JP2012040945A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire which improves at least one of pattern noise and steering stability while maintaining heel-and-toe wear.SOLUTION: A tread part of the pneumatic tire has a shoulder area wherein a plurality of pitch variations are arranged by a first pitch arrangement to be dispersed circumferentially in the tire and a center area wherein a plurality of pitch variations are arranged by a second pitch arrangement to be dispersed circumferentially in the tire between the circumferential grooves serving as a boundary. When the plurality of pitch variations are arranged in the order of the pitch length, and the pitch variations adjacent to each other are called the adjacent pitch variations, the first pitch arrangement is the arrangement wherein the pitch variations same as the pitch adjacent circumferentially in the tire or the adjacent pitch variations are arranged. In the second pitch arrangement, there are a part having the pitch variations except the adjacent pitch variations on the pitch adjacent circumferentially in the tire, and in the arrangement, the number wherein the pitch variations of the shortest pitch length are continuously adjacent is three or less. The number of the pitch variations in the first pitch arrangement is larger than the number of the pitch variations in the second pitch arrangement.

Description

  The present invention relates to a pneumatic tire provided with a tread pattern.

Conventionally, a pneumatic tire having a tread pattern has been provided with a pitch variation in which the pattern pitch length is dispersed in the tire circumferential direction in order to reduce pattern noise.
Pitch variation refers to distributing the pattern noise frequency by dispersing the pitch length on the tire circumference so that the level of pattern noise at a specific frequency does not increase when the tire rolls on the ground.
Since the pitch variation has a very large degree of freedom in how to distribute the pitch length, more and more pitch variations and pneumatic tires to which the pitch variations are applied have been proposed.

  For example, a tread pattern of a tire tread is formed by a pattern constituent unit row in which three or more types of pattern constituent units having different pitches P, which are circumferential lengths, are arranged in the tire peripheral direction. It comprises a pattern constituent unit row arranged to include the pattern constituent units arranged at intervals of one or more adjacent pitches, and has a test subject pattern constituent unit row obtained by performing a predetermined test. Pitch variation pneumatic tires are known (Patent Document 1).

There is also known a pneumatic tire for making it possible to achieve both improvement in steering stability on a dry road surface and reduction in pattern noise (Patent Document 2).
That is, in the pneumatic tire in which the tire front and back mounting directions with respect to the vehicle are designated, a plurality of tires arranged in the tire circumferential direction in the vehicle inner side (IN) and the vehicle outer side (OUT) with the tire equator E of the tread therebetween. The block elements on the inner side of the vehicle have a pitch number of 60 to 80, the number of types of block elements on the inner side of the vehicle is four or more, and the pitch number of block elements on the outer side of the vehicle is 50 to 70. The number of pitch types of the block elements outside the vehicle is four or more. Further, the pitch number of the block elements inside the vehicle is made larger than the pitch number of the block elements outside the vehicle, and the ratio of the average pitch length of the block elements outside the vehicle to the average pitch length of the block elements inside the vehicle is 1.05. The range is ˜1.20.

JP 2001-130226 A JP 2009-262874 A

In the pneumatic tire described in the above-mentioned Patent Document 1, since it is arranged including the pattern constituent units arranged by skipping one or more adjacent pitches in the order of the length, the shortest pitch having the shortest length is aligned, It is possible to prevent the block rigidity of the tread from becoming small. Therefore, it is possible to suppress a decrease in responsiveness due to a decrease in block rigidity in steering stability.
However, since it is arranged to include one or more pattern constituent units that are arranged adjacent to each other in the order of the length, there is a portion where the change in the adjacent pitch length is large in the tire circumferential direction. May cause wear. The heel & toe wear refers to a form in which the wear difference between adjacent land portions in the tire circumferential direction is greatly different and a wear step is generated in a sawtooth shape in the tire circumferential direction. When rolling tires, there are many cases where noise occurs when the heel and toe wear parts touch the ground.

  In the pneumatic tire described in Patent Document 2, it is possible to achieve both improvement in handling stability including turning performance on a dry road surface and improvement in vibration riding comfort including pattern noise. Nothing is said about suppression of toe wear.

  Accordingly, an object of the present invention is to provide a pneumatic tire capable of improving at least one of pattern noise and steering stability while maintaining heel & toe wear in a mode different from the pitch variation. .

One embodiment of the present invention is a pneumatic tire provided with a tread pattern.
The pneumatic tire has a circumferential groove in the tread portion.
The tread portion has a pitch length different from a pattern region on the shoulder side formed by distributing a plurality of pitch types having different pitch lengths in the tire circumferential direction by the first pitch arrangement with the circumferential groove as a boundary. A center-side pattern region formed by dispersing and arranging a plurality of pitch types in the tire circumferential direction by the second pitch arrangement.
For each of the first pitch arrangement and the second pitch arrangement, when arranging the plurality of pitch types in the order of the pitch length, when adjacent pitch types are referred to as adjacent pitch types,
The first pitch arrangement is an arrangement in which the same pitch type or the adjacent pitch type is arranged in a pitch adjacent in the tire circumferential direction. The second pitch arrangement includes a portion in which a pitch type other than the adjacent pitch type is arranged on a pitch adjacent to the tire circumferential direction, and the number of adjacent pitch types having the shortest pitch length is 3 or less. Is an array.
The number of pitch types in the first pitch arrangement is larger than the number of pitch types in the second pitch arrangement.

In the pneumatic tire, the ratio of the longest pitch length to the shortest pitch length in the first pitch arrangement is preferably 1.4 to 1.7.
The ratio of the longest pitch length to the shortest pitch length in the first pitch arrangement is preferably larger than the ratio of the longest pitch length to the shortest pitch length in the second pitch arrangement.

  Further, the second pitch array is preferably an array in which the number of adjacent pitch types included in a range where the pitch length is 10% longer than the shortest pitch length is 3 or less. .

  The circumferential groove and the shoulder-side pattern region are provided in each of the half tread portions on both sides of the center line of the tread portion, and the pneumatic tire is attached to a regular rim, And the width in the tire direction of the ground contact shape measured under the condition of 80% of the normal load as the ground contact width in the tread portion, the circumferential groove is 40 to 90 of the ground contact width of the tread portion. % Is preferably within the range of%.

  At this time, for example, the plurality of pitch types used for the first pitch arrangement in each of the half tread portions are the same as each other.

The pattern area on the shoulder side in the half tread portion of the pneumatic tire is designated to be mounted on the inside or outside of the vehicle,
The number of pitch types of the first pitch array in the pattern area on the shoulder side mounted on the inside of the wheel is P _IN, and the pitch types of the first pitch array in the pattern area on the shoulder side mounted on the outside of the wheel the number and P _OUT, when the number of pitch type of the second pitch sequence and P _CE, a P _CE ≦ P _OUT, a P _CE <P _iN, it is preferable. More preferably, P _CE ≦ P _OUTE <P _IN .

  According to the pneumatic tire, heel and toe wear can be maintained, and at least one of pattern noise and steering stability can be improved.

It is an expanded view of the tread pattern of the pneumatic tire for passenger cars of this embodiment. (A), (b) is a figure explaining the pitch variation in the tread pattern shown in FIG. It is an expanded view of the tread pattern of the pneumatic tire for passenger cars of other embodiments of the present invention.

  Hereinafter, the pneumatic tire of the present invention will be described in detail.

(First embodiment)
FIG. 1 is a development view of a tread pattern 10 provided on a tread of a passenger car pneumatic tire (hereinafter referred to as a tire) according to a first embodiment.
The passenger car tire according to the present embodiment refers to a tire defined in Chapter A of JATMA YEAR BOOK 2008 (Japan Automobile Tire Association Standard), for example. In addition, the pneumatic tire of the present invention can be applied to a small truck tire defined in Chapter B or a truck and bus tire defined in Chapter C.

The tread pattern 10 includes circumferential ribs 12 and 14, a block 16, and a shoulder block 18 in order from the tire center line CL.
The tread pattern 10 is divided into a pattern region R _CE on the center side and a pattern region R _s on both shoulder sides by a circumferential groove 20 provided between the block 16 and the shoulder block 18.
The circumferential rib 12 is defined by two circumferential grooves 22, and the circumferential rib 12 is provided with an inclined lug groove 24 whose one end is closed.
The circumferential rib 14 is defined between the circumferential groove 22 and the circumferential narrow groove 26.
The block 16 is defined by a circumferential narrow groove 26, a circumferential groove 20, and an inclined lug groove 28 that connects the circumferential narrow groove 26 and the circumferential groove 20.
The shoulder block 18 is provided with a shoulder lug groove 30 extending from the shoulder ground contact end and connected to the circumferential groove 20 and a shoulder closing lug groove 32 extending from the shoulder ground contact end and closed halfway.

For the circumferential grooves 20 and 22, for example, the groove width is 6 to 9 mm, and the groove depth is 7 to 9 mm. For the circumferential narrow groove 26, for example, the groove width is 1 to 3 mm, and the groove depth is 4 to 5 mm. For the inclined lug groove 24, for example, the groove width is 2 to 6 mm, and the groove depth is 3 to 7 mm.
Moreover, about the inclination lug groove | channel 28, for example, a groove width is 2-7 mm and a groove depth is 3-7 mm.
For the shoulder lug groove 30 in the pattern region on the shoulder side, for example, the groove width is 2 to 4 mm and the groove depth is 3 to 6 mm. For the shoulder closing lug groove 32, for example, the groove width is 2 to 4 mm, and the groove depth is 3 to 6 mm.

The circumferential groove 20 of the tread pattern 10 is preferably located within the range of 40 to 90% of the ground contact width of the tread portion with the center line CL as the center, and more preferably within the range of 50 to 70%. The contact width of the tread portion refers to the width in the tire direction of the contact shape measured when the tire is mounted on a normal rim and is measured under the conditions of normal internal pressure and 80% of the normal load.
Here, the regular rim means “standard rim” defined in JATMA, “Design Rim” defined in TRA, or “Measuring Rim” defined in ETRTO. The normal internal pressure means “maximum air pressure” defined by JATMA, the maximum value of “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” defined by TRA, or “INFLATION PRESSURES” defined by ETRTO. The normal load means the “maximum load capacity” defined in JATMA, the maximum value of “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” defined in TRA, or “LOAD CAPACITY” defined in ETRTO.

  As described above, the circumferential groove 20 is provided within the range of 40 to 90% of the ground contact width of the tread portion with the center line CL as the center, for example, one of the front wheels or the rear wheels of the mounted vehicle, for example, a front wheel drive vehicle In the tread portion of the rear wheel, in the pattern area on the center side between the circumferential grooves 20 on both sides, the block rigidity of the tread in the area that contacts the ground when the rear wheel is loaded is prevented from being reduced in a part on the tire circumference. This is to suppress a decrease in responsiveness to steering from a straight traveling state, and to suppress heel and toe wear in the pattern areas outside the circumferential grooves 20 on both sides (pattern areas on the shoulder side).

Such a tread pattern 10 has the following pitch variations.
Here, the pitch of the tread pattern 10 is a minimum unit in which the same pattern is repeated. For example, FIG. 1 shows the pitch length P ₁ of the pattern region R _s on the shoulder side and the pitch length P ₂ of the pattern region R _CE on the center side.

Specifically, a plurality of pitch types having different pitch lengths are distributed in the tire circumferential direction in the shoulder-side pattern region R _s and the center-side pattern region R _CE with the circumferential groove 20 in the tread portion as a boundary. The arrangement form is different. Here, when a plurality of pitch types are arranged in the order of the pitch length, when adjacent pitch types are referred to as adjacent pitch types, the pitch arrangement of the shoulder-side pattern region is adjacent in the tire circumferential direction at any pitch. This is an arrangement in which the same pitch type or adjacent pitch type is arranged in the pitch. The pitch arrangement of the pattern area on the center side includes a portion in which a pitch type other than the adjacent pitch type is arranged on a pitch adjacent in the tire circumferential direction, and the number of adjacent pitch types having the shortest pitch length is 3 or less. Is an array. At this time, the number of pitch types in the pitch array arranged in the shoulder-side pattern region is larger than the number of pitch types in the pitch array arranged in the center-side pattern region.

FIG. 2A is a diagram for explaining an example of the pitch arrangement of the pattern area on the center side. Here, A to C are pitch types having different pitch lengths, and “C3” and “B2” in FIG. 2A mean that three pitch types C are continuous, and the pitch type B is It means that two are arranged in succession. Therefore, in the case of FIG. 2A, in order from the left, there is one pitch type C, one pitch type B, one pitch type A, one pitch type C, and one pitch type B. One pitch type A, ... represents that the tires are sequentially arranged in the tire circumferential direction.
The pitch arrangement shown in FIG. 2A includes a portion in which a pitch type other than the adjacent pitch type is arranged on a pitch adjacent in the tire circumferential direction, and the number of adjacent pitch types having the shortest pitch length is 3 An array that is: For example, a pitch type C that is not an adjacent pitch type is arranged for the third “A1” from the left in FIG. In addition, the shortest pitch type C is 3 or less in number provided continuously.
Further, in the pitch arrangement shown in FIG. 2 (a), the number of adjacent pitch types included in a range where the pitch length is 10% longer than the shortest pitch length is 3 or less. It is preferable at the point which improves.

On the other hand, FIG. 2B is a view for explaining an example of the pitch arrangement of the pattern region R _s on the shoulder side. Here, A to E are pitch types having different pitch lengths, and A to C may be the same as or different from the pitch types A to C in FIG. Note that “A5” and “B3” in the figure mean that five pitch types A are continuous, and three pitch types B are continuous, as in the above description.
The pitch arrangement shown in FIG. 2 (b) is an arrangement in which the same pitch type or adjacent pitch type is arranged in the pitches adjacent in the tire circumferential direction. That is, when the pitch type changes, the adjacent pitch type is always arranged. For example, when the pitch type B changes, the pitch type A or the pitch type C is always arranged at the adjacent pitch.
Thus, the pitch arrangement which is provided on the center side of the pattern area R _CE number of pitch species (pitch sequence shown in FIG. 2 (a)) is 3, the pitch sequences arranged on the shoulder side of the pattern area R _s ( The number of pitch types in the pitch arrangement shown in FIG. That is, the number of pitch species in the pitch sequence is provided in the shoulder side of the pattern area R _s is larger than the number of pitches species in pitch arrangement provided on the center side of the pattern area R _CE. This is because the number of pitch types having an intermediate pitch length between the longest pitch length and the shortest pitch length increases by increasing the number of pitch types on the shoulder side. For this reason, the frequency distribution of the pattern noise can be improved by the pitch arrangement shown in FIG. Further, by using the pitch arrangement shown in FIG. 2B for the pattern region on the shoulder side, the number of pitch types of the intermediate pitch length is increased, so that the change between adjacent pitch lengths is reduced, and the block rigidity changes. Becomes smaller. For this reason, heel & toe wear is also improved.

The number of pitch types in the pitch arrangement as shown in FIG. 2 (a) and the pitch arrangement as shown in FIG. 2 (b) is preferably 12 or less, and 8 or less. It is more preferable that When the number of pitch types exceeds 12, the effect of frequency dispersion in pattern noise is saturated, and effective frequency dispersion cannot be achieved compared to the number of pitch types.
Further, the pitch arrangement of the pattern area R _CE on the center side is such that the pitch length is included in a range 10% longer than the shortest pitch length (in the example shown in FIG. 2A, the pitch length of the pattern type C). It is more preferable from the viewpoint of improving pattern noise, steering stability, and heel & toe wear that the number of the adjacent consecutive numbers is 3 or less.
Furthermore, it is preferable that the ratio of the longest pitch length to the shortest pitch length of the pitch arrangement in the shoulder side pattern region is larger than the ratio of the longest pitch length to the shortest pitch length of the pitch arrangement in the center side pattern region. When the ratio in the pattern area on the shoulder side is equal to or less than the ratio in the pattern area on the center side, the amount of decrease in the block rigidity that partially decreases on the tire circumference is reduced, and the steering stability is improved. The frequency dispersion in noise is bad. Therefore, a lower limit is set for the ratio in the pattern region on the shoulder side. The lower limit is preferably the above ratio in the pattern region on the center side.
Furthermore, the ratio of the longest pitch length to the shortest pitch length of the pitch arrangement in the pattern region on the shoulder side is preferably 1.4 to 1.7. When the ratio is smaller than 1.4, the frequency dispersion in the pattern noise is bad. When the ratio exceeds 1.7, the amount of decrease in block rigidity that partially decreases on the tire circumference increases, and steering stability decreases.

  The tire 10 having such a pitch arrangement can improve at least one of pattern noise and steering stability while maintaining heel and toe wear, as can be seen from examples described later.

(Second Embodiment)
FIG. 3 is a development view of the tread pattern 100 provided on the tread of the tire according to the second embodiment. The tread pattern 100 is an asymmetric pattern with respect to the tire center line CL. Specifically, it is specified that the shoulder-side pattern region R _s in the half tread portion of the tire is mounted on the inside or the outside of the vehicle. In the tread pattern 100 shown in FIG. 3, the pattern region on the left shoulder side in the drawing is a region R _IN located on the vehicle inner side, and the pattern region on the right shoulder side in the drawing is a region R _OUT located on the vehicle outer side. .

Specifically, like the tread pattern 10, the tread pattern 100 includes circumferential ribs 112, 114, a block 116, and a shoulder block 118 in order from the tire center line CL.
The tread pattern 100 is divided into a pattern region R _CE on the center side and a pattern region R _S (R _sIN , R _OUT ) on both shoulder sides by a circumferential groove 120 provided between the block 116 and the shoulder block 118.
Since the circumferential ribs 112 and 114 and the block 116 have the same configuration as the circumferential ribs 12 and 14 and the block 16 of the tread pattern 10, description thereof is omitted.

Unlike the shoulder block 18 of the tread pattern 10, the shoulder block 118 extends from the ground end toward the circumferential groove 120 in a region _RIN , and a shoulder lug groove 130 that connects the ground end and the circumferential groove 120. And a shoulder closing lug groove 132 that is closed at the same time. The shoulder lug groove 130 and the shoulder closing lug groove 132 are provided adjacent to each other in the tire circumferential direction. Thus, region R _IN is different from the tread pattern 10 does not form a rib land portion connected continuously in the tire circumferential direction.
On the other hand, in the region R _OUT , a shoulder closing lug groove 132 that extends from the ground contact end toward the circumferential groove 120 but is blocked in the middle, and a closed sipe 134 that extends from the ground contact end side toward the circumferential groove 120 are provided. Yes. Therefore, similarly to the toledo pattern 10, the region _Rout forms ribs that are continuously connected to the land portion in the tire circumferential direction.

The pitch arrangement in the region R _CE of the tread pattern 100 is provided with a pitch variation as shown in FIG. 2A, similarly to the pattern region on the center side in the tread pattern 10. Specifically, the arrangement includes a portion in which a pitch type other than the adjacent pitch type is arranged in the pitch adjacent to the tire circumferential direction, and the number of adjacent pitch types having the shortest pitch length is 3 or less. .
On the other hand, the pitch sequence in the region R _IN of the tread pattern 100, similar to the shoulder side of the pattern region in the tread pattern 10, a pitch variation as shown in FIG. 2 (b) has been subjected. Specifically, the pitch arrangement is an arrangement in which the same pitch seeds or adjacent pitch seeds are arranged in adjacent pitches in the tire circumferential direction.
The pitch arrangement in the region R _OUT of the tread pattern 100 is also an arrangement in which the same pitch type or the adjacent pitch type is arranged in the pitch adjacent in the tire circumferential direction, like the pitch arrangement in the region R _IN .

Here, the number of pitch seeds in the pitch array of the region R _CE is P _CE , the number of pitch seeds in the pitch array of the region R _OUT is P _OUT, and the number of pitch seeds in the pitch array of the region R _IN is P _IN . To do. At this time, it is preferable that P _CE <P _IN and P _CE ≦ P _OUT . More preferably, P _CE ≦ P _OUT <P _IN .
By limiting the number of pitch types in this way, at least one of pattern noise and steering stability can be improved while maintaining heel & toe wear.

Here, the number of pitch types is preferably 12 or less in the pitch arrangement of the pattern area on the center side and the pitch arrangement of the pattern area on the shoulder side, similarly to the tread pattern 10. More than the number is more preferable. When the number of pitch types exceeds 12, the effect of frequency dispersion in pattern noise is saturated, and effective frequency dispersion cannot be achieved compared to the number of pitch types.
Similarly to the tread pattern 10, the pitch arrangement of the center-side pattern region _RCE has a pitch length of 10% with respect to the shortest pitch length (in the example shown in FIG. 2A, the pitch length of the pattern type C). It is more preferable from the viewpoint of improvement in pattern noise, steering stability, and heel & toe wear that the pitch type included in the long range is an array in which the number of adjacent adjacent pitch types is 3 or less.
Furthermore, it is preferable that the ratio of the longest pitch length to the shortest pitch length of the pitch arrangement in the shoulder side pattern region is larger than the ratio of the longest pitch length to the shortest pitch length of the pitch arrangement in the center side pattern region. When the above ratio in the pattern area on the shoulder side is equal to or less than the above ratio in the pattern area on the center side, the amount of decrease in the portion where the block rigidity is reduced on the tire circumference is reduced, and steering stability is improved. The frequency dispersion at is poor. Therefore, the lower limit of the ratio in the pattern area on the shoulder side is the ratio in the pattern area on the center side.
Furthermore, the ratio of the longest pitch length to the shortest pitch length of the pitch arrangement in the pattern region on the shoulder side is preferably 1.4 to 1.7. When the ratio is smaller than 1.4, the frequency dispersion in the pattern noise is bad. When the ratio exceeds 1.7, the amount of decrease in block rigidity that partially decreases on the tire circumference increases, and steering stability decreases.

In the tire having the tread pattern 100, it is specified that the shoulder-side pattern region R _s (regions R _IN , R _OUT ) is mounted on the inside or the outside of the vehicle. Region R _CE affects steering stability (especially straightness), and region R _OUT affects heel & toe wear, pattern noise, and steering stability (especially turning), region R _IN affects heel & toe wear and pattern noise. Thus, for the tread pattern 10, to increase the number P _IN pitch species in the region R _IN, by reducing the number P _OUT pitch species in the region R _OUT, steering stability (particularly turning performance) of the pattern noise More preferably, both can be achieved. Of course, as shown in FIG. 2B, the pitch arrangement of the region R _IN and the region R _OUT is provided with a pitch arrangement that reduces the difference in block rigidity between adjacent blocks. The occurrence of wear can be suppressed. Note that even if the number P _OUT of pitch types in the region R _OUT is the same as the number P _CE of pitch types in the region R _CE , both steering stability and pattern noise can be achieved.

(Example)
The tire of this embodiment, the conventional tire, and the like were manufactured and evaluated for steering stability, pattern noise, and heel & toe wear. The tire size of the tire to be evaluated is 205 / 55R16.
The tire was assembled on a regular rim, filled with regular internal pressure, mounted on four wheels of a 1.5-liter class front wheel drive vehicle, and evaluated by applying a load of 80% of the regular load. The normal rim, normal internal pressure, and normal load mentioned here are defined in the above-mentioned JATMA, ETRTO, and TRA.

Evaluation of steering stability is a sensory evaluation of the driver when driving on a dry road surface at 100 km / hour.
Regarding the pattern noise, sensory evaluation was performed for the pattern noise sound during straight traveling at 100 km / hour.
On the other hand, the heel & toe wear was evaluated by measuring the wear state of the tread pattern after running the front wheel drive vehicle for 10,000 km using calipers, and evaluating the heel & toe wear as good or worse. Specifically, the level difference between the adjacent pitches of the tread pattern was measured to determine the level difference.
The sensory evaluation results were indexed based on Conventional Example 1. The larger the value of the index, the better the evaluation.

In Conventional Example 1, both the center-side pattern region R _CE and the shoulder-side pattern region R _s have a pitch arrangement as shown in FIG. 2B, and the number of pitch types is five.
In Conventional Example 2, both the center-side pattern region R _CE and the shoulder-side pattern region R _s have a pitch arrangement as shown in FIG. 2A, and the number of pitch types is five.
In the conventional example 3, as in the conventional example 1, both the center side pattern region R _CE and the shoulder side pattern region R _s have a pitch arrangement as shown in FIG. All were set to 5. In the conventional example 3, it was 1.7 the ratio of the shortest pitch length of the longest pitch length in any of the center side of the pattern area R _CE and the shoulder side of the pattern area R _s. In Conventional Example 1, the ratio is 1.4.
In Conventional Example 4, as in Conventional Example 2, both the center side pattern region R _CE and the shoulder side pattern region R _s have a pitch arrangement as shown in FIG. 2A, and the number of pitch types is as follows. All were set to 5. In Conventional Example 4, the ratio of the longest pitch length to the shortest pitch length is 1.7 in both the center side pattern region R _CE and the shoulder side pattern region R _s . In Conventional Example 2, the ratio is 1.4.

In Comparative Example 1, the center-side pattern region R _CE has a pitch arrangement as shown in FIG. 2A, and the shoulder-side pattern region R _s has a pitch arrangement as shown in FIG. The number of species was 5 for all. In both the center side pattern region R _CE and the shoulder side pattern region R _s , the ratio of the longest pitch length to the shortest pitch length was set to 1.4.
In Comparative Example 2, the center-side pattern region R _CE has a pitch arrangement as shown in FIG. 2A, and the shoulder-side pattern region R _s has a pitch arrangement as shown in FIG. The number of species was 5 for all. In both the center side pattern region R _CE and the shoulder side pattern region R _s , the ratio of the longest pitch length to the shortest pitch length was set to 1.7.
In Comparative Example 3, the pattern area R _CE on the center side has a pitch arrangement as shown in FIG. 2A, the pattern area R _s on the shoulder side has a pitch arrangement as shown in FIG. The number of seeds was 7 in the center-side pattern region R _CE and 3 in the shoulder-side pattern region R _S. In both the center side pattern region R _CE and the shoulder side pattern region R _s , the ratio of the longest pitch length to the shortest pitch length was set to 1.4.

In each of Examples 1 to 5, the pattern area R _CE on the center side has a pitch arrangement as shown in FIG. 2A, and the pattern area R _s on the shoulder side has a pattern as shown in FIG. The pitch is arranged, and the number of pitch types is 5 in the center-side pattern region R _CE and 7 in the shoulder-side pattern region R _S. In Examples 1-5, the center side of the pattern area R _CE and the shoulder side of the pattern area R _s, and the ratio of the shortest pitch length of the longest pitch length is variously changed.
Tables 1 and 2 below show the specifications and evaluation results.

As can be seen from Tables 1 and 2, in Examples 1 to 5, it is possible to improve at least one of pattern noise and steering stability while maintaining heel and toe wear.
In particular, the margin for improving the evaluation results (pattern noise and steering stability) of Examples 1 to 3 in which the ratio of the longest pitch length to the shortest pitch length (longest / shortest pitch ratio) satisfies 1.4 to 1.7 is large. .

  As mentioned above, although the pneumatic tire of this invention was demonstrated in detail, this invention is not limited to the said embodiment, Of course, in the range which does not deviate from the main point of this invention, you may make a various improvement and change. is there.

10,100 tread pattern 12, 14, 112, 114 circumferential rib 16, 116 block 18, 118 shoulder block 20, 22, 120, 122 circumferential groove 24, 28, 124 inclined lug groove 26, 126 circumferential narrow groove 30 , 130 Shoulder lug groove 32, 132 Shoulder closing lug groove 134 Closed sipe

Claims (8)

A pneumatic tire provided with a tread pattern,
The pneumatic tire has a circumferential groove in a tread portion,
The tread portion has a pitch length different from a pattern region on the shoulder side formed by distributing a plurality of pitch types having different pitch lengths in the tire circumferential direction by the first pitch arrangement with the circumferential groove as a boundary. A center-side pattern region formed by dispersing and arranging a plurality of pitch types in the tire circumferential direction by the second pitch arrangement;
For each of the first pitch arrangement and the second pitch arrangement, when arranging the plurality of pitch types in the order of the pitch length, when adjacent pitch types are referred to as adjacent pitch types,
The first pitch arrangement is an arrangement in which the same pitch type or the adjacent pitch type is arranged in a pitch adjacent to the tire circumferential direction,
The second pitch arrangement includes a portion in which a pitch type other than the adjacent pitch type is arranged on a pitch adjacent to the tire circumferential direction, and the number of adjacent pitch types having the shortest pitch length is 3 or less. An array,
The pneumatic tire according to claim 1, wherein the number of pitch types in the first pitch arrangement is larger than the number of pitch types in the second pitch arrangement.   The pneumatic tire according to claim 1, wherein a ratio of a longest pitch length to a shortest pitch length in the first pitch arrangement is 1.4 to 1.7.   The air retirement according to claim 1 or 2, wherein a ratio of the longest pitch length to the shortest pitch length in the first pitch arrangement is larger than a ratio of the longest pitch length to the shortest pitch length in the second pitch arrangement.   The second pitch array is an array in which the number of adjacent pitch types included in a range where the pitch length is 10% longer than the shortest pitch length is 3 or less. The pneumatic tire according to any one of the above. The circumferential groove and the pattern region on the shoulder side are provided on each of the half tread portions on both sides of the center line of the tread portion,
When the pneumatic tire is mounted on a normal rim and the width in the tire direction of the contact shape measured under the conditions of normal air pressure and 80% of the normal load is determined as the contact width in the tread portion, The pneumatic tire according to any one of claims 1 to 4, wherein the directional groove is located within a range of 40 to 90% of a ground contact width of the tread portion with the center line as a center.   The pneumatic tire according to claim 5, wherein a plurality of pitch types used for the first pitch arrangement in each of the half tread portions is the same as each other. The pattern area on the shoulder side in the half tread portion of the pneumatic tire is designated to be mounted on the inside or outside of the vehicle,
The number of pitch types of the first pitch array in the pattern area on the shoulder side mounted on the inside of the wheel is P _IN, and the pitch types of the first pitch array in the pattern area on the shoulder side mounted on the outside of the wheel the number and P _OUT, when the number of pitch type of the second pitch sequence and P _CE, a P _CE ≦ P _OUT, a P _CE <P _iN, pneumatic tire according to claim 5 or 6 . The pneumatic tire according to claim 7, wherein P _CE ≦ P _OUT <P _IN .