Patent Publication Number: US-2010108218-A1

Title: Extensible non-load bearing cut resistant tire side-wall component cotaining elastomeric filament, tire containing said component, and processes for making same

Description:
BACKGROUND OF INVENTION 
     1. Field of the Invention 
     This invention relates to an extensible non-load bearing cut-resistant component for use in the side walls of a tire. The component is made with ply-twisted yarns made from at least two different types of singles yarns, with one of the singles yarn having staple fiber sheaths and cores of continuous inorganic filaments and with one of the singles yarn having cut resistant staple fiber and at least one continuous elastomeric filament, that singles yarn being free or substantially free of inorganic filaments. 
     2. Description of Related Art 
     Tire cut resistance is an important attribute, particularly when the tire is designed for off-the-road use, such as in the case of radial light truck tires and tires for SUVs (called RLT tires). In particular, the sidewalls of tires can be cut or slashed by a variety of threats. 
     High tenacity aramid filaments in the form of cords have been incorporated into sidewalls of tires as mechanical reinforcement, acting as load-bearing structures within the sidewalls of the tire by attachment to the beads of the tire. Generally these aramid filaments have been present in the form of continuous filaments so as to provide strong mechanical properties. There are many references that disclose the use of combinations of various continuous filaments, including aramid continuous filaments, with metal wires or other inorganic continuous filaments in load bearing applications in tires. 
     U.S. Pat. No. 6,691,757 discloses a radial tire having two side-cut shields, one each disposed in each sidewall of the tire, the side-cut shields comprising at least two plies of arrays of parallel filaments, with each parallel array disposed at an angle to the adjacent array. The filaments in the filament arrays can be an organic or inorganic material, such as steel, polyamide, aromatic polyamide, or rayon. This type of reinforcement requires a substantial amount of material in the tire side wall because a single ply layer of material cannot provide multi-axial cut protection. 
     International Patent Application Publication WO 2007/048683 discloses bi-elastic reinforcement of tires that can be a knitted fabric. The fabric can be constituted by synthetic fibers, natural fibers or a mixture of these fibers. The elastic knitted fabric has a void fraction of at least 40% in order that the knitted fabric can be sufficiently compressed. The void fraction is calculated by comparing the volumetric mass of the knitted fabric with that of compacted material measured by any classic means. The use of bi-elastic reinforcement improves the resistance to the propagation of cracks. 
     None of these references deal with the use in a tire side wall of a fabric containing the combination of cut resistant polymeric fiber and inorganic fiber wherein improved cut resistance of the tire is the primary attribute and load bearing is not a major consideration. 
     Fabrics used in tires generally have been made from heavy cords; references that do disclose fabrics either rely on positioning of the fabrics in certain layers in the tread of the tire or the use of very “tight” fabrics or those that have high surface cover factors to provide puncture resistance. 
     For example, U.S. Pat. No. 4,649,979 to Kazusa et al. discloses a bicycle tire having a plurality of carcass plies and a breaker ply intermediate those plies under the tread. The breaker ply can be composed of various materials of high strength and improves the cutting and puncture of the tire. The breaker is usually formed from a fabric made of aromatic polyamide, high strength nylon, polyester, vinylon, rayon or glass fibers, or metallic materials such as a wire net or a plurality of steel wires. 
     Research Disclosure 42159 (May 1999), discloses the use of penetration-resistant woven material, specifically tightly woven p-oriented aromatic polyamide fabrics, as sleeves for tires to reduce or eliminate punctures. 
     U.S. Pat. No. 6,534,175 to Zhu and Prickett and U.S. Pat. No. 6,952,915 to Prickett disclose comfortable cut resistant fabric to be used in protective clothing. Such fabrics are designed to essentially provide protection to human skin and are made from at least one cut resistant yarn comprising a strand having a sheath of cut resistant staple fibers and a metal fiber core plied with a strand comprising cut resistant fibers free of metal fibers, and in the case of the &#39;915 patent the second strand also contains elastomeric filament. However, because of the weak nature of staple fibers, these fabrics have not been thought to be acceptable in tire components. Yarn tenacity is reduced when a continuous filament yarn is replaced with a staple spun yarn, so in a typical application the staple yarn mass and the basis weight of any fabrics made from such staple yarns would have to be increased to such a degree so as to make application of such large yarns, cords, or fabrics impractical. Further, it is not clear that such fabrics, designed to protect human skin, have adequate open area to allow adequate penetration of rubber compounds during tire manufacture. 
     What is needed therefore is a method of providing improved cut protection to a tire, particularly in the sidewall area, that provides multi-directional cut protection in the sidewall with one layer of material, and is not dependent on the material being a load-bearing structure. 
     BRIEF SUMMARY OF THE INVENTION 
     This invention relates to an extensible cut resistant tire side-wall component, and a tire containing such component, the side-wall component comprising a textile fabric, wherein a single layer of said fabric provides multi-directional cut resistance in the plane of the fabric, the fabric comprising at least one ply-twisted yarn having
         i) at least one single yarn having a sheath/core construction, the sheath comprising cut-resistant polymeric staple fibers and the core comprising an inorganic fiber, and   ii) at least one single yarn comprising cut resistant staple fiber and at least one continuous elastomeric filament and being free or substantially free of inorganic fibers; and       

     the fabric further having a coating for improved adhesion of the fabric to rubber such that the cut resistant tire side-wall component has a free area of from 18 to 65 percent. 
     This invention also relates to a process for making a cut resistant tire side-wall component, comprising:
         a) providing at least one ply-twisted yarn having
           i) at least one single yarn having a sheath/core construction with the sheath comprising cut-resistant polymeric staple fibers and a core comprising an inorganic fiber, and   ii) at least one single yarn comprising cut resistant staple fiber and at least one continuous elastomeric filament and being free or substantially free of inorganic fibers;   
           b) knitting or weaving the ply-twisted yarn into a fabric having a free area of from 18 to 65 percent, and   c) applying a coating on the fabric for improved adhesion of the fabric to rubber, while maintaining the free area of the tire side-wall component in the range of from 18 to 65 percent.       

    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1 to 4  are illustrations of various embodiments of cut-resistant tire side-wall components in a tire. 
         FIG. 5 and 6  are digital images of fabrics useful in cut-resistant tire side-wall components. 
         FIG. 7  illustrates some preferred embodiments of the fabric used in the cut resistant tire side-wall component. 
         FIG. 8  is a representation of one single yarn comprising a sheath of cut resistant polymeric staple fibers and a core inorganic filament. 
         FIG. 9  is a representation of a ply-twisted yarn comprising two singles yarns. 
         FIG. 10  is a representation of an elastomeric singles yarn. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Tire Side-Wall Components 
     This invention relates to a cut resistant tire side-wall component comprising a textile fabric comprising at least one single yarn having a sheath/core construction, the sheath comprising cut-resistant polymeric staple fibers and the core comprising an inorganic fiber. By “tire side-wall component” is meant a material that can be used in the side walls of tires; that is, the area between the bead of the tire and the tread. Generally this is a strip of textile fabric impregnated with rubber material that is inserted into the tire side wall but not attached to the bead; or a protective envelope of rubber impregnated textile fabric positioned from one bead on one side of the tire across the crown of the tire to the bead on the other side of the tire but not attached to either bead. “Bead” means that part of the tire comprising an annular tensile member wrapped by ply cords and shaped, with or without other reinforcement elements such as flippers, chippers, apexes, toe guards and chafers, to fit the wheel rim. “Tread” means that portion of a tire that comes into contact with the road when the tire is normally inflated and under normal load. “Crown” means that portion of the tire within the width limits of the tire tread. “Carcass” means the tire structure apart from the belt structure, tread, undertread, and sidewall rubber over the plies, but including the beads. 
     As shown in  FIG. 1 , a tire  1  typically has two beads  2 , two sidewalls  3 , a crown area  4 , and a thread area  5  forming the outer surface of the crown area. One embodiment of the cut-resistant tire side-wall components  6  are shown butting up to but not wrapping the beads  2 .  FIG. 2  shows another embodiment of the tire having cut-resistant tire side-wall components  7  that encompass the entire side walls of the tire from the bead on either side to generally the edge of the crown on either side of the tire.  FIG. 3  shows yet another embodiment of multiple cut-resistant tire side-wall components  8 ; these are illustrated as overlapping but they could be shown abutting each other in the side wall.  FIG. 4  shows yet another embodiment of the cut-resistant tire side-wall component in the form of a protective envelope  9  extending from, but not wrapped around, one bead on one side of the tire to the other bead on the other side of the tire, across the crown area of the tire. The particular shape of the tire carcass, tread, beads, etc. shown in the figures is for illustration and is not intended to be limiting; for example, the tire could have a higher or lower profile. 
     This invention relates to a cut-resistant tire side-wall component that is non-load bearing. The inflated carcass of the tire must support the weight of the car on the road surface. Load-bearing components efficiently mechanically transfer the load on the bead of the tire to the tread while retaining the lateral load in the inflated tire. Such load-bearing components provide such efficient mechanical transfer of the load by being attached to the bead of the tire; that is, by being wrapped around and stabilized to the bead during the manufacture of the tire. For example, in  FIG. 4 , each of the ends of load-bearing carcass ply  12  wraps around respective tire beads  2  on either side of the tire in the sidewall to form a load-bearing structure. By “non-load bearing” is meant the tire side-wall component is not attached to the bead; that is, it is not wrapped around the bead during manufacture as are conventional radial plies or other carcass components and therefore the cut resistant tire side wall component does not efficiently transfer the load on the bead to the tread or retain lateral loads in the inflated tire. Because this cut-resistant tire component is not load bearing, it can be efficiently designed to provide advanced cut protection with a single fabric layer or ply. 
     The amount of area in the tire side wall covered by the cut resistant side-wall component can vary as desired; the component can cover the full area of the side wall or a portion of the area. While multiple side-wall components can be utilized in the side walls of tires, and they can overlap or not as desired, in a preferred embodiment the cut resistant tire side wall component uses only a single layer or ply of fabric. In fact the tire side wall component provides multi-directional cut resistance in the plane of the fabric or in the tire side wall with a single layer or ply of fabric, thereby reducing the number of cut-resistant side wall components needed in the tire. 
     The side-wall components are built into the side walls of the tires and are impregnated with tire rubber during the manufacture of the tires. Generally both side walls of the tires will contain cut resistant side-wall components. If desired, one side-wall component piece can be used to cover both side walls. For example, one side-wall component piece can be incorporated into a first side wall area extending from the first bead area to the first edge of the tread area, with the piece being shaped such that is extends across the tread area to the second edge of the tread area, and further across the second opposing sidewall area to the second bead area. In this fashion, the side-wall component is somewhat like a carcass ply incorporated from one bead to the other opposing bead in the tire; however, the side-wall component is not wrapped around and stabilized to the bead so efficient load bearing is not achieved by this type of ply. 
     Cut-Resistant Fabrics 
     In one preferred embodiment, the textile fabric used in the tire side-wall component is a knitted fabric. “Knitted” is meant to include a structure producible by interlocking a series of loops of one or more yarns by means of needles or wires, such as warp knits (e.g., tricot, milanese, or raschel) and weft knits (e.g., circular or flat). It is thought the knit structure provides increased mobility for the yarns in the fabric during the manufacture of tires, allowing for improved fabric flexibility and expansion. Cut resistance and flexibility are affected by tightness of the knit and that tightness can be adjusted to meet any specific need. A very effective combination of cut resistance and flexibility has been found in, for example, single jersey knits, but other knits, including terry, rib, or other knits could be used. In another embodiment, the textile fabric used in the tire side-wall component is a woven fabric. “Woven” is meant to include any fabric made by weaving; that is, interlacing or interweaving at least two yarns typically at right angles. Generally such fabrics are made by interlacing one set of yarns, called warp yarns, with another set of yarns, called weft or fill yarns. The woven fabric can have essentially any weave, such as, plain weave, crowfoot weave, basket weave, satin weave, twill weave, unbalanced weaves, and the like. Plain weave is the most common. 
     In one embodiment, the textile fabric and the side-wall component have a free area of from 18 to 65 percent. “Free area” is a measure of the openness of the fabric and is the amount of area in the fabric plane that is not covered by yarns. It is a visual measurement of the tightness of the fabric and is determined by taking an electronic image of the light from a light table passing through a six-inch by six-inch square sample of the fabric and comparing the intensity of the measured light to the intensity of white pixels. In some preferred embodiments the fabric and side-wall component have a free area of from 25 to 65 percent and in some embodiments 30 to 65 percent, while in some preferred embodiments the free area of the fabric and tire side-wall component is from 40 to 65 percent. This openness of the fabric provides adequate space for the tire rubber to fully impregnate the side-wall component.  FIGS. 5 and 6  are digital images of one useful knit fabric  10  and woven fabric  11  having 55 percent and 40 percent free area, respectively. 
     In some embodiments, the textile fabric is woven and has an unbalanced weave with the number of threads per inch in one direction, such as the weft or fill direction, being greater than the number of threads in the warp direction. In some preferred embodiments, the fabric has 4 to 7 threads per inch (16 to 28 threads/decimeter) in one direction, while in the other the fabric has 7 to 17 threads per inch (28 to 67 threads/decimeter). In other embodiments the fabric has 4 to 12 threads per inch (16 to 63 threads/decimeter) in one direction and 7 to 17 threads per inch (28 to 67 threads/decimeter) in the other direction. Likewise, in some preferred embodiments, the textile fabric is knitted and the number of wales is not equal to the number of courses. In some especially preferred embodiments, the number of wales is less than the number of courses, creating a very open knitted structure. In some preferred embodiments, the knitted fabric has 4 to 7 wales per inch (16 to 28 wales/decimeter) and 7 to 17 courses per inch (28 to 67 courses/decimeter). In other embodiments the knitted fabric has 4 to 12 wales per inch (16 to 63 wales/decimeter) and 7 to 17 courses per inch (28 to 67 courses/decimeter). 
       FIG. 7  illustrates the properties of some embodiments of the cut resistant tire side-wall component. The triangular chart has on the first axis basis weight of the textile fabric from 0 to 18 ounces per square yard (610 grams per square meter), on the second axis yarn linear density from 0 to 5000 denier (0 to 5600 dtex), and on the third axis free area from 0 to 100%. In some embodiments, textile fabrics have a basis weight of from 1.9 to 14 oz/yd 2  (64 to 475 g/m 2 ), preferably 1.9 to 11 oz/yd 2  (64 to 373 g/m 2 ), and most preferably 3.5 to 11 oz/yd 2  (119 to 373 g/m 2 ), the fabrics at the high end of the basis weight range providing more cut protection. In some embodiments, the ply-twisted yarns in the fabrics have a linear density of 400 to 4000 denier (440 to 4400 dtex), preferably 1200 to 3400 denier (1300 to 3800 dtex), and most preferably 1200 to 3000 denier (1300 to 3300 dtex). As used herein, these ranges of yarn linear density refer to the total linear density of an end or a thread used as a unit in the fabric, with the end or thread being either, one or more plied yarns co-fed to a knitting machine, one or more plied yarns, and/or combinations of these yarns. 
       FIG. 7  shows some preferred fabric structures with the Area A-D-G-E being an embodiment of preferred fabric properties. Alternate embodiments illustrating preferred free area operating ranges are represented by lines A-D for 25% free area, A′-D′ for 30% free area, and A″-D″ for 40% free area. One preferred combination of properties is the area designated by the letters B-F-G-D, which would describe a textile fabric having a free area of 25 to 65% made from 1200 to 3400 denier (1300 to 3800 dtex) yarns, and having a basis weight of 1.9 to 11 ounces per square yard (64 to 373 g/m 2 ). Another preferred combination of properties is the area designated by the letters B-C-H, representing 1200 to 3000 denier (1300 to 3300 dtex) yarns, 25 to 60% free space, and a basis weight of 3.5 to 11 ounces per square yard (119 to 373 g/m 2 ). Other preferred combinations can be generated by substituting the A-D, B-D, or B-C boundary with the appropriate A′-D′ or A″-D″ lines (or likewise B′-D″ or B″-D″ or B′-C′ or B″-C″) representing different free area boundaries. 
     If more than 65% free area is present in the textile fabric, it is believed the cut resistance of the material suffers because there simply is not enough fabric available to retard a cut. If less than 18% free area is present, it is believed that adequate rubber penetration through the fabric will not be attained, causing tire manufacturing and operational problems. If yarns having a linear density of more than 3400 denier (3800 dtex) or basis weights in excess of 14 ounces per square yard (475 g/m 2 ) are used, the fabrics become too bulky to be practically useful as tire side-wall components; while if yarns having a linear density of less that 400 denier (440 dtex) or fabrics having a basis weight of less than 1.9 ounces per square yard (64 g/m 2 ) are used, it is believed cut resistance will be significantly reduced. 
     Coating 
     The textile fabric having a free area of from 18 to 65 percent further has a coating for good adhesion of the fabric to rubber. After the coating is applied to the textile fabric, the resulting coated fabric retains a free area of from 18 to 65 percent and forms the cut resistant side-wall component. As in the fabric without coating, some preferred embodiments the fabric after coating has a free area of from 25 to 65 percent and in some embodiments 30 to 65 percent, while in some preferred embodiments the fabric after coating has a free area of from 40 to 65 percent. In a preferred embodiment, the coating comprises an epoxy resin subcoat and a resorcinol-formaldehyde topcoat. 
     The coating is a polymeric material designed to increase the adhesion of the fabric to the rubber matrix. Generally the coating is the same as can be used as for dipped tire cords. The coating can be selected from epoxies, isocyanates, and various resorcinol-formaldehyde latex mixtures. 
     Sheath/Core Singles Yarns 
     The ply-twisted yarn comprises at least one single yarn having a sheath/core construction, the sheath being organic cut resistant staple fiber and the core being at least one inorganic filament. By “yarn” is meant an assemblage of staple fibers spun or twisted together to form a continuous strand. As used herein, a yarn generally refers to what is known in the art as a singles yarn, which is the simplest strand of textile material suitable for such operations as weaving and knitting. A spun staple yarn can be formed from staple fibers with more or less twist; a continuous multifilament yarn can be formed with or without twist. When twist is present in a singles yarn, it is all in the same direction. 
     One embodiment of such yarn is shown in  FIG. 8  as yarn  20 . The organic cut resistant staple fiber sheath  21  can be wrapped, spun or fasciated around inorganic filament core  22 . These can be achieved by means such as core-spun spinning such as DREF spinning or any method of core insertion of the inorganic material using ring spinning; air-jet spinning with standard Murata or Murata Vortex jet-like spinning; open-end spinning, and the like. Preferably the staple fiber is consolidated around the inorganic filament core at a density sufficient to cover the core. The degree of coverage depends on the process used to spin the yarn; for example, core-spun spinning such as DREF spinning (disclosed, for example, in U.S. Pat. Nos. 4,107,909; 4,249,368; and 4,327,545) provides better coverage than other spinning processes. Other spinning processes can generally provide only partial coverage of the core but even partial coverage is assumed a sheath/core structure for the purposes of this invention. The sheath can also include some fibers of other materials to the extent that decreased cut resistance, due to that other material, can be tolerated. 
     Alternatively, the single yarn can be a wrapped yarn, having one or more core yarns that are spirally wrapped by at least one other yarn. These yarns can be used to fully or partially wrap the core yarn with another yarn. Dense spiral wrappings or multiple wrappings can cover practically the entire core yarn. 
     The single yarns having an inorganic filament core and an organic cut resistant staple fiber sheath are generally 20 to 70 weight percent inorganic with a total linear density of 400 to 2800 dtex. In some embodiments, the ratio of material in the sheath to the core, on a weight basis, is preferably from 75/25 to 40/60. 
     In some embodiments, the organic cut-resistant staple fibers preferably used in this invention have a length of preferably 2 to 20 centimeters, preferably 3.5 to 6 centimeters. In some preferred embodiments they have a diameter of 10 to 35 micrometers and a linear density of 0.5 to 7 dtex. 
     The single yarns can have some twist. The ply-twisted yarns, also, can have some twist and the twist in the ply-twisted yarn is generally opposite the twist in the single yarns. In any of the single yarns twist is generally in the range of 19.1 to 38.2 Tex system twist multiplier (2 to 4 cotton count twist multiplier). The knit fabric can be made from a feed of ply-twisted or a multiple of single or ply-twisted yarns and the yarn bundle fed to the machine need not have twist, although twist can be put into the bundle if desired. 
     It is believed the preferred cut-resistant singles yarn containing steel in many embodiments is a singles yarn having a 3 to 6 mil (0.076 to 0.152 mm) steel core with a sheath/core weight ratio of about 50/50. For example, 5-mil (0.125 mm) steel has a denier of about 850 denier (935 dtex) and at 50/50 ratio would mean the final singles yarn would have be about 1700 denier (1900 dtex). It is believed the preferred cut-resistant singles yarn containing fiberglass in many embodiments is a singles yarn having a 400 to 800 denier (440 to 890 dtex) fiberglass core with a sheath/core weight ratio of about 50/50. For example 600 denier (680 dtex) fiberglass at a 50/50 ratio would mean the final singles yarn would be about 1200 denier (1300 dtex). 
     In some preferred embodiments the organic cut resistant staple fibers have a cut index of at least 0.8 and preferably a cut index of 1.2 or greater. The most preferred staple fibers have a cut index of 1.4 or greater. The cut index is the cut performance of a 475 grams/square meter (14 ounces/square yard) fabric woven or knitted from 100% of the fiber to be tested, that is then measured by ASTM F1790-97 (measured in grams, also known as the Cut Protection Performance (CPP)) divided by the areal density (in grams per square meter) of the fabric being cut. For example fibers of poly(p-phenylene terephthalamide) can have a CPP of 1050 g and a cut index of 2.2 g/g/m 2 ; fibers of ultra-high molecular weight polyethylene can have a CPP of 900 g and a cut index of 1.9 g/g/m 2 ; and nylon and polyester fibers can have a CPP of 650 g and a cut index of 1.4 g/g/m 2 . 
     Ply-Twisted Yarns 
     The yarn in the textile fabric is present in the form of a ply-twisted yarn. As use herein the phrases “ply-twisted yarn” and “plied yarn” can be used interchangeably and refer to two or more yarns, i.e., singles yarns, twisted or plied together. It is well known in the art to twist single yarns (also commonly known, when used with staple yarns, as “singles” yarns) together to make ply-twisted yarns. Each single yarn can be, for example, a collection of staple fibers spun into what is known in the art as a spun staple yarn. By the phrase “twisting together at least two individual single yarns”, is meant the two single yarns are twisted together without one yarn fully covering the other. This distinguishes ply-twisted yarns from covered or wrapped yarns where a first single yarn is completely wrapped around a second single yarn so that the surface of the resulting yarn only exposes the first single yarn.  FIG. 9  illustrates ply-twisted yarn  24  made from single yarns  20  and  23 .  FIG. 8  is a representation of a single yarn  20  used in the ply-twisted yarn, the single yarn having a sheath/core construction with a sheath of cut resistant staple fibers  21  and an inorganic fiber core  22 . It is not intended that the figure be limiting on the size of the filaments, particularly the inorganic fiber core, which in many cases will be significantly smaller than the overall single yarn. The single yarns may have additional twist, which is not shown in figures for the purposed of clarity. In some embodiments, the ply-twisted yarns include at least two different single yarns. The ply-twisted yarns can include other materials as long as the function or performance of the yarn or fabric made from that yarn is not compromised for the desired use. 
     Ply-twisted yarns can be made from single yarns using either a two-step or combined process. In the first step of the two-step process, two or more single yarns are combined parallel to one another with no ply twist and wound onto a package. In the next step, the two or more combined yarns are then ring twisted around each another (or together) with the reverse twist of the single yarns to form a ply-twisted yarn. Ply-twisted yarns normally have “Z” twist (single yarns normally have “S” twist). Alternatively, a combined process can be employed to ply twist the singled yarns, which combines both of these steps in one operation. Ply twisted yarns are normally twist balanced to eliminate yarn liveliness. 
     The ply-twisting is accomplished by twisting the single yarns into ply-twisted yarns having a Tex system twist multiplier of from 14.4. to 33.6, preferably 19.2 to 31.2. (Equivalent to a cotton count twist multiplier of from 1.5 to 3.5, preferably 2.0 to 3.25). Twist multiplier is well known in the art and is the ratio of turns per inch to the square root of the yarn count. The ply-twisted yarns may then be combined with other same or different ply-twisted yarns, or other filaments or yarns to form a yarn bundle to form a fabric, or the individual ply-twisted yarns can be used to form the fabric, depending on the desired fabric requirements. 
     In some embodiments, one or more ply-twisted yarns are combined into a bundle of yarns for making cords or for weaving or knitting cut resistant fabrics. Fabric properties can be changed by the addition of other single yarns made from staple fibers that do not contain inorganic filaments into the ply-twisted yarns or into the bundle of yarns. Preferably, these single yarns contain organic cut resistant fiber. Such single yarns generally have a linear density of 400 to 2800 dtex. 
     The ply-twisted yarn is formed from at least two singles yarns; at least one of those singles yarn has a sheath/core construction, the sheath comprising cut-resistant polymeric staple fibers and the core comprising an inorganic fiber. The ply-twisted yarn also has, in addition to the sheath/core singles yarn, at least one other singles yarn comprising cut resistant staple fiber and at least one continuous elastomeric filament and being free or substantially free of inorganic fibers. The singles yarn comprising the elastomeric filament is ply-twisted with the other singles yarn(s) while being fully extended; that is, the singles yarn comprising the elastomeric filament is tensioned 1 to 5 times its relaxed state while being ply-twisted with the other singles yarn(s). This provides the final fabric with extensibility from the yarn in addition to any extensibility provided by the weave or knit structure of the fabric. 
     Depending on the application and the size of the singles yarn, the ply-twisted yarn can be used as is or combined with other ply-twisted yarns. Alternatively, two lighter weight ply-twisted yarns can be combined together to form a bundle (having four single yarns total), that can be fed to a knitting machine with or without further twisting the ply-twisted yarns together. Alternatively, a yarn bundle can be made containing a ply-twisted yarn that also includes other single yarns, preferably cut-resistant staple fiber that does not have any inorganic filaments. These alternatives are not intended to be limiting and more than two ply-twisted yarns can be used in a yarn bundle. Many combinations are possible, depending on the number of ply-twisted yarns desired in the yarn bundle and the amount of cut protection is desired. 
     Elastomeric Yarns 
     The ply twisted yard includes a single yarn containing at least one continuous elastomeric filament. This can include the form of a sheath/core single yarn having the elastomeric filament(s) as the core and staple fiber as the sheath, although it is not critical that the elastomeric filament(s) actually be fully covered by the sheath. 
     The preferred elastomeric fiber is a spandex fiber, however, any fiber generally having stretch and recovery can be used. As used herein, “spandex” has its usual definition, that is, a manufactured fiber in which the fiber-forming substance is a long chain synthetic polymer composed of at least 85% by weight of a segmented polyurethane. 
     Among the segmented polyurethanes of the spandex type are those described in, for example, U.S. Pat. Nos. 2,929,801; 2,929,802; 2,929,803; 2,929,804; 2,953,839; 2,957,852; 2,962,470; 2,999,839; and 3,009,901. 
     Single yarns with an elastomeric filament core, are illustrated in  FIG. 10 . Ring-spun elastomeric single yarn  26  is shown having at least one elastomeric filament  27  and a partially covering ring-spun sheath  28  of staple fiber. The elastomeric filament(s) comprising 2 to 25 weight percent of the total sheath/core single yarn linear density of 100 to 2800 dtex. In some processes for making spandex elastomeric filaments, coalescing jets are used to consolidate the spandex filaments immediately after extrusion. It is also well known that dry-spun spandex filaments are tacky immediately after extrusion. The combination of bringing a group of such tacky filaments together and using a coalescing jet will produce a coalesced multifilament yarn, which is then typically coated with a silicone or other finish before winding to prevent sticking on the package. Such a coalesced grouping of filaments, which is actually a number of tiny individual filaments adhering to one another along their length, is superior in many respects to a single filament of spandex of the same linear density. 
     The elastomeric filament in the elastomeric single yarn used is preferably a continuous filament and can be present in the single elastomeric yarn in the form of one or more individual filaments or one or more coalesced grouping of filaments. However, it is preferred to use only one coalesced grouping of filaments in the preferred elastomeric single yarn. Whether present as one or more individual filaments or one or more coalesced groupings of filaments the overall linear density of the elastomer filament(s) in the relaxed state is generally between 17 and 560 dtex (15 and 500 denier) with the preferred linear density range being 44 to 220 dtex (40 to 200 denier). 
     The elastomeric singles yarn can be made by the process disclosed in U.S. Pat. No. 6,952,915 to Prickett. It is preferred to incorporate the elastomeric fiber into an elastomeric single yarn under tension by drawing or stretching the fiber prior to the combination with staple fibers by using a slower delivery speed of the elastomeric fiber relative to the final elastomeric single yarn speed. This drawing can be described as the stretch ratio of the elastomeric fiber, which is the final elastomeric single yarn speed divided by the delivery speed of the elastomeric fiber. Typical stretch ratios are 1.5 to 5.0 with 1.5 to 3.50 being preferred. Low stretch ratios yield less elastic recovery while very high stretch ratios make the single yarns difficult to process and the fabric unsuitable for use in the tire forming process. The optimum stretch ratio is also dependent on the percent weight content of elastomeric core. Tension devices can also be employed to tension and stretch the elastomeric fiber. The optimum tension applied to the elastomeric yarn is ultimately determined for each fabric, based on the suitability of the fabric in the tire forming process. 
     Cut-Resistant Fibers 
     The preferred cut-resistant staple fibers are para-aramid fibers. By para-aramid fibers is meant fibers made from para-aramid polymers; poly(p-phenylene terephthalamide) (PPD-T) is the preferred para-aramid polymer. By PPD-T is meant the homopolymer resulting from mole-for-mole polymerization of p-phenylene diamine and terephthaloyl chloride and, also, copolymers resulting from incorporation of small amounts of other diamines with the p-phenylene diamine and of small amounts of other diacid chlorides with the terephthaloyl chloride. As a general rule, other diamines and other diacid chlorides can be used in amounts up to as much as about 10 mole percent of the p-phenylene diamine or the terephthaloyl chloride, or perhaps slightly higher, provided only that the other diamines and diacid chlorides have no reactive groups which interfere with the polymerization reaction. PPD-T, also, means copolymers resulting from incorporation of other aromatic diamines and other aromatic diacid chlorides such as, for example, 2,6-naphthaloyl chloride or chloro- or dichloroterephthaloyl chloride; provided, only that the other aromatic diamines and aromatic diacid chlorides be present in amounts which do not adversely affect the properties of the para-aramid. 
     Additives can be used with the para-aramid in the fibers and it has been found that up to as much as 10 percent, by weight, of other polymeric material can be blended with the aramid or that copolymers can be used having as much as 10 percent of other diamine substituted for the diamine of the aramid or as much as 10 percent of other diacid chloride substituted for the diacid chloride of the aramid. 
     P-aramid fibers are generally spun by extrusion of a solution of the p-aramid through a capillary into a coagulating bath. In the case of poly(p-phenylene terephthalamide), the solvent for the solution is generally concentrated sulfuric acid, the extrusion is generally through an air gap into a cold, aqueous, coagulating bath. Such processes are generally disclosed in U.S. Pat. Nos. 3,063,966; 3,767,756; 3,869,429, and 3,869,430. P-aramid fibers are available commercially as Kevlar® fibers, which are available from E. I. du Pont de Nemours and Company, and Twaron® fibers, which are available from Teijin, Ltd. 
     Other preferred cut resistant fibers useful in this invention are ultra-high molecular weight or extended chain polyethylene fiber generally prepared as discussed in U.S. Pat. No. 4,457,985. Such fiber is commercially available under the trade names of Dyneema® available from Toyobo and Spectra® available from Honeywell. Other preferred cut resistant fibers are aramid fibers based on copoly(p-phenylene/3,4′-diphenyl ether terephthalamide) such as those known as Technora® available from Teijin, Ltd. Less preferred but still useful at higher weights are fibers made from polybenzoxazoles such as Zylon® available from Toyobo; anisotropic melt polyester such as Vectran® available from Celanese; polyamides; polyesters; and blends of preferred cut resistant fibers with less cut resistant fibers. 
     Other cut-resistant fibers include aliphatic polyamide fiber, such as fiber containing nylon polymer or copolymer. Nylons are long chain synthetic polyamides having recurring amide groups (—NH—CO—) as an integral part of the polymer chain, and include nylon 66, which is polyhexamethylenediamine adipamide, and nylon 6, which is polycaprolactam. Other nylons can include nylon 11, which is made from 11-amino-undecanoic acid; and nylon 610, which is made from the condensation product of hexamethylenediamine and sebacic acid. 
     Other cut-resistant fibers include polyester fiber, such as fiber containing a polymer or copolymer composed of at least 85% by weight of an ester of dihydric alcohol and terephthalic acid. The polymer can be produced by the reaction of ethylene glycol and terephthalic acid or its derivatives. In some embodiments the preferred polyester is polyethylene terephthalate (PET). PET may include a variety of comonomers, including diethylene glycol, cyclohexanedimethanol, poly(ethylene glycol), glutaric acid, azelaic acid, sebacic acid, isophthalic acid, and the like. In addition to these comonomers, branching agents like trimesic acid, pyromellitic acid, trimethylolpropane and trimethyloloethane, and pentaerythritol may be used. PET may be obtained by known polymerization techniques from either terephthalic acid or its lower alkyl esters (e.g., dimethyl terephthalate) and ethylene glycol or blends or mixtures of these. Another potentially useful polyester is polyethylene napthalate (PEN). PEN may be obtained by known polymerization techniques from 2,6 napthalene dicarboxylic acid and ethylene glycol. 
     Cores 
     In some embodiments, the inorganic filament core can be a single filament; in some embodiments the inorganic filament core may be multifilament. In some preferred embodiments it is preferably a single metal filament or several metal or glass filaments, as needed or desired for a particular situation. 
     By “metal filament” is meant filament or wire made from a ductile metal such as stainless steel, copper, aluminum, bronze, and the like. If desired these metal filaments can be coated to improve adhesion in rubber. An example is a steel filament coated with brass. The metal filaments are generally continuous wires. In some embodiments useful metal filaments are 50 to 200 micrometers in diameter, and are preferably 75 to 150 micrometers in diameter. For convenience, the Core Size Conversion Table lists the relationship between steel diameters and equivalent linear density. 
     
       
         
           
               
            
               
                   
               
               
                 Steel Core Size Conversion Table 
               
            
           
           
               
               
               
               
               
            
               
                 Mil 
                 Micron 
                 Denier 
                 dTex 
                 Tex 
               
               
                   
               
            
           
           
               
               
               
               
               
            
               
                 2 
                 50 
                 130 
                 144 
                 14 
               
               
                 3 
                 75 
                 293 
                 325 
                 33 
               
               
                 4 
                 100 
                 520 
                 578 
                 58 
               
               
                 4.5 
                 113 
                 658 
                 731 
                 73 
               
               
                 5 
                 125 
                 813 
                 903 
                 90 
               
               
                 5.5 
                 138 
                 983 
                 1092 
                 109 
               
               
                 6 
                 150 
                 1170 
                 1300 
                 130 
               
               
                 7 
                 175 
                 1593 
                 1769 
                 177 
               
               
                 8 
                 200 
                 2080 
                 2304 
                 230 
               
               
                   
               
            
           
         
       
     
     By “glass filament” is meant continuous multi-filament yarn formed from silica-based formulations. These formulations include E-glass, S-glass, C-glass, D-glass, A-glass and the like. In some embodiments useful glass filaments are 1 to 25 micrometers in diameter, and are preferably 3 to 15 micrometers in diameter. In some embodiments useful multi-filament yarns have a linear density of from 110 to 2800 dtex. 
     Tires 
     This invention also relates to tire comprising a non-load bearing cut resistant tire side-wall component; specifically, a tire having a tread area, a first side wall area extending from a first edge of the tread area to a first bead area, and a second side wall area extending from a second edge the tread area to a second bead area, the tire comprising the cut resistant tire side-wall component as described herein in the form of a single layer of textile fabric providing multi-directional cut resistance in the plane of the fabric located in the first sidewall, the fabric not being wrapped around either bead. In some embodiments, the fabric forms a protective envelop for the tire, the fabric being located in the first sidewall area extends from the first bead area to the first edge of the tread area, across the tread area to the second edge of the tread area, and across the second sidewall area to the second bead area, but is not wrapped around either bead. 
     It is understood that, if desired, there are multiple points during the manufacture of the tire that a cut-resistant tire side-wall component can be incorporated into the tire. For example, radial tires having cut-resistant tire side-wall components can be made in the following manner. The tire assembly is carried out in at least two stages. The first stage building is done on a flat collapsible steel building drum. The tubeless liner is applied, then the body ply which is turned down at the edges of the drum. The steel beads are applied and the liner/ply is turned up. If a protective envelope of the cut-resistant tire side-wall component comprising one layer of an uncured, coated woven or knit fabric is desired, it is incorporated into the tire at this time in the form of an essentially continuous surface from one bead to the other, but not wrapped around either bead. On the other hand, if it is desired for the cut-resistant tire side-wall component to be added as only an insert extending only from the bead to the crown, or from the bead to some portion of the sidewall, one layer of the uncured, coated woven or knit fabric is cut to the proper dimension and added at this point. The chafer and sidewall are combined at the extruder; they are applied together as an assembly. The drum collapses and the tire is ready for second stage. 
     Second stage building is done on an inflatable bladder mounted on steel rings. The green first stage cover is fitted over the rings and the bladder inflates it, up to a belt guide assembly. The steel belts are applied with their cords crossing at a low angle. The tread rubber is then applied. The tread assembly is rolled to consolidate it to the belts and the green cover is detached from the machine. If desired the tire building process can be automated with each component applied separately along a number of assembly points. 
     Process for Making 
     This invention also relates to a process for making a cut resistant tire side-wall component comprising: 
     a) providing at least one ply-twisted yarn having
         i) at least one single yarn having a sheath/core construction with the sheath comprising cut-resistant polymeric staple fibers and a core comprising an inorganic fiber, and   ii) at least one single yarn comprising cut resistant staple fiber and at least one continuous elastomeric filament and being free or substantially free of inorganic fibers;       

     b) knitting or weaving the ply-twisted yarn into a fabric having a free area of from 18 to 65 percent; and 
     c) applying a coating on the fabric for improved adhesion of the fabric to rubber, while maintaining the free area of the tire side-wall component of from 18 to 65 percent. 
     The yarn can be formed into either knitted or woven fabrics, however in preferred embodiments the fabric is knitted. Knitted fabrics can be made on a range of different gauge knitting machines. A wide variety of flat-bed and circular knitting machines can be employed. For example, Sheima Seiki knitting machines can be used to make the knitted fabrics. If desired, multiple ends or yarns can be supplied to the knitting machine; that is, a bundle of yarns or a bundle of plied yarns can be co-fed to the knitting machine and knitted into fabrics. In some embodiments it is desirable to add functionality to the fabrics by co-feeding one or more other staple or continuous filament yarns with one or more spun staple yarns having an intimate blend of fibers. The tightness of the knit can be adjusted to meet any specific need. Very effective cut resistance has been found in, for example, single jersey knit, interwoven knit, mesh knit and terry knit patterns. 
     Generally the coating is applied to the fabric while the fabric is under some degree of tension and then dried for further processing. In many instances, more than one application of coating is needed. One preferred process for applying a coating on the fabric, used with fabrics having a high content of aramid fiber, is a two-step coating process. In the first step, a primer or subcoat of epoxide or mixtures of epoxide and blocked isocyanate is applied on the fabric, followed by drying; this is then followed by a second step of applying a resorcinol-formaldehyde latex (RFL) on the fabric followed by additional drying. If desired, the RFL coating can also contain carbon black. 
     The coating is applied to the fabric generally by dipping. Preferably the coating substantially or completely coats the yarns in the fabrics without appreciably closing up the open areas in the fabric between yarns. In other words, the coating applied to the fabric is substantial enough to provide adequate adhesion between the fabrics and the tire rubber, while not closing up the fabric to the penetration of that same tire rubber during the manufacture of the tire. The free-area of the fabric can be maintained by adjusting the coating viscosity and loading on the fabric, and in a preferred embodiment this is accomplished such that the free area is not appreciably or substantially changed when coating dries. That is, the difference in the free area of the uncoated fabric and the free area of the fabric having a dried or cured coating is less than 25 percent, and most preferably less than 15 percent. The coating, after drying, is generally cured when the coated fabric is used in the manufacture of the tire. 
     Test Methods 
     Cut Resistance. There are no standardized methods to measure the cut resistance of materials used for tire applications. The closest standard method is ASTM 1790-04, “Standard Test Method for Measuring Cut Resistance of Materials Used in Protective Clothing.” The limitation of this method was the inability to simulate the boundary conditions associated with sidewall tension due to internal tire pressure. To develop a new method to test tire laminates, ASTM 1790-04 was used as a basis for developing a test and analysis protocol. In this test the sample is stretched to a specified load, next the sample is pressed against the cutting edge with a plastic mandrel, finally the cutting edge, loaded at a specified force, is drawn one time across the sample until the sample is cut or the blade has moved 3.50 inches (88.9 mm). The cutting edge is a stainless steel knife blade having a sharp edge 3.75 inches (95.25 mm) long. A new cutting edge is used for each test. The sample is a rectangular section of rubber and cord composite 0.25 inch×5.00 inch (6.35 mm×127 mm). The mandrel is a made of a hard plastic with two grooves cut into the surface. A horizontal groove keeps the sample from moving with the cutting edge, while a vertical groove allows the cutting edge to penetrate the sample. Cut through is recorded by monitoring the sample tension. When the tension drops to zero the sample has been cut. The degree to which the sample is loaded in tension varies depending on sample construction. To determine the appropriate load, five 0.25″×5.00″ samples are pulled and the load versus strain curve is recorded. The average load to stretch the sample 2.5% is recorded and this load is used to tension the sample in the cut test. A constant strain boundary condition was deemed more appropriate than a constant load condition for non-load bearing members of the tire. 
     The test is repeated for a minimum of five times at five different mandrel loadings. These data are used to develop a graph with mandrel load on the abscissa and distance the blade traveled to cut the sample on the ordinate. This produces a graph of cut distance as a function of mandrel loading. To compare different composite constructions relative cut performance, the cut distances at a given mandrel loading are averaged together. Then a power function is fit through the average data. The curve can be plotted against similar curves for alternative constructions. Materials requiring more mandrel loading to produce similar cut distances are considered more cut resistant. Materials are compared at the value at a 1 inch (2.54 cm) cut length. 
     Free Area Determination. A six-inch by six-inch (15.2×15.2 cm) square sample of the material to be measured is placed flat on a light table having the intensity of 330 foot candles (3550 lux). If needed, several 12 inch (30.5 cm) long pieces of ¼ inch (6.35 mm) steel bar stock are used to hold down the edges of the sample to prevent bowing and wrinkling. An image of the sample back-lit by the light table is captured using a 6.5 mega-pixel digital SLR camera with a 24 mm lens suspended above the table on an extruded aluminum frame. To complete the measurement of free area the captured image is transferred to ADOBE PhotoShop® for processing and analysis. 
     Once in PhotoShop® the color image is converted to a grayscale image using the Image&gt;Mode-Grayscale function. Next the image is converted to a high contrast black and white image using the Image&gt;Adjustments&gt;Threshold function. A threshold setting of 128 is selected (0=black and 255=white). All pixels lighter than the threshold are converted to white; all pixels darker are converted to black. To further analyze the high contrast image it is necessary to select a representative area of the sample. To do this the rectangular marquee tool is used to highlight a representative section of the sample. The highlighted area is cropped Image&gt;Crop. Finally, the mean intensity of the image is measured using the histogram tool. Since the image was converted to a high intensity black and white image, open areas in the sample have a pixel intensity of 255 and areas with fabric coverage have an intensity of  0 . The measure of free area of the sample is obtained by dividing the mean pixel intensity by the intensity of a white pixel (255). 
     Twist multiplier is the ratio of the turns per inch to the square root of the yarn count. As used herein, the cotton count twist multiplier is the number of turns per inch divided by the square root of the cotton count, and the Tex system twist multiplier is the number of turns per inch multiplied times the square root of the linear density of the yarn in Tex. 
     EXAMPLE 1  
     Ply-twisted yarns comprising a first singles yarn having a cut-resistant polymeric staple fiber sheath and an inorganic fiber core, and a second singles yarn having cut-resistant staple fiber and a least one elastomeric filament, are made using the process as disclosed in U.S. Pat. No. 6,952,915 to Prickett. 
     A set of first singles yarns having an aramid staple fiber sheath and a core of either one end of stainless steel monofilament or fiberglass multifilament glass yarn are summarized in Table 1A. The aramid fibers are poly(p-phenylene terephthalamide) fibers sold under the trade name Kevlar® fiber by E. I. du Pont de Nemours and Company as Merge 1F1208 Type 970 Royal Blue producer-colored staple. These fibers have a cut length of about 3.8 centimeters and a linear density of 1.6 dtex per filament. The steel monofilament is 304 L stainless steel sold by Bekaert Corporation. The fiberglass is multi-filament E glass fiberglass yarn sold by AGY. 
     The aramid fibers are fed through a standard carding machine used in the processing of short staple spun yarns to make carded sliver. The carded sliver is processed using two pass drawing (breaker/finisher drawing) into drawn sliver. A sheath/core singles yarn is produced using a DREF III friction spinning process; the aramid sliver and various sizes of inorganic filaments are fed into the process to produce the singles yarns of Table 1A. 
     
       
         
           
               
               
               
               
               
               
               
             
               
                 TABLE 1A 
               
               
                   
               
               
                   
                   
                   
                   
                   
                   
                 Final 
               
               
                   
                   
                 Fiberglass 
                 Steel 
                 Weight 
                 Final Yarn 
                 Yarn 
               
               
                   
                 Steel 
                 Linear 
                 Linear 
                 Percent of 
                 Linear 
                 English 
               
               
                   
                 Diameter 
                 Density 
                 Density 
                 Steel or 
                 Density 
                 Cotton 
               
               
                 Yarn 
                 (Microns) 
                 (dtex) 
                 (dtex) 
                 Fiberglass 
                 (dtex) 
                 Count 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 1-1 
                 50 
                 — 
                 144 
                 24 
                 590 
                  10/1 
               
               
                 1-2 
                 100 
                 — 
                 578 
                 23 
                 2565 
                 2.3/1 
               
               
                 1-3 
                 150 
                 — 
                 1300 
                 51 
                 2565 
                 2.3/1 
               
               
                 1-4 
                 — 
                 110 
                 — 
                 19 
                 590 
                  10/1 
               
               
                 1-5 
                 75 
                 — 
                 325 
                 41 
                 797 
                 7.4/1 
               
               
                   
               
            
           
         
       
     
     Elastomeric singles yarns are made with aramid cut-resistant staple fibers and elastomeric filaments. The elastomeric filament is a spandex composition of coalesced monofil sold by Invista under the tradename Lycra® Spandex Coalesced Monofil. Poly(p-phenylene terephthalamide) (PPD-T) fibers about 3.8 centimeters long and 1.6 dtex per filament, sold by E. I. du Pont de Nemours and Company as natural color Type 970 Kevlar® staple aramid fiber, are fed through a standard carding machine as used in the processing of short staple ring spun yarns to make carded sliver. The carded sliver is processed using two pass drawing (breaker/finisher drawing) into drawn sliver which is processed on a roving frame. 
     The elastomeric singles yarns are sheath-core yarns having a spandex core; they are produced by ring-spinning one or two ends of the PPD-T roving and inserting one tensioned spandex filament core just prior to twisting. The spandex core can be centered between two drawn roving ends or adjacent to a single end roving end just prior to the final draft rollers. The spandex core is tensioned or drawn by underfeeding the material at a slower speed (S 2 ) than the final yarn speed (S 1 ). 
     The amount of tension or stretch is determined by the speed ratio of the initial spandex feeder speed (S 2 ) to the final draft roller (and yarn) speed (S 1 ), this ratio (S 1 /S 2 ) being shown as the stretch or draw ratio in the table below. 
     
       
         
           
               
               
               
               
               
             
               
                 TABLE 1B 
               
               
                   
               
               
                   
                 Linear density of 
                   
                 Final Yarn 
                 Final Yarn 
               
               
                   
                 Spandex End 
                 Stretch Ratio 
                 Linear Density 
                 English 
               
               
                 Yarn 
                 (dtex) 
                 (S1/S2) 
                 (dtex) 
                 Cotton Count 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
               
            
               
                 1-8  
                 44 
                 3.5 
                 590 
                 10/1 
               
               
                 1-9  
                 78 
                 2.5 
                 590 
                 10/1 
               
               
                 1-10 
                 78 
                 3.5 
                 590 
                 10/1 
               
               
                 1-11 
                 156 
                 3 
                 738 
                  8/1 
               
               
                 1-12 
                 156 
                 4 
                 738 
                  8/1 
               
               
                 1-13 
                 Two 156 
                 2.5 
                 738 
                  8/1 
               
               
                   
               
            
           
         
       
     
     Ply-twisted yarns are made by plying each of the above-described elastomeric singles yarns having stretched spandex core(s) ( 1 - 8  to  1 - 13 ) and the singles yarns in Table  1 A; the resultant ply-twisted yarns are shown in Table 1C. The optimum level of ply twist depends upon the linear density of the ply-twisted yarn and its components and the stretch ratio and linear density of spandex-containing yarn. The combination of all these factors determines the extensibility of the fabric in the tire building process. For these ply-twisted yarn examples a 16.9 twist multiplier (1.77 cotton count twist multiplier) is used. 
                                                 TABLE 1C                                       Final Yarn           Ply-   First   Second   Weight   Weight   Weight   Linear   Final Yarn       Twist   Singles   Singles   Percent   Percent   Percent   Density   English       Yarn   Yarn   Yarn   Steel   Fiberglass   Spandex   (dtex)   Cotton Count                  1-11   1-1   1-8    12   —   1.1   1180    10/2s       1-12   1-1   1-9    12   —   2.6   1180    10/2s       1-13   1-5   1-10   23   —   1.4   1387   8.5/2s       1-14   1-2   1-11   18   —   1.5   3303   3.6/2s       1-15   1-2   1-12   18   —   1.1   3303   3.6/2s       1-16   1-3   1-13   39       3.6   3303   3.6/2s       1-17   1-4   1-8    —   9.5   1.1   1180    10/2s                    
The ply twisted yarns are knitted into fabrics having a fabric areal density of about 200 (g/m 2 ) and a free area in the range of 18 to 65% using a 7 gauge Sheima Seiki knitting machine.
 
     EXAMPLE 2  
     The fabrics of Example 1 are coated by a step-wise process. The fabric is dipped first in a primer epoxide solution, the viscosity of the solution having been adjusted to allow for essentially complete coverage of the yarns in the fabric without closing up the free area between the yarns. The primer is then dried on fabric, applying only enough tension to the fabric to prevent the fabric from appreciably shrinking or the free area from collapsing. The fabric is then dipped in a topcoat of resorcinol-formaldehyde latex, and again the viscosity of the latex having been adjusted to allow for essentially complete coverage of the yarns in the fabric without closing up the free area between the yarns. The topcoat is then dried on fabric, applying only enough tension to the fabric to prevent the fabric from appreciably shrinking or the free area from collapsing. When measured, the difference in the free area of the uncoated fabric and the free area of the fabric having a dried coating is less than 25 percent. 
     EXAMPLE 3  
     Radial tires having tire components containing the ply-twisted yarn can be made in the following manner. The tire assembly is carried out in at least two stages. The first stage building is done on a flat collapsible steel building drum. The tubeless liner is applied, then the body ply which is turned down at the edges of the drum. The steel beads are applied and the liner/ply is turned up. At this point, if desired, the coated knit fabric comprising the ply-twisted sheath/core yarn, or a fabric comprising a cord containing the ply-twisted sheath/core yarn can be incorporated into the tire in the form of an essentially continuous surface from one bead to the other. The chafer and sidewall are combined at the extruder; they are applied together as an assembly. Again, if desired, sidewall inserts can be added at this point, the inserts being a coated knit fabric comprising the ply-twisted sheath/core yarn, or a fabric comprising a cord containing the ply-twisted sheath/core yarn. The drum collapses and the tire is ready for second stage. 
     Second stage building is done on an inflatable bladder mounted on steel rings. The green first stage cover is fitted over the rings and the bladder inflates it, up to a belt guide assembly. The steel belts are applied with their cords crossing at a low angle. At this point, alternatively, fabrics containing the ply-twisted sheath/core yarn can be incorporated into the tire. The tread rubber is then applied. The tread assembly is rolled to consolidate it to the belts and the green cover is detached from the machine. If desired the tire building process can be automated with each component applied separately along a number of assembly points. It is understood that, if desired, there are multiple points during the manufacture of the tire that a knit or woven fabric comprising the ply-twisted sheath/core yarn or a cord containing the ply-twisted sheath/core yarn can be incorporated into the tire.