JP4275372B2

JP4275372B2 - Pneumatic tire

Info

Publication number: JP4275372B2
Application number: JP2002254173A
Authority: JP
Inventors: 新冨田; 靖雄大澤; 貴文澤田; 隆成佐口; 一人藤田
Original assignee: Bridgestone Corp
Current assignee: Bridgestone Corp
Priority date: 2002-08-30
Filing date: 2002-08-30
Publication date: 2009-06-10
Anticipated expiration: 2022-08-30
Also published as: JP2004090769A

Description

【０００１】
【発明の属する技術分野】
この発明は、乗用車に用いて好適な空気入りタイヤに関し、特に偏摩耗を抑制する技術を提案するものである。
【０００２】
【従来の技術】
一般に空気入りタイヤでは、車両に装着されて装着の内側となる部分の摩耗に関しては、前輪で問題になる場合が多い。これはもともとの車両設定がネガティブキャンバーであったり、トーアウトであるものが比較的多いことに加えて、制動時に前輪の荷重が増加し、前輪のアライメントがネガティブキャンバーでかつトーアウトに増加することが大きな要因となっている。
ネガティブキャンバーの場合、装着内側となるショルダー部の接地長が、外側の接地長よりも長くなるので、この状態でトーインもしくはトーアウトの微小なスリップ角が加わった場合、タイヤの横ずれが大きくなって、装着内側となるショルダー部が横力を余計に負担することになり、これが装着内側となるショルダー部が外側のショルダー部に対してより多く摩耗する偏摩耗の要因となる。
【０００３】
また、装着内側となるショルダー部の縦たわみが外側のショルダー部よりも大きくなるので、幅が広がり、その幅が広がった領域が引きずられて制動方向の力を受けこれも偏摩耗の要因となる。
しかも装着内側となるショルダー部は、外側のショルダー部に較べて撓みが大きく回転半径が小さくなるので、引きずられて制動方向の力を受ける。この力の負担は接地端に近い領域ほど大きくなり、偏摩耗核はこの領域に発生しやすい。
このようにして装着内側となるショルダー部に発生する偏摩耗は、車両への装着状態においては見えにくく、運転者が気づきにくいので、適切な処置をしないままに放置した場合には偏摩耗が進展して、最悪の場合、タイヤバースト等の故障の原因ともなるおそれがあった。
【０００４】
【発明が解決しようとする課題】
そこで、このような問題を解決するべく、本発明者は、特開２００１−３５４０１０において、装着内側のショルダー部の周方向剛性を、装着外側のショルダー部の周方向剛性よりも大きくしたタイヤを提案した。これによれば、ネガティブキャンバーをつけた場合において、装着内側の制動方向のせん断力を小さくして、装着内側のショルダー部分の偏摩耗を抑制することができる。
【０００５】
本発明は、この従来技術をさらに改良したものであり、より効果的に、装着されて内側となる側のショルダー部分の偏摩耗を抑制できる空気入りタイヤを提供するものである。
【０００６】
【課題を解決するための手段】
本発明に係る空気入りタイヤは、トレッドに、その周方向に連続して延びる少なくとも二本の周溝を設け、それらの周溝により区画される陸部列のうち、車両に装着されて内側となる幅方向端側の陸部列に周溝から独立した、最大深さが周溝の深さの１／３以上である複数の孔を設け、その陸部列の幅方向中心を通る線に対して幅方向端側の陸部列部分の凹部容積を、幅方向中心を通る線の幅方向内側の陸部列部分の凹部容積より大きくし、車両に装着されて内側となる幅方向端側の陸部列の周方向剛性を、車両に装着されて外側となる幅方向端側の陸部列の周方向剛性よりも大きくしてなる。
【０００７】
ここで周方向剛性とは、陸部の周方向長さをａ、幅方向長さをｂ、半径方向の厚みをｔ、ヤング率をＥとすると、Ｇ＝（ａ×ｂ×Ｅ）／（３×ｔ×（１＋１／３（ｔ／ａ）^２））で計算されるものである。
また、凹部容積とは、幅方向端側及び内側のそれぞれの陸部列部分内の周溝、横溝、孔の全ての容積をタイヤの全周にわたって積算したものである。
さらに、周溝とは、トレッド幅の２．５％以上の幅を持つタイヤ周方向に延びる溝である。
【０００８】
ここで、トレッド幅とは、タイヤを適用リムに装着するとともに、規定の空気圧を充填し、そこに最大負荷能力に対応する質量を負荷したときの接地幅をいうものとする。ここで適用リムとは下記の規格に規定されたリムをいい、最大負荷能力とは、下記の規格でタイヤに負荷することが許される最大の質量をいい、規定の空気圧とは、下記の規格において、最大負荷能力に対応して規定される空気圧をいう。
そして規格とは、タイヤが生産又は使用される地域に有効な産業規格によって決められている。例えば、アメリカ合衆国では”The Tire and Rim Association Inc.のYear Book”であり、欧州では”The European Tire and Rim Technical OrganizationのStandards Manual”であり、日本では日本自動車タイヤ協会の”JATMA Year Book”である。
【０００９】
装着内側の幅方向端側の陸部列の周方向剛性を、装着外側の幅方向端側陸部列の周方向剛性よりも大きくすることにより、ネガティブキャンバーが付与された場合に、装着内側の幅方向端側の陸部列の回転半径が、装着外側の幅方向端側の陸部列の回転半径に較べて小さくなって、装着内側の幅方向端側の陸部列が、装着外側のショルダー部に対して相対的に車両進行方向とは逆の、つまり制動方向の力を受け、偏摩耗が発生することを防止することができる。
【００１０】
また、車両に装着されて内側となる幅方向端側の陸部列に周溝から独立した、最大深さが周溝の深さの１／３以上である複数の孔を設けることにより、孔を設けた領域のせん断剛性を低減させて、横力が増えた場合にはこの領域での横力の負担を小さくして、横力に対する反力の発生を抑制し、また、この領域が制動方向に引きずられた場合にも、制動方向の力に対する反力の発生を抑制して、偏摩耗の発生を抑制することができる。また、孔の最大深さを、周溝の深さの１／３以上とすることにより、タイヤの摩耗が進展した場合でも、複数の孔を設けることによる偏摩耗の発生の抑制効果を確保することができる。
さらに、凹部容積を装着内側の陸部列の中心線より幅方向外側の陸部列部分で、中心線より幅方向内側の陸部列部分より大きくすることで、偏摩耗の発生しやすい幅方向外側で、偏摩耗の抑制効果を高めることができる。
【００１１】
また、好ましくは、車両に装着されて内側となる幅方向端側の陸部列を、細幅周溝により幅方向外側の陸部列部分と幅方向内側の陸部列部分とに分割して、その幅方向外側の陸部列部分の幅を、幅方向内側の陸部列部分の幅よりも狭くするとともに、トレッド幅の１／１０以下とする。
【００１２】
これによれば、もっとも偏摩耗が発生しやすい接地端近傍の陸部部分を陸部列から分離して、それより内側の陸部列への摩耗の進展を抑制することができる。ここで幅方向外側の陸部列部分の幅を、幅方向内側の陸部列部分の幅よりも狭く、トレッド幅の１／１０以下とすることにより、偏摩耗体積を減らし外観を良好に保つことができる。
ここで、細幅周溝とは、トレッド幅の２．５％未満の幅を持つタイヤ周方向に延びる溝である。
【００１３】
さらに好ましくは、幅方向外側の陸部列部分の外側面の、タイヤ幅方向の断面内における外輪郭形状の曲率中心のうちの少なくとも一つを、その輪郭線の外側に位置させる一方、幅方向内側の陸部列部分の外輪郭形状の曲率中心を、その輪郭線の内側に位置させる。
【００１４】
これによれば、車両に装着されて内側となる幅方向端側の陸部列内の、幅方向外側の陸部列部分の偏摩耗体積を減らし、外観を良好に保つことができる。
【００１５】
ここで、細幅周溝の幅を、溝底からトレッド表面側にむかって漸次広くすることが好ましい。
【００１６】
これによれば、細幅周溝が路面上の小石等の異物をかみこんだ場合でも、その異物を外れやすくして、異物を抱き込んだまま走行することにより、偏摩耗核が幅方向内側の陸部列部分に発生することを防止することができる。
ここで、細幅周溝は装着内側のみに配置するのが好ましい。装着外側に配置すると、横力の影響が大きいので、周溝の幅方向外側の陸部列が、それより幅方向内側の陸部列へ摩耗が進展することを抑制する効果を発揮することができず、その幅方向内側の陸部列に直接偏摩耗が発生してしまうからである。
【００１７】
さらに、タイヤの最大負荷能力の７０％以上の負荷の作用下で、車両に装着されて内側となる幅方向端側の陸部列の、複数の孔を配置された領域の少なくとも一部が接地するようにトレッドを構成することが好ましい。
【００１８】
これによれば、例えばＦＦ車の制動時の後輪のように、前輪に比して後輪荷重が小さくなり接地幅が小さくなる場合でも、装着内側の幅方向端側の陸部列に孔を設けることによる偏摩耗の発生および進展の抑制の効果を担保することができる。
ここで、最大負荷能力とは、ＪＡＴＭＡ、ＥＴＲＴＯ、ＴＲＡ等の規定の条件下でタイヤの負荷することが許される最大の荷重を言う。
【００１９】
さらに好ましくは、車両に装着されて内側となる幅方向端側の陸部列において、タイヤ赤道線から遠ざかるにつれて孔の開口寸法を大きくする。
【００２０】
これによれば、前述した孔を設けることによる、偏摩耗の発生および進展の抑制の効果を、横力や制動力の負担が大きい接地端に近づくにつれて大きくすることができる。また、偏摩耗の抑制に対し効果的な領域に孔を配置して、それ以外の部分になるべく配置しないようにする事により、それ以外の部分では操縦安定性やトレッド耐久性を良好に保つことが可能となる。
【００２１】
またここで、車両に装着されて内側となる幅方向端側の陸部列において、タイヤ赤道線から遠ざかるにつれて複数の孔相互間の間隔を小とすることが好ましい。
【００２２】
これによっても、偏摩耗の抑制効果を、接地端近傍で大きくすることができ、偏摩耗の抑制に対して効果的な領域のみに孔を配置して、その他の部分の操縦安定性やトレッド耐久性を良好に保つことができる。
【００２３】
さらに好ましくは、車両に装着されて内側となる幅方向端側の陸部列において、タイヤ赤道線から遠ざかるにつれて孔の深さを深くする。
【００２４】
これによっても、偏摩耗の抑制効果を、接地端近傍で大きくすることができ、偏摩耗の抑制に対して効果的な領域のみに孔を配置して、その他の部分の操縦安定性やトレッド耐久性を良好に保つことができる。
【００２５】
【発明の実施の形態】
以下に、この発明の実施の形態を図面に示すところに基づいて説明する。
図１は本発明の実施の形態を、車両への装着姿勢のタイヤの正面視で示すトレッドパターンの展開図である。タイヤの内部構造は、一般的なラジアルタイヤのそれと同様であるので、ここでは図示を省略する。トレッド１に、その周方向に連続して延びる少なくとも二本、図では三本の周溝２を設け、それらの周溝２により区画される陸部列のうち、車両に装着されて内側となる幅方向端側の、陸部列３と、車両に装着されて外側となる幅方向端側の陸部列４とのうち、陸部列４には横溝５を設け、陸部列３の周方向剛性を陸部列４の周方向剛性より大きくなるようにし、三本の周溝間に区画される他の二列の陸部列６、７のそれぞれにも、それぞれ横溝８、９を設けられる。
さらに、陸部列３に、周溝２から独立した複数の孔１０を設け、陸部列３の中心線Ｃｉより幅方向外側の陸部列部分の凹部容積を、その中心線の幅方向内側の陸部列部分の凹部容積よりも大きくする。
【００２６】
これによれば、陸部列３の周方向剛性を、陸部列４の周方向剛性よりも大きくすることにより、陸部列３が接地面内で圧縮変形されて、接地長さが長くなり、横溝が縮んで、回転半径が小さくなって、回転半径の大きい陸部列４側のショルダー部に対して、車両進行方向とは逆方向側の力つまり制動方向の力を受け、偏摩耗が発生することを防止することができる。
また、陸部列３の、横溝本数を低減することにより、周方向の幾何学的な不連続部分を少なくして、周方向の不均一摩耗であるヒールアンドトウ摩耗をも抑制することができる。
【００２７】
また、三本の周溝２により、陸部列３、４より幅方向内側に区画される二列の陸部列６、７にも、それぞれ横溝８、９を設けることにより、それらの溝縁を制動力および駆動力の増加に有効に寄与させることができ、併せて、トレッド中央域の排水性能を向上することができる。
【００２８】
これらの孔１０は、それらを設けた領域のせん断剛性を低減させて、横力に対するこの領域の負担を小さくして、反力の発生を抑制し、また、この領域が制動方向に引きずられた場合にも、制動力に対する反力の発生を抑制して、偏摩耗の発生を抑制することができる。
【００２９】
また、孔１０の最大深さを、周溝２の深さの１／３以上とすることにより、タイヤの摩耗が進展した場合でも、複数の孔１０を設けることによる偏摩耗の発生の抑制効果を確保することができる。
さらに、凹部容積を装着内側の陸部列の中心線Ｃｉより幅方向外側の陸部列部分で、中心線Ｃｉより幅方向内側の陸部列部分より大きくすることで、偏摩耗の発生しやすい幅方向外側で、偏摩耗の抑制効果を高めることができる。
【００３０】
また、好ましくは、車両に装着されて内側となる幅方向端側の陸部列３を、細幅周溝１１により幅方向外側の陸部列部分１２と幅方向内側の陸部列部分１３とに分割して、その幅方向外側の陸部列部分１２の幅ｗを、幅方向内側の陸部列部分１３の幅ｗ０よりも狭くするとともに、トレッド幅Ｗの１／１０以下とする。
【００３１】
これによれば、もっとも偏摩耗が発生しやすい接地端近傍の幅方向外側の陸部列部分１２を分離して、それより内側の陸部列部分１３への摩耗の進展を抑制することができる。また、幅方向外側の陸部列部分１２の幅ｗを、幅方向内側の陸部列部分１３の幅ｗ０よりも狭くかつ、トレッド幅Ｗの１／１０以下とすることにより、偏摩耗体積を減らし外観を良好に保つことができる。
【００３２】
さらに好ましくは、図２に示すように、幅方向外側の陸部列部分１２の外側面、タイヤ幅方向の断面内における外輪郭形状の少なくとも一方の曲率中心Ｃ１を、その輪郭線Ｓ１の外側に位置させる一方、幅方向内側の陸部列部分１３の外輪郭形状の曲率中心Ｃ２を、その輪郭線Ｓ２の内側に位置させてなる。
【００３３】
これによれば、もっとも偏摩耗が発生しやすい接地端近傍の幅方向外側の陸部列部分１２の偏摩耗体積を一層減らして、外観を良好に保つことができる。
【００３４】
ここで、細幅周溝１１の幅ｗ１０は、図２に示すように、溝底からトレッド表面側にむかって漸次広くすることが好ましい。
【００３５】
これによれば、細幅周溝１１が路面上の小石等の異物をかみこんだ場合でも、その異物を外れやすくして、異物を抱き込んだまま走行することにより、偏摩耗核が幅方向内側の陸部列部分１３に発生することを防止することができる。
【００３６】
さらに、タイヤの最大負荷能力の７０％以上の負荷の作用下で、装着内側の陸部列３の幅方向内側の陸部列部分１３の、複数の孔１０を配置された領域の少なくとも一部が接地するようにトレッドを構成することが好ましい。
【００３７】
これによれば、例えばＦＦ車の後輪のように、前輪に比して低荷重となり接地幅が小さくなる場合でも、前述した複数の孔１０の形成領域を接地させることによって偏摩耗の発生および進展の抑制の効果を担保することができる。
【００３８】
さらに好ましくは、装着内側の陸部列３の幅方向内側の陸部列部分１３において、タイヤ赤道線から遠ざかるにつれて孔１０の開口寸法Ｒを大きくする。
【００３９】
これによれば、前述した複数の孔１０を設けることによる、偏摩耗の発生および進展の抑制の効果を、横力や制動力の負担が大きい接地端に近づくにつれて大きくすることができる。また、偏摩耗の抑制に対し効果的な領域に孔１０を配置して、それ以外の部分になるべく配置しないようにする事により、それ以外の部分で操縦安定性やトレッド耐久性を良好に保つことが可能となる。
【００４０】
また好ましくは、装着内側の陸部列３の幅方向内側の陸部列部分１３において、タイヤ赤道線から遠ざかるにつれて複数の孔１０相互間の間隔Ｑを小とする。
【００４１】
これによっても、偏摩耗の抑制効果を、接地端近傍で大きくすることができ、偏摩耗の抑制に対し効果的な領域のみに複数の孔を配置して、操縦安定性やトレッド耐久性を良好に保つことができる。
【００４２】
また好ましくは、タイヤ赤道線から遠ざかるにつれて孔１０の深さを深くする。
【００４３】
これによっても、偏摩耗の抑制効果を、接地端近傍で大きくすることができ、偏摩耗の抑制に対し効果的な領域のみに複数の孔１０を配置して、操縦安定性やトレッド耐久性を良好に保つことができる。
【００４４】
【実施例】
本発明の一実施形態たる空気入りタイヤの、偏摩耗の抑制性能を評価する目的で、サイズが２０５／６５Ｒ１５の、二種類の実施例タイヤと、五種類の比較例タイヤとを、呼びが６Ｊ×１５のリムに装着して、タイヤへの充填空気圧を２２０ｋＰａとし、テスト車両に装着し、３万ｋｍ走行した後、装着内側のトレッド部の摩耗を測定し、偏摩耗の抑制性能の評価を行った。その結果を表１に示す。
実施例１のトレッドパターンは、図１に示すように、トレッド１に、その周方向に連続して延びる少なくとも二本、図では三本の周溝２を設け、それらの周溝２により区画される陸部列のうち、車両に装着されて内側となる幅方向端側の、陸部列３と、車両に装着されて外側となる幅方向端側の陸部列４とのうち、陸部列４には横溝５を設け、陸部列３の周方向剛性を陸部列４の周方向剛性より大きくなるようにし、三本の周溝間に区画される他の二列の陸部列６、７のそれぞれにも、それぞれ横溝８、９を設けられ、陸部列３に、周溝２から独立した複数の孔１０を設け、陸部列３の中心線Ｃｉより幅方向外側の陸部列部分の凹部容積を、その中心線の幅方向内側の陸部列部分の凹部容積よりも大きくし、車両に装着されて内側となる幅方向端側の陸部列３を、細幅周溝１１により幅方向外側の陸部列部分１２と幅方向内側の陸部列部分１３とに分割して、その幅方向外側の陸部列部分１２の幅を、幅方向内側の陸部列部分１３の幅よりも狭く、トレッド幅の１／１０以下としてなる。
【００４５】
細幅周溝１１の深さは５．０ｍｍ、溝底での幅は１．５ｍｍ、トレッド表面での幅は３．０ｍｍとしている。また、陸部列部分１２の幅は２ｍｍ、陸部列部分１３の幅は１８ｍｍとしている。
車両に装着されて内側となる陸部列の、幅方向内側の陸部列部分１３に、周溝２および細幅周溝１１から独立した複数の孔１０を設ける。複数の孔１０は二列の孔列からなり、幅方向外側の孔は、直径は２．５ｍｍ、深さは６ｍｍ、中心間距離は７．５ｍｍとし、幅方向内側の孔は、直径は１．５ｍｍ、深さは６ｍｍ、中心間距離は７．５ｍｍとしている。
【００４６】
実施例２のトレッドパターンは、図３に示すように、実施例１を基本とし、細幅周溝を設けず、その位置に、直径が２．５ｍｍ、深さは６ｍｍ、中心間距離は７．５ｍｍの孔列を設けたものである。
比較例１のトレッドパターンは、図４に示すように、装着外側の幅方向外側となる陸部列には横溝を設けず、装着内側の幅方向外側となる陸部列に横溝を設けたものである。
比較例２のトレッドパターンは、図５に示すように、実施例１に示すトレッドパターンを装着外側と内側とで逆としたものである。
比較例３のトレッドパターンは、図６に示すように、実施例１を基本とし、幅方向外側の陸部列部分１２の幅を１４ｍｍ、幅方向内側の陸部列部分１３の幅を６ｍｍとし、陸部列部分１３に、直径が２．５ｍｍ、深さは６ｍｍ、中心間距離は７．５ｍｍの孔列を設けたものである。
比較例４のトレッドパターンは、図７に示すように、実施例１を基本とし、細幅周溝を設けず、直径が３．０ｍｍ、深さは６ｍｍ、中心間距離は７．５ｍｍの孔列と、直径が２．０ｍｍ、深さは６ｍｍ、中心間距離は７．５ｍｍの孔列と、直径が１．０ｍｍ、深さは６ｍｍ、中心間距離は７．５ｍｍの孔列とを、幅方向内側からこの順番にて設けたものである。
比較例５のトレッドパターンは、図８に示すように、実施例１を基本とし、複数の孔を設けないものである。
性能評価は、比較例タイヤ１をコントロールタイヤとして、１００点満点で評価した。数値は小さいほど良好であることを示す。
【００４７】
【表１】

【００４８】
表１において、比較例タイヤ１と実施例タイヤ１とを比較すると、実施例タイヤ１は、比較例タイヤ１に較べ、大幅に、車両に装着されて内側となる陸部列の偏摩耗を防止できていることが分かる。
比較例タイヤ１と比較例タイヤ２とを比較すると、車両に装着されて外側となる陸部列の横溝成分を小さくし、細幅周溝を設けて幅方向内側と外側との陸部列部分に分離して、孔を設けると、旋回時の横力を負担しきれず、偏摩耗抑制性能はかえって悪くなる事がわかる。この場合、細幅周溝の外側の陸部列が横力に対しては機能せず、内側陸部列に偏摩耗が発生するため、外観も悪くなる。
【００４９】
実施例タイヤ１と比較例タイヤ５とを比較すると、幅方向内側の陸部列部分に孔を設けることにより、偏摩耗をさらに抑制できていることが分かる。
実施例タイヤ１と実施例タイヤ２とを比較すると、細幅周溝により車両に装着されて内側となる陸部列を幅方向外側と内側に分離することにより、偏摩耗をさらに抑制することができることが分かる。
実施例タイヤ１と比較例タイヤ３とを比較すると、幅方向外側の陸部列部分の幅が大きすぎると、偏摩耗の抑制効果が小さいことが分かる。
実施例タイヤ２と比較例タイヤ４とを比較すると、孔の配列は、幅方向外側の孔の直径を大きくするほうが、偏摩耗を抑制するに際し効果的であることが分かる。
【００５０】
【発明の効果】
以上に述べたところから明らかなように、この発明によれば、トレッドに、その周方向に連続して延びる少なくとも二本の周溝を設け、それらの周溝により区画される陸部列のうち、車両に装着されて内側となる幅方向端側の陸部列に周溝から独立した、最大深さが周溝の深さの１／３以上である複数の孔を設け、その陸部列の幅方向中心を通る線に対して幅方向端側の陸部列部分の凹部容積を、幅方向中心を通る線の幅方向内側の陸部列部分の凹部容積より大きくし、車両に装着されて内側となる幅方向端側の陸部列の周方向剛性を、車両に装着されて外側となる幅方向端側の陸部列の周方向剛性よりも大きくすることにより、装着内側の幅方向端側の陸部列の回転半径が、装着外側の幅方向外側の陸部列の回転半径に較べて小さくなって、装着内側の幅方向端側の陸部列が回転半径の大きい装着外側の幅方向端側の陸部列に対して車両進行方向とは逆方向の力、つまり制動方向の力を受け、偏摩耗が発生することを防止することができる。
【図面の簡単な説明】
【図１】本発明の実施の形態を、車両への装着姿勢のタイヤの正面視で示すトレッドパターンの展開図である。
【図２】本発明のトレッドパターンの一部を示す幅方向断面図である。
【図３】本発明の他の実施の形態を、車両への装着姿勢のタイヤの正面視で示すトレッドパターンの展開図である。
【図４】比較例タイヤの形態を、車両への装着姿勢のタイヤの正面視で示すトレッドパターンの展開図である。
【図５】比較例タイヤの他の形態を、車両への装着姿勢のタイヤの正面視で示すトレッドパターンの展開図である。
【図６】比較例タイヤの他の形態を、車両への装着姿勢のタイヤの正面視で示すトレッドパターンの展開図である。
【図７】比較例タイヤの他の形態を、車両への装着姿勢のタイヤの正面視で示すトレッドパターンの展開図である。
【図８】比較例タイヤの他の形態を、車両への装着姿勢のタイヤの正面視で示すトレッドパターンの展開図である。
【符号の説明】
１トレッド部
２周溝
３陸部列（装着内側）
４陸部列（装着外側）
５横溝
６陸部列
７陸部列
８横溝
９横溝
１０孔
１１細幅周溝
１２陸部列部分（幅方向外側）
１３陸部列部分（幅方向内側）[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pneumatic tire suitable for use in a passenger car, and particularly proposes a technique for suppressing uneven wear.
[0002]
[Prior art]
In general, with pneumatic tires, there is often a problem with the front wheels regarding the wear of the portion that is attached to the vehicle and that is inside the vehicle. In addition to the fact that the original vehicle setting is a negative camber or a relatively large number of toe-outs, the load on the front wheels increases during braking, and the alignment of the front wheels increases to a negative camber and toe-out. It is a factor.
In the case of negative camber, the ground contact length of the shoulder part on the inner side is longer than the outer contact length, so if a small slip angle of toe-in or toe-out is added in this state, the lateral deviation of the tire becomes large, The shoulder portion on the inner side of the mounting will bear an extra lateral force, which causes uneven wear in which the shoulder portion on the inner side of the mounting wears more on the outer shoulder portion.
[0003]
In addition, since the vertical deflection of the shoulder portion on the inner side is larger than that of the outer shoulder portion, the width is widened, and the widened region is dragged and receives a force in the braking direction, which also causes uneven wear. .
In addition, the shoulder portion on the inner side of the mounting has a larger deflection than the outer shoulder portion and has a smaller radius of rotation, so that it is dragged and receives a force in the braking direction. The load of this force is greater in the region closer to the ground contact end, and uneven wear nuclei are likely to occur in this region.
The uneven wear that occurs in the shoulder portion on the inner side in this way is difficult to see in the mounted state on the vehicle and is difficult for the driver to notice. In the worst case, there is a possibility of causing a failure such as a tire burst.
[0004]
[Problems to be solved by the invention]
Therefore, in order to solve such a problem, the present inventors, in JP 2001-354010, the circumferential rigidity of the shoulder portion of the inner side, a large tire than the circumferential rigidity of the shoulder portion of the mounting outside the side Proposed. According to this, in the case of wearing a negative camber, to reduce the shearing force of the braking direction of the inner side, Ru can be suppressed uneven wear of the shoulder portion of the inner side.
[0005]
The present invention is a further improvement of this prior art and provides a pneumatic tire that can more effectively suppress uneven wear of the shoulder portion on the inner side of the tire.
[0006]
[Means for Solving the Problems]
The pneumatic tire according to the present invention, the tread, at least two circumferential grooves extending continuously in the circumferential direction is provided, of the land portion rows are partitioned by their circumferential grooves, it is mounted on vehicles the inside A line extending through the center in the width direction of the land portion row is provided with a plurality of holes whose maximum depth is 1/3 or more of the depth of the circumferential groove in the land portion row on the width direction end side. width recess volume of land row portion of the direction end side, larger than the recess volume of the land row portion in the width direction inner side of a line passing through the widthwise center, widthwise end of the inner is attached to the vehicle with respect to The circumferential rigidity of the land portion row on the side is made larger than the circumferential rigidity of the land portion row on the width direction end side that is attached to the vehicle and is on the outside .
[0007]
Here, the circumferential rigidity is defined as G = (a × b × E) / () where the circumferential length of the land portion is a, the widthwise length is b, the radial thickness is t, and the Young's modulus is E. 3 × t × (1 + 1/3 (t / a) ² )).
Further, the recess volume is obtained by integrating all the volumes of the circumferential groove, the lateral groove, and the hole in each land portion row portion on the width direction end side and on the inner side over the entire circumference of the tire.
Furthermore, the circumferential groove is a groove extending in the tire circumferential direction having a width of 2.5% or more of the tread width.
[0008]
Here, the tread width refers to a contact width when a tire is mounted on an applicable rim, a prescribed air pressure is filled, and a mass corresponding to the maximum load capacity is loaded thereon. The applicable rim here refers to the rim specified in the following standards, the maximum load capacity refers to the maximum mass allowed to be applied to the tire according to the following standards, and the specified air pressure refers to the following standards: Means the air pressure defined corresponding to the maximum load capacity.
The standard is determined by an industrial standard effective in the region where the tire is produced or used. For example, “Year Book of The Tire and Rim Association Inc.” in the United States, “Standards Manual of The European Tire and Rim Technical Organization” in Europe, and “JATMA Year Book” of the Japan Automobile Tire Association in Japan. .
[0009]
When the negative camber is applied by making the circumferential rigidity of the land portion row on the width direction end side on the inner side larger than the circumferential rigidity of the width direction end side land portion row on the outer side of the attachment, The rotation radius of the land portion row on the width direction end side is smaller than the rotation radius of the land portion row on the width direction end side on the outer side of the attachment, and the land portion row on the width direction end side of the attachment side becomes smaller on the outer side of the attachment. It is possible to prevent the occurrence of uneven wear by receiving a force in the braking direction that is opposite to the vehicle traveling direction relative to the shoulder portion.
[0010]
Further, by providing a plurality of holes having a maximum depth of 1/3 or more of the depth of the circumferential groove, which is independent from the circumferential groove, in the land portion row on the inner side in the width direction that is mounted on the vehicle, If the lateral force increases by reducing the shear rigidity of the area where the slab is provided, the burden of the lateral force in this area is reduced, and the generation of reaction force against the lateral force is suppressed. Even when dragged in the direction, it is possible to suppress the occurrence of uneven wear by suppressing the generation of reaction force against the force in the braking direction. In addition, by setting the maximum depth of the hole to 1/3 or more of the depth of the circumferential groove, even when tire wear progresses, the effect of suppressing the occurrence of uneven wear is ensured by providing a plurality of holes. be able to.
Furthermore, the width direction in which uneven wear is likely to occur by making the concave volume larger in the land portion row portion on the outer side in the width direction than the center line of the land portion row on the inner side, and on the land portion row portion on the inner side in the width direction from the center line. On the outside, the effect of suppressing uneven wear can be enhanced.
[0011]
Preferably, the land portion row on the inner side in the width direction that is mounted on the vehicle is divided into a land portion row portion on the outer side in the width direction and a land portion row portion on the inner side in the width direction by a narrow circumferential groove. The width of the land portion row portion on the outer side in the width direction is made narrower than the width of the land portion row portion on the inner side in the width direction, and is 1/10 or less of the tread width.
[0012]
According to this, the land portion in the vicinity of the ground contact end where uneven wear is most likely to occur can be separated from the land portion row, and the progress of wear toward the inner land portion row can be suppressed. Here, the width of the land portion row portion on the outer side in the width direction is narrower than the width of the land portion row portion on the inner side in the width direction, and is 1/10 or less of the tread width, thereby reducing the uneven wear volume and keeping the appearance good. be able to.
Here, the narrow circumferential groove is a groove extending in the tire circumferential direction having a width of less than 2.5% of the tread width.
[0013]
More preferably, at least one of the curvature centers of the outer contour shape in the cross section in the tire width direction of the outer side surface of the land portion row portion on the outer side in the width direction is positioned outside the contour line, while in the width direction. The center of curvature of the outer contour shape of the inner land portion row portion is positioned inside the contour line.
[0014]
According to this, the uneven wear volume of the land part row | line | column part of the width direction outer side in the land part row | line | column by the side of the width direction edge | end side which is mounted | worn with and becomes an inner side can be reduced, and an external appearance can be maintained favorable.
[0015]
Here, it is preferable that the width of the narrow circumferential groove is gradually increased from the groove bottom toward the tread surface side.
[0016]
According to this, even when the narrow circumferential groove encloses foreign matter such as pebbles on the road surface, it is easy to remove the foreign matter, and traveling while holding the foreign matter, Can be prevented from occurring in the land portion row portion.
Here, the narrow circumferential groove is preferably disposed only on the inner side of the mounting. When arranged outside the mounting, the influence of lateral force is large, so that the land portion row on the outer side in the width direction of the circumferential groove can exert an effect of suppressing the progress of wear to the land portion row on the inner side in the width direction. This is because uneven wear occurs directly in the land portion row on the inner side in the width direction.
[0017]
Furthermore, at least a part of the region where the plurality of holes are arranged in the land portion row on the inner side in the width direction that is attached to the vehicle and becomes the inner side under the action of a load of 70% or more of the maximum load capacity of the tire is grounded. It is preferable to configure the tread as described above.
[0018]
According to this, even if the rear wheel load is smaller than the front wheel and the ground contact width is smaller than the front wheel, for example, the rear wheel during braking of the FF vehicle, a hole is formed in the land portion row on the width direction end side on the inner side of the mounting. It is possible to secure the effect of suppressing the occurrence of uneven wear and the progress due to the provision of.
Here, the maximum load capacity refers to the maximum load that is allowed to be applied to the tire under specified conditions such as JATMA, ETRTO, and TRA.
[0019]
More preferably, in the land portion row on the inner side in the width direction that is attached to the vehicle, the opening size of the hole is increased as the distance from the tire equator line increases.
[0020]
According to this, the effect of suppressing the occurrence of uneven wear and the progress due to the provision of the above-described holes can be increased as approaching the ground contact end where the load of lateral force and braking force is large. Also, by placing holes in areas that are effective for suppressing uneven wear and avoiding other parts as much as possible, keep the steering stability and tread durability good in other parts. Is possible.
[0021]
Here, in the land portion row on the inner side in the width direction that is mounted on the vehicle, it is preferable that the interval between the plurality of holes is reduced as the distance from the tire equator line increases.
[0022]
Even in this way, the effect of suppressing uneven wear can be increased in the vicinity of the ground contact edge. Holes are arranged only in areas effective for suppressing uneven wear, and steering stability and tread durability of other parts are also provided. The property can be kept good.
[0023]
More preferably, the depth of the hole is increased as the distance from the tire equator line increases in the land portion row on the inner side in the width direction that is attached to the vehicle.
[0024]
Even in this way, the effect of suppressing uneven wear can be increased in the vicinity of the ground contact edge. Holes are arranged only in areas effective for suppressing uneven wear, and steering stability and tread durability of other parts are also provided. The property can be kept good.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a development view of a tread pattern showing an embodiment of the present invention in a front view of a tire mounted on a vehicle. Since the internal structure of the tire is the same as that of a general radial tire, the illustration is omitted here. The tread 1 is provided with at least two circumferential grooves 2 that extend continuously in the circumferential direction, and in the figure, three circumferential grooves 2, and is mounted on the vehicle inside the land portion row defined by the circumferential grooves 2. Of the land portion row 3 on the width direction end side and the land portion row 4 on the outer side in the width direction that is mounted on the vehicle, the land portion row 4 is provided with a lateral groove 5, The lateral rigidity is made larger than the circumferential rigidity of the land portion row 4, and the

lateral grooves

8, 9 are also provided in each of the other two rows of land portions 6, 7 partitioned between the three circumferential grooves. It is done.
Further, a plurality of holes 10 independent of the circumferential groove 2 are provided in the land portion row 3, and the concave portion volume of the land portion row portion outside in the width direction from the center line Ci of the land portion row 3 is set in the width direction inside of the center line. It is made larger than the concave volume of the land portion row portion.
[0026]
According to this, by making the circumferential rigidity of the land portion row 3 larger than the circumferential rigidity of the land portion row 4, the land portion row 3 is compressed and deformed in the ground contact surface, and the contact length becomes longer. The lateral groove shrinks, the turning radius becomes smaller, and the shoulder portion on the land portion row 4 side having the larger turning radius receives a force in the direction opposite to the vehicle traveling direction, that is, a force in the braking direction. Occurrence can be prevented.
Further, by reducing the number of lateral grooves in the land portion row 3, it is possible to reduce the geometric discontinuity in the circumferential direction, and to suppress heel and toe wear that is uneven wear in the circumferential direction. .
[0027]
Further, by providing the

lateral grooves

8 and 9 in the two rows of land portions 6 and 7 that are divided inward in the width direction from the

land portions rows

3 and 4 by the three circumferential grooves 2, the groove edges thereof are provided. Can effectively contribute to an increase in braking force and driving force, and at the same time, drainage performance in the central region of the tread can be improved.
[0028]
These holes 10 reduce the shear rigidity of the region in which they are provided, reduce the burden of this region on lateral forces, suppress the generation of reaction force, and this region is dragged in the braking direction. Even in this case, it is possible to suppress the occurrence of uneven wear by suppressing the generation of reaction force against the braking force.
[0029]
Further, by setting the maximum depth of the hole 10 to 1/3 or more of the depth of the circumferential groove 2, even if tire wear progresses, the effect of suppressing the occurrence of uneven wear by providing the plurality of holes 10 is provided. Can be secured.
Furthermore, uneven wear is likely to occur by making the concave volume larger in the land portion row portion on the outer side in the width direction than the center line Ci of the inner land portion row on the inner side than in the land portion row portion on the inner side in the width direction from the center line Ci. The effect of suppressing uneven wear can be enhanced on the outer side in the width direction.
[0030]
Further, preferably, the land portion row 3 on the inner side in the width direction that is mounted on the vehicle is divided into a land portion row portion 12 on the outer side in the width direction and a land portion row portion 13 on the inner side in the width direction by the narrow circumferential groove 11. The width w of the land portion row portion 12 on the outer side in the width direction is made narrower than the width w0 of the land portion row portion 13 on the inner side in the width direction, and is 1/10 or less of the tread width W.
[0031]
According to this, it is possible to separate the land portion row portion 12 on the outer side in the width direction near the grounding end where uneven wear is most likely to occur, and to suppress the progress of wear to the land portion row portion 13 on the inner side. . Further, by setting the width w of the land portion row portion 12 on the outer side in the width direction to be narrower than the width w0 of the land portion row portion 13 on the inner side in the width direction and 1/10 or less of the tread width W, the uneven wear volume is reduced. Reduced appearance can be kept good.
[0032]
More preferably, as shown in FIG. 2, at least one curvature center C1 of the outer contour shape in the outer surface of the land portion row portion 12 on the outer side in the width direction and in the cross section in the tire width direction is outside the contour line S1. On the other hand, the curvature center C2 of the outer contour shape of the land portion row portion 13 on the inner side in the width direction is positioned inside the contour line S2.
[0033]
According to this, the uneven wear volume of the land portion row portion 12 on the outer side in the width direction near the ground contact end where uneven wear is most likely to occur can be further reduced, and the appearance can be kept good.
[0034]
Here, the width w10 of the narrow circumferential groove 11 is preferably gradually increased from the groove bottom toward the tread surface as shown in FIG.
[0035]
According to this, even when the narrow circumferential groove 11 entraps foreign matters such as pebbles on the road surface, the uneven wear nuclei are formed in the width direction by making the foreign matters easy to remove and traveling while holding the foreign matters. It can be prevented from occurring in the inner land portion row portion 13.
[0036]
Furthermore, at least a part of a region where the plurality of holes 10 are arranged in the land portion row portion 13 on the inner side in the width direction of the land portion row 3 on the inner side under the action of a load of 70% or more of the maximum load capacity of the tire. It is preferable to configure the tread so that is grounded.
[0037]
According to this, even when the load is lower than the front wheels and the ground contact width is reduced, such as the rear wheel of an FF vehicle, the occurrence of uneven wear is caused by grounding the formation region of the plurality of holes 10 described above. The effect of restraining progress can be secured.
[0038]
More preferably, in the land portion row portion 13 on the inner side in the width direction of the land portion row 3 on the inner side, the opening dimension R of the hole 10 is increased as the distance from the tire equator line increases.
[0039]
According to this, it is possible to increase the effect of suppressing the occurrence of uneven wear and the suppression of the progress due to the provision of the plurality of holes 10 as approaching the ground contact end where the load of lateral force and braking force is large. In addition, by arranging the holes 10 in an area effective for suppressing uneven wear and avoiding as much as possible in other parts, the steering stability and tread durability are kept good in other parts. It becomes possible.
[0040]
Preferably, in the land portion row portion 13 on the inner side in the width direction of the land portion row 3 on the inner side, the interval Q between the plurality of holes 10 is reduced as the distance from the tire equator line increases.
[0041]
Even in this way, the effect of suppressing uneven wear can be increased in the vicinity of the ground contact edge, and multiple holes are arranged only in the area effective for suppressing uneven wear, resulting in good steering stability and tread durability. Can be kept in.
[0042]
Preferably, the depth of the hole 10 is increased as the distance from the tire equator line increases.
[0043]
Even in this case, the effect of suppressing uneven wear can be increased in the vicinity of the ground contact end, and a plurality of holes 10 are arranged only in an area effective for suppressing uneven wear, thereby improving steering stability and tread durability. Can keep good.
[0044]
【Example】
For the purpose of evaluating the uneven wear suppression performance of a pneumatic tire according to an embodiment of the present invention, two types of example tires of size 205/65 R15 and five types of comparative example tires are called. Equipped with a 6J x 15 rim, with a tire filling air pressure of 220 kPa, mounted on a test vehicle, traveled for 30,000 km, measured the wear on the inner tread, and evaluated uneven wear suppression performance Went. The results are shown in Table 1.
As shown in FIG. 1, the tread pattern of Example 1 is provided with at least two circumferential grooves 2 extending in the circumferential direction in the tread 1, and three circumferential grooves 2 in the figure, and is partitioned by the circumferential grooves 2. Of the land portion row, the land portion row 3 on the width direction end side that is attached to the inside of the vehicle and the land portion row 4 on the width direction end side that is attached to the vehicle and that is on the outside, The row 4 is provided with a lateral groove 5 so that the circumferential rigidity of the land portion row 3 is larger than the circumferential rigidity of the land portion row 4, and the other two rows of land portion rows defined between the three circumferential grooves. 6 and 7 are also provided with

lateral grooves

8 and 9, respectively, and a plurality of holes 10 independent of the circumferential groove 2 are provided in the land portion row 3, and the land on the outer side in the width direction from the center line Ci of the land portion row 3. The width of the concave portion of the partial row portion is larger than the concave portion volume of the land portion row portion on the inner side in the width direction of the center line, and the inner portion is attached to the vehicle. The land row 3 of the end side, is divided into a land row portion 1 2 and a land row portion 1 3 in the width direction inner side in the width direction outside by the narrow circumferential grooves 1 1, land portion in the width direction outside the width of the column portions 1 2, narrower than the width of the land row portion 1 3 in the width direction inner side, made as one-tenth or less of the tread width.
[0045]
The depth of the narrow circumferential grooves 1 1 5.0 mm, the width at the groove bottom 1.5 mm, the width of the tread surface is set to 3.0 mm. The width of the land row portion 1 2 is 2 mm, the width of the land row part 1 3 is set to 18 mm.
The land row formed of the inner is attached to a vehicle, in the width direction inside of the land row portion 13, provided with a plurality of holes 1 0 independent circumferential grooves 2 and the narrow circumferential grooves 1 1. A plurality of holes 1 0 consists hole array of two rows, the width direction outer side of the hole, 2.5mm diameter, depth and 6 mm, center distance and 7.5 mm, the width direction inside of the pores, the diameter The distance is 1.5 mm, the depth is 6 mm, and the center-to-center distance is 7.5 mm.
[0046]
As shown in FIG. 3, the tread pattern of the second embodiment is based on the first embodiment, and is not provided with a narrow circumferential groove. At that position, the diameter is 2.5 mm, the depth is 6 mm, and the center distance is 7 A hole array of 5 mm is provided.
As shown in FIG. 4, the tread pattern of Comparative Example 1 is provided with a lateral groove on the land portion row on the outer side in the width direction on the inner side of the mounting, without a horizontal groove on the land portion row on the outer side in the width direction of the mounting. It is.
As shown in FIG. 5, the tread pattern of Comparative Example 2 is obtained by reversing the tread pattern shown in Example 1 between the outer side and the inner side.
As shown in FIG. 6, the tread pattern of Comparative Example 3 is based on Example 1, and the width of the land portion row portion 12 on the outer side in the width direction is 14 mm, and the width of the land portion row portion 13 on the inner side in the width direction is 6 mm. The land portion row portion 13 is provided with a hole row having a diameter of 2.5 mm, a depth of 6 mm, and a center-to-center distance of 7.5 mm.
As shown in FIG. 7, the tread pattern of Comparative Example 4 is based on Example 1, is not provided with a narrow circumferential groove, has a diameter of 3.0 mm, a depth of 6 mm, and a center distance of 7.5 mm. A row of holes having a diameter of 2.0 mm, a depth of 6 mm, and a center distance of 7.5 mm; and a row of holes having a diameter of 1.0 mm, a depth of 6 mm, and a center distance of 7.5 mm; They are provided in this order from the inner side in the width direction.
As shown in FIG. 8, the tread pattern of Comparative Example 5 is based on Example 1 and does not have a plurality of holes.
The performance evaluation was performed on a 100-point scale with the comparative example tire 1 as a control tire. It shows that it is so favorable that a numerical value is small.
[0047]
[Table 1]

[0048]
In Table 1, when the comparative example tire 1 and the example tire 1 are compared, the example tire 1 is significantly attached to the vehicle and prevents uneven wear of the land portion row as compared with the comparative example tire 1. You can see that it is made.
Comparing the comparative example tire 1 and the comparative example tire 2, the lateral groove component of the land portion row which is mounted on the vehicle and becomes the outside is reduced, and a narrow circumferential groove is provided so that the land portion row portion between the inner side and the outer side in the width direction It can be seen that if the holes are provided separately, the lateral force at the time of turning cannot be fully borne and the uneven wear suppression performance is rather deteriorated. In this case, the outer land portion row outside the narrow circumferential groove does not function with respect to lateral force, and uneven wear occurs in the inner land portion row, resulting in poor appearance.
[0049]
When Example tire 1 and Comparative example tire 5 are compared, it can be seen that uneven wear can be further suppressed by providing a hole in the land portion row portion on the inner side in the width direction.
Comparing the example tire 1 and the example tire 2, it is possible to further suppress uneven wear by separating the land portion row that is attached to the vehicle by the narrow circumferential groove and becomes the inner side in the width direction. I understand that I can do it.
When Example tire 1 and Comparative example tire 3 are compared, it can be seen that if the width of the land portion row portion on the outer side in the width direction is too large, the effect of suppressing uneven wear is small.
Comparing Example tire 2 and Comparative example tire 4, it can be seen that increasing the diameter of the holes on the outer side in the width direction is more effective in suppressing uneven wear.
[0050]
【The invention's effect】
As is apparent from the above description, according to the present invention, the tread is provided with at least two circumferential grooves extending continuously in the circumferential direction thereof, and among the land portion rows partitioned by the circumferential grooves. , independent land portion row in the width direction end side as the inner side is attached to the vehicles from the circumferential groove, the maximum depth is provided with a plurality of holes is 1/3 or more of the depth of the circumferential grooves, the land portions the recess volume of land row portion of the widthwise end side with respect to a line passing through the widthwise center of the column, and greater than the recess volume of the land row portion in the width direction inner side of a line passing through the widthwise center, attached to the vehicle the are in circumferential rigidity of the land portion rows in the width direction end side serving as the inner is, the land row of mounted on the vehicle width direction end side as the outer by large to Rukoto than the circumferential stiffness, inner side of the The turning radius of the land portion row on the width direction end side becomes smaller than the turning radius of the land portion row on the outer side in the width direction of the installation outside. Uneven wear due to the force in the direction opposite to the vehicle traveling direction, that is, the force in the braking direction, with respect to the land portion row on the width direction end side on the outer side of the attachment with a large turning radius. Can be prevented.
[Brief description of the drawings]
FIG. 1 is a development view of a tread pattern showing an embodiment of the present invention in a front view of a tire mounted on a vehicle.
FIG. 2 is a cross-sectional view in the width direction showing a part of the tread pattern of the present invention.
FIG. 3 is a development view of a tread pattern showing another embodiment of the present invention in a front view of a tire mounted on a vehicle.
FIG. 4 is a development view of a tread pattern showing the form of a comparative tire in a front view of a tire mounted on a vehicle.
FIG. 5 is a development view of a tread pattern showing another form of a comparative example tire in front view of a tire mounted on a vehicle.
FIG. 6 is a development view of a tread pattern showing another form of the comparative example tire in front view of the tire mounted on the vehicle.
FIG. 7 is a development view of a tread pattern showing another form of a comparative example tire in front view of a tire mounted on a vehicle.
FIG. 8 is a development view of a tread pattern showing another form of a comparative example tire in front view of a tire mounted on a vehicle.
[Explanation of symbols]
1 Tread part 2 Circumferential groove 3 Land part row (mounting inside)
4 Land section (outside)
5 Horizontal groove 6 Land portion row 7 Land portion row 8 Horizontal groove 9 Horizontal groove 10 Hole 11 Narrow circumferential groove 12 Land portion row portion (width direction outside)
13 Land part row part (width direction inside)

Claims

A tread, at least two circumferential grooves extending continuously in the circumferential direction is provided, of the land portion rows are partitioned by their circumferential grooves, the widthwise end side to be the inside are mounted on vehicles land portion The row is provided with a plurality of holes whose maximum depth is 1/3 or more of the depth of the circumferential groove independent from the circumferential groove, and the land on the width direction end side with respect to the line passing through the center in the width direction of the land portion row. The concave portion volume of the partial row portion is larger than the concave portion volume of the land portion row portion on the inner side in the width direction of the line passing through the center in the width direction, and the circumferential rigidity of the land portion row on the inner side in the width direction attached to the vehicle is inside. Is a pneumatic tire that is made larger than the circumferential rigidity of the land portion row on the width direction end side that is attached to the vehicle and is on the outside .

The land portion row on the inner side in the width direction mounted on the vehicle is divided into a land portion row portion on the outer side in the width direction and a land portion row portion on the inner side in the width direction by a narrow circumferential groove, and the outer side in the width direction. 2. The pneumatic tire according to claim 1, wherein the width of the land portion row portion is narrower than the width of the land portion row portion on the inner side in the width direction and is 1/10 or less of the tread width.

At least one of the curvature centers of the outer contour shape in the cross section in the tire width direction on the outer surface of the land portion row portion on the outer side in the width direction is positioned outside the contour line, while the land portion on the inner side in the width direction The pneumatic tire according to claim 2, wherein the center of curvature of the outer contour shape of the row portion is positioned inside the contour line.

The pneumatic tire according to any one of claims 2 to 3, wherein the width of the narrow circumferential groove is gradually increased from the groove bottom toward the tread surface side.

Under the action of a load of 70% or more of the maximum load capacity of the tire, at least a part of a region where a plurality of holes are arranged in the land portion row on the inner side in the width direction that is mounted on the vehicle and is in contact with the vehicle. The pneumatic tire according to claim 1, comprising a tread.

The pneumatic tire according to any one of claims 1 to 5, wherein an opening size of the hole is increased as the distance from the tire equator line increases in a land portion row on the inner side in the width direction that is attached to the vehicle.

The pneumatic tire according to any one of claims 1 to 6, wherein a distance between the plurality of holes is reduced as the distance from the tire equator line increases in the land portion row on the inner side in the width direction that is attached to the vehicle.

The pneumatic tire according to any one of claims 1 to 7, wherein the depth of the hole is increased as the distance from the tire equator line increases in the land portion row on the inner side in the width direction that is mounted on the vehicle.