JP2021167172A - Pneumatic tire - Google Patents

Abstract

To provide a pneumatic tire improved in durability against high inner pressure, while achieving high load bearing capability and space-saving.SOLUTION: An outside diameter OD of a pneumatic tire 10 is 350 mm or more and 600 mm or less, and a width SW of the tire is 125 mm or more and 255 mm or less. Oblateness of the pneumatic tire 10 is 40% or more and 75% or less, and a rim diameter RD of a rim wheel is 10 inches or more and 22 inches or less, and a rim width RW of the rim wheel is 3.8 inches or more and 8 inches or less, which satisfy relational expressions of 0.78≤RW/SW≤0.99 and 0.56≤RD/OD≤0.75. Total of cross sectional areas of belt cords 51a per unit width W in a shoulder region S1 of a tread is same as total of cross sectional areas of the belt cords 51a per unit width W in a center region S2 of the tread, or larger than total of cross sectional areas of the belt cords 51a per unit width W in the center region S2.SELECTED DRAWING: Figure 4

Description

The present disclosure relates to small diameter pneumatic tires with enhanced load bearing capacity.

Conventionally, pneumatic tires having a smaller diameter while increasing the load-bearing capacity (maximum load capacity) have been known (see Patent Document 1). It is said that such pneumatic tires can save space for small vehicles and secure a large riding space.

JP-A-2018-138435

In recent years, a new small shuttle bus has been proposed that focuses on the transportation of people and goods in the city. Such a small shuttle bus has a total length of about 5 m and a total width of about 2 m, and it is assumed that the gross vehicle weight may exceed 3 tons. Space saving is also required for pneumatic tires mounted on such small shuttle buses.

Further, it is assumed that a high internal pressure is set for the pneumatic tire mounted on such a small shuttle bus, and sufficient durability against a high internal pressure is required.

In particular, in such a pneumatic tire, there is a problem that the shoulder portion of the tread without the belt layer tends to grow in the tire radial direction due to the high internal pressure.

Therefore, the following disclosure is made in view of such a situation, and aims to provide a pneumatic tire having improved durability against a high internal pressure while achieving high load-bearing capacity and space saving. ..

One aspect of the present disclosure is a pneumatic tire (pneumatic tire 10) provided with a belt layer (for example, a belt layer 50) inside the tread (tread 20) in contact with the road surface in the tire radial direction. The outer diameter OD is 350 mm or more and 600 mm or less, the tire width SW of the pneumatic tire is 125 mm or more and 255 mm or less, and the flatness ratio of the pneumatic tire is 40% or more and 75% or less. The rim diameter RD of the rim wheel (rim wheel 100) assembled to the pneumatic tire is 10 inches or more and 22 inches or less, and the rim width RW of the rim wheel is 3.8 inches or more and 8 inches or less. , 0.78 ≦ RW / SW ≦ 0.99, and 0.56 ≦ RD / OD ≦ 0.75, and the belt layer is provided with a plurality of belt cords (belt cords) provided along a predetermined direction. It is composed of one or more belts (belts 51) having 51a), and at least one of the belts is a resin-coated belt in which the belt cord is coated with a resin material, and the unit width in the shoulder region of the tread. The total cross-sectional area of the belt cord per unit is the same as the total cross-sectional area of the belt cord per unit width in the center region of the tread, or the total cross-sectional area of the belt cord per unit width in the center region. Wider than.

According to the above-mentioned pneumatic tire, durability against high internal pressure can be enhanced while achieving high load bearing capacity and space saving.

FIG. 1 is an overall schematic side view of the vehicle 1 on which the pneumatic tire 10 is mounted. FIG. 2 is a cross-sectional view of the pneumatic tire 10 and the rim wheel 100. FIG. 3 is a cross-sectional view of the pneumatic tire 10. FIG. 4 is a partially enlarged cross-sectional view of the belt layer 50. FIG. 5 is a partially exploded plan view of the carcass 40 and the belt layer 50. FIG. 6 is a partially exploded plan view of the carcass 40 and the belt layer 50A of the pneumatic tire 10A according to the first modification. FIG. 7 is a partially exploded plan view of the carcass 40 and the belt layer 50B of the pneumatic tire 10B according to the second modification. FIG. 8 is a partially enlarged cross-sectional view of the belt layer 50C of the pneumatic tire 10C according to the third modification.

Hereinafter, embodiments will be described with reference to the drawings. The same functions and configurations are designated by the same or similar reference numerals, and the description thereof will be omitted as appropriate.

(1) Schematic configuration of a vehicle on which a pneumatic tire is mounted FIG. 1 is an overall schematic side view of a vehicle 1 on which the pneumatic tire 10 according to the present embodiment is mounted. As shown in FIG. 1, in the present embodiment, the vehicle 1 is a four-wheeled vehicle. The vehicle 1 is not limited to four wheels, and may have a six-wheel configuration or an eight-wheel configuration.

The vehicle 1 is equipped with a predetermined number of pneumatic tires 10 according to the wheel configuration. Specifically, the pneumatic tire 10 assembled to the rim wheel 100 is mounted on the vehicle 1 at a predetermined position.

Vehicle 1 belongs to a new small shuttle bus that focuses on the transportation of people and goods in the city. In the present embodiment, the new small shuttle bus is assumed to be a vehicle having a total length of 4 m to 7 m, a total width of about 2 m, and a gross vehicle weight of about 3 tons. However, the size and the gross vehicle weight are not necessarily limited to the relevant range, and may be out of the relevant range to some extent.

Further, the small shuttle bus is not necessarily limited to the transportation of people, but may be used for the transportation of goods, mobile stores, mobile offices, and the like.

Furthermore, since the small shuttle bus focuses on the transportation of people and goods in the city, it assumes a relatively low traveling speed range (maximum speed of 70 km / h or less, average speed of about 50 km / h). .. Therefore, hydroplaning measures do not have to be emphasized. However, the small shuttle bus may be used for transportation between cities and may have a high speed traveling range (for example, a maximum speed of 100 km / h).

In the present embodiment, it is assumed that the vehicle 1 is an electric vehicle having an automatic driving function (assuming level 4 or higher), but the automatic driving function is not essential and does not have to be an electric vehicle. No.

When the vehicle 1 is an electric vehicle, it is preferable to use an in-wheel motor (not shown) as a power unit. The entire unit of the in-wheel motor may be provided in the inner space of the rim wheel 100, or a part of the unit may be provided in the inner space of the rim wheel 100.

Further, when an in-wheel motor is used, it is preferable that the vehicle 1 has an independent steering function in which each wheel can be independently steered. As a result, it is possible to turn on the spot and move in the lateral direction, and since a power transmission mechanism is not required, the space efficiency of the vehicle 1 can be improved.

As described above, the vehicle 1 is required to have high space efficiency. Therefore, the pneumatic tire 10 preferably has a small diameter as much as possible.

On the other hand, since it is mounted on the vehicle 1 having a gross vehicle weight corresponding to the vehicle size and application, a high load capacity (maximum load capacity) is required.

The pneumatic tire 10 has a load-bearing capacity corresponding to the gross vehicle weight of the vehicle 1 while reducing the outer diameter OD (not shown in FIG. 1, see FIG. 2) in order to satisfy such a requirement.

Further, when the vehicle 1 is provided with an in-wheel motor and an independent steering function, it is preferable that the flatness ratio of the pneumatic tire 10 is low from the viewpoint of improving responsiveness, and considering the accommodation space of the in-wheel motor or the like, the pneumatic tire The rim diameter RD of 10 (not shown in FIG. 1, see FIG. 2) is preferably large.

(2) Configuration of Pneumatic Tire FIG. 2 is a cross-sectional view of the pneumatic tire 10 and the rim wheel 100. Specifically, FIG. 2 is a cross-sectional view of the pneumatic tire 10 assembled to the rim wheel 100 along the tire width direction and the tire diameter direction. Note that in FIG. 2, the hatching display of the cross section is omitted (the same applies to FIGS. 3 and later).

The pneumatic tire 10 has a relatively small diameter, but is wide. Specifically, the rim diameter RD, which is the diameter of the rim wheel 100 assembled to the pneumatic tire 10, is 10 inches or more and 22 inches or less. The rim diameter RD may be 12 inches or more and 17.5 inches or less in consideration of other numerical ranges.

As shown in FIG. 2, the rim diameter RD is the outer diameter of the rim body portion of the rim wheel 100, and does not include the portion of the rim flange 110.

The tire width SW of the pneumatic tire 10 is 125 mm or more and 255 mm or less. As shown in FIG. 2, the tire width SW means the cross-sectional width of the pneumatic tire 10, and when the pneumatic tire 10 includes a rim guard (not shown), the rim guard portion is not included.

Further, the flatness of the pneumatic tire 10 is 40% or more and 75% or less. The flatness is calculated using Equation 1.

Flatness (%) = tire cross-section height H / tire width SW (cross-section width) x 100 ... (Equation 1)
The outer diameter OD, which is the outer diameter of the pneumatic tire 10, is 350 mm or more and 600 mm or less. The outer diameter OD is preferably 500 mm or less.

When the outer diameter OD is such a size and the rim width of the rim wheel 100 assembled to the pneumatic tire 10 is RW, the pneumatic tire 10 satisfies the relationship of (Equation 2) and (Equation 3). .. The rim width RW is 3.8 inches or more and 8 inches or less.

0.78 ≤ RW / SW ≤ 0.99 ... (Equation 2)
0.56 ≤ RD / OD ≤ 0.75 ... (Equation 3)
The pneumatic tire 10 preferably satisfies 0.78 ≦ RW / SW ≦ 0.98, and more preferably 0.78 ≦ RW / SW ≦ 0.95. Further, the pneumatic tire 10 preferably satisfies 0.56 ≦ RD / OD ≦ 0.72, and more preferably 0.56 ≦ RD / OD ≦ 0.71.

The pneumatic tire 10 satisfying such a relationship can secure the air volume necessary for supporting the gross vehicle weight of the vehicle 1 while having a small diameter. ^{Specifically, the air volume needs to be 20,000 cm 3} or more in consideration of the load bearing performance. Further, considering space saving, it is necessary that the ^{size is 80,000 cm 3 or less.}

The rim width RW is not particularly limited as long as the above relationship is satisfied, but it is preferable that the rim width RW is as wide as possible from the viewpoint of ensuring the air volume. For example, the rim width can be 3.8 to 7.8 J.

Similarly, from the viewpoint of securing the air volume, it is preferable that the ratio of the rim diameter RD to the outer diameter OD is small, that is, the flatness is high. However, as described above, the flatness is preferably low from the viewpoint of responsiveness, and the rim diameter RD is preferably large in consideration of the accommodation space of the in-wheel motor or the like. Therefore, the flatness and the rim diameter RD Is a trade-off between air volume and responsiveness and accommodation space such as in-wheel motors.

An example of a suitable size for the pneumatic tire 10 is 205 / 40R15. The compatible rim width is about 7.5J. In addition, 215 / 45R12 is mentioned as another example of a suitable size. In this case, the compatible rim width is about 7.0J.

Further, although not particularly limited, the set internal pressure (normal internal pressure) of the pneumatic tire 10 is assumed to be 400 to 1,100 kPa, and in reality, 500 to 900 kPa. In Japan, for example, the normal internal pressure is the air pressure corresponding to the maximum load capacity of JATTA (Japan Automobile Tire Association) in the YearBook, and the regular load is the maximum load capacity (maximum) corresponding to the maximum load capacity in the JATMA YearBook. Load). ETRTO in Europe, TRA in the United States, and tire standards of other countries are supported.

Further, it is assumed that the load borne by the pneumatic tire 10 is 500 to 1,500 kgf, and in reality, about 900 kgf.

FIG. 3 is a cross-sectional view of the pneumatic tire 10. Specifically, FIG. 3 is a cross-sectional view of the pneumatic tire 10 and the rim wheel 100 along the tire width direction and the tire radial direction.

As shown in FIG. 3, the pneumatic tire 10 includes a tread 20, a tire side portion 30, a carcass 40, a belt layer 50, and a bead portion 60. As shown in FIG. 3, the cross-sectional shape of the pneumatic tire 10 is symmetrical with respect to the tire equatorial line CL as a reference.

The tread 20 is a portion in contact with the road surface. A pattern (not shown) is formed on the tread 20 according to the usage environment of the pneumatic tire 10 and the type of vehicle to be mounted.

The pattern formed on the tread 20 is not particularly limited, but in the present embodiment, a plurality of circumferential grooves are formed on the tread 20. Specifically, the tread 20 is formed with a plurality of circumferential main grooves 21 and circumferential main grooves 22. The tread 20 may be formed with a groove (lug groove) in the width direction (not shown).

The circumferential main groove 21 is formed on the outermost side in the tire width direction. The circumferential main groove 22 is formed inside the tire width direction, that is, on the tire equatorial line CL side with respect to the circumferential main groove 21.

The tire side portion 30 is connected to the tread 20 and is located inside the tread 20 in the tire radial direction. The tire side portion 30 is a region from the outer end of the tread 20 in the tire width direction to the upper end of the bead portion 60. The tire side portion 30 is sometimes called a sidewall or the like.

The carcass 40 is an annular member that forms the skeleton (tire skeleton) of the pneumatic tire 10. The carcass 40 has a radial structure in which carcass cords 41 (not shown in FIG. 3, see FIG. 5) arranged radially along the tire radial direction are covered with a rubber material. However, the structure is not limited to the radial structure, and a bias structure in which the carcass cords 41 are arranged so as to intersect in the tire radial direction may be used.

The material of the carcass cord 41 is not particularly limited, but is preferably formed of any of aromatic polyamide fibers, carbon fibers, and steel in consideration of the use of the pneumatic tire 10 as described above.

The belt layer 50 is provided inside the tread 20 in the tire radial direction. Specifically, the belt layer 50 is an annular shape provided between the tread 20 and the carcass 40 and extending along the tire circumferential direction.

The belt layer 50 may be composed of one or more belts. The configuration of the belt layer 50 will be described later.

The bead portion 60 is connected to the tire side portion 30 and is located inside the tire side portion 30 in the tire radial direction. The bead portion 60 is an annular shape extending in the tire circumferential direction, and the carcass 40 is folded back from the inside in the tire width direction to the outside in the tire width direction via the bead portion 60.

(3) Configuration of Belt Layer 50 Next, a specific configuration of the belt layer 50 will be described. FIG. 4 is a partially enlarged cross-sectional view of the belt layer 50. FIG. 5 is a partially exploded plan view of the carcass 40 and the belt layer 50.
In the present embodiment, the belt layer 50 is composed of one belt 51. As shown in FIGS. 4 and 5, the belt 51 has a plurality of belt cords 51a provided along a predetermined direction.

Further, in the present embodiment, the belt 51 is a resin-coated belt in which the belt cord 51a is coated with a resin material. Specifically, the belt 51 is a single-layer spiral belt formed by winding a belt cord 51a coated with a resin material along the tire circumferential direction. The specific configuration of the spiral belt is described in, for example, Japanese Patent Application Laid-Open No. 2018-65526.

As the resin material, a rubber material constituting the tire side portion 30 and a resin material having a higher tensile elastic modulus than the rubber material constituting the tread 20 are used. As the resin material, an elastic thermoplastic resin, a thermoplastic elastomer (TPE), a thermosetting resin, or the like can be used. Considering the elasticity during running and the moldability during manufacturing, it is desirable to use a thermoplastic elastomer.

Examples of the thermoplastic elastomer include polyolefin-based thermoplastic elastomer (TPO), polystyrene-based thermoplastic elastomer (TPS), polyamide-based thermoplastic elastomer (TPA), polyurethane-based thermoplastic elastomer (TPU), and polyester-based thermoplastic elastomer (TPC). , Dynamic crosslinked thermoplastic elastomer (TPV) and the like.

Examples of the thermoplastic resin include polyurethane resin, polyolefin resin, vinyl chloride resin, and polyamide resin. Further, as the thermoplastic resin material, for example, the deflection temperature under load (at 0.45 MPa load) specified in ISO 75-2 or ASTM D648 is 78 ° C. or higher, and the tensile yield strength specified in JIS K7113 is high. Those having a tensile fracture elongation of 10 MPa or more, a tensile fracture elongation of 50% or more specified in JIS K7113, and a Bikat softening temperature (method A) specified in JIS K7206 of 130 ° C. or more can be used.

Further, the cord itself of the belt cord 51a is preferably formed of any of aromatic polyamide fibers, carbon fibers and steel.

The distance G1 between the belt cords 51a provided in the shoulder area S1 is closer than the distance G2 between the belt cords 51a provided in the center area S2. That is, the distance G1 of the belt cords 51a in the shoulder area S1 is narrower than the distance G2 of the belt cords 51a in the center area S2. Here, the interval G1 and the interval G2 may be interpreted as the distance between the adjacent belt cords 51a with respect to the center of the adjacent belt cords 51a in the tire width direction.

The shoulder region S1 may mean a region of the tread 20 outside the tire width direction from the circumferential main groove 21 formed on the tread 20 in the tire width direction. In the present embodiment, the shoulder region S1 may be interpreted as a region outside the tire width direction from the center of the circumferential main groove 21 in the tire width direction.

Further, the center region S2 may mean a region of the tread 20 inside the shoulder region S1 in the tire width direction, that is, a region other than the shoulder region S1 in the tire width direction including the tire equatorial line CL.

In the present embodiment, the belt cord 51a provided in the shoulder region S1 is provided along the tire circumferential direction. Similarly, the belt cord 51a provided in the center region S2 is provided along the tire circumferential direction.

In addition, "along the tire circumferential direction" may mean that it is parallel to the tire circumferential direction, but it may be slightly inclined with respect to the tire circumferential direction.

As described above, the distance G1 between the belt cords 51a in the shoulder region S1 is closer than the distance G2 between the belt cords 51a in the center region S2. On the other hand, the cord diameter (which may be called the diameter) of the belt cord 51a remains the same in the shoulder region S1 and the center region S2.

Therefore, the total cross-sectional area of the belt cord 51a per unit width W in the shoulder region S1 is wider than the total cross-sectional area of the belt cord 51a per unit width W in the center region S2.

The value of the unit width W is not particularly limited, but as shown in FIG. 4, the value is larger than the value including at least two or three belt cords 51a (depending on the tire size, for example, about 5 mm). Is preferable.

The total cross-sectional area of the belt cord 51a per unit width W in the shoulder region S1 may be the same as the total cross-sectional area of the belt cord 51a per unit width W in the center region S2. In this case, as will be described later, the cord diameter of the belt cord 51a may be different between the shoulder region S1 and the center region S2. Further, in this case, the shoulder area S1 and the center area S2 may be formed by separate belts. That is, the belt layer 50 may be composed of a plurality of belts.

(4) Action / Effect According to the above-described embodiment, the following action / effect can be obtained. The pneumatic tire 10 can be used for a new small shuttle bus that focuses on the transportation of people and goods in the city, like the vehicle 1 described above.

Specifically, the outer diameter OD of the pneumatic tire 10 is 350 mm or more and 600 mm or less, and the tire width SW is 125 mm or more and 255 mm or less. The flatness of the pneumatic tire 10 is 40% or more and 75% or less.

The rim diameter RD of the rim wheel 100 assembled to the pneumatic tire 10 is 10 inches or more and 22 inches or less, and the rim width RW is 3.8 inches or more and 8 inches or less.

The pneumatic tire 10 having such a size further satisfies the following relationship.

0.78 ≤ RW / SW ≤ 0.99, and 0.56 ≤ RD / OD ≤ 0.75
Therefore, the diameter is sufficiently smaller than the size of the vehicle 1, which can contribute to space saving of the vehicle 1.

Further, according to the pneumatic tire 10, in order to satisfy the relationship of 0.78 ≦ RW / SW ≦ 0.99, the rim width RW is wide with respect to the tire width SW, that is, a wide tire can be configured, and a high load capacity is possible. It is easy to secure the air volume required to exert the effect. If the rim width RW becomes too wide, the tire width SW also widens, the space efficiency decreases, and the bead portion 60 easily comes off from the rim wheel 100.

Further, according to the pneumatic tire 10, since the relationship of 0.56 ≦ RD / OD ≦ 0.75 is satisfied, the rim diameter RD with respect to the outer diameter OD is large, and it is easy to secure a storage space for an in-wheel motor or the like. If the rim diameter RD becomes too small, the diameter size of the disc brake or the drum brake becomes small. Therefore, the effective contact area of the brake becomes small, and it becomes difficult to secure the required braking performance.

That is, according to the pneumatic tire 10, when it is mounted on a new small shuttle bus or the like, it is possible to achieve high space efficiency while having a higher load capacity.

Further, since the rim diameter RD of the pneumatic tire 10 is 10 inches or more and 22 inches or less, it is possible to secure a necessary and sufficient storage space for an air volume and an in-wheel motor while maintaining a small diameter. In addition, braking performance and driving performance can be ensured.

Further, the tire width SW of the pneumatic tire 10 is 125 mm or more and 255 mm or less, and the flatness of the pneumatic tire 10 is 40% or more and 75% or less. Storage space can be secured.

In the present embodiment, the belt 51 is a resin-coated belt in which the belt cord 51a is coated with a resin material. Further, the total cross-sectional area of the belt cord 51a per unit width W in the shoulder region S1 is wider than the total cross-sectional area of the belt cord 51a per unit width W in the center region S2.

Since the pneumatic tire 10 has the size as described above, the air volume filled in the internal space of the pneumatic tire 10 assembled to the rim wheel 100 is reduced, and the internal pressure is increased to support a high load. Set.

Therefore, in particular, the shoulder portion of the tread 20 not provided with the belt layer 50 tends to grow in the tire radial direction due to the high internal pressure, but the interval G1 of the belt cord 51a in the shoulder region S1 is the belt cord in the center region S2. By making the interval G2 of 51a denser, the cross-sectional area of the belt cord 51a per unit width W in the shoulder region S1 is made larger than the total cross-sectional area of the belt cord 51a per unit width W in the center region S2. In particular, growth (diameter growth) in the tire radial direction in the shoulder region S1 can be suppressed.

That is, according to the pneumatic tire 10, it is possible to improve the durability against a high internal pressure while achieving a high load-bearing capacity and space saving.

In the present embodiment, as described above, the distance G1 between the belt cords 51a in the shoulder region S1 is narrower and denser than the distance G2 between the belt cords 51a in the center region S2. Therefore, in particular, the diameter growth in the shoulder region S1 can be suppressed more effectively.

In the present embodiment, the belt cord 51a in the shoulder region S1 is provided along the tire circumferential direction. Further, the belt cord 51a in the center region S2 is also provided along the tire circumferential direction.

Therefore, the belt 51 having a plurality of belt cords 51a provided along the tire circumferential direction can effectively suppress the diameter growth even when the pneumatic tire 10 is set to a high internal pressure.

(5) Other Embodiments Although the embodiments have been described above, it is obvious to those skilled in the art that various modifications and improvements are possible without being limited to the description of the embodiments.

FIG. 6 is a partially exploded plan view of the carcass 40 and the belt layer 50A of the pneumatic tire 10A according to the first modification. Hereinafter, a portion different from the pneumatic tire 10 described above will be mainly described, and the description thereof will be omitted as appropriate for the same portion.

As shown in FIG. 6, the pneumatic tire 10A includes a belt layer 50A. The belt layer 50A is composed of a plurality of belts, specifically, a pair of belts 52 and a belt 53.

The belt 52 has a plurality of belt cords 52a. The belt 52 is provided in the shoulder area S1. The belt cord 52a is provided along the tire circumferential direction.

The belt 53 has a plurality of belt cords 53a. The belt 53 is provided in the center area S2.

The belt cord 53a is provided so as to be inclined with respect to the tire circumferential direction. Specifically, the belt 53 constitutes a so-called interlaced belt, and the plurality of belt cords 53a are a belt cord that inclines to one side with respect to the tire circumferential direction and a belt that inclines to the other side with respect to the tire circumferential direction. Includes code and.

The belt 52 may be a resin-coated belt like the belt 51 described above. Further, the belt 53 may be a resin-coated belt or a rubber-coated belt coated with a rubber material. Alternatively, the belt 52 may be a rubber-coated belt and the belt 53 may be a resin-coated belt.

That is, at least one of the belt 52 and the belt 53 may be a resin-coated belt. Further, both the belt 52 and the belt 53 may be resin-coated belts.

FIG. 7 is a partially exploded plan view of the carcass 40 and the belt layer 50B of the pneumatic tire 10B according to the second modification.

As shown in FIG. 7, the pneumatic tire 10B includes a belt layer 50B. The belt layer 50B is composed of two layers, a belt 51 and a belt 55.

The belt 51 is the same as the belt 51 provided on the pneumatic tire 10. The belt 55 is provided inside the tire radial direction with respect to the belt 51. Specifically, the belt 55 is provided between the carcass 40 and the belt 51.

The belt 55 has a plurality of belt cords 55a. The belt 55 is preferably provided at least in the center region S2. However, as shown in FIG. 7, the belt 55 may be further provided up to the shoulder region S1.

The belt cord 55a is provided so as to be inclined with respect to the tire circumferential direction. Specifically, the belt 55 constitutes a so-called interlaced belt like the belt 53 according to the first modification, and the plurality of belt cords 53a include a belt cord that inclines to one side with respect to the tire circumferential direction and a tire. Includes a belt cord that inclines to the other side with respect to the circumferential direction.

The belt 55 may be a resin-coated belt or a rubber-coated belt coated with a rubber material.

FIG. 8 is a partially enlarged cross-sectional view of the belt layer 50C of the pneumatic tire 10C according to the third modification. As shown in FIG. 8, the pneumatic tire 10C includes a belt layer 50C.

The belt layer 50C has a structure similar to that of the belt layer 50 described above, but includes a plurality of types of belt cords having different diameters. Specifically, the belt layer 50C includes a plurality of belt cords 51c and a plurality of belt cords 51d.

The cord diameter (diameter φ1) of the belt cord 51c is larger than the cord diameter (diameter φ2) of the belt cord 51d. The belt cord 51c is provided in the shoulder region S1, and the belt cord 51d is provided in the center region S2.

That is, the diameter of the belt cord 51c in the shoulder region S1 is larger than the diameter of the belt cord 51d in the center region S2. As a result, similarly to the belt 51, the total cross-sectional area of the belt cord 51c per unit width W in the shoulder region S1 becomes wider than the total cross-sectional area of the belt cord 51d per unit width W in the center region S2. There is.

Similar to the pneumatic tire 10, the pneumatic tire 10A, the pneumatic tire 10B, and the pneumatic tire 10C according to the modification examples 1 to 3 also achieve high load bearing capacity and space saving, and high internal pressure. It is possible to increase the durability against.

Further, in the above-described embodiment and modification, the belt cord in the shoulder region S1 is provided along the tire circumferential direction, but also in the shoulder region S1, the belt cord is greatly inclined with respect to the tire circumferential direction. It doesn't matter if you do.

Although the present disclosure has been described in detail above, it is clear to those skilled in the art that the present disclosure is not limited to the embodiments described in the present disclosure. The present disclosure may be implemented as an amendment or modification without departing from the purpose and scope of the present disclosure, which is determined by the description of the scope of claims. Therefore, the description of the present disclosure is for the purpose of exemplary explanation and does not have any limiting meaning to the present disclosure.

1 Vehicle 10,10A, 10B, 10C Pneumatic tire 20 Tread 21,22 Circumferential main groove 30 Tire side part 30 Tire side part 40 Carcus 41 Carcus code 50, 50A, 50B, 50C Belt layer 51, 52, 53, 55 Belts 51a, 51c, 51d, 52a, 53a, 55a Belt cord 100 Rim wheel 110 Rim flange

Claims (6)

A pneumatic tire with a belt layer inside the tread that contacts the road surface in the radial direction.
The outer diameter OD of the pneumatic tire is 350 mm or more and 600 mm or less.
The tire width SW of the pneumatic tire is 125 mm or more and 255 mm or less.
The flatness of the pneumatic tire is 40% or more and 75% or less.
The rim diameter RD of the rim wheel assembled to the pneumatic tire is 10 inches or more and 22 inches or less.
The rim width RW of the rim wheel is 3.8 inches or more and 8 inches or less.
0.78 ≤ RW / SW ≤ 0.99, and 0.56 ≤ RD / OD ≤ 0.75
Meet the relationship,
The belt layer is composed of one or more belts having a plurality of belt cords provided along a predetermined direction.
At least one of the belts is a resin-coated belt in which the belt cord is coated with a resin material.
The total cross-sectional area of the belt cord per unit width in the shoulder area of the tread is the same as the total cross-sectional area of the belt cord per unit width in the center area of the tread, or per unit width in the center area. A pneumatic tire that is wider than the total cross-sectional area of the belt cord. The pneumatic tire according to claim 1, wherein the belt cord in the shoulder region is provided along the tire circumferential direction. The pneumatic tire according to claim 1 or 2, wherein the belt cord in the center region is provided along the tire circumferential direction. The pneumatic tire according to claim 1 or 2, wherein the belt cord in the center region is provided so as to be inclined with respect to the tire circumferential direction. The pneumatic tire according to any one of claims 1 to 3, wherein the distance between the belt cords in the shoulder region is narrower than the distance between the belt cords in the center region. The pneumatic tire according to any one of claims 1 to 3, wherein the diameter of the belt cord in the shoulder region is larger than the diameter of the belt cord in the center region.

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