such tires is stationary, as well as when it is moving. 
       
    
    
     DETAILED DESCRIPTION 
       [0031]    In the drawings like reference numerals generally designate identical or corresponding parts throughout the several views. Referring to  FIGS. 1-3 , there are shown illustrations of a tire showing exemplary locations of tread markers  22  in the tread of a tire. In particular,  FIG. 1  illustrates a vehicle tire  10  with a portion of the tire wall removed as indicated by reference  12 . Tread markers are distributed both radially around the perimeter of the tire, as well as across the width of the tire (as shown in  FIG. 3 ). 
         [0032]      FIG. 2  shows partial sectional view  12  at a magnified scale. Wall portion  18  is in general made up of a casing  16  and tread  14  that is secured to the casing by vulcanization, a process well known to the industry. In general, the “end of life” of a tire is reached when the tread  14  wears down to a pre-determined minimal thickness, which is indicated in the drawings by dashed line  20 . Also shown is an exemplary placement of a tread marker  22  relative to the end of life  20  of the tire. 
         [0033]    To manufacture a tire that will have tread markers  22  inserted, the following process is used. A casing and uncured rubber compound components are inserted into a tire mold, heated and pressurized. After vulcanization of the rubber occurs, the mold and tire are cooled to a temperature that provides the tire with mechanical properties sufficient for removal from the mold without damage. The outer diameter of the tire mold, in addition to having metal tread inserts, which form the surfaces of the treads, includes a plurality of generally cylindrically shaped metal inserts that extend radially from the tread&#39;s outer surface inwardly to a predetermined depth toward the central axis of the tire. (Other shapes could be used, particularly if the tread markers have non-circular cross sections.) These cylindrical mold inserts, when removed from the cured tire, form blind holes in the tread (not shown). The number and placement of the cylindrical inserts corresponds to the desired number and placement of tread markers  22  in the finished tire, as shown, for example in  FIGS. 1-3  and  11 . The diameter of the blind holes are smaller than a width of the tread markers so that the markers are held in place by compressive stresses imposed on the tread markers by the surrounding rubber tread. Many of the enclosed embodiments of the tread markers may be inserted with standard stud insertion tools, or stud guns, which insert spreader fingers into the blind hole, expand it, insert the tread marker  22 , and release the blind hole. Stud guns are available, for example, from Bruno Wessel at www.brunowessel.com, or OKU Automatik, OKU, of Germany at http://www.oku.de/index.html?uk/produkte/Spikes/einsetzpistolen/navigationpkw.html. 
         [0034]      FIG. 3  illustrates an end view of the vehicle tire  10  showing an exemplary tread pattern  19  in the tread  14 . A portion of the tire wall has been removed to show an exemplary placement of tread markers  22 . 
         [0035]      FIGS. 4-10  illustrate several embodiments of tread markers to be used in tires, and are shown, rather than in the context of sectional views through a tire, as the tread markers by themselves. Each illustrated embodiment of a tread marker has a generally cylindrical outer shape, having generally circular lateral cross sections. However, other cross sectional geometries, for example oval, elliptical, square, rectangular, triangular, and the like, are contemplated and could easily be substituted for those illustrated. 
         [0036]    Referring now to  FIGS. 4A-B  there is shown a first embodiment of a colorized tread marker designated generally by the numeral  200 . The tread marker  200  has a head portion  208 , a body portion  210 , an outer surface  212 , and an inner surface  214 . The head portion  208  of the tread marker  200  is generally of a larger diameter than the body portion  210  and, once installed, helps prevent the tread marker from dislodging from the tire and additionally helps distribute the vehicle load, which may be transferred through the outer surface  212  from the roadway.  FIG. 4C  shows an exploded view of tread marker  200 . The tread marker  200  comprises a jacket  202 , a disk  204 , and a plug  206 . The three components may be made from several types of materials including, for example, thermoplastics such as nylons, polyolefins, thermoplastic rubbers, or acrylonitrile butadiene styrene (ABS), or other polymers such as polyolefins, polyurethanes, or natural or synthetic rubbers, or combinations thereof. Each component may be formed through such processes as molding, for example injection molding, compression molding, transfer molding, casting, extrusion, or the like. In one embodiment, the chosen material for the tread marker, in use, should wear away at a rate similar to or greater than that of the surrounding tread. The color of the material used in each of the three components may be the same, however, it is preferred that each component be a different color. In this embodiment an example color scheme is one where the jacket  202  is black and matches the surrounding tire tread, the disk  204  is yellow or white, and the plug  206  is red. The three components nest together and may be fused together by means well known in the art such as ultrasonic welding or through the use of adhesives or friction. 
         [0037]      FIG. 5D  is a longitudinal cross section of the first embodiment of a tread marker  200  showing the relations between the three components.  FIGS. 5A-C  are lateral cross sections that show how the tread marker&#39;s wear surface looks to a consumer at various stages of wear. The wear surface  226  initially starts at the tread marker&#39;s outer surface  212 , and progressively moves toward the tread marker&#39;s inner surface  214  as the tire wears. 
         [0038]    In use, as the tread marker  200  wears away along with the tire tread  14  ( FIG. 1 ), this embodiment has three distinctive wear regions ( 220 ,  222 , and  224 ) as shown in  FIG. 5D . When a tire having these tread markers is first used, wear occurs in the first wear region  220 . This initial wear region is depicted in  FIG. 5A , section A-A. The consumer would see the cross hatched section shown of each tread marker located around the perimeter of the tire. When the exemplary color scheme is used, the tread marker is not readily apparent to the consumer in the first wear region  220 , since the color of the jacket  202  of the tread marker  200  matches the black of the surrounding tread  14  ( FIG. 1 ). 
         [0039]    After a significant level of tread wear has occurred, the second wear region  222  is reached as shown in  FIG. 5D . The consumer sees crosshatched circular areas, as shown in  FIG. 5B , section B-B. When the exemplary color scheme is used, the consumer will be alerted to a tire that is becoming worn when he or she sees a circular yellow (or white) area corresponding to disk  204  appearing on the tread of the tire. The yellow circular areas may also serve to indicate to the consumer that preventive maintenance should be undertaken or is recommended. For example, if the yellow areas are appearing toward one shoulder of a tire and not the other, uneven tire wear is occurring, and wheel alignment, balancing, or tire pressure adjustment should be performed to both increase the life of the tire, as well as provide a greater level of safety to the consumer. 
         [0040]    As the tire reaches the end of its effective life, the third wear region  224  is reached, as shown in  FIG. 5D . The consumer sees the crosshatched circular areas, as shown in  FIG. 5C , section C-C. When the exemplary color scheme is used, the consumer will be alerted to a tire that is becoming worn when he or she sees bright red circular areas corresponding to plug  206  on the tread of the tire. At this point the tire is in need of replacement. 
         [0041]      FIG. 6D  is a longitudinal cross section of a second embodiment of a tread marker. As with the first embodiment, each component has rotational symmetry with the tread marker longitudinal axis (here axis  301 ). The second embodiment comprises components configured generally in a stack. Three components are shown here, though any number could be used. Here, for exemplary purposes, there is shown a thread marker  300  comprising a top piece  302 , a middle piece  304 , and a base  306 .  FIG. 6  shows the relations between the three components, along with lateral cross sections ( FIGS. 6A ,  6 B, and  6 C) that show how the tread marker&#39;s wear surface looks to a consumer at various stages of wear. The materials and construction of this embodiment of a thread marker are similar to that mentioned above with respect to a first embodiment, as is the exemplary color scheme of black-yellow(or white)-red. Also similar to the first embodiment, wear surface  326  initially starts at the tread marker&#39;s outer surface  312 , and progressively moves toward the tread marker&#39;s inner surface  314  as the tire wears. 
         [0042]    In use, as the tread marker  300  wears away along with the tire tread  14  ( FIG. 1 ), this embodiment also has three distinctive wear regions ( 320 ,  322 , and  324 ). When a tire having these tread markers is first used, wear occurs in the first wear region  320 , and is visible to a consumer as the cross hatched area of  FIG. 6A , section A-A. When the exemplary color scheme is used, the tread marker is not readily apparent to the consumer in the first wear region  320 , since the color of the top piece  302  of the tread marker  300  matches the black of the surrounding tread  14  ( FIG. 1 ). 
         [0043]    After a significant level of tread wear has occurred, the second wear region  322  is reached, and is visible to a consumer as the cross hatched area of  FIG. 6B , section B-B. When the exemplary color scheme is used, the consumer will be alerted to a tire that is becoming worn when he or she sees yellow or white circular regions appearing on the tread of the tire. As in the first embodiment, the yellow circular regions may also serve to indicate to the consumer that uneven tire wear is occurring and that preventive maintenance such as wheel alignment, balancing, or tire pressure adjustment should be made to both increase the life of the tire, as well as provide a greater level of safety to the consumer. 
         [0044]    As the tire reaches the end of its effective life, the third wear region  324  is reached, and is visible to a consumer as the cross hatched area of  FIG. 6C , section C-C. When the exemplary color scheme is used, the consumer will be alerted to a tire that has reached its end of life when he or she sees bright red circular areas that have replaced the yellow (or white) circular areas on the tread of the tire. At this point the tire is in need of immediate replacement. 
         [0045]    In a related embodiment, the tread marker material comprises a sensor material, such as a magnetic material within a polymeric matrix, which is progressively worn away. As the sensor material is worn away, the signal level received by a second sensor, such as a Hall-effect sensor, decreases. The sensor material, sensor, a radio-frequency identification (RFID) chip, and a power supply (battery, button battery, or piezoelectric power source, for example) are integrated into a system that transmits the tread wear condition to a receiver in communication with a vehicle&#39;s instrument panel to give a readout of the percent life remaining on the tires. In one embodiment substantially all of the system components may be embedded into a tread indicator. For example, the top piece  302  and middle piece  304  of the second embodiment would comprise the sensor material, and the base  306  would comprise the sensor, power supply and RFID chip transmitter. 
         [0046]      FIG. 7D  is a longitudinal cross section of a third embodiment of a tread marker. The third embodiment comprises components that are stacked, but the interfaces between adjacent components may be at angles other than normal to the tread marker axis, to show, for example, the percentage of life spent (or remaining) in the tire&#39;s effective life. Alternately, the interfaces between adjacent components, for example between top piece  402  and middle piece  404 , could be stair-stepped to yield the same general result, while perhaps providing for more reliable manufacture. Three components are shown here, though any number could be used with multiply angled interfaces therebetween. This embodiment also utilizes a rotational locator feature that is used by assembly equipment to automatically align all of the tread markers inserted into a tire so that they all face the same direction from the perspective of a viewer looking at the tire&#39;s outer surface. The rotational locator feature, shown here for illustrative purposes, is a flat portion  428  located on the outside perimeter of the head portion  430  of the tread marker  400 . Other rotational locator features located on the head portion  430  or the body portion  432 , such as one or more notches or indents, or external features, such as one or more small protruding nubs or fingers, could be used with equal effectiveness. 
         [0047]    This embodiment, and subsequent embodiments having rotational locator features, require specialized equipment for the reliable insertion of the tread markers into the blind holes of the tire in an oriented fashion. A customized feed mechanism, such as a magazine, clip, vibratory bowl, linear feed mechanism or the like, is required to align the tread markers prior to their insertion. Such a mechanism may comprise, for example, a clip or magazine similar to those used with semiautomatic or automatic firearms. 
         [0048]    Spring loaded box or tubular magazines, having features which align the tread markers, are preloaded with a predetermined number of the tire markers. In addition to supporting the inner surface  414  and/or the outer surface  412 , two substantially parallel alignment surfaces are required. One alignment surface butts up against flat portion  428 , and the other butts up against the outer diameter of the body portion  432 . The distance between the two alignment surfaces is slightly larger than the lateral distance from the flat portion to the diametrically opposed tangent to the outer diameter of the body portion, to allow for the feeding of the tread markers into a stud gun, while preventing misaligned tread markers from fitting into the magazine or clip. The magazine is attached to a stud gun and provides the aligned tread markers to the gun for subsequent aligned insertion. 
         [0049]    Alternately, a vibratory bowl into which a plurality of the tread markers are poured may be used, and is more appropriate to a high volume automated assembly operation. The vibratory bowl is adapted to orient the tread markers as they are vibrated from an inner portion of the bowl to an outer perimeter of the bowl where the tread markers exit to the insertion apparatus. Although many means may be used to align the tread markers, an exemplary means is provided herein. The vibratory bowl has a track with a slot slightly larger than the diameter of the body portion  432 , but smaller than the large outer diameter of head portion  430  so that the tread markers do not fall through the slot. As the tread markers vibrationally move over the slot, the outer surface  412  falls through a slot and the markers proceed up and around the vibratory bowl. As the tread markers exit the vibratory bowl, all with their outer surface  412  pointing downward, the tread markers proceed down an incline having a similar slot. In addition, above the slot is a perpendicular guide surface running along the slot which touches the large outer diameter of the head portion  430 . As the tread markers  400  translate along the slot, the perpendicular guide surface gradually shifts closer to the slot so that the tread markers  400  that initially rotate along their axes as they translate laterally, stop rotating as they translate because the guide surface is located too close to the slot to permit the large outer diameter of the body portion  432  to fit therebetween. The tread markers have now become rotationally aligned with the flat portion  428  located adjacent the perpendicular guide surface. The perpendicular guide surface becomes parallel with the slot at a distance that allows the aligned tread markers to continue translating along the slot without further rotation. The rotationally aligned tread markers are then inserted into the blind holes of the tire in an aligned relation to a tangent of the tire tread to a predetermined depth. 
         [0050]    Turning back to  FIG. 7A-D , here, for exemplary purposes, there is shown a thread marker comprising a top piece  402 , a middle piece  404 , and a base  406 .  FIG. 7D  shows the relations between the three components.  FIGS. 7A-C  show how the tread marker&#39;s wear surface looks at various stages of wear. The materials and construction of this embodiment of a thread marker are similar to that mentioned above with respect to a first embodiment, as is the exemplary color scheme of black-yellow(or white)-red. Other colors could be substituted for each component. Also similar to the first embodiment, wear surface  426  initially starts at the tread marker&#39;s outer surface  412 , and progressively moves toward the tread marker&#39;s inner surface  414  as the tire wears. 
         [0051]    In use, as the tread marker wears away along with the tire tread, this embodiment has two distinctive wear regions ( 420  and  422  as shown in  FIG. 7D ). The first wear region  420  is quite different than those in the previously mentioned embodiments. This embodiment entails a wear region that may be used to give an instantaneous high-resolution indication of the percentage of wear that the surrounding tread has undergone. When a tire having these tread markers is used, wear initially occurs in the first wear region  420 . In an embodiment, the location of the wear line  429  gives an indication of the amount of life spent or remaining in the portion of the tread in the immediate vicinity of that marker. More particularly, X i , shown in  FIG. 7A , section A-A, is the location of the wear line  429  relative to the diameter d of the body portion  432  of tread marker  400  gives the percent of a tire&#39;s life that has been spent at that location of the tread. This relation is given by the following equation: 
         [0000]      % life spent= X   i   /d* 100 
         [0052]    As an example, the wear line in  FIG. 7A , section A-A, indicates approximately 33% life spent (X i  is about ⅓ the length of d), and section B-B indicates about 66% life spent (X i  is about ⅔ the length of d). 
         [0053]    When the exemplary color scheme is used, the tread markers on a new set of tires are not readily apparent to the consumer, since the color of the top piece  402  of the tread marker  400  matches the black of the surrounding tread  14  ( FIG. 1 ). As the tread and tread markers wear, the wear line  429 , as viewed in  FIG. 7A  section A-A and  FIG. 7B  section B-B, generally moves from right to left, and the yellow (or white) area increases, thereby providing the consumer with a good instantaneous indication of how soon the tires will need to be replaced. As in the first and second embodiments, the yellow circular areas may also serve to indicate to the consumer that uneven tire wear is occurring and that preventive maintenance such as wheel alignment, balancing, or tire pressure adjustment should be made to both increase the life of the tire, as well as provide a greater level of safety to the consumer. 
         [0054]    Alternately, top piece may be of a color that contrasts with that of the surrounding tire tread to give a visual indication fo the percent of life remaining, given by the equation: 
         [0000]      % life remaining=( d−X   i )/ d *100 
         [0055]    As the tire reaches the end of its effective life, the second wear region  422  (shown in  FIG. 7D ) is reached, and is visible to a consumer as the cross hatched area of  FIG. 7C , section C-C. When the exemplary color scheme is used, the consumer will be alerted to a tire in need of replacement when he or she sees bright red circular areas that have replaced the yellow (or white) areas on the tread of the tire. At this point the tire is in need of immediate replacement. 
         [0056]    In a related embodiment, not illustrated, the interface between base  406  and middle piece  404  is angled similarly as the interface between middle piece  404  and top piece  402 , above, and the interface between the middle piece  404  and top piece  402  either remains angled, as shown above, or may be perpendicular to the tread marker axis. In this embodiment, for example, using the exemplary color scheme, if the two interfaces are at the same angle to the axis in the longitudinal section shown, the middle piece  404  would be an angled slice of yellow (or white) material. As this related embodiment wears down, the same progression of the wear line  429  would occur, except now there would be two of them. The consumer would initially see the black indicator, then as the first wear line  429  transverses from left to right, a second wear line (not shown), which is the exposed interface between the yellow middle piece  404  and the red base  406 , would follow wear line  429  across the face of the exposed wear surface. For example, a consumer would observe a yellow band followed by a red area traversing across the wear surface as the tread marker wears down, and the end of life condition would occur once the yellow area has worn away, and a red circular area is seen by the consumer. 
         [0057]    Alternately, in a simpler embodiment, middle piece  404  and base  406  comprise one piece, colored red for example, and top piece  402  could be black so that only one colored portion is used to indicate the progression of the tire&#39;s lifetime. 
         [0058]      FIG. 8B  is a side view of a fourth embodiment of a tread marker  500 .  FIG. 8A  is a top view of the fourth embodiment of a tread marker  500 .  FIG. 8C  is a lateral sectional view of the fourth embodiment of a tread marker  500 . The fourth embodiment comprises components configured generally in a stack. Two components are shown here, though any number could be used. Here, for exemplary purposes, there is shown a thread marker comprising a generally cylindrical top piece  502 , and a base  506 . The materials and construction of this embodiment of a thread marker are similar to that mentioned above with respect to the above embodiments. However, the manufacture of the top piece  502  utilizes additional manufacturing methods. Top piece  502  comprises indicia  504 , comprising an icon, symbol or source of manufacture, distribution, or point of consumer purchase, that runs along the axis  501  of top piece  502 , with a surrounding matrix  505 . Top piece  502  may be made, for example, by through such manufacturing methods as insert molding, overlay molding, coextrusion, overjacket extrusion, serial extrusion processes, or the like. In one embodiment, an extrusion through dual dies is made. The first die has the shape of indicia  504  and the second die has a generally circular shape whose diameter is substantially that of top piece  502 , and includes indent  518 . A long rod of material is made, having a cross section of the crosshatched regions of  FIG. 8C . The rod is subsequently cut to length, each piece is rotationally located with respect to base  506 , and the two pieces are fixed together through sonic welding, or through another welding, solvent bonding, or adhesive bonding technique. 
         [0059]    Also similar to the above embodiments, wear surface  526  initially starts at the tread marker&#39;s outer surface  512 , and progressively moves toward the tread marker&#39;s inner surface  514  as the tire wears. This embodiment also utilizes a rotational locator feature that is used by assembly equipment to automatically align all of the tread markers inserted into a tire so that they all face the same direction from the perspective of a viewer looking at the tire&#39;s outer surface. One rotational locator feature illustrated is a flat portion  528  located on the outside perimeter of the head portion  530  of the tread marker  500 . Another rotational locator feature illustrated is an indent  518  located on the outside perimeter of the body portion  532  of the tread marker  500 . Indent  518  is used to rotationally align the top piece  502  with the base  506  during tread marker  500  assembly and/or to rotationally align the assembled tread marker  500  with a tangent of the outer diameter of tire tread during the insertion of the tread markers into the tire. Other rotational locator features located on the head portion  530  or the body portion  532 , such as one or more notches or indents, or external features, such as one or more small protruding nubs or fingers, could be used with equal effectiveness. 
         [0060]    In use, as the tread marker wears away along with the tire tread, this embodiment has two distinctive wear regions ( 520  and  522  as shown in  FIG. 8B ). When a tire having these tread markers is used, wear occurs in the first wear region  520 , and is visible to a consumer as the cross hatched areas of  FIG. 8C , lateral cross section C-C. Materials of any color may be used for the components. In one embodiment, the indicia of source  504  and surrounding matrix  505  of top piece  502  are of contrasting colors, with the matrix  505  perhaps matching the color of the surrounding tread. An exemplary color of base  506  is bright red, and indicates to the consumer a tire&#39;s end of life. 
         [0061]    As the tire reaches the end of its effective life, the second wear region  522  is reached, and the indicia of source  504  is no longer observable. The disappearance of the indicia of source  504 , could alternately be positioned to indicate the expiration of one or more of the manufacturer&#39;s warrantees. Such an embodiment may have an additional component disposed between the top piece  502  and the base  506 . 
         [0062]    Turning now to  FIGS. 9A-B , there are shown a top view and a front view of a fifth embodiment of a tread marker  600 . The fifth embodiment, in general, comprises a combination of the third and fourth embodiments. The tread marker  600  includes a central piece  602  that comprises indicia of source  604  and matrix  605 , similar to top piece  502  of the fourth embodiment, a top annular piece  606 , analogous with the angled top piece  402  of the third embodiment, a middle annular piece  608  (shown in  FIG. 10  A-B), analogous with the angled middle piece  404  of the third embodiment, and a base  610 . The materials and construction of this embodiment of a thread marker are similar to that mentioned above with respect to a above embodiments, as is the exemplary color scheme of black-yellow(or white)-red for the indicator elements. Other colors could be substituted for each component. Any colors may be chosen for the central piece  602 . 
         [0063]    Turning now to  FIGS. 10A-B , there is shown a side view of the fifth embodiment of the tread marker  600  with partial sectional sections to show the interface between the top annular piece  606  and the middle annular piece  608 . In addition, an exemplary progression of wear lines on sequential wear surfaces is shown in  FIG. 10A  ( 1 - 4 ). Each sequentially numbered line indicates the location of the wear line as the tread marker  600  progressively wears as indicated by correspondingly numbered wear surfaces shown on edge in the side view below ( 616 - 1  through  616 - 4 ). 
         [0064]    In use, as tread marker  600  wears, the wear line  629 , that occurs on wear surface  626  as the result of the angular interface between the top annular piece  606  and the middle annular piece  608  become exposed, moves from right to left in  FIG. 10A , progressing from 1 to 2 to 3 to 4 ( 629 - 1  through  629 - 4 ), for example. If the exemplary color scheme is used, the annular area to the right of the wear line is yellow and that to the left is a shade of black that matches the tire tread color. As in the third embodiment, above, this progression may give a high-resolution visual indication that shows the percentage of life spent (or remaining) in the tire&#39;s life, which may be calculated by the equations given above.  FIGS. 10A-B  show the interface between the top annular piece  606  and the middle annular piece  608  as comprising two adjoining planar surfaces; alternately, the interfaces between the top annular piece  606  and the middle annular piece  608  may be stair-stepped to yield the same general result, while perhaps providing for more reliable manufacture. If the exemplary color scheme is used, once the wear surface  626  reaches the base  610 , the consumer sees the wear surface change from a view of the central piece  602 , and its indicia of source, surrounded by the annular yellow/black area, which had become all yellow, to an all-red area that indicates that it is time to replace the tire. Four components are shown here, though any number could be used with multiply angled interfaces therebetween. 
         [0065]    This embodiment also utilizes rotational locator features that may be used by assembly equipment to automatically align the tread markers with the surface of the tire so that upon insertion they all face the same direction from the perspective of a viewer looking at the tire&#39;s outer surface. The first exemplary rotational locator feature is a flat portion  628  located on the outside perimeter of the head portion  630  of the tread marker  600 . A second exemplary rotational locator feature is a central piece rotational indexing feature  618 , located in central piece  602 , which may additionally be used in aligning the central portion  606  with the annular portions  606  and  608  during assembly of tread marker  600 . Other rotational locator features located on the head portion  630  or the body portion  632 , such as one or more notches or indents, or external features, such as one or more small protruding nubs or fingers, could be used with equal effectiveness. 
         [0066]      FIG. 11A-F  shows exemplary arrangements of tread markers in a tire tread which yield visually attractive tread marker patterns both when a vehicle having such tires is stationary, as well as when it is moving.  FIG. 11  A shows an orthogonal pattern  702  distributed around the perimeter of a tire.  FIG. 11  B shows a diagonal pattern  704  distributed around the perimeter of a tire.  FIG. 11  C shows a serpentine pattern  706  distributed around the perimeter of a tire.  FIG. 11  D shows a V-shaped pattern  708  distributed around the perimeter of a tire.  FIG. 11  E shows a “not” symbol (ø) pattern  710  distributed around the perimeter of a tire. This pattern works particularly well in embodiments using the exemplary color scheme, where each tread marker shows a bright red section when the tire reaches the end of its effective life. When the consumer sees a red “not” symbol (ø) he or she knows, as do others, that the tire needs to be replaced.  FIG. 11  F shows indicia of source of manufacture, distribution, or point of consumer purchase pattern  712  distributed around the perimeter of a tire. 
         [0067]    It should be understood that even though these numerous characteristics and advantages of various embodiments have been set forth in the foregoing description, together with details of the structure and function of the embodiments, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size and arrangement of parts within the principals of the invention(s) claimed in the appended claims to the full extent indicated by the broad general meaning of the terms in that the appended claims are expressed.