JP2013124011A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire which suppresses ply steering, and which improves uniformity and high speed durability, while maintaining steering stability and riding comfortability.SOLUTION: In the pneumatic tire in which a belt layer 6 is arranged at an outer circumference side of a carcass layer 5 in a tread part 1, and a belt reinforcing layer 8 is arranged at an outer circumference side of the belt layer 6, and a mounting direction to the vehicle is specified, the belt layer 6 includes an arc form belt cord 7, and the arc form belt cord 7 is arranged in a convex form toward outside at the vehicle mounting time, and the belt reinforcing layer 8 is composed of a reinforcing cord 9 which extends to a tire circumference direction. A winding density outside the reinforcing cord 9 at the vehicle mounting time is arranged lower than a winding density inside the vehicle at the mounting time.

Description

  The present invention relates to a pneumatic tire in which price tear is suppressed while at the same time achieving both handling stability and riding comfort, while improving umiformity and high-speed durability.

  In general, a pneumatic tire is required to achieve both high handling stability and riding comfort. Also, pneumatic tires are required to improve uniformity and high-speed durability beyond conventional levels.

  In order to improve steering stability, it is necessary to increase the tire rigidity, whereas in order to improve riding comfort, it is necessary to reduce the tire rigidity, so that the two are in a contradictory relationship. Therefore, it has been a difficult task to achieve both handling stability and riding comfort.

  On the other hand, in a pneumatic tire in which a belt layer is disposed on the outer peripheral side of the carcass layer in the tread portion, there is a vehicle flow problem that when the vehicle is moved straight away from the handle, the vehicle bends and flows to one side. As a cause of the vehicle flow, there is a price tear generated when the belt cord of the belt layer is inclined in the tire circumferential direction.

  For this reason, Patent Document 1 proposes a pneumatic tire that suppresses the occurrence of price tear by folding back along the tire equator when the belt cord of the belt layer extends from one end to the other end. Yes. However, in this pneumatic tire, since the belt cord inclination changes discontinuously on the tire equator, there is a problem that the behavior changes abruptly in a transitional state from straight to turning or from turning to straight. In addition, since all belt cords are folded along the equator line, there is a problem that productivity is lowered, and it is impossible to solve the problem of improving both handling stability and riding comfort. Furthermore, in the pneumatic tire described in Patent Document 1, the uniformity and high-speed durability could not be improved beyond the conventional level.

JP 2009-90675 A

  An object of the present invention is to provide a pneumatic tire that suppresses price tear while improving maneuverability and high-speed durability while achieving both handling stability and riding comfort.

  The pneumatic tire of the present invention that achieves the above object has a configuration in which a belt layer is disposed on the outer peripheral side of the carcass layer in the tread portion, and a belt reinforcing layer is disposed on the outer peripheral side of the belt layer, and the mounting direction with respect to the vehicle is designated. In the pneumatic tire, the belt layer includes a belt cord extending in an arc shape, the arc belt cord is arranged so as to protrude outward when the vehicle is mounted, and the belt reinforcing layer is the tire. The reinforcing cord extends in the circumferential direction, and the reinforcing cord is arranged so that the winding density on the outside when the vehicle is mounted is lower than the winding density on the inside when the vehicle is mounted.

  In the pneumatic tire of the present invention, the belt cords that extend in an arc shape constituting the belt layer are arranged so as to protrude outward when the vehicle is mounted. Since the angle with respect to the tire circumferential direction is reduced and the arrangement density is increased, the in-plane bending rigidity is increased and the steering stability is improved. In addition, the end of the arc belt cord is arranged inside the belt layer when the vehicle is installed, so the angle with respect to the tire circumferential direction is increased and the arrangement density is reduced, so the out-of-plane bending rigidity is reduced and the riding comfort is improved. To do. This is because pneumatic tires are generally attached to the negative camber on the vehicle, so the vehicle inner side, which has a low out-of-plane bending rigidity, contacts the ground when traveling straight, improving ride comfort and the outside of the vehicle with a high in-plane bending rigidity when turning Since the vehicle is grounded and a load is applied thereto, the handling stability is improved. Further, when traveling straight, the inner side of the vehicle is mainly grounded and the price tear component caused by the inclination of the belt cord of the belt layer is reduced, so that the vehicle flow can be suppressed. In addition, since the belt cord is arranged in an arc shape, the inclination angle of the belt cord gradually changes, so that the behavior change in a transitional state from straight traveling to turning or from turning to straight traveling can be moderated. .

  In the pneumatic tire of the present invention, the reinforcing cords constituting the belt reinforcing layer are arranged so that the outer winding density when the vehicle is mounted is lower than the inner winding density when the vehicle is mounted, so that the belt layer swells in the tire radial direction. Higher durability of pneumatic tires by increasing the winding density of the inner reinforcement cord when wearing the vehicle, and lowering the winding density of the outer reinforcement cord when wearing the vehicle, where the swelling of the belt layer is relatively suppressed Uniformity can be improved beyond the conventional level.

  The end of the arc-shaped belt cord is positioned at the inner end of the belt layer when the vehicle is mounted, and the apex outside the arc-shaped belt cord in the tire width direction is positioned at the outer end of the belt layer when mounted on the vehicle. It is preferable.

  It is preferable that an angle θ with respect to the tire circumferential direction of a tangent line of the arcuate belt cord at the inner end of the belt layer when the vehicle is mounted is 50 to 90 °. By making the angle θ within such a range, the ride comfort can be sufficiently improved, and the price tear component can be reduced to suppress the vehicle flow.

  At the inner end of the belt layer when the vehicle is mounted, a tire circumferential distance P between the end of the arc belt cord and the end of the arc belt cord adjacent to the tire circumferential direction is 1.5 to 4.5 mm. Preferably there is. By setting the tire circumferential direction distance P of the arc-shaped belt cord within such a range, it is possible to ensure the belt rigidity at the inner end portion and the outer end portion when the vehicle is mounted and to ensure both driving stability and durability. .

  In the pneumatic tire of the present invention, a region having a width of 10% of the width W of the belt layer extends from the inner end of the belt layer when the vehicle is mounted to the tire equator, and the tire extends from the outer end of the belt layer when the vehicle is mounted. When a region having a width 10% of the width W of the belt layer to the equator is defined as a region Wout, the density Mout of the reinforcing cord wound around the region Wout is 0 of the density Min of the reinforcing cord wound around the region Win. It is preferable to be in the range of ˜50%. By making the relationship between the winding density Mout and Min of the reinforcing cord within the above-described range, the high-speed durability and uniformity can be further improved.

It is sectional drawing of the tire meridian direction which shows an example of embodiment of the pneumatic tire of this invention. It is explanatory drawing which shows typically an example of embodiment of the belt layer and belt reinforcement layer of the pneumatic tire of this invention. FIG. 3 is an explanatory diagram schematically showing the arrangement of one belt cord in the belt layer of FIG. 2. It is explanatory drawing which shows typically the other example of embodiment of the belt layer which comprises the pneumatic tire of this invention. It is a graph which illustrates typically the distribution of the winding density of the reinforcement cord which constitutes the pneumatic tire of the present invention. 6 is a graph corresponding to FIG. 5 illustrating another example of the winding density distribution. FIG. 6 is a graph corresponding to FIG. 5 showing still another example of the winding density distribution. FIG. FIG. 6 is a graph corresponding to FIG. 5 showing still another example of the winding density distribution. FIG.

  FIG. 1 is a meridian direction sectional view showing an example of an embodiment of a pneumatic tire of the present invention.

  In FIG. 1, the mounting direction of the pneumatic tire T is designated with respect to the vehicle, the symbol IN represents the inside when the vehicle is mounted, and the symbol OUT represents the outside when the vehicle is mounted. The pneumatic tire T includes a tread portion 1, a sidewall portion 2, and a bead portion 3. A carcass layer 5 is mounted between a pair of left and right bead cores 4 embedded in the bead portion 3, and both end portions thereof are bead cores. 4 is folded from the inside to the outside of the tire. A belt layer 6 is disposed over the circumference of the tire on the outer peripheral side of the carcass layer 5 of the tread portion 1. A belt reinforcing layer 8 is disposed on the outer peripheral side of the belt layer 6 so as to wind the reinforcing cord in a spiral shape in the tire circumferential direction.

  In the pneumatic tire of the present invention, at least one belt layer 6 is constituted by a belt cord 7 extending in an arc shape as shown in FIG. 2, and each arc-shaped belt cord 7 is arranged on the outer side OUT when the vehicle is mounted. It is arranged so as to become convex. The belt reinforcing layer 8 disposed on the outer peripheral side of the belt layer 6 is composed of a reinforcing cord 9 wound in the tire circumferential direction, and the winding density of the inner side IN is high and the winding density of the outer side OUT is low when the vehicle is mounted. Thus, the winding density of the outer side OUT is arranged to be lower than the winding density of the inner side IN when the vehicle is mounted.

  As shown for one cord in FIG. 3, the arc-shaped belt cord 7 has its end portions e and e positioned at the inner end portion 6 i of the belt layer 6 when the vehicle is mounted, and the tire width of the arc-shaped belt cord 7. The arcuate apex a on the outer side in the direction is preferably located at the outer end 6o of the belt layer 6 when the vehicle is mounted. It should be noted that both ends e of the arc belt cord 7 are preferably positioned at the inner end 6i when the belt layer 6 is mounted on the vehicle, but at least one end e is the inner end 6i when the belt layer 6 is mounted on the vehicle. The other end may be located at the circumferential end of the belt layer 6. This is a form allowed for the convenience of molding including the step of winding the belt layer 6.

  In the present invention, the arrangement of all the arc-shaped belt cords 7 constituting the belt layer 6 is convex toward the outer side OUT when the vehicle is mounted, so that the tire circumferential direction R of the belt cord 7 is on the outer side when the belt layer 6 is mounted on the vehicle. As the angle with respect to becomes smaller, the arrangement density becomes higher, so the in-plane bending rigidity becomes higher. Further, since the end portion e of the arc-shaped belt cord 7 is disposed on the inner side of the belt layer 6 when the vehicle is mounted, the angle with respect to the tire circumferential direction is increased and the arrangement density is reduced, so that the out-of-plane bending rigidity is reduced. The pneumatic tire of the present invention is mounted on a negative camber in a vehicle. For this reason, when the vehicle goes straight, the vehicle inside of the pneumatic tire is mainly grounded, and the out-of-plane bending rigidity inside the vehicle is reduced, so that the riding comfort is improved. Further, when the vehicle turns, a load is mainly applied to the outside of the pneumatic tire, and the in-plane bending rigidity on the outside of the vehicle is increased, so that the steering stability is improved.

  Further, in the present invention, since the inside of the vehicle is grounded mainly when the vehicle goes straight, the price tear component due to the inclination of the belt cord of the belt layer is reduced. Since the price tear component is thus suppressed, the vehicle flow can be suppressed. Furthermore, the belt cord is arranged in an arc shape so that the inclination angle of the belt cord changes gradually, so when the vehicle moves from straight running to turning and the load moves from the inside to the outside when a pneumatic tire is installed, or turning When the load is shifted from the outside to the inside when the pneumatic tire is mounted from the vehicle to the straight running, the behavior change in the transient state in the region where the load is applied can be moderated.

  FIG. 4 is an explanatory view schematically showing a belt layer constituting another embodiment of the pneumatic tire of the present invention. The reference numerals are the same as those shown in FIGS.

  4, in the pneumatic tire of the present invention, the angle θ with respect to the tire circumferential direction R of the tangent line of the circular belt cord 7 at the inner end 6i of the belt layer 6 when the vehicle is mounted is preferably 50 ° to 90 °. The angle is preferably 80 ° to 90 °. If the angle θ is less than 50 °, the out-of-plane rigidity on the inner side when the vehicle is mounted becomes high, so that the effect of improving riding comfort cannot be sufficiently obtained. In addition, since the price tear component due to the inclination angle of the belt cord gradually increases, it becomes difficult to suppress the vehicle flow.

  Further, as shown in FIG. 4, the pneumatic tire of the present invention has an arcuate belt cord in which the end e of the arcuate belt cord 7 is adjacent to the tire circumferential direction R at the inner end 6i of the belt layer 6 when the vehicle is mounted. 7 is preferably 1.5 to 4.5 mm, more preferably 2.2 to 2.8 mm. When the distance P is less than 1.5 mm, the density around the apex a of the arc-shaped belt cord 7 on the outer side when the belt layer 6 is mounted on the vehicle becomes excessive, and the rigidity of the belt layer becomes too large. When the distance P exceeds 4.5 mm. The belt rigidity inside the belt layer 6 when the vehicle is mounted becomes too small. In any case, not only the motion performance of the pneumatic tire is deteriorated but also the tire durability is lowered. The arc-shaped belt cords adjacent to each other in the tire circumferential direction are belt cords that overlap each other near the apex of the convex portion of the arc. The distance between the belt cords is the distance in the tire circumferential direction between the center points of the two belt cords.

  The material of the belt cord is not particularly limited, but a steel cord is preferable. By constituting the belt cord with a steel cord, it becomes easy to maintain the arrangement form of the belt cord formed in an arc shape.

  In the pneumatic tire of the present invention, the belt reinforcing layer 8 is configured by winding the reinforcing cord 9 in a spiral shape in the tire circumferential direction, and the winding density of the outer cord OUT when the reinforcing cord 9 is attached to the vehicle inner side IN when the vehicle is attached. Make it lower than the winding density. As a result, the winding density of the reinforcing cord 9 on the inner side IN when the vehicle is easy to swell in the tire radial direction is increased, and the swelling of the reinforcing cord 9 on the outer side OUT is reduced when the vehicle is installed. Reduce the density. By arranging the reinforcing cord 9 in this way, the high-speed durability and uniformity of the pneumatic tire can be improved to a level higher than the conventional level. The material of the reinforcing cord is not particularly limited, but an organic fiber cord is preferable. As a result, the belt layer can be prevented from rising while suppressing an increase in the weight of the pneumatic tire.

Here, the winding density of the reinforcing cord 9 means the density of the reinforcing cord 9 per unit width in the tire width direction. For example, if the cord diameter of the reinforcing cord 9 is constant, it is the number of windings of the reinforcing cord 9 per unit width, and the unit when the unit width is 5 cm is a book / 5 cm. Further, the cord diameters of the reinforcing cords 9 wound on the inner side IN when the vehicle is mounted and the outer side OUTs when the vehicle is mounted are different, the cord diameter of the reinforcing cord 9 on the inner side IN when the vehicle is mounted is thicker, The cord diameter of 9 can be reduced. In this case, the winding density is represented by the sum of the cross-sectional areas of the reinforcing cords 9 wound per unit width in the tire meridian direction cross section. For example, when a reinforcing cord 9 having a cord diameter of 1 mm (cross-sectional area = 0.785 mm ² ) is used on the inner side IN when the vehicle is mounted and the cord is wound 10 times per 5 cm width, the winding density is 7.85 mm ² / When the reinforcing cord 9 having a cord diameter = 0.5 mm (cross-sectional area = 0.196 mm ² ) is used at the outer side OUT when the vehicle is mounted and this cord is wound 10 times per 5 cm width, the winding density is It becomes 1.96mm ² / 5cm.

  In the present invention, the winding density of the reinforcing cords 9 constituting the belt reinforcing layer 8 may be gradually decreased from the inner side IN when the vehicle is mounted toward the outer side OUT when the vehicle is mounted. The concept of the distribution of the winding density of the reinforcing cord 9 in the tire width direction is illustrated in FIGS.

  5 to 8 represents the position of the belt layer in the tire width direction, the left hand (vertical axis side) represents the inner side when the vehicle is mounted, and the right hand represents the outer side when the vehicle is mounted. The vertical axis of the graph represents the winding density of the reinforcing cord 9, and the higher the density, the larger the number of windings per unit width or the total cross-sectional area.

  5 to 8, the winding density of the inner reinforcing cord is high when the vehicle is mounted, the winding density of the outer reinforcing cord is low when the vehicle is mounted, and the winding density is from the inner side to the outer side when the vehicle is mounted. It shows that it gets smaller gradually.

  FIG. 5 conceptually shows that the winding density decreases almost linearly from the inside when the vehicle is mounted to the outside when the vehicle is mounted. Such a winding density distribution is obtained by using a reinforcing cord having a constant cord diameter and increasing the interval at which the reinforcing cord is wound in the width direction at a constant rate.

  FIG. 6 conceptually shows that the ratio of decreasing the winding density on the inner side when the vehicle is mounted is reduced, and the ratio of decreasing the winding density on the outer side when the vehicle is mounted is increased. As a result, when the inclination angle of the belt cord is large up to the vicinity of the central region in the tire width direction, the winding density of the reinforcing cord in this region is increased to suppress the belt layer from rising and improve the high speed durability and uniformity. Can do. The distribution of the winding density uses a reinforcing cord with a constant cord diameter, and increases the interval for winding the reinforcing cord in the width direction at a small rate on the inside when the vehicle is mounted, and at a large rate on the outside when the vehicle is mounted. It is obtained by increasing the winding interval.

  FIG. 7 conceptually shows that the winding density decreases in a stepped manner with a certain step from the inside when the vehicle is mounted to the outside when the vehicle is mounted. Such a distribution of winding density uses a reinforcing cord with a constant cord diameter, makes the interval for winding the reinforcing cord constant in one region in the width direction, makes the winding interval small and constant inside that region, and It is obtained by making the winding interval large and constant outside the region. Alternatively, a plurality of reinforcing cords having different cord diameters are prepared, a reinforcing cord having a constant cord diameter is wound at a constant interval in one region in the width direction, and a reinforcing cord having a thick cord diameter inside the region is defined as the previous region. It is obtained by winding at the same interval and winding reinforcing cords having a small cord diameter outside the region at the same interval. Also, the two methods described above can be combined.

  FIG. 8 shows that in the winding density distribution shown in FIG. 7, the ratio (step) for decreasing the winding density on the inner side when the vehicle is mounted is reduced, and the ratio (step) for decreasing the winding density on the outer side when the vehicle is mounted is increased. This is a conceptual illustration.

  In the pneumatic tire of the present invention, as shown in FIG. 2, an area having a width of 10% of the width W of the belt layer from the inner end 6i of the belt layer 6 when the vehicle is mounted to the tire equator CL is defined as a region Win, a belt. When a region having a width of 10% of the width W of the belt layer 6 from the outer end 6o to the tire equator CL when the vehicle is mounted on the layer 6 is defined as a region Wout, the winding density Mout of the reinforcing cord 9 wound around the region Wout Is preferably in the range of 0 to 50%, more preferably 5 to 50%, of the winding density Min of the reinforcing cord 9 wound around the region Win. If the winding density Min of the reinforcing cord 9 wound around the region Win is too large, the suppression of the bulge becomes excessive, and there is a possibility that the high speed durability and the umiformity may be reduced.

In addition, the winding density in the region Win is preferably 50 to 250/5 cm, more preferably 70 to 250/5 cm as the number of ends. The winding density in the area Wout is preferably 0 to 125/5 cm, more preferably 5 to 125/5 cm as the number of ends. Further represented by the total cross-sectional area per unit width of the reinforcing cord, preferably 3.14~39.3mm ² / 5cm in regions Win, more preferably 7.85~28.0mm ² / 5cm, the region Wout preferably It is good to set it as 0-7.85mm < ² > / 5cm, More preferably, it is 0.63-6.28mm < ² > / 5cm. When the widths of the regions Win and Wout are different from the unit width, the proportional calculation is performed from the winding density per width of the regions Win and Wout and the ratio of the unit width and the widths of the regions Win and Wout.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further, the scope of the present invention is not limited to these Examples.

  In pneumatic tires of tire size 225 / 55R17, ten types of pneumatic tires (Examples 1 to 7, Examples 1 to 7, Comparative examples 1 to 3 were produced. In Tables 1 and 2, the description in the column of “belt cord form” indicates that the belt cord is a steel cord having a linear shape or an arc shape. The description in the column of “the direction of the convex portion of the belt cord” indicates whether the direction of the convex portion of the arc in the arc-shaped belt cord is the outer side or the inner side when the vehicle is mounted. The description in the column of “belt cord angle θ” indicates an inclination angle with respect to the tire circumferential direction in the case of a linear belt cord, and an inclination angle with respect to the tire circumferential direction of a tangent at the end portion in the case of an arc belt cord. In addition, the description in the column “distance P between belt cords” indicates the distance between tire cords adjacent to each other in the tire circumferential direction in a linear belt cord, and belt cords adjacent in the tire circumferential direction in an arc belt cord. The tire circumferential direction distance between the end portions of the tire is shown.

  For the belt reinforcing layers described in Tables 1 and 2, the description in the column of “density distribution of reinforcing cord (inside to outside)” indicates whether the winding density of the reinforcing cord is constant or gradually changes. When gradually changing, it indicates whether the density gradually decreases from the inside when the vehicle is mounted to the outside when the vehicle is mounted (high → low), or whether the density gradually increases (low → high). The description in the column “ratio of reinforcing cord density (Mout / Min)” is the ratio of the density Mout of the reinforcing cord wound around the region Wout to the density Min of the reinforcing cord wound around the region Win (Mout / Min). Is expressed as a percentage (%).

  About the obtained 10 types of pneumatic tires, steering stability, riding comfort, vehicle flow, uniformity and high-speed durability were evaluated by the following methods.

Steering stability The obtained pneumatic tire is assembled to a wheel with a rim size of 17 × 71 / 2J, mounted on a test vehicle of a domestic SUV negative camber, and a 4km round test course is performed at 120km / h under the condition of air pressure of 230kPa. The vehicle was run and the sensitivity was evaluated by three specialized panelists. The evaluation results are shown in the “Steering Stability” column of Tables 1 and 2 with a score of 5 out of 5 with Comparative Example 1 being 3 (standard). The larger the value of this score, the better the steering stability.

Riding comfort The obtained pneumatic tire is assembled to a wheel with a rim size of 17 × 71 / 2J and mounted on a test vehicle of a domestic SUV negative camber, and a straight test course with unevenness is set at 50 km / h under the condition of air pressure of 230 kPa. The vehicle was run on a vehicle, and a sensitive evaluation was conducted by three specialized panelists. The evaluation results are shown in the column of “Riding comfort” in Tables 1 and 2, assuming a comparative score of 3 (standard) and a maximum score of 5 points. The larger the value of this score, the better the ride performance.

Vehicle flow The obtained pneumatic tire is assembled to a wheel with a rim size of 17 × 71 / 2J and mounted on a test vehicle of a domestic SUV negative camber. A flat straight test course is carried out at 100 km / h under conditions of air pressure of 230 kPa. A distance (deflection amount) deviated left and right from the straight line was measured after running 100 mm from the time when the hand was released from the handle during straight running. The obtained results are shown in the column of “vehicle flow” in Tables 1 and 2 as an index for setting the reciprocal of Comparative Example 1 to 100. The larger the vehicle flow index, the smaller the deflection amount, which means that the vehicle flow is suppressed.

Uniformity The obtained pneumatic tire was assembled to a wheel having a rim size of 17 × 7 J, and the RFV was measured by a force variation tester according to the tire uniformity measuring method of JIS D4230. The obtained results are shown in the “Uniformity” column of Tables 1 and 2 as an index that sets Comparative Example 1 to 100. The larger the index, the better the uniformity.

High-speed durability The obtained pneumatic tire is assembled to a wheel with a rim size of 17 × 7J, attached to an indoor drum tester compliant with JIS D4230, and high-speed durability described in “6.4 High-speed performance test A” of JIS D4230. A high-speed durability test was conducted in accordance with the property test, and the distance traveled until the tire failed was measured. The obtained results are shown in the column of “High-speed durability” in Tables 1 and 2 as an index for setting Comparative Example 1 to 100. Higher index means higher speed durability.

DESCRIPTION OF SYMBOLS 1 Tread part 5 Carcass layer 6 Belt layer 6i Inner edge part at the time of vehicle wearing of a belt layer 6o Outer edge part at the time of vehicle wearing of a belt layer 7 Arc-shaped belt cord 8 Belt reinforcement layer 9 Reinforcement cord a The convex part of an arc-shaped belt cord Vertex e End of arc belt cord T Pneumatic tire R Tire circumferential direction

Claims (5)

In a pneumatic tire having a configuration in which a belt layer is disposed on the outer peripheral side of the carcass layer in the tread portion, and a belt reinforcing layer is disposed on the outer peripheral side of the belt layer, and the mounting direction with respect to the vehicle is designated.
The belt layer includes a belt cord extending in an arc shape, the arc-shaped belt cord is arranged so as to protrude outward when the vehicle is mounted, and the belt reinforcing layer extends in the tire circumferential direction. A pneumatic tire characterized in that the reinforcing cord is arranged such that the winding density on the outer side when mounted on the vehicle is lower than the winding density on the inner side when mounted on the vehicle.   The end of the arc-shaped belt cord is positioned at the inner end of the belt layer when the vehicle is mounted, and the apex outside the arc-shaped belt cord in the tire width direction is positioned at the outer end of the belt layer when mounted on the vehicle. The pneumatic tire according to claim 1.   3. The pneumatic tire according to claim 1, wherein an angle θ of a tangent line of the arc-shaped belt cord at the inner end portion of the belt layer with respect to the tire circumferential direction is 50 to 90 °. 4.   At the inner end of the belt layer when the vehicle is mounted, a tire circumferential distance P between the end of the arc belt cord and the end of the arc belt cord adjacent to the tire circumferential direction is 1.5 to 4.5 mm. The pneumatic tire according to any one of claims 1 to 3, wherein the pneumatic tire is provided.   The region of 10% of the width W of the belt layer from the inner end to the tire equator when the belt layer is mounted to the tire equator is the region Win, and 10 of the width W of the belt layer from the outer end of the belt layer to the tire equator when the vehicle is mounted. When a region having a% width is defined as a region Wout, the density Mout of the reinforcing cord wound around the region Wout is in a range of 0 to 50% of the density Min of the reinforcing cord wound around the region Win. The pneumatic tire according to any one of claims 1 to 4, characterized in that:

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