JPH04197807A - Pneumatic radial tire - Google Patents

Abstract

PURPOSE:To enhance the wandering and cross slip properties of a pneumatic tire by providing two longitudinal auxiliary grooves within an area of a tread shoulder portion which is regulated from the end edge of the tread, and providing siping in an inside block located between longitudinal shoulder grooves and the longitudinal auxiliary grooves, the number of and interval among the siping being regulated. CONSTITUTION:A tread shoulder portion SH is provided with a group 4 of longitudinal auxiliary grooves consisting of two longitudinal auxiliary grooves 3, i.e., an inner longitudinal auxiliary groove G3 and an outer longitudinal auxiliary groove G4. The group 4 of longitudinal auxiliary grooves are disposed within an area M between an outside point P by which the distance of more than 3mm and below 6mm from the end edge E of a tread is separated into the equatorial line C side portion of the tire and an inside point Q by which the distance W2 of more than 0.04 times and below 0.1 times the width TW of the tread from the end edge of the tread is separated into the equatorial line side portion of the tire. More than one and five or fewer siping S each connecting a longitudinal shoulder groove G1 to the inner longitudinal auxiliary groove G3 is provided in an inner block BI. The siping is formed by center siping and a pair of side siping, which are separated from one another at an interval of more than 8mm and below 16mm.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention improves lateral skidding resistance and wandering resistance, improves runnability on icy and snowy roads, and improves durability by increasing resistance to uneven wear. Regarding pneumatic tires.

[Conventional technology]

2. Description of the Related Art Spiked tires, in which chains are attached to tires or spikes are driven into the tires, have conventionally been used for driving on icy or snowy roads. However, in recent years, due to the damage to road surfaces caused by spikes and the dust raised by scraping the road surface, people have begun to refrain from installing spiked tires and chains with hard spikes, and so-called studless tires without spikes have become popular. It is being done.

Such studless tires have a problem in that they have inferior running performance on icy and snowy roads compared to the spiked tires, and are particularly prone to skidding when turning on icy and snowy roads.

[Problem to be solved by the invention]

The main purpose of conventional studless tires is to improve straight-line performance on icy and snowy roads, and for this reason, the tire tread surface has a different circumferential length between the center and the tread shoulder. However, various attempts have been made to prevent uneven wear and wandering caused by this slip.

For example, as shown in FIG. 6(a), shoulder block a
There are sipes S...- extending in the lateral direction, and small vertical grooves g around the inclined part k of the tread end. Although this structure slightly lowers the rigidity of the shoulder block a and prevents wandering on dry roads, it does not prevent sideslips on icy and snowy roads.

Also, as shown in Fig. 6(b), an attempt was made to provide a large number of sipes S at small intervals, or the shoulder block a
Although the rigidity in the circumferential direction of the tire was reduced and wandering was reduced, it was ineffective against forces acting in the axial direction of the tire and was far from improving structural slip resistance. Moreover, there is a problem in that uneven wear of the toe and heel occurs frequently before and after the siping of the block near both ends of the tread.

It is also disclosed in Japanese Patent Application Laid-open No. 56-21905 and FIG. 6(C)
As shown in Fig. 2, it has been proposed that the shoulder block a is provided with a plurality of horizontal sipings S and one small vertical groove g that goes around near the tread edge e, but wandering is suppressed by the siping S. On the other hand, against forces applied from the lateral direction, such as cornering force, the small vertical grooves g provide support and lateral slip is slightly reduced. However, the above-mentioned proposal is intended to increase the driving force and braking force in the tire circumferential direction, that is, when traveling straight, and does not particularly take into account the stability of the structure, and is therefore insufficient.

As described above, conventional tires for use on icy and snowy roads lack consideration for sideslip properties during turns.

As a result of intensive research, the inventors created two vertical grooves near one end of the shoulder by restricting the installation position, in order to improve the structure's verticality and wandering resistance, as well as uneven wear resistance. In addition, they have discovered that by providing siping on the shoulder block by regulating the installation position and number of sipes, the structure can improve slip resistance, wander resistance, and uneven wear resistance.

The present invention improves wandering property and side-slip property by providing two longitudinal sub-grooves extending in the circumferential direction in the tread shoulder part and providing sipes with a restricted number on blocks located inside the sub-grooves. The purpose of the present invention is to provide a pneumatic tire that can improve both of the above characteristics, as well as improve resistance to uneven wear and durability.

[Means to solve the problem]

The present invention provides a tread that is continuous in the tire circumferential direction in the tread shoulder portion, is at least 0.2 times the tread width (TW), and is 0.2 times the tread width (TW).
．． A vertical shoulder groove (G1) arranged at a distance of three times or less from the tire equator, a plurality of lateral grooves (G2) intersecting the shoulder groove (G1) and extending to the tread edge (E), and a tread edge (E). ) and a distance of 0.04 times or more and 0°1 times or less of the tread width (TW) from the outer point (P) separating the tire equator side by a distance of 3 mm or more and 6 mm or less from the tread edge (E). The inner point separating the tire towards the equator (
Q) and extending in the circumferential direction of the tire and opening at the lateral groove (G2), the inner vertical and minor grooves (G3) on the tire equator side and the outer side on the tread edge (E) side. The vertical and minor grooves (G
4) By providing a group of vertical and minor grooves consisting of two vertical and minor grooves, the tread shoulder portion is provided with the vertical shoulder groove (G1), the horizontal groove (G2), and the inner vertical and minor groove (G3).
) surrounded by the inner block row (B1), the horizontal groove (G2), and the inner and outer vertical and minor grooves (G2).
3), the middle block (BM
), and the outer vertical and minor grooves (G4),
It forms an outer block row consisting of an outer block (BO) along the lateral groove (G2) and the tread edge (E), and also forms an inner block (BI) and an intermediate block (B O).
M) The tread surface of the outer block (BO) in the tire meridian direction is formed into a smoothly continuous convex curved surface consisting of an arc with a radius of curvature of 450 to 700 mm, and the tread edge is in contact with the surface and the shoulder wall surface. The inner block (NI) has at least one and five square shoulders connecting the vertical shoulder groove (G1) and the inner longitudinal minor groove (G3). The siping (S) below the book is replaced with the adjacent siping (S).
This is a pneumatic tire in which the spacing between S) is set to be 8 mm or more and 16 mm or less.

Further, the groove depth (D1) of the inner and outer longitudinal grooves (G3, G4) is equal to the groove depth (D1) of the longitudinal shoulder groove (G1).
O) 0.3 times or more and 1.20 times or less, groove width (WG)
2. It is desirable that the length be 0 mm or more and 4.5 mm or less.

[Effect]

Since two vertical and minor grooves are provided in the tread shoulder portion in a regulated area M near the tread edge E starting from the tread edge E, the edges of the vertical and minor grooves are aligned in the circumferential direction of the tire. Since an edge is formed and the tire grips in the area M against the force acting in the tire axial direction, including the cornering force when turning, it is possible to prevent the tire from skidding when turning. In addition, by limiting the number of vertical and minor grooves to two, it is possible to prevent a decrease in the rigidity of the tire axial direction in the above region, and to ensure steering stability when traveling straight and turning.

Also, the siping S is the vertical shoulder groove G1 of the inner block BI.
Since the middle block BM and the outer block BO cross between the inner vertical and minor grooves G3, there is no siping, and therefore the middle and outer blocks BM and BO maintain rigidity in the circumferential direction. It becomes extremely easy to follow the inner block BI, which further improves the structural slip resistance, and also increases the starting force and braking force during straight running, and improves the running performance on icy and snowy roads in a well-balanced manner.

Furthermore, since the number of sipings S is set to five or less per block, uneven wear and chipping of the blocks caused by the sipings S can be prevented, and the durability of the tread portion is improved.

Moreover, each of the inner, middle, and outer blocks (Bl, BM).

Since the tread surface of the BI consists of a convex curved surface of 450 to 700 mm and the tread edge is formed as a square shoulder, occurrence of uneven wear at the tread edge, which conventionally tends to occur, is prevented.

In this way, the present invention improves wandering performance and side slipping performance in a well-balanced manner by organically combining and integrating the vertical and minor grooves, sipes, and tread surface shape in the tread shoulder portion of the above structure. This increases uneven wear resistance and improves durability.

〔Example〕

An embodiment of the present invention will be described below based on the drawings.

In FIGS. 1 to 3, the pneumatic tire 1 has a tread shoulder portion SH with a vertical shoulder groove G1 that continues in the tire circumferential direction, and a tread edge E that intersects with the vertical shoulder groove G1.
A plurality of horizontal shoulder grooves G2.・It is arranged near the tread edge and extends in the tire circumferential direction, and consists of two vertical and minor grooves 3, an inner vertical and minor groove G3 and an outer vertical and minor groove G4 that open at the lateral grooves G2 and G2. A group of vertical and minor grooves 4 is provided.

Therefore, in the tread shoulder portion SH, an inner block row L consisting of inner blocks Bl surrounded by the vertical shoulder grooves G1, lateral grooves G2, G2, and inner longitudinal sub-grooves G3 is provided.
l, the horizontal grooves G2, G2, and the inner and outer longitudinal grooves G3, G4.
It has an intermediate block row LM consisting of intermediate blocks BM surrounded by an outer vertical and minor groove G4, lateral grooves G2, G2 and a tray, and an outer block row LO along the edge E,
A shoulder pattern is formed in the tread shoulder portion by these blocks Bl, BM, and BO.

The tread shoulder portion SH is located on both sides of the tread center portion CE through which the tire equator C passes, and
Together with this, a tread portion 12 is formed. In addition, in this embodiment, the tread center part CE has a vertical central groove GM approximately on the tire equator C.
A central lateral groove GP extending in the tire meridian direction is provided between the longitudinal central groove GM and the longitudinal shoulder groove G1, and these grooves GM and Gl are provided in the tread center CE.
, GP is formed.

In this embodiment, the vertical shoulder groove G1, the horizontal shoulder groove G2, the vertical central groove GM, and the central horizontal groove GP all have the same groove depth DO.

The pneumatic tire 1 also includes sidewall portions 13.1 extending inward in the tire radial direction from both ends of the tread portion 12.
3 and a beat portion 15.15 located at the radially inner end of the sidewall portion 13, each beat portion 15,]5
A troital-shaped carcass 17 passing through the sidewall portion 13.13 and the tread portion 12 is passed between the beat cores 16.16 provided in the frame, and a belt layer 19 is disposed on the outside in the radial direction and within the tread portion 12. are doing.

The carcass 17 has a carcass cord connected to the equator C of the tire.
On the other hand, in this embodiment, it is a so-called radial or semi-radial direction arrangement body arranged at an angle of 80 degrees to 90 degrees,
In addition to steel cords, fiber cords such as nylon, polyester, rayon, and aromatic polyamide are used as carcass cords.

In the present embodiment, the belt layer 19 has three belt blazers arranged from the carcass 17 side toward the outside in the radial direction of the tire.

Further, the belt layer 19 includes belt cords arranged at an angle to each bell and braai and crossing each other, and the belt cords are made of nylon, polyester, rayon, aromatic polyamide, etc. in addition to steel, similar to the carcass 17. fiber cord is used.

The vertical shoulder groove G1 is spaced apart from the tire equator C by a distance of 0.2 times or more and 0.3 times or less of the tread width TW, which is the distance between the tread edges E1E in the tire axial direction; Vertical and minor groove group 4 is 3m from the trend edge E
An outer point P that separates the tire equator C side by a distance of m or more and 6 mm or less, and an inner side that separates the tire equator side from the tread edge E by a distance W2 that is 0.04 times or more and 0.1 times or less the tread width TW. It is placed in a region M between the point Q and the point Q.

In this way, the vertical and minor groove groups 4 are arranged near the tread edge E of the tread shoulder portion SH and at a distance from the tread edge E.

The longitudinal sub-groove group 4 consists of an inner longitudinal sub-groove G3 on the tire equator C side and an outer longitudinal sub-groove G4 on the tread edge E side, and the inner and outer longitudinal sub-grooves G3 and G4 are located at the tread edge. Extends in a straight line in the tire circumferential direction approximately parallel to the edge E, and both ends thereof are connected to the lateral grooves G2, G2.
It is open.

Further, the tread portion 12 has the inner block B1 and the middle block 3M1 in the tread shoulder portion SH.
Each tread surface F of the outer block BO is smoothly continuous and formed into a convex curved surface having a radius of curvature TR of 450 mm or more and 700 mm or less.

Further, the tread edge E is formed as a so-called square shoulder where the tread surface F and the heartrest wall surface (W) extending from the sidewall portion 13 intersect at a crossing angle.

By forming the tread edge E as a square shoulder in this manner, it is possible to suppress skidding on an icy road, improve running stability on an icy and snowy road, and prevent shoulder drop wear.

The inner and outer vertical and minor grooves G3 and G4 each have a groove depth Dl,
Dl is set to be at least 0.3 times and at most 1.2 times the groove depth DO of the vertical shoulder groove G1. In addition, the inner and outer vertical and minor grooves G3
, G4 groove width WG, WG is 2.0 mm or more and 4.5
It is preferable to set it to below mm. In addition, vertical shoulder groove G
If there is a difference in height and height at the bottom of one groove, the groove depth Do at the deepest position is used as a reference. Furthermore, the groove depth Dl,
Regarding the groove width WG, in this embodiment, the inner and outer vertical and minor grooves G3,
Although G4 has the same groove depth Dl and groove width WG, the groove depth Dl or groove width WG may be different between the inner and outer longitudinal and sub-grooves G3 and G4 within the above range.

In addition, the groove depth Dl of each of the inner and outer vertical and minor grooves G3 and G4 is shallow,
Even if there is a difference in depth, it is desirable that the groove depth D1 is within the above range with respect to the groove depth Do of the vertical shoulder groove G1. Furthermore, there is no problem if a groove depth of 50% of the lower limit can be ensured within a range of 30% or less of the total length of the longitudinal and minor grooves G3 and G4.

In the area M, if the distance W3 from the tread edge E of the outer point P is less than 3 mm, the rigidity of the outer block BO near the tread edge E will decrease significantly and uneven wear will occur, while 6 mm If it exceeds this, the rigidity of the outer block BO will increase and sideways slip will occur. If the distance W2 from the tread edge E of the inner point Q exceeds 0.1 times the tread width TW, the stiffness of the shoulder block 2 in the vicinity of the tread edge E will increase, and side slip will occur. Wandering property decreases. Conversely, set the inner point Q to 0
．． If it is less than 04 times, the inner and outer longitudinal grooves G3,
As a result of the narrowing of the interval between G4, the middle block BM and the outer block BO are sandwiched between these blocks BM and BO.
The rigidity of the material decreases and uneven wear occurs.

Further, if the groove depth Do is less than 0.3 times the vertical shoulder groove G1, the rigidity of the region M increases, and the grip force in the axial direction of the tire decreases, which may cause lateral slippage. If it exceeds twice that, the rigidity of the region M will be significantly reduced, leading to a decrease in steering stability, uneven wear, and even side-slip.

Also, if the groove width WG is less than 2.0 mm, use shoulder block 2.
If a force in the axial direction of the tire is applied to the tire, the opposing groove side walls may come into contact with each other, making it impossible to suppress sideways skidding, and if the thickness exceeds 4.5 mm, uneven wear will occur, impairing durability. Along with middle and outer block B
M and BO become interposed and their rigidity decreases excessively, causing lateral slip. Therefore, it is preferable to set the groove depth Dl and the groove width WG within the above ranges.

If the number of vertical and minor grooves in region M is one, grip will be insufficient in response to the force acting in the axial direction of the tire, causing sideways skidding when turning on an icy and snowy road, and camber thrust will be low, making it difficult to overcome ruts. becomes difficult. On the other hand, if there are more than three, the stiffness of the shoulder block 2 in the tire axial direction becomes small, resulting in a decrease in steering stability.

Moreover, the groove width WG of the vertical and minor grooves G3 and G4 is as shown in FIG.
), 2 of the respective lengths of the vertical and minor grooves G3 and G4.
The widening portion WL may be provided locally within the range of 0% or less, or the vertical and minor grooves G3 and G4 may be formed in a wavy shape as shown in FIG. 4(b), and further, as shown in FIG. 4(C) In addition to being able to form zigzag grooves with different bending angles at the groove bottom and groove opening, it is also possible to employ vertical and minor grooves G3 and G4 having various groove shapes such as trapezoidal and triangular shapes.

Note that the inclination of the vertical and minor grooves G3 and G4 in the groove depth direction is ±5° with respect to the vertical line N to the tread surface F of the tread portion 12.
In order to ensure structural slip resistance, it is preferable that the angle of inclination is less than or equal to θ, preferably in the direction of the vertical line N.

The inner block BI is provided with one or more and five or less, in this embodiment three, sipes S-- connecting between the vertical shoulder groove G1 and the inner vertical sub-groove G3.

In this embodiment, the sipe S is a central sipe S that extends vertically at approximately the center of the inner block B■ and parallel to the lateral groove G2.
M, and a pair of side sipes SE, SE arranged on both sides of the central sipe SM and bent into a two-character shape,
The distance between the central sipe SM and the side SE, that is, the distance between adjacent sipes S, is set to be 8 mm or more and 16n+m or less.

The depth D2 of the siping S is 0.5 times or more and 1.0 times or less the groove depth Dl of the vertical and minor grooves G2, and the groove width W
It is preferable that S is 0.3 mm or more and 1.5 mm or less. Further, the groove depth D2 of the siping S is the vertical and minor grooves G.
3. Similar to G4, there may be a locally shallow portion, and there is no problem in the groove width WS having a locally widening portion.

In this way, the siping S is provided only in the inner block B1 and uses the inner vertical and minor grooves G3 as the groove ends, so there is no siping in the middle block BM and the outer block BO, so the sipes are located near the tread edge E. It is possible to prevent the occurrence of uneven wear that tends to occur.

In one block B1, if the number of siping S exceeds 5 or the siping interval becomes 8 mm or less, the rigidity of the inner block B1 decreases and uneven wear occurs.
In addition, block cracks may occur from the siping S.

Conversely, if no sipes S are provided, or if the distance between the sipes S exceeds 16 mm, the inner block B1
The rigidity of the vehicle becomes stiff, causing sideways slipping when driving.

In this way, the siping S of the present invention has the above-mentioned vertical and minor groove group 4.
In cooperation with this, the rigidity of the shoulder block 2 in the tire axial direction can be made appropriate, and when driving on an icy road, especially when turning, sideslip can be reduced and uneven wear can be prevented from occurring.

[Specific example: Tire size is 11.0OR2014PR and 1.2
Tires (Examples 1 to 4) having the configurations shown in the figures were prototyped according to the specifications shown in Table 1, and their performance was tested. For comparison, a conventional configuration (Comparative Example 1.
2) Prototypes of devices other than those of the present invention (Comparative Examples 3 to 7) were also manufactured and tested.

The test method is based on the following conditions.

b) Camber thrust Using a maneuverability tester, the tire internal pressure was 7.25 KSC.

Measurements were made under the conditions of a load of 2.840 kg and a camber angle of 6°. The larger the value on the positive side, the better.

7.25 NSC internal pressure was applied to the sample tire, and it was installed on a 2-D truck, and the steering force was determined based on the feeling of driving the actual vehicle by the driver, and Example 3 was compared to 10
It is expressed as an index set to 0. The higher the number, the better.

c) Resistance to rib tear The occurrence of tire damage was investigated by rubbing the tire against the rim cloth while driving on an actual vehicle, and the results were expressed as an index with Example 3 set at 100. The higher the number, the better.

2) Attach the sample tire to the actual vehicle and drive it on a 100% paved road for an average of 80km under the load conditions stipulated by JIS.
m/h 60. Run OOOkm, vertical shoulder groove G
1, and the groove depths of vertical and minor grooves G3 and G4 before and after running, the difference between the measured values before and after running is taken as the amount of wear, and the reciprocal thereof is Example 3
It is expressed as an index with 100. A large number indicates good quality.

e) Performance on ice and snow A braking test on ice and snow was conducted under the same conditions as the shoulder drop wear test described in section 2) on an actual vehicle, and a braking test on ice and snow and a climbing test were conducted.

1) Braking test A speed and braking distance measuring device and test tires were installed on the test vehicle, the test vehicle was driven at a constant initial speed on a test road surface (normally compressed snow, on a water platen), and the test vehicle was stopped at a certain point by applying sudden braking. The braking distance until the car came to a stop was measured.

2) The boarding test was conducted on two lanes with gradients of 4% and 7%, and the test vehicle was stopped on the boarding road (normally compacted snow), then started, and whether or not it could be started was confirmed.

To calculate the climbing acceleration time, the test vehicle was started from a stopped state using the zero start acceleration method, and the climbing acceleration time for a 50 m section was measured. At this time, two gears were used.

Road surface description Normally compacted snow A road surface where snow is compacted using tire rollers or tamp trucks.

(Friction coefficient is around 0.3 for studless tires) Ice floe A road surface that is frozen by spraying water on the snow compaction in the shape of a snowflakes and then compacting it with a tire roller, aiming to create an ice burn similar to the actual road.

(Coefficient of friction is around 0.11 for studless tires) In the evaluation, the reciprocal of the braking distance in the control test is expressed as an index with Example 3 set to 100, and in the pitching test, the reciprocal of the acceleration time in Example 3 is expressed as the reciprocal of the braking distance in the control test. It is expressed as an index with 100 as 100, and the average value of both is shown in Table 1.

The higher the number, the better.

As a result of the above-mentioned tests, the example has higher camphar thrust and better steering holding power than the comparative example, improving both wandering and sideslip properties, as well as rib tear resistance and shoulder drop. It was confirmed that by being superior to wear, it not only improves wear resistance but also improves steering stability on icy and snowy roads.

Furthermore, as shown in FIGS. 5(a) and 5(b), in Example 3, the camber thrust CT with respect to the camber angle CA is larger on the positive side than in Comparative Example 1.2, and structural resistance is improved. It was also confirmed that the compatibility was excellent.

〔Effect of the invention〕

As shown above, the pneumatic tire of the present invention has two longitudinal and sub-grooves in the tread shoulder part within a regulated range from the tread edge, and a number of sub-grooves in the block between the longitudinal shoulder groove and the longitudinal sub-groove. The main idea is to provide sipes with regulated spacing, which improves both wandering and sideslip properties, increases steering stability on icy and snowy roads, and
Can improve uneven wear resistance and durability.

The present invention is applicable not only to new tires but also to solid tires with retreaded treads.

[Brief explanation of the drawing]

Fig. 1 is a plan view showing a developed tire tread portion of an embodiment of the present invention, Fig. 2 is a sectional view taken along the line X-X, and Fig. 3 (
a) is a perspective view showing the tread shoulder portion; FIG. 3(b) is a perspective view showing the tread shoulder portion;
) is a cross-sectional view showing the vertical and minor grooves enlarged, and FIGS. 4(a)-
(C) is a plan view showing another example of vertical and minor grooves, FIG. 5(a) is a diagram showing the relationship between camber thrust and camber angle, and FIG. 5(b) is a diagram showing the effect. The side view shown and FIGS. 6(a) to 6(C) are perspective views showing the prior art. 3-・- vertical minor groove, 4- vertical minor groove group, Bl-・,
inner block, BM-11,2 middle block, BC
L-one outside block, C-411,-tire equator,
Dl, D O-, groove depth, E 9. -)-Red edge, F-, tread surface, G1-vertical shoulder groove, G2-horizontal groove, G3 inner longitudinal groove, G4-outer longitudinal groove, L1- inner block row, L M--Middle block row, LO-, --outer block row, M,-,-area, N
-・Plumb line, P-outside point, Q-...-inside point,
s-1, siping, SH-hot/red shoulder part, TR------ radius of curvature, W--wall surface, W G
-Groove width, TW-, tread width. Patent applicant Sumitomo Rubber Industries Co., Ltd. Agent
Patent Attorney Tadashi Naemura IK2 Diagram] 2 03 (b) R Foil 4! m(a) 54! E(b)
4th Snake (C) Figure 5 (a) Heinj de Ichi^ (CA) Figure 5 (b)

Claims (1)

[Scope of Claims] 1. Vertical shoulder grooves that are continuous in the tire circumferential direction in the tread shoulder portion and are spaced apart from the tire equator by a distance of 0.2 times or more and 0.3 times or less the tread width (TW). G1), a plurality of lateral grooves (G2) that intersect with the shoulder groove (G1) and extend to the tread edge (E), and an outer point separating the tread edge (E) by a distance of 3 mm or more and 6 mm or less on the tire equator side. (P) and the tread edge (E
) to 0.04 times or more of the tread width (TW) and 0
．． The inner point (Q) that separates the tire equator side by a distance less than 1 time
The inner vertical and minor grooves (G3) on the equator side of the tire, which extend in the tire circumferential direction and open in the area (M) between the lateral grooves (G2), and the outer vertical grooves on the tread edge (E) side. Minor groove (G4)
By providing a longitudinal sub-groove group consisting of two longitudinal sub-grooves, the tread shoulder part has an inner vertical groove group surrounded by the longitudinal shoulder groove (G1), the lateral groove (G2) and the inner longitudinal sub-groove (G3). an inner block row consisting of blocks (B1), the horizontal groove (G2), inner and outer longitudinal grooves (G3),
An intermediate block row consisting of intermediate blocks (BM) surrounded by (G4), outer vertical and minor grooves (G4), and horizontal grooves (
G2) and the outer block (B) along the tread edge (E)
The tread surfaces of the inner block (BI), middle block (BM), and outer block (BO) in the tire meridian direction are smoothly continuous and have a diameter of 450 to 450. It is formed into a convex curved surface consisting of a circular arc with a radius of curvature of 700 mm, and the tread edge is formed by a square shoulder where the surface and the shoulder wall surface intersect at a crossing angle,
The vertical shoulder groove (G) is formed in the inner block (BI).
1) A pneumatic tire comprising one or more and five or less sipes (S) connecting the inner vertical and minor grooves (G3) with an interval between adjacent sipes (S) of 8 mm or more and 16 mm or less. 2. The inner and outer longitudinal sub-grooves (G3, G4) each have a groove depth (D1) equal to the groove depth (D1) of the longitudinal shoulder groove (G1).
D0) 0.3 times or more and 1.20 times or less, groove width (WG
) is 2.0 mm or more and 4.5 mm or less.