JP2016037100A - Pneumatic tire - Google Patents

Pneumatic tire Download PDF

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Publication number
JP2016037100A
JP2016037100A JP2014160286A JP2014160286A JP2016037100A JP 2016037100 A JP2016037100 A JP 2016037100A JP 2014160286 A JP2014160286 A JP 2014160286A JP 2014160286 A JP2014160286 A JP 2014160286A JP 2016037100 A JP2016037100 A JP 2016037100A
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ground plane
rubber
tread rubber
pneumatic tire
void ratio
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JP2014160286A
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JP5793227B1 (en
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早智雄 坂本
Sachio Sakamoto
早智雄 坂本
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Toyo Tire Corp
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Toyo Tire and Rubber Co Ltd
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Priority to JP2014160286A priority Critical patent/JP5793227B1/en
Priority to DE102015112753.9A priority patent/DE102015112753A1/en
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
    • B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
    • B60C11/03—Tread patterns
    • B60C11/0327—Tread patterns characterised by special properties of the tread pattern
    • B60C11/033—Tread patterns characterised by special properties of the tread pattern by the void or net-to-gross ratios of the patterns
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
    • B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
    • B60C11/0041—Tyre tread bands; Tread patterns; Anti-skid inserts comprising different tread rubber layers
    • B60C11/005—Tyre tread bands; Tread patterns; Anti-skid inserts comprising different tread rubber layers with cap and base layers
    • B60C11/0058—Tyre tread bands; Tread patterns; Anti-skid inserts comprising different tread rubber layers with cap and base layers with different cap rubber layers in the axial direction
    • B60C11/0066—Tyre tread bands; Tread patterns; Anti-skid inserts comprising different tread rubber layers with cap and base layers with different cap rubber layers in the axial direction having an asymmetric arrangement
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
    • B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
    • B60C11/03—Tread patterns
    • B60C11/0304—Asymmetric patterns
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
    • B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
    • B60C11/0008—Tyre tread bands; Tread patterns; Anti-skid inserts characterised by the tread rubber
    • B60C2011/0016—Physical properties or dimensions
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
    • B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
    • B60C11/03—Tread patterns
    • B60C11/12—Tread patterns characterised by the use of narrow slits or incisions, e.g. sipes
    • B60C2011/129—Sipe density, i.e. the distance between the sipes within the pattern
    • B60C2011/1295—Sipe density, i.e. the distance between the sipes within the pattern variable

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Tires In General (AREA)

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire which has improved braking performance and turning performance on an ice road surface.SOLUTION: A pneumatic tire has an inner side tread rubber 52 which forms an inner side ground plane Fwhich becomes an inner side (IN) with a tire equator CL as a reference at the time of installation of a vehicle, and an outer side tread rubber 53 which an outer side ground plane Fwhich becomes an outer side (OUT) with the tire equator CL as a reference at the time of installation of the vehicle. The outer side tread rubber 53 is configured from a rubber having a hardness higher than that of the inner side tread rubber 52, and a sipe density of the inner side ground plane Fis so set as to be higher than a sipe density of the outer side ground plane F.SELECTED DRAWING: Figure 1

Description

本開示は、アイス路面を走行するための空気入りタイヤに関する。   The present disclosure relates to a pneumatic tire for traveling on an ice road surface.

アイス路面を走行する際に使用される空気入りタイヤは、当然ながらアイス路面での制動性能と旋回性能が求められる。   The pneumatic tire used when traveling on an ice road surface is naturally required to have braking performance and turning performance on the ice road surface.

この要求に応えるためのアプローチの一つの手段として、接地面を形成するトレッドゴムをタイヤの装着内側と外側とで配合の異なる非対称配合にしたり、トレッドパターンを装着内側と外側とで異なる非対称構造にしたりすることが考えられる。   As one of the approaches to meet this demand, the tread rubber that forms the contact surface is made into an asymmetrical composition with different composition on the inside and outside of the tire, or the tread pattern is made into an asymmetric structure with different on the inside and outside of the tire. Can be considered.

タイヤを装着内側と外側とで非対称配合及び非対称構造にする例示として、例えば特許文献１には、装着内側のトレッド部分を装着外側のトレッド部分よりも軟らかいゴムで構成し、且つサイプ密度を疎にしたタイヤが開示されている。   For example, in Patent Document 1, the tread portion on the inner side of the tire is made of a softer rubber than the tread portion on the outer side of the tire, and the sipe density is sparse. A tire is disclosed.

特開２０１０−６１０８号公報JP 2010-6108 A

特許文献１によれば、雪上性能を向上させることができるとの記載がある。しかし、アイス路面における更なる性能向上が望まれる。   According to Patent Document 1, there is a description that the performance on snow can be improved. However, further performance improvement on the ice road surface is desired.

本開示の目的は、アイス路面における制動性能及び旋回性能を向上させた空気入りタイヤを提供することである。   An object of the present disclosure is to provide a pneumatic tire with improved braking performance and turning performance on an ice road surface.

本開示は、上記目的を達成するために、次のような手段を講じている。   In order to achieve the above object, the present disclosure takes the following measures.

本開示の空気入りタイヤは、タイヤ周方向に延びる複数の主溝によって区画される複数の陸部と、前記複数の陸部に形成されるサイプと、を有し、車両に対する装着方向が指定される空気入りタイヤであって、
タイヤ赤道を基準として車両装着時に内側となる内側接地面を形成する内側トレッドゴムと、タイヤ赤道を基準として車両装着時に外側となる外側接地面を形成する外側トレッドゴムと、を有し、前記外側トレッドゴムは前記内側トレッドゴムよりもゴム硬度が高硬度のゴムで形成されており、前記内側接地面のサイプ密度は、前記外側接地面のサイプ密度よりも高密度に設定されていることを特徴とする。 The pneumatic tire of the present disclosure includes a plurality of land portions defined by a plurality of main grooves extending in the tire circumferential direction, and sipes formed in the plurality of land portions, and a mounting direction with respect to the vehicle is designated. A pneumatic tire,
An inner tread rubber that forms an inner grounding surface that is the inner side when the vehicle is mounted on the basis of the tire equator, and an outer tread rubber that forms an outer grounding surface that is the outer side when the vehicle is mounted on the basis of the tire equator. The tread rubber is made of rubber having a hardness higher than that of the inner tread rubber, and the sipe density of the inner ground surface is set higher than the sipe density of the outer ground surface. And

このように、外側トレッドゴムは内側トレッドゴムよりもゴム硬度が高硬度のゴムで形成することにより、装着内側では路面への密着度が向上し、装着外側では車両のふらつきを低減でき、アイス路面での制動性能と旋回性能を双方とも向上させることが可能となる。それでいて、内側接地面のサイプ密度は外側接地面のサイプ密度よりも高密度であるので、装着内側ではサイプの除水効果とエッジ効果が高まって路面への密着度が向上し、装着外側では剛性の低下を抑制して車両のふらつきを低減できる。したがって、ゴム硬度とサイプ密度を双方とも適切に設定することによって、アイス路面での制動性能と旋回性能を双方とも相乗的に向上させることが可能となる。   In this way, the outer tread rubber is made of a rubber whose hardness is higher than that of the inner tread rubber, so that the adhesion to the road surface is improved on the inner side of the mounting, and the vehicle wobble can be reduced on the outer side of the mounting. Both braking performance and turning performance can be improved. Nevertheless, the sipe density of the inner contact surface is higher than the sipe density of the outer contact surface, so that the water removal effect and edge effect of the sipe are enhanced on the inner side of the installation, and the degree of adhesion to the road surface is improved. It is possible to reduce the wobbling of the vehicle by suppressing the decrease of the vehicle. Accordingly, by appropriately setting both the rubber hardness and the sipe density, it becomes possible to synergistically improve both the braking performance and the turning performance on the ice road surface.

本実施形態の空気入りタイヤの一例を示すタイヤ子午線断面図。The tire meridian sectional view showing an example of the pneumatic tire of this embodiment. トレッドゴムに形成されたトレッドパターンを模式的に示す図。The figure which shows typically the tread pattern formed in the tread rubber.

以下、本開示の一実施形態の空気入りタイヤについて、図面を参照して説明する。   Hereinafter, a pneumatic tire according to an embodiment of the present disclosure will be described with reference to the drawings.

図１に示すように、空気入りタイヤＴは、一対のビード部１と、各々のビード部１からタイヤ径方向ＲＤ外側に延びるサイドウォール部２と、両サイドウォール部２のタイヤ径方向ＲＤ外側端に連なるトレッド部３とを備える。ビード部１には、鋼線等の収束体をゴム被覆してなる環状のビードコア１ａと、硬質ゴムからなるビードフィラー１ｂとが配設されている。   As shown in FIG. 1, the pneumatic tire T includes a pair of bead portions 1, sidewall portions 2 that extend outward from the respective bead portions 1 in the tire radial direction RD, and outer sides in the tire radial direction RD of both sidewall portions 2. And a tread portion 3 connected to the end. The bead portion 1 is provided with an annular bead core 1a formed by covering a converging body such as a steel wire with rubber and a bead filler 1b made of hard rubber.

また、このタイヤＴは、トレッド部３からサイドウォール部２を経てビード部１に至るトロイド状のカーカス層４を備える。カーカス層４は、一対のビード部同士１の間に設けられ、少なくとも一枚のカーカスプライにより構成され、その端部がビードコア１ａを介して巻き上げられた状態で係止されている。カーカスプライは、タイヤ赤道ＣＬに対して略直角に延びるコードをトッピングゴムで被覆して形成されている。カーカス層４の内側には、空気圧を保持するためのインナーライナーゴム４ａが配置されている。   The tire T includes a toroidal carcass layer 4 that extends from the tread portion 3 through the sidewall portion 2 to the bead portion 1. The carcass layer 4 is provided between a pair of bead portions 1 and is constituted by at least one carcass ply, and its end is locked in a state of being wound up via a bead core 1a. The carcass ply is formed by covering a cord extending substantially perpendicular to the tire equator CL with a topping rubber. Inside the carcass layer 4 is disposed an inner liner rubber 4a for maintaining air pressure.

さらに、サイドウォール部２におけるカーカス層４の外側には、サイドウォールゴム６が設けられている。また、ビード部１におけるカーカス層４の外側には、リム装着時にリム（図示しない）と接するリムストリップゴム７が設けられている。本実施形態では、カーカス層４のトッピングゴム、リムストリップゴム７及びサイドウォールゴム６が導電性ゴムで形成されている。勿論、これらゴムを非導電性ゴムで形成してもよい。   Further, a sidewall rubber 6 is provided outside the carcass layer 4 in the sidewall portion 2. A rim strip rubber 7 is provided outside the carcass layer 4 in the bead portion 1 so as to come into contact with a rim (not shown) when the rim is mounted. In the present embodiment, the topping rubber, the rim strip rubber 7 and the side wall rubber 6 of the carcass layer 4 are made of conductive rubber. Of course, these rubbers may be formed of non-conductive rubber.

トレッド部３におけるカーカス層４の外側には、カーカス層４を補強するためのベルト４ｂと、ベルト補強材４ｃと、トレッドゴム５とが内側から外側に向けて順に設けられている。ベルト４ｂは、複数枚のベルトプライにより構成されている。ベルト補強材４ｃは、タイヤ周方向に延びるコードをトッピングゴムで被覆して構成されている。ベルト補強材４ｃは、必要に応じて省略しても構わない。   On the outer side of the carcass layer 4 in the tread portion 3, a belt 4b for reinforcing the carcass layer 4, a belt reinforcing material 4c, and a tread rubber 5 are provided in order from the inner side to the outer side. The belt 4b is composed of a plurality of belt plies. The belt reinforcing member 4c is configured by covering a cord extending in the tire circumferential direction with a topping rubber. The belt reinforcing material 4c may be omitted as necessary.

トレッドゴム５は、接地面を構成するキャップ部５０と、キャップ部５０のタイヤ径方向内側に設けられるベース部５１とを有する。上記において接地面は、正規リムにリム組みし、正規内圧を充填した状態でタイヤを平坦な路面に垂直に置き、正規荷重を加えたときの路面に接地する面であり、そのタイヤ幅方向ＷＤの最外位置が接地端Ｅとなる。なお、正規荷重及び正規内圧とは、ＪＩＳ Ｄ４２０２（自動車タイヤの諸元）等に規定されている最大荷重（乗用車用タイヤの場合は設計常用荷重）及びこれに見合った空気圧とし、正規リムとは、原則としてＪＩＳ Ｄ４２０２等に定められている標準リムとする。   The tread rubber 5 includes a cap portion 50 that constitutes a ground contact surface, and a base portion 51 that is provided on the inner side in the tire radial direction of the cap portion 50. In the above, the ground contact surface is a surface that is assembled to a regular rim and filled with a regular internal pressure, the tire is placed vertically on a flat road surface, and is grounded to the road surface when a regular load is applied. The outermost position is the ground contact E. The normal load and the normal internal pressure are the maximum load (design normal load in the case of passenger car tires) specified in JIS D4202 (specifications of automobile tires) and the air pressure commensurate with this. As a rule, the standard rim specified in JIS D4202 and the like is used.

本実施形態のタイヤは、車両に対する装着方向が指定されており、タイヤの側面に、車両に対する装着方向（例えば内側である外側である旨）が表示される。   In the tire according to the present embodiment, the mounting direction with respect to the vehicle is specified, and the mounting direction with respect to the vehicle (for example, the inside being the outside) is displayed on the side of the tire.

図１に示すように、キャップ部５０は、タイヤ赤道ＣＬを基準として車両装着時に内側（ＩＮ）となる内側接地面Ｆｉｎを形成する内側トレッドゴム５２と、タイヤ赤道ＣＬを基準として車両装着時に外側（ＯＵＴ）となる外側接地面Ｆｏｕｔを形成する外側トレッドゴム５３と、を有する。本実施形態では、図１及び図２に示すように、トレッドゴム５は、タイヤ赤道ＣＬにてタイヤ周方向に延びる主溝５ａと、内側接地面Ｆｉｎにおいてタイヤ周方向ＰＤに延びる２つの主溝５ａと、外側接地面Ｆｏｕｔにおいてタイヤ周方向ＰＤに延びる２つの主溝５ａとを有する。接地面は、これら５つの主溝５ａによって複数の陸部８ａ，８ｂに区画される。陸部８ａ，８ｂには、サイプ９が形成されている。図２に示す陸部８ａは、タイヤ周方向に連続するリブ状陸部８ａである。同図に示す陸部８ｂは、タイヤ幅方向ＷＤに延びる横溝５ｂによってタイヤ周方向ＰＤに複数に分割された複数のブロック状陸部８ｂである。 As shown in FIG. 1, the cap portion 50 has an inner tread rubber 52 forming the inner ground plane F in which the inner (IN) when the vehicle mounted relative to the tire equator CL, the vehicle when mounted relative to the tire equator CL And an outer tread rubber 53 that forms an outer grounding surface Fout serving as an outer side (OUT). In the present embodiment, as shown in FIGS. 1 and 2, the tread rubber 5 includes a main groove 5a extending in the tire circumferential direction at the tire equator CL and two main grooves extending in the tire circumferential direction PD at the inner ground surface Fin. A groove 5a and two main grooves 5a extending in the tire circumferential direction PD on the outer ground contact surface Fout are provided. The grounding surface is divided into a plurality of land portions 8a and 8b by these five main grooves 5a. Sipes 9 are formed in the land portions 8a and 8b. The land portion 8a shown in FIG. 2 is a rib-like land portion 8a that is continuous in the tire circumferential direction. The land portion 8b shown in the figure is a plurality of block-shaped land portions 8b divided into a plurality of portions in the tire circumferential direction PD by lateral grooves 5b extending in the tire width direction WD.

なお、本実施形態では、主溝５ａの数、リブ状陸部８ａ及びブロック状陸部８ｂの配置についてトレッドパターンの一例を示したが、これに限定されず、種々変更可能である。   In the present embodiment, an example of the tread pattern is shown with respect to the number of the main grooves 5a and the arrangement of the rib-like land portions 8a and the block-like land portions 8b. However, the present invention is not limited to this, and various changes can be made.

本実施形態では、外側トレッドゴム５３は内側トレッドゴム５２よりもゴム硬度が高硬度のゴムで形成されている。ゴム硬度は、硬度は、ＪＩＳ Ｋ６２５３のデュロメータ硬さ試験（タイプＡ）に準じて測定した硬度を意味する。このように、装着内側と装着外側とでゴム硬度を異ならせるのは、装着内側と装着外側とで役割分担をするためである。具体的には、装着内側は装着外側に比べて制動性能に寄与率が高いため、装着内側のゴムに柔らかいゴムを使用すれば、路面の凹凸への密着度（追従性）が向上するので、アイス路面での制動性能が向上する。一方、装着外側は装着内側に比べて旋回性能に寄与率が高いため、装着外側のゴムに硬いゴムを使用すれば、車両のふらつきを低減でき、旋回性能が向上する。   In the present embodiment, the outer tread rubber 53 is formed of rubber having a higher hardness than the inner tread rubber 52. The rubber hardness means a hardness measured according to a durometer hardness test (type A) of JIS K6253. The reason why the rubber hardness is made different between the mounting inner side and the mounting outer side is to share the roles between the mounting inner side and the mounting outer side. Specifically, the inner side of the mounting has a higher contribution rate to the braking performance than the outer side of the mounting, so if soft rubber is used for the rubber on the inner side of the mounting, the degree of adhesion to the unevenness of the road surface (followability) will improve. The braking performance on the ice road surface is improved. On the other hand, since the outer side of the mounting has a higher contribution rate to the turning performance than the inner side of the mounting, the use of a hard rubber as the rubber on the outer side of the mounting can reduce the vehicle wobble and improve the turning performance.

内側トレッドゴム５２と外側トレッドゴム５３の硬度差があれば、アイス路面の制動性能と旋回性能を共に向上させるという効果が発揮されるが、効果を顕著に発揮させるためには硬度差が３度以上あることが好ましい。   If there is a difference in hardness between the inner tread rubber 52 and the outer tread rubber 53, the effect of improving both the braking performance and turning performance of the ice road surface is exhibited, but in order to exert the effect remarkably, the hardness difference is 3 degrees. It is preferable that there is more.

好ましくは、内側トレッドゴム５２と外側トレッドゴム５３の硬度差が１０度以下であることが望ましい。硬度差が大きくなればなるほど、内側接地面Ｆｉｎの剛性が小さくなると共に、外側接地面Ｆｏｕｔの剛性が高くなる。硬度差が大きくなりすぎて、両者の剛性バランスが崩れると、一方の接地面が働きにくくなり、他方の接地面のみでの動作となり、性能の向上効果が低減するからである。例えば、制動時においては外側接地面Ｆｏｕｔが寄与しにくくなり、内側接地面Ｆｉｎ単独での動作となり、旋回時には内側接地面Ｆｉｎが寄与しにくくなり、外側接地面Ｆｏｕｔ単独での動作となる。上記剛性バランスが崩れなければ、制動時及び旋回時に外側接地面Ｆｏｕｔ及び内側接地面Ｆｉｎが働き、両性能の向上効果が低減しない。 Preferably, the hardness difference between the inner tread rubber 52 and the outer tread rubber 53 is 10 degrees or less. As the hardness difference increases, the rigidity of the inner ground plane F in decreases and the rigidity of the outer ground plane F out increases. This is because if the hardness difference becomes too large and the rigidity balance between the two is lost, one of the ground planes becomes difficult to work, and only the other ground plane is operated, reducing the performance improvement effect. For example, hardly contribute outer ground plane F out at the time of braking, it is the operation of the inside contact surface F in itself, the inner contact surface F in hardly contribute to the cornering, operation outside the ground plane F out alone It becomes. If collapse the rigidity balance, work the outer ground plane F out and the inner ground plane F in during braking and turning, the effect of improving both performance is not reduced.

剛性バランスが崩れにくい範囲として、内側トレッドゴム５２のゴム硬度は、４０度以上且つ５５度以下に設定し、外側トレッドゴム５３のゴム硬度は、４５度以上且つ５５度以下にすることが考えられる。本実施形態では、内側トレッドゴム５２のゴム硬度は４９度であり、外側トレッドゴム５３のゴム硬度は５４度である。勿論、このゴム硬度は一例であり、限定されない。   As a range in which the rigidity balance is not easily lost, the rubber hardness of the inner tread rubber 52 is set to 40 degrees or more and 55 degrees or less, and the rubber hardness of the outer tread rubber 53 is considered to be 45 degrees or more and 55 degrees or less. . In the present embodiment, the inner tread rubber 52 has a rubber hardness of 49 degrees, and the outer tread rubber 53 has a rubber hardness of 54 degrees. Of course, this rubber hardness is an example and is not limited.

更に、アイス路面での制動性能と旋回性能の双方を向上させるために、内側接地面Ｆｉｎのサイプ密度は、外側接地面Ｆｏｕｔのサイプ密度よりも高密度に設定している。サイプ密度[mm/mm2]は、接地面における単位面積あたりのサイプ長さである。このように、装着内側と装着外側とでサイプ密度を異ならせているのは、装着内側と装着外側とで役割分担をするためである。具体的には、サイプ密度を高密度にすれば、サイプの除水効果とエッジ効果が高まり、路面への密着性が上がるものの、接地面の剛性が下がってしまう。そこで、制動性能の寄与度が高い装着内側のサイプ密度を高密度にして、アイス路面での制動性能を向上させている。旋回性能の寄与度が高い装着外側のサイプ密度は低密度にして、剛性低下を抑制し、旋回性能を向上させている。 Furthermore, in order to improve both the braking performance and the turning performance on the ice road surface, the sipe density of the inner ground plane F in is set higher than the sipe density of the outer ground plane F out . The sipe density [mm / mm 2 ] is the sipe length per unit area on the ground contact surface. The reason why the sipe density is made different between the inner side and the outer side is because the roles are divided between the inner side and the outer side. Specifically, if the sipe density is increased, the water removal effect and edge effect of the sipe are increased and the adhesion to the road surface is increased, but the rigidity of the ground contact surface is decreased. Therefore, the sipe density on the inner side where the contribution of braking performance is high is increased to improve the braking performance on the ice road surface. The sipe density on the outer side of the wearing, which has a high contribution to the turning performance, is set to a low density to suppress a decrease in rigidity and improve the turning performance.

内側接地面Ｆｉｎと外側接地面Ｆｏｕｔのサイプ密度に差があれば、アイス路面の制動性能と旋回性能を共に向上させるという効果が発揮されるが、効果を顕著に発揮させるためにはサイプ密度差は、０．００５[mm/mm2]以上あることが好ましい。 If there is a difference in the sipe density of the inner ground plane F in the outer ground plane F out, the effect is exhibited that improve both the braking performance and the turning performance of the ice road surface, in order to significantly exhibit the effect sipes The density difference is preferably 0.005 [mm / mm 2 ] or more.

装着内外での剛性バランスを損なわないためには、内側接地面Ｆｉｎと外側接地面Ｆｏｕｔのサイプ密度差は、０．０３[mm/mm2]以下であることが好ましい。 In order not to impair the rigidity balance inside and outside the mounting, the sipe density difference between the inner ground plane F in and the outer ground plane F out is preferably 0.03 [mm / mm 2 ] or less.

剛性バランスが崩れにくい範囲として、内側接地面Ｆｉｎのサイプ密度は、０．１３[mm/mm2]以上且つ０．２３[mm/mm2]以下に設定し、外側接地面Ｆｏｕｔのサイプ密度は、０．１[mm/mm2]以上且つ０．２[mm/mm2]以下に設定することが考えられる。本実施形態では、内側接地面Ｆｉｎのサイプ密度は０．１５[mm/mm2]であり、外側接地面Ｆｏｕｔのサイプ密度は０．１４[mm/mm2]である。勿論、これらサイプ密度は一例であり、これに限定されない。 As a range rigidity balance is difficult to collapse, the sipe density of the inner ground plane F in is, 0.13 [mm / mm 2] or more and is set to 0.23 [mm / mm 2] or less, the outer ground plane F out sipes The density may be set to 0.1 [mm / mm 2 ] or more and 0.2 [mm / mm 2 ] or less. In the present embodiment, the sipe density of the inner ground plane F in is 0.15 [mm / mm 2 ], and the sipe density of the outer ground plane F out is 0.14 [mm / mm 2 ]. Of course, these sipe densities are examples, and are not limited to these.

このように、ゴム硬度とサイプ密度を設定することで、アイス路面での制動性能と旋回性能の向上効果を相乗させている。   In this way, by setting the rubber hardness and the sipe density, the braking performance on the ice road surface and the effect of improving the turning performance are combined.

更に、内側接地面Ｆｉｎのボイド比は、外側接地面Ｆｏｕｔのボイド比よりも小さくなるようにトレッドパターンを形成している。ボイド比は、接地面積に対する溝面積の比率（％）であり、｛１−実接地面積（陸部面積）／接地面積（陸部面積＋溝面積）｝×１００の式により算出できる。上記のように、ゴム硬度及びサイプ密度を設定すれば、内側接地面Ｆｉｎが柔らかく且つサイプ密度が密になり、トレッド剛性が落ちるので、内側接地面Ｆｉｎのボイド比を小さくすることで、陸部が多くなり、剛性の著しい低下を緩和している。同様に、外側接地面Ｆｏｕｔが硬く且つサイプ密度が疎になり、トレッド剛性が高くなるので、外側接地面Ｆｏｕｔを大きくすることで、陸部を少なくし、剛性の著しい増大を緩和している。 Further, the tread pattern is formed so that the void ratio of the inner ground plane F in is smaller than the void ratio of the outer ground plane F out . The void ratio is the ratio (%) of the groove area to the ground contact area, and can be calculated by the equation {1−actual ground contact area (land area) / ground contact area (land area + groove area)} × 100. As described above, by setting the rubber hardness and the sipe density, soft and sipe density inner contact surface F in becomes dense, so the tread rigidity is lowered, by reducing the void ratio of the inner ground plane F in, The land area has increased, relieving the significant decrease in rigidity. Similarly, the outer ground contact surface Fout is hard and the sipe density is sparse and the tread rigidity is increased. By increasing the outer contact surface Fout , the land portion is reduced, and the significant increase in rigidity is reduced. Yes.

内側接地面Ｆｉｎと外側接地面Ｆｏｕｔのボイド比の差は、０．５％以上且つ５％以下にするのが剛性バランスを整えるうえで好ましい。 Difference in void ratio of the inner ground contact surface F in the outer ground plane F out is preferable in that adjust the rigidity balance to below and 5% to 0.5%.

剛性バランスが崩れにくい範囲として、内側接地面Ｆｉｎのボイド比は、２０％以上且つ３５％以下であり、外側接地面Ｆｏｕｔのボイド比は、２５％以上且つ４０％以下であることが考えられる。本実施形態では、内側接地面Ｆｉｎのボイド比は２６％であり、外側接地面Ｆｏｕｔのボイド比は３０％である。勿論、これらボイド比は一例であり、限定されない。 As a range in which the rigidity balance is not easily lost, the void ratio of the inner ground plane F in is 20% to 35%, and the void ratio of the outer ground plane F out is 25% to 40%. It is done. In the present embodiment, the void ratio of the inner ground plane F in is 26%, and the void ratio of the outer ground plane F out is 30%. Of course, these void ratios are examples and are not limited.

以上のように、本実施形態の空気入りタイヤは、タイヤ周方向ＰＤに延びる複数の主溝５ａによって区画される複数の陸部８ａ，８ｂと、複数の陸部８ａ，８ｂに形成されるサイプ９と、を有し、車両に対する装着方向が指定される空気入りタイヤであって、タイヤ赤道ＣＬを基準として車両装着時に内側（ＩＮ）となる内側接地面Ｆｉｎを形成する内側トレッドゴム５２と、タイヤ赤道ＣＬを基準として車両装着時に外側（ＯＵＴ）となる外側接地面Ｆｏｕｔを形成する外側トレッドゴム５３と、を有し、外側トレッドゴム５３は内側トレッドゴム５２よりもゴム硬度が高硬度のゴムで形成されており、内側接地面Ｆｉｎのサイプ密度は、外側接地面Ｆｏｕｔのサイプ密度よりも高密度に設定されている。 As described above, the pneumatic tire according to the present embodiment includes the sipe formed in the plurality of land portions 8a and 8b and the plurality of land portions 8a and 8b defined by the plurality of main grooves 5a extending in the tire circumferential direction PD. 9, has, a pneumatic tire mounting direction is specified with respect to the vehicle, an inner tread rubber 52 forming the inner ground plane F in which the inner (iN) when the vehicle mounted relative to the tire equator CL And an outer tread rubber 53 that forms an outer ground contact surface Fout that becomes the outer side (OUT) when the vehicle is mounted on the basis of the tire equator CL. The outer tread rubber 53 has a higher hardness than the inner tread rubber 52. It is in the rubber forming and sipe density of the inner ground plane F in is set at a high density than the sipe density of the outer ground plane F out.

このように、外側トレッドゴム５３は内側トレッドゴム５２よりもゴム硬度が高硬度のゴムで形成することにより、装着内側では路面への密着度が向上し、装着外側では車両のふらつきを低減でき、アイス路面での制動性能と旋回性能を双方とも向上させることが可能となる。それでいて、内側接地面Ｆｉｎのサイプ密度は外側接地面Ｆｏｕｔのサイプ密度よりも高密度であるので、装着内側ではサイプの除水効果とエッジ効果が高まって路面への密着度が向上し、装着外側では剛性の低下を抑制して車両のふらつきを低減できる。したがって、ゴム硬度とサイプ密度を双方とも適切に設定することによって、アイス路面での制動性能と旋回性能を双方とも相乗的に向上させることが可能となる。 As described above, the outer tread rubber 53 is formed of a rubber whose hardness is higher than that of the inner tread rubber 52, so that the degree of adhesion to the road surface is improved on the inner side of the mounting, and the fluctuation of the vehicle can be reduced on the outer side of the mounting. Both braking performance and turning performance on the ice road surface can be improved. Yet, the sipe density of the inner ground plane F in is because it is more dense than the sipe density of the outer ground plane F out, improved degree of adhesion to the road surface is increasing water removing effect and the edge effect of the sipe in the inner side, On the outer side of the mounting, the reduction in rigidity can be suppressed and the vehicle wobble can be reduced. Accordingly, by appropriately setting both the rubber hardness and the sipe density, it becomes possible to synergistically improve both the braking performance and the turning performance on the ice road surface.

本実施形態では、内側トレッドゴム５２と外側トレッドゴム５３の硬度差は、３度以上且つ１０度以下であり、内側接地面Ｆｉｎと外側接地面Ｆｏｕｔのサイプ密度差は、０．００５[mm/mm2]以上且つ０．０３[mm/mm2]以下である。 In the present embodiment, the hardness difference between the inner tread rubber 52 and the outer tread rubber 53 is 3 degrees or more and 10 degrees or less, and the sipe density difference between the inner ground plane F in and the outer ground plane F out is 0.005 [ mm / mm 2 ] or more and 0.03 [mm / mm 2 ] or less.

この構成によれば、アイス路面での制動性能と旋回性能の向上効果を顕著に発揮できると共に、装着内外での剛性バランスが崩れて両性能の向上効果が低減することを回避できる。   According to this configuration, it is possible to significantly improve the braking performance and the turning performance on the ice road surface, and it is possible to avoid the reduction of the improvement effect of both performances due to the loss of the rigidity balance inside and outside the mounting.

本実施形態では、内側トレッドゴム５２のゴム硬度は、４０度以上且つ５５度以下であり、外側トレッドゴム５３のゴム硬度は、４５度以上且つ５５度以下であり、内側接地面Ｆｉｎのサイプ密度は、０．１３[mm/mm2]以上且つ０．２３[mm/mm2]以下であり、外側接地面Ｆｏｕｔのサイプ密度は、０．１[mm/mm2]以上且つ０．２[mm/mm2]以下である。 In the present embodiment, the rubber hardness of the inner tread rubber 52 is 40 degrees or less and not more than 55 degrees, the rubber hardness of the outer tread rubber 53, or less and 55 degrees 45 degrees, sipes of the inner ground plane F in The density is 0.13 [mm / mm 2 ] or more and 0.23 [mm / mm 2 ] or less, and the sipe density of the outer ground plane F out is 0.1 [mm / mm 2 ] or more and 0. 2 [mm / mm 2 ] or less.

この構成は、装着内外での剛性バランスが崩れにくい数値範囲内なので、本開示の好ましい一例として挙げられる。   Since this configuration is within a numerical range in which the rigidity balance inside and outside the mounting is not easily lost, it is cited as a preferred example of the present disclosure.

本実施形態では、内側接地面Ｆｉｎのボイド比は、外側接地面Ｆｏｕｔのボイド比よりも小さい。 In the present embodiment, the void ratio of the inner ground plane F in is smaller than the void ratio of the outer ground plane F out .

この構成によれば、装着内外の剛性バランスを調整しやすくなる。   According to this structure, it becomes easy to adjust the rigidity balance inside and outside the mounting.

本実施形態では、内側接地面Ｆｉｎと外側接地面Ｆｏｕｔのボイド比の差は、０．５％以上且つ５％以下である。 In the present embodiment, the difference in void ratio between the inner ground plane F in and the outer ground plane F out is 0.5% or more and 5% or less.

このようにすれば、装着内外の剛性バランスを整えるうえで好ましい。   This is preferable for adjusting the rigidity balance between the inside and outside of the wearing.

本実施形態では、内側接地面Ｆｉｎのボイド比は、２０％以上且つ３５％以下であり、外側接地面Ｆｏｕｔのボイド比は、２５％以上且つ４０％以下である。 In this embodiment, the void ratio of the inner ground plane F in is 20% to 35%, and the void ratio of the outer ground plane F out is 25% to 40%.

この数値範囲が、剛性バランスが崩れにくい範囲として挙げられる   This numerical range is listed as the range where the rigidity balance is not easily lost.

本実施形態では、内側接地面Ｆｉｎには、タイヤ周方向ＰＤに連続するリブ状陸部８ａが形成され、外側接地面Ｆｏｕｔには、タイヤ周方向ＰＤに複数に分割された複数のブロック状陸部８ｂが形成されている。 In this embodiment, the inner ground plane F in, are formed rib-like land portion 8a continuous in the tire circumferential direction PD is, the outer ground plane F out, a plurality of blocks divided into a plurality in the tire circumferential direction PD A land portion 8b is formed.

内側接地面Ｆｉｎのボイド比を、外側接地面Ｆｏｕｔのボイド比よりも小さくする一例として挙げられる。 As an example, the void ratio of the inner ground plane F in is made smaller than the void ratio of the outer ground plane F out .

本実施形態では、トレッドゴム５の両側端部をサイドウォールゴム６のタイヤ径方向ＲＤ外側端に載せてなるトレッドオンサイド構造を採用しているが、この構造に限られるものではなく、トレッドゴムの両側端部にサイドウォールゴムを載せてなるサイドオントレッド構造を採用することも可能である。   In the present embodiment, a tread-on-side structure in which both end portions of the tread rubber 5 are placed on the outer end in the tire radial direction RD of the sidewall rubber 6 is employed. However, the present invention is not limited to this structure. It is also possible to adopt a side-on-tread structure in which side wall rubber is placed on both ends of the.

［他の実施形態］
（１）本実施形態では、一対のビード部１と、各々のビード部１・１からタイヤ径方向ＲＤ外側に伸びるサイドウォール部２と、各々のサイドウォール部２・２のタイヤ径方向ＲＤ外側端に連なるトレッド部３と、一対のビード部１・１同士の間に設けられたトロイド状のカーカス層４と、トレッド部３においてカーカス層４よりも外側に設けられ且つ接地面を形成するトレッドゴム５とを備え、トレッドゴム５には、タイヤ周方向に延びる主溝５ａが５本形成されているが、トレッドパターンは適宜変更可能である。 [Other Embodiments]
(1) In the present embodiment, a pair of bead portions 1, a sidewall portion 2 extending outward from the respective bead portions 1 and 1 in the tire radial direction RD, and an outer side in the tire radial direction RD of the respective sidewall portions 2 and 2. A tread portion 3 connected to the end, a toroidal carcass layer 4 provided between the pair of bead portions 1, 1, and a tread provided outside the carcass layer 4 in the tread portion 3 and forming a ground contact surface The tread rubber 5 includes five main grooves 5a extending in the tire circumferential direction, but the tread pattern can be changed as appropriate.

本開示の構成と効果を具体的に示すために、下記実施例について下記の評価を行った。   In order to specifically show the configuration and effects of the present disclosure, the following evaluations were performed on the following examples.

（１）アイス路面での制動性能
サイズ：２３５／５０Ｒ１８のタイヤを使用し、２３００ｃｃのＬクラスミニバンの実車にて走行速度を４０ｋｍ／ｈから０ｋｍ／ｈに落としたときの制動距離を測定し、指数評価を行った。アイス路面での制動距離を制動性として評価した。比較例１における性能を１００として指数で評価した。当該指数が大きいほど制動性能が高く好ましい。 (1) Brake performance on ice road surface Size: Use 235 / 50R18 tires, measure the braking distance when the running speed is reduced from 40 km / h to 0 km / h with a real vehicle of 2300cc L-class minivan, Index evaluation was performed. The braking distance on the ice road surface was evaluated as braking performance. The performance in Comparative Example 1 was evaluated with an index of 100. The larger the index, the better the braking performance.

（２）アイス路面での旋回性能
上記サイズのタイヤを取り付けた実車を用い、アイス路面走行により官能評価にて比較した。旋回性能は、比較例１における性能を１００として指数で評価した。当該指数が大きいほど旋回性能が高く好ましい。 (2) Turning performance on ice road surface Using an actual vehicle equipped with a tire of the above size, comparison was made by sensory evaluation by running on an ice road surface. The turning performance was evaluated by an index with the performance in Comparative Example 1 as 100. The larger the index, the higher the turning performance and the better.

比較例１
内側トレッドゴムのゴム硬度を４９度とし、外側トレッドゴムのゴム硬度を５４度として、ゴム硬度が装着内側（ＩＮ）＜装着外側（ＯＵＴ）となるようにした。
内側接地面のサイプ密度を０．１４[mm/mm2]とし、外側接地面のサイプ密度を０．１５[mm/mm2]とし、サイプ密度が装着内側（ＩＮ）＜装着外側（ＯＵＴ）となるようにした。
内側接地面のボイド比を２６％とし、外側接地面のボイド比を３０％とし、ボイド比が装着内側（ＩＮ）＜装着外側（ＯＵＴ）となるようにした。 Comparative Example 1
The rubber hardness of the inner tread rubber was set to 49 degrees and the rubber hardness of the outer tread rubber was set to 54 degrees so that the rubber hardness would be the mounting inner side (IN) <the mounting outer side (OUT).
The sipe density of the inner ground plane is 0.14 [mm / mm 2 ], the sipe density of the outer ground plane is 0.15 [mm / mm 2 ], and the sipe density is inside (IN) <outside (OUT) It was made to become.
The void ratio of the inner ground plane was set to 26%, the void ratio of the outer ground plane was set to 30%, and the void ratio was set so that the mounting inner side (IN) <the mounting outer side (OUT).

比較例２
内側接地面のボイド比を３０％とし、外側接地面のボイド比を２６％とし、ボイド比が装着内側（ＩＮ）＞装着外側（ＯＵＴ）となるようにした。それ以外は、比較例１のタイヤと同じとした。 Comparative Example 2
The void ratio of the inner ground plane was set to 30%, the void ratio of the outer ground plane was set to 26%, and the void ratio was set so that the mounting inner side (IN)> the mounting outer side (OUT). Otherwise, the tire was the same as the tire of Comparative Example 1.

比較例３
内側トレッドゴムのゴム硬度を５４度とし、外側トレッドゴムのゴム硬度を５４度として、ゴム硬度が装着内側（ＩＮ）＝装着外側（ＯＵＴ）となるようにした。
内側接地面のサイプ密度を０．１５[mm/mm2]とし、外側接地面のサイプ密度を０．１５[mm/mm2]とし、サイプ密度が装着内側（ＩＮ）＝装着外側（ＯＵＴ）となるようにした。
内側接地面のボイド比を３０％とし、外側接地面のボイド比を３０％とし、ボイド比が装着内側（ＩＮ）＝装着外側（ＯＵＴ）となるようにした。 Comparative Example 3
The rubber hardness of the inner tread rubber was set to 54 degrees, and the rubber hardness of the outer tread rubber was set to 54 degrees so that the rubber hardness was set to the mounting inner side (IN) = the mounting outer side (OUT).
The sipe density of the inner ground plane is 0.15 [mm / mm 2 ], the sipe density of the outer ground plane is 0.15 [mm / mm 2 ], and the sipe density is the mounting inner side (IN) = mounting outer side (OUT) It was made to become.
The void ratio of the inner ground plane was set to 30%, the void ratio of the outer ground plane was set to 30%, and the void ratio was set so that the mounting inner side (IN) = the mounting outer side (OUT).

比較例４
内側トレッドゴムのゴム硬度を４９度とし、外側トレッドゴムのゴム硬度を５４度として、ゴム硬度が装着内側（ＩＮ）＜装着外側（ＯＵＴ）となるようにした。それ以外は、比較例３のタイヤと同じとした。 Comparative Example 4
The rubber hardness of the inner tread rubber was set to 49 degrees and the rubber hardness of the outer tread rubber was set to 54 degrees so that the rubber hardness would be the mounting inner side (IN) <the mounting outer side (OUT). Other than that, it was the same as the tire of Comparative Example 3.

比較例５
内側接地面のサイプ密度を０．１４[mm/mm2]とし、外側接地面のサイプ密度を０．１５[mm/mm2]とし、サイプ密度が装着内側（ＩＮ）＜装着外側（ＯＵＴ）となるようにした。それ以外は、比較例３のタイヤと同じとした。 Comparative Example 5
The sipe density of the inner ground plane is 0.14 [mm / mm 2 ], the sipe density of the outer ground plane is 0.15 [mm / mm 2 ], and the sipe density is inside (IN) <outside (OUT) It was made to become. Other than that, it was the same as the tire of Comparative Example 3.

実施例１
内側接地面のサイプ密度を０．１５[mm/mm2]とし、外側接地面のサイプ密度を０．１４[mm/mm2]とし、サイプ密度が装着内側（ＩＮ）＞装着外側（ＯＵＴ）となるようにした。それ以外は、比較例１のタイヤと同じとした。 Example 1
The sipe density of the inner ground plane is 0.15 [mm / mm 2 ], the sipe density of the outer ground plane is 0.14 [mm / mm 2 ], and the sipe density is the mounting inner side (IN)> the outer mounting side (OUT) It was made to become. Otherwise, the tire was the same as the tire of Comparative Example 1.

実施例２
内側接地面のボイド比を３０％とし、外側接地面のボイド比を２６％とし、ボイド比が装着内側（ＩＮ）＞装着外側（ＯＵＴ）となるようにした。それ以外は、実施例１のタイヤと同じとした。 Example 2
The void ratio of the inner ground plane was set to 30%, the void ratio of the outer ground plane was set to 26%, and the void ratio was set so that the mounting inner side (IN)> the mounting outer side (OUT). Otherwise, the tire was the same as the tire of Example 1.

実施例３
内側接地面のボイド比を３０％とし、外側接地面のボイド比を３０％とし、ボイド比が装着内側（ＩＮ）＝装着外側（ＯＵＴ）となるようにした。それ以外は、実施例１のタイヤと同じとした。 Example 3
The void ratio of the inner ground plane was set to 30%, the void ratio of the outer ground plane was set to 30%, and the void ratio was set so that the mounting inner side (IN) = the mounting outer side (OUT). Otherwise, the tire was the same as the tire of Example 1.

Figure 2016037100
Figure 2016037100

表１より、実施例１〜３は、比較例１〜５に対してアイス路面での制動性能と旋回性能の両方が向上していることが分かる。実施例１〜３は、ボイド比を変更したものであるが、実施例１〜３のいずれにおいても比較例１〜５よりも両性能が向上しているので、ゴム硬度がＩＮ＜ＯＵＴで、サイプ密度がＩＮ＞ＯＵＴであれば、ボイド比の大小関係を任意に設定できることが分かる。   From Table 1, it can be seen that in Examples 1 to 3, both braking performance and turning performance on the ice road surface are improved compared to Comparative Examples 1 to 5. In Examples 1 to 3, the void ratio was changed. However, in both Examples 1 to 3, both performances were improved as compared with Comparative Examples 1 to 5, so that the rubber hardness was IN <OUT. It can be seen that if the sipe density is IN> OUT, the void ratio can be arbitrarily set.

実施例１が最もよく、その次に実施例３、その次に実施例２が良いことから、ボイド比がＩＮとＯＵＴの剛性バランスを調整していると推測される。   Since Example 1 is the best, followed by Example 3 and then Example 2, it is presumed that the void ratio adjusts the rigidity balance between IN and OUT.

比較例４は、比較例３に対してゴム硬度をＩＮ＜ＯＵＴに変更したものである。比較例５は、比較例３に対してサイプ密度をＩＮ＜ＯＵＴに変更したものです。比較例４、５は共に比較例３よりも両性能が低下している。ゴム硬度及びサイプ硬度のいずれか一方についてＩＮ＜ＯＵＴとしても、両性能が低下することが分かる。   In Comparative Example 4, the rubber hardness is changed to IN <OUT with respect to Comparative Example 3. In Comparative Example 5, the sipe density is changed to IN <OUT compared to Comparative Example 3. Both performances of Comparative Examples 4 and 5 are lower than those of Comparative Example 3. It can be seen that both performances are reduced even if IN <OUT for either rubber hardness or sipe hardness.

なお、上記の各実施形態で採用している構造を他の任意の実施形態に採用することは可能である。   In addition, it is possible to employ | adopt the structure employ | adopted by said each embodiment as another arbitrary embodiment.

５…トレッドゴム
５ａ…主溝
５２…内側トレッドゴム
５３…外側トレッドゴム
８ａ…リブ状陸部（陸部）
８ｂ…ブロック状陸部（陸部）
９…サイプ
ＣＬ…タイヤ赤道
Ｆｉｎ…内側接地面
Ｆｏｕｔ…外側接地面
ＩＮ…車両装着時内側
ＯＵＴ…車両装着時外側 5 ... tread rubber 5a ... main groove 52 ... inner tread rubber 53 ... outer tread rubber 8a ... rib-shaped land (land)
8b ... Block-shaped land (land)
9 ... sipes CL ... tire equator F in ... the inner ground plane F out ... outside the ground plane IN ... vehicle when mounted inside OUT ... vehicle when mounted outside

Claims (7)

タイヤ周方向に延びる複数の主溝によって区画される複数の陸部と、前記複数の陸部に形成されるサイプと、を有し、車両に対する装着方向が指定される空気入りタイヤであって、
タイヤ赤道を基準として車両装着時に内側となる内側接地面を形成する内側トレッドゴムと、タイヤ赤道を基準として車両装着時に外側となる外側接地面を形成する外側トレッドゴムと、を有し、前記外側トレッドゴムは前記内側トレッドゴムよりもゴム硬度が高硬度のゴムで形成されており、
前記内側接地面のサイプ密度は、前記外側接地面のサイプ密度よりも高密度に設定されていることを特徴とする空気入りタイヤ。 A pneumatic tire having a plurality of land portions defined by a plurality of main grooves extending in a tire circumferential direction, and a sipe formed in the plurality of land portions, wherein a mounting direction for a vehicle is designated,
An inner tread rubber that forms an inner grounding surface that is the inner side when the vehicle is mounted on the basis of the tire equator, and an outer tread rubber that forms an outer grounding surface that is the outer side when the vehicle is mounted on the basis of the tire equator. The tread rubber is formed of rubber having a higher hardness than the inner tread rubber,
The pneumatic tire according to claim 1, wherein a sipe density of the inner ground plane is set higher than a sipe density of the outer ground plane. 前記内側トレッドゴムと前記外側トレッドゴムの硬度差は、３度以上且つ１０度以下であり、
前記内側接地面と前記外側接地面のサイプ密度差は、０．００５[mm/mm2]以上且つ０．０３[mm/mm2]以下である、請求項１に記載の空気入りタイヤ。 The hardness difference between the inner tread rubber and the outer tread rubber is 3 degrees or more and 10 degrees or less,
2. The pneumatic tire according to claim 1, wherein a sipe density difference between the inner ground surface and the outer ground surface is 0.005 [mm / mm 2 ] or more and 0.03 [mm / mm 2 ] or less. 前記内側トレッドゴムのゴム硬度は、４０度以上且つ５５度以下であり、
前記外側トレッドゴムのゴム硬度は、４５度以上且つ５５度以下であり、
前記内側接地面のサイプ密度は、０．１３[mm/mm2]以上且つ０．２３[mm/mm2]以下であり、
前記外側接地面のサイプ密度は、０．１[mm/mm2]以上且つ０．２[mm/mm2]以下である、請求項１又は２に記載の空気入りタイヤ。 The inner tread rubber has a rubber hardness of 40 degrees or more and 55 degrees or less,
The outer tread rubber has a rubber hardness of 45 degrees or more and 55 degrees or less,
The sipe density of the inner ground plane is 0.13 [mm / mm 2 ] or more and 0.23 [mm / mm 2 ] or less,
The pneumatic tire according to claim 1 or 2, wherein the sipe density of the outer ground contact surface is 0.1 [mm / mm 2 ] or more and 0.2 [mm / mm 2 ] or less. 前記内側接地面のボイド比は、前記外側接地面のボイド比よりも小さい、請求項１〜３のいずれかに記載の空気入りタイヤ。   The pneumatic tire according to claim 1, wherein a void ratio of the inner ground contact surface is smaller than a void ratio of the outer ground contact surface. 前記内側接地面と前記外側接地面のボイド比の差は、０．５％以上且つ５％以下である請求項４に記載の空気入りタイヤ。   The pneumatic tire according to claim 4, wherein a difference in void ratio between the inner ground contact surface and the outer ground contact surface is not less than 0.5% and not more than 5%. 前記内側接地面のボイド比は、２０％以上且つ３５％以下であり、
前記外側接地面のボイド比は、２５％以上且つ４０％以下である、請求項４又は５に記載の空気入りタイヤ。 The void ratio of the inner ground plane is 20% or more and 35% or less,
The pneumatic tire according to claim 4 or 5, wherein a void ratio of the outer ground contact surface is 25% or more and 40% or less. 前記内側接地面には、タイヤ周方向に連続するリブ状陸部が形成され、前記外側接地面には、タイヤ周方向に複数に分割された複数のブロック状陸部が形成されている請求項４〜６のいずれかに記載の空気入りタイヤ。   A rib-like land portion continuous in a tire circumferential direction is formed on the inner ground contact surface, and a plurality of block-shaped land portions divided into a plurality in the tire circumferential direction are formed on the outer ground contact surface. The pneumatic tire according to any one of 4 to 6.
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