Patent Description:
The commercial truck market is moving towards an increase in overall vehicle weight, which is due in part to the increase in weight of the motor and equipment. The increase in overall vehicle weight requires a tire capable of handling the additional loading. Thus, a tire with improved crown durability and increased load carrying capacity is desired.

<CIT> describes a tire in accordance with the preamble of claim <NUM>.

A similar tire is also known from <CIT>. In this tire, the folded belts do not overlap with shoulder circumferential grooves in the axial direction, however.

<CIT> describes a further truck tire having a folded ply.

"Aspect Ratio" means the ratio of a tire's section height to its section width.

"Axial" and "axially" mean the lines or directions that are parallel to the axis of rotation of the tire.

"Bead" or "Bead Core" mean generally that part of the tire comprising an annular tensile member, the radially inner beads are associated with holding the tire to the rim being wrapped by ply cords and shaped, with or without other reinforcement elements such as flippers, chippers, apexes or fillers, toe guards and chafers.

"Belt Structure" (or "Reinforcing Belts" or "Belt Package") means at least two annular layers or plies of parallel cords, woven or unwoven, underlying the tread, unanchored to the bead.

"Carcass" means a laminate of tire ply material and other tire components cut to length suitable for splicing, or already spliced, into a cylindrical or toroidal shape. Additional components may be added to the carcass prior to its being vulcanized to create the molded tire.

"Circumferential" means lines or directions perpendicular to the axial direction.

"Cord" means one of the reinforcement strands, including fibers, which are used to reinforce the plies.

"Extensible" means a cable, cord, wire, or reinforcement having an elongation at <NUM>% of the breaking load greater than <NUM>%, when measured from a cord extracted from a cured tire. The tensile measurements such as the load at break (maximum load in N), strength at break (in MPa) and elongation at break (total elongation in %) are performed in tension in accordance with ISO <NUM>-1B (<NUM>) at a pre-load no more than <NUM> MPa tested on a cable or wire when taken from a cured tire.

"Inner Liner" means the layer or layers of elastomer or other material that form the inside surface of a tubeless tire and that contain the inflating fluid within the tire.

"Ply" means a cord-reinforced layer of elastomer-coated, radially deployed or otherwise parallel cords.

"Radial" and "radially" mean directions radially toward or away from the axis of rotation of the tire.

"Radial Ply Structure" means the one or more carcass plies or which at least one ply has reinforcing cords oriented at an angle of between <NUM>° and <NUM>° with respect to the equatorial plane of the tire.

The invention relates to a tire in accordance with claim <NUM>.

In accordance with the invention, a pneumatic tire is provided comprising a tread and a belt structure located radially inward of the tread, the belt structure including a pair of working belts, wherein the working belts are reinforced plies each comprising parallel reinforcement elements, wherein the angle of the reinforcement elements in the respective working belt ranges from <NUM> degrees to <NUM> degrees with respect to the circumferential direction, wherein the belt structure further includes a relatively low angle belt preferably positioned radially between the working belts, the relatively low angle belt comprising parallel reinforcement elements angled at less than <NUM> degrees, preferably less than <NUM> degrees, with respect to the circumferential direction, wherein the relatively low angle belt has folded belt edges forming a first and second narrow belt at the lateral ends of the relatively low angle belt, and wherein the first and second narrow belt are each positioned radially inward of and each at least partially extend axially under a respective axially outermost groove on each respective lateral side of the tread.

In accordance with a preferred aspect of the invention, the reinforcement elements in the working belts and/or in the relatively low angle belt have an elongation at <NUM>% of the breaking load greater than <NUM>%, alternatively greater than <NUM>%, when measured at the reinforcement elements extracted from a cured tire.

In accordance with a preferred aspect of the invention, the reinforcement elements in the working belts and/or in the relatively low angle belt are wires comprising steel or are hybrid cords.

In accordance with a preferred aspect of the invention, the axial width of each of the narrow belts is in the range of from <NUM> to <NUM> and/or the axial width of each of the narrow belts is less than <NUM>/<NUM>, preferably in a range of from <NUM> percent to <NUM> percent, of the tread arc width.

In accordance with a preferred aspect of the invention, the axial width of each of the narrow belts is in the range of one to two times, preferably <NUM> to <NUM> times, the axial width of the respective groove located radially outward of the respective narrow belt.

In accordance with a preferred aspect of the invention, the reinforcement elements in the working belts and/or in the relatively low angle belt have an elongation at <NUM>% of the breaking load greater <NUM>% or greater than <NUM>%, when measured at the reinforcement elements extracted from a cured tire.

In accordance with a preferred aspect of the invention, the radially inner working belt has an axial width equal or about equal to the tread arc width or in a range of from <NUM> percent to <NUM> percent of the tread arc width.

In accordance with a preferred aspect of the invention, the radially outer working belt has an axial width less, preferably at least <NUM> percent less, than the radially inner working belt; and/or and wherein the radially inner working belt is the axially widest belt of the belt structure.

In accordance with a preferred aspect of the invention, the relatively low angle belt has an axial width in the range of from <NUM> to <NUM> percent of the tread arc width.

In accordance with a preferred aspect of the invention, the tire further includes a top belt as the radially outermost belt of the belt structure.

In accordance with a preferred aspect of the invention, the tire further includes a transition belt located radially inwards of the working belts.

In accordance with a preferred aspect of the invention, the transition belt comprises parallel reinforcement elements making an angle in a range of from <NUM> to <NUM> degrees, preferably from <NUM> to <NUM> degrees right, with the circumferential direction; and/or wherein the transition belt has an axial width in a range of from <NUM> to <NUM> percent of the tread arc width.

In accordance with a preferred aspect of the invention, the aspect ratio of the tire is less than or equal to <NUM>.

In accordance with a preferred aspect of the invention, the folded belts each comprise parallel reinforcement elements angled at the same angle as the adjacent second working belt.

In accordance with the invention, the tire further comprises a rubber spacer layer located between the folded belt edges that preferably extends over at least <NUM> percent, more preferably at least <NUM> percent, of the axial distance between the axially innermost ends of the folded belt edges.

<FIG> illustrates a first embodiment of a pneumatic tire, suitable for use as a truck tire. The tire <NUM> has a tread <NUM> with a non-skid depth. The tire tread <NUM> comprises a plurality of circumferentially continuous ribs, which may vary, but are shown for example as ribs <NUM>, <NUM> and <NUM>. Positioned between each rib are circumferential grooves <NUM>, <NUM>, <NUM>, which are preferably continuous. The tread may also comprise optional sipes (not shown). The tread pattern is not limited to same, and may comprise, for example, a plurality of blocks and grooves (not shown).

The tire <NUM> further comprises a casing which includes two opposed sidewalls <NUM> which extend down from the tread <NUM> to the bead area (not shown). The casing of the tire preferably includes an inner liner <NUM> which is typically formed of halobutyl rubber which forms an air impervious barrier. The tire casing preferably further includes one or more radial plies <NUM> extending from the tread, down the sidewall to the tire bead and wrapped about or otherwise secured to each annular bead.

The tire <NUM> further includes a belt package <NUM> which is located between the tread and the one or more casing plies <NUM>. The belt package comprises layers of reinforcement. The ply <NUM> and the belt reinforcing structure <NUM> are made from cord reinforced elastomeric material, wherein the cords are preferably steel wire or polyamide filaments and the elastomer preferably being rubber.

The belt reinforcing structure <NUM> includes a radially innermost first working belt <NUM>. The first working belt <NUM> is located radially inwards of the second working belt <NUM> and is preferably the widest belt layer of the belt reinforcing structure <NUM>. The first working belt <NUM> has a width which is preferably equal or, about equal, i.e., ± <NUM>%, to the tread arc width. The breaker angle of belt <NUM> is between <NUM> and <NUM> degrees, preferably with a right orientation, more preferably in the range of <NUM> to <NUM> degrees. Belt <NUM> is preferably made of extensible wire which has a % elongation at <NUM>% of breaking load of greater than <NUM>%. The wire is preferably a hybrid cord or a steel wire.

The second working belt <NUM> is the second member of the working belt pair. The second working belt <NUM> has a width less than the width of the first working belt <NUM> and is preferably radially outward of the first working belt <NUM>. Preferably, the second working belt <NUM> has a width less than the width of belt <NUM> by a step off, which preferably ranges from <NUM> to <NUM>. Belt <NUM> has a breaker angle between <NUM> and <NUM> degrees, preferably with a left orientation, more preferably in the range of <NUM> to <NUM> degrees. Belt <NUM> is preferably made of extensible wire and is the same as the wire of the first working belt <NUM>. More preferably, the wire has the same construction with the same but opposite angular orientation as the wire of belt <NUM>.

The belt structure <NUM> further comprises a relatively low angle belt <NUM> which is preferably located between the working pair belts, <NUM>, <NUM>. The relatively low angle belt <NUM> has reinforcements that are oriented circumferentially at <NUM> degrees or less, preferably <NUM> degrees or less, more preferably <NUM> degrees. The relatively low angle belt <NUM> has a belt width which is preferably less than the belt width of the working belts <NUM>, <NUM>.

The relatively low angle belt <NUM> is preferably formed from spirally winding a rubberized strip of one or more cords in a pattern as shown in <FIG>. Preferably, the strip has <NUM>, <NUM> or <NUM> steel cords, and has a width in the range of from <NUM> to <NUM>, more preferably from <NUM> to <NUM>. As shown in <FIG>, a rubberized strip of reinforcement cords is wound on a drum, starting on the right-hand side <NUM> of the drum, at a location axially inward from the right edge of the drum. The strip is applied at the starting location <NUM> and then helically wound in an axially outward direction towards the axially outer edge <NUM> of the drum. The strip is then wound in a change of direction towards the left-hand side <NUM> of the drum. The strip direction is then reversed and wound towards the center of the drum terminating at point <NUM>. As shown in <FIG>, the layup results in a wide relatively low angle belt <NUM> that has folded belt edges <NUM>, wherein the relatively low angle belt has folded belt edges forming a first and second narrow belt <NUM> at the lateral ends of the relatively low angle belt. The folded belt edges <NUM> have a relatively narrow axial width and are located on each lateral edge of the belt and are positioned radially inward of the axially outermost shoulder groove <NUM>. The folded belt edge belt <NUM> preferably is the narrowest belt. The axial width of the folded belt <NUM> is preferably in the range of one to four times the axial width of the groove <NUM>. Preferably, the folded belt <NUM> has the same angle and orientation as the adjacent belt <NUM>. As best shown in <FIG>, a rubber spacer <NUM> is preferably located between the folded belt edges <NUM>, and functions to fill the void between the folded belt edges <NUM>.

The relatively low angle belt <NUM> has a width sized to avoid compression in the shoulder area. The belt width of the relatively low angle belt <NUM> is preferably in the range of <NUM>% to <NUM>% of the tread arc width, and even more preferably in the range of <NUM>-<NUM>%. The relatively low angle belt <NUM> is preferably wide enough to decrease the strain cycles in the breaker wedge and is just stopped before the shoulder area to avoid zero degree wire compression and a too round footprint.

The relatively low angle belt <NUM> is preferably formed using high tensile steel and preferably has a % elongation at <NUM>% of breaking load of <NUM> or more, for measurements taken from a cured tire. For measurements taken from bare cords, the % elongation at <NUM>% of breaking load is <NUM> or more. Alternatively, the relatively low angle belt <NUM> may be formed using non-metal reinforcements such as aramid, carbon fiber, polyketone or POK.

The belt structure <NUM> may further comprise an optional top belt <NUM>. This top belt <NUM> preferably has an axial width less than the working belts <NUM>, <NUM>.

The aspect ratio of the tire described above may vary. The aspect ratio is preferably in the range of from <NUM> to <NUM> such as <NUM> or <NUM>.

Claim 1:
A pneumatic tire comprising a tread (<NUM>) and a belt structure (<NUM>) located radially inward of the tread (<NUM>), the belt structure (<NUM>) including a pair of working belts (<NUM>, <NUM>), wherein the working belts (<NUM>, <NUM>) are reinforced plies each comprising parallel reinforcement elements, wherein the angle of the reinforcement elements in the respective working belt (<NUM>, <NUM>) ranges from <NUM> degrees to <NUM> degrees with respect to the circumferential direction, wherein the belt structure (<NUM>) further includes a relatively low angle belt (<NUM>) preferably positioned radially between the working belts (<NUM>, <NUM>), the relatively low angle belt (<NUM>) comprising parallel reinforcement elements angled at less than <NUM> degrees, preferably less than <NUM> degrees, with respect to the circumferential direction, wherein the relatively low angle belt (<NUM>) has folded belt edges (<NUM>) forming a first and second narrow belt at the lateral ends of the relatively low angle belt (<NUM>), and wherein the first and second narrow belt are each positioned radially inward of and each at least partially extend axially under a respective axially outermost groove (<NUM>) on each respective lateral side of the tread (<NUM>), characterized in that the belt structure (<NUM>) further comprises a rubber spacer layer (<NUM>) located between the folded belt edges (<NUM>).