JP3884866B2

JP3884866B2 - Pneumatic tires for passenger cars

Info

Publication number: JP3884866B2
Application number: JP23757798A
Authority: JP
Inventors: 康次郎大聖; 修一塚田; 和致実藤
Original assignee: Yokohama Rubber Co Ltd
Current assignee: Yokohama Rubber Co Ltd
Priority date: 1998-08-24
Filing date: 1998-08-24
Publication date: 2007-02-21
Anticipated expiration: 2018-08-24
Also published as: JP2000062416A

Description

【０００１】
【発明の属する技術分野】
本発明は、乗用車用空気入りタイヤに関し、更に詳しくは、荷重耐久性を従来と同等レベル以上確保しながら操縦安定性の改善を図るようにした乗用車用空気入りタイヤに関する。
【０００２】
【従来の技術】
従来、２層のカーカス層を配置した乗用車用空気入りタイヤにおいて、ビードコアの周りに折り返されたカーカス層両端部に隣接して補強層を配設することにより、高荷重負荷走行時や高速走行時の耐久性、操縦安定性を向上するようにしている。
【０００３】
上記のような補強層として、例えば、スチールコードを配列した補強層を用いる提案がある。しかし、このようにスチールコードを使用した補強層では、操縦安定性を更に改善するため、その外周端をタイヤ断面高さの４５％を越えてタイヤ外径側に延在させると、高荷重負荷走行時にその外周端が剥離故障を起こし易くなり、荷重耐久性が悪化するという問題があった。
【０００４】
【発明が解決しようとする課題】
本発明の目的は、荷重耐久性を従来レベル以上に維持しながら操縦安定性を一層高めることが可能な乗用車用空気入りタイヤを提供することにある。
【０００５】
【課題を解決するための手段】
上記目的を達成する本発明の乗用車用空気入りタイヤは、ビードコアを埋設した左右のビード部間に２層のカーカス層を配置した乗用車用空気入りタイヤにおいて、内周側のカーカス層両端部を前記ビードコアの周りにタイヤ内側から外側に巻き上げる一方、外周側のカーカス層両端部を前記内周側のカーカス層両端部の外側にして前記ビードコアの周りにタイヤ外側から内側に巻き下げ、前記内周側及び外周側のカーカス層両端部の間に芳香族ポリアミド繊維からなる補強コードをタイヤ周方向に対し傾斜して配列した２層の補強層を、その補強コードが交差するように設けると共に、それら補強層の外周端及び内周端をそれぞれずらして配置し、かつその外周端をタイヤ断面高さＨの４５〜６５％となる位置まで延在させ、内側の補強層の外周端を外側の補強層のそれよりもタイヤ外径側に位置させる一方、外側の補強層の内周端を内側の補強層のそれよりもタイヤ内径側に位置させたことを特徴とする。
【０００６】
また、本発明の他の乗用車用空気入りタイヤは、ビードコアを埋設した左右のビード部間に２層のカーカス層を配置した乗用車用空気入りタイヤにおいて、内周側のカーカス層両端部を前記ビードコアの周りにタイヤ内側から外側に巻き上げる一方、外周側のカーカス層両端部を前記内周側のカーカス層両端部の外側にして前記ビードコアの周りにタイヤ外側から内側に巻き下げ、前記内周側及び外周側のカーカス層両端部の間にスチールコードからなる補強コードをタイヤ周方向に対し傾斜して配列した１層の補強層とその外側の芳香族ポリアミド繊維からなる補強コードをタイヤ周方向に対し傾斜して配列した１層の補強層とを、その補強コードが交差するように設け、それら補強層の外周端及び内周端をそれぞれずらして配置すると共に、芳香族ポリアミド繊維からなる補強コードを有する補強層の外周端をスチールコードからなる補強コードを有する補強層のそれよりもタイヤ外径側となるように配置し、その両補強層の外周端をタイヤ断面高さＨの４５〜６５％となる位置まで延在させたことを特徴とする。
【０００７】
上記のように本発明は、芳香族ポリアミド繊維からなる補強コードを配列した補強層をカーカス層の両端部側間に配置することにより、該補強層をタイヤ断面高さＨの４５％を越えてタイヤ外径側に延在させても、スチールコードを配列したような硬い補強層ではないため、高荷重負荷走行時にその外周端が容易にゴムと剥離する剥離故障を招くことがない。そのため、荷重耐久性を悪化させないばかりか、その改善を行うことができる。
【０００８】
また、芳香族ポリアミド繊維からなる補強コードをタイヤ周方向に対し傾斜して配列した２層の補強層を、その補強コードが交差するように設け、その外周端をタイヤ断面高さＨの４５〜６５％となる位置まで延在させることにより、サイドウォール部の曲げ剛性を高い範囲にわたって高めることができ、それによって、操縦安定性を一層改善することが可能になる。
【０００９】
その上、それら補強層の外周端と内周端を共にずらすようにしているため、２層の補強層の端末一致による大きな段差に応力集中が起こるのを回避することができるので、補強層の端末剥離を容易に招くことがない。
また、２層配置したカーカス層の内、内側のカーカス層両端部をビードコアの周りにタイヤ内側から外側に巻き上げる一方で、外側のカーカス層両端部をタイヤ外側から内側に巻き下げる構造にすることで、内側のカーカス層両端部を外側のカーカス層でカバーし、２層共にタイヤ内側から外側に巻き上げた構造のように、カーカス層のエッジがカバーさせれずにタイヤ外側に位置することがないので、高速走行時のスタンティングウェーブ現象によりカーカス層両端部とサイドウォール部のゴムとの間で生じる大きな剪断力によって、カーカス層端部がサイドウォール部のゴムから剥離しようとするのを効果的に抑えることができる。
【００１０】
一方、芳香族ポリアミド繊維からなる補強コードを配列した上記２層の補強層に代えて、タイヤ外側から内側に巻き下げた外側のカーカス層両端部とタイヤ内側から外側に巻き上げた内側のカーカス層両端部との間に、タイヤ内側にスチールコードからなる補強コードを配列した１層の補強層を配置し、その外側に芳香族ポリアミド繊維からなる補強コードを配列した１層の補強層を配置すると共に、芳香族ポリアミド繊維からなる補強コードを有する補強層の外周端をスチールコードからなる補強コードを有する補強層のそれよりもタイヤ外径側となるようにずらして配置し、内側のスチールコード補強層の外周端を外側のカーカス層と外側の補強層の２層で保護するようにしたので、スチールコード補強層を用いた場合であっても、それらの補強層をタイヤ断面高さＨの４５％を越えてタイヤ外径側に延在させ、高荷重負荷走行してもその外周端が容易にゴムと剥離することがなく、従来と同等レベルの荷重耐久性を得ることができる。
【００１１】
また、両補強層をその補強コードが交差するように設け、その両補強層の外周端をタイヤ断面高さＨの４５〜６５％となる位置まで延在させたので、サイドウォール部の曲げ剛性を広い範囲にわたって大きくすることができ、操縦安定性を一層向上することができる。
【００１２】
【発明の実施の形態】
以下、本発明の構成について添付の図面を参照しながら詳細に説明する。
図１は本発明の乗用車用空気入りタイヤの一例を示し、１はトレッド部、２はビード部、３はサイドウォール部である。左右のビード部２に連接してタイヤ外径側に左右のサイドウォール部３が延設され、この左右のサイドウォール部３間にタイヤ周方向に延在するトレッド部１が設けられている。
【００１３】
タイヤの内側には、左右のビード部２間にわたってナイロンコードやレーヨンコード等のテキスタイルコードをタイヤ径方向に配列した２層のカーカス層４Ａ，４Ｂが配置されている。左右のビード部２にはビードコア５がそれぞれ埋設され、そのビードコア５の外周にはビードフィラー６が配設されている。
カーカス層外周側のトレッド部１には複数のベルト層７が埋設され、そのベルト層７上には、ベルト層７を全面にわたって保護するベルトカバー層８が設けられている。ＣＬはタイヤセンターラインである。
【００１４】
本発明では、上記のような構成の空気入りタイヤにおいて、内周側のカーカス層４Ａの両端部４ａが、ビードコア５の周りにビードフィラー６を挟み込むようにしてタイヤ内側から外側に折り返されて巻き上げられ、サイドウォール部３に沿ってその中央部までタイヤ外径側に延在している。
外周側のカーカス層４Ｂの両端部４ｂは、内周側のカーカス層両端部４ａの外側でビードコア５の周りにタイヤ外側から内側に巻き下げられ、そのエッジ４b'がビードコア５の内端側でかつタイヤ内側まで延在している。
【００１５】
ビードフィラー６のタイヤ外側で上記内周側及び外周側のカーカス層両端部４ａ，４ｂの間には、芳香族ポリアミド繊維からなる補強コードを配列した２層の補強層９Ａ，９Ｂが介設されている。この環状に形成される補強層９Ａ，９Ｂは、タイヤ周方向に対し傾斜して配列された補強コードが交差するように設けられている。
【００１６】
補強層９Ａ，９Ｂの外周端９a₁，９b₁は、ビードフィラー６の外周端６ａを越えてタイヤ外径側に延在する一方、内周側のカーカス層両端部４ａのエッジ４a'よりもタイヤ内径側で、ビードヒールａからトレッド部表面頂部までのタイヤ径方向長さであるタイヤ断面高さＨの４５〜６５％となる位置まで延在するようになっている（補強層の高さｈ＝０．４５〜０．６５Ｈ）。
【００１７】
また、補強層９Ａ，９Ｂの外周端９a₁，９b₁及び内周端９a₂，９b₂は、共にずらして配置され、図１，２では、内側の補強層９Ａの外周端９a₁が外側の補強層９Ｂの外周端９b₁よりもタイヤ外径側に位置する一方、外側の補強層９Ｂの内周端９b₂は内側の補強層９Ａの内周端９a₂よりもタイヤ内径側に位置している。
【００１８】
このように本発明は、スチールコードを配列した硬い補強層ではなく、芳香族ポリアミド繊維からなる補強コードを配列した補強層をカーカス層４Ａ，４Ｂの両端部４ａ，４ｂ間に用いることにより、該補強層をタイヤ断面高さＨの４５％を越えてタイヤ外径側に延在させても、高荷重負荷走行時にその外周端が容易に剥離故障を起こすことがなく、荷重耐久性を低下させないばかりか、その改善も図ることができる。
【００１９】
また、芳香族ポリアミド繊維からなる補強コードをタイヤ周方向に対し傾斜して配列した２層の補強層９Ａ，９Ｂを、その補強コードが交差するように設けると共に、その外周端９a₁，９b₁をタイヤ断面高さＨの４５〜６５％となる位置まで延在させたので、サイドウォール部３の曲げ剛性を従来よりも広い範囲にわたって高めることができ、それによって操縦安定性を更に高くすることができる。
【００２０】
しかも、それら補強層９Ａ，９Ｂの外周端９a₁，９b₁及び内周端９a₂，９b₂をずらして配置しているので、２層の補強層９Ａ，９Ｂの端末が一致したような大きな段差によって起こる応力の集中を回避し、補強層９Ａ，９Ｂの端末剥離を抑制することができる。
【００２１】
また、２層配置したカーカス層４Ａ，４Ｂの内、内側のカーカス層４Ａの両端部４ａをビードコア５の周りにタイヤ内側から外側に巻き上げ、外側のカーカス層４Ｂの両端部４ｂをタイヤ外側から内側に巻き下げる、所謂１ー１ＰＬ（プライロック）構造にすることにより、内側のカーカス層４Ａの両端部４ａをカーカス層４Ｂで保護し、２層共にタイヤ内側から外側に巻き上げた所謂２ー０ＰＬ（プライロック）構造のように、カーカス層のエッジが保護されることなくタイヤ外側に位置することがないので、高速走行時のスタンティングウェーブ現象によりカーカス層端部とサイドウォール部３のゴムとの間で剪断力が作用しても、該カーカス層端部がサイドウォール部３のゴムから剥離する剥離故障が容易に発生することがない。
【００２２】
上記補強層９Ａ，９Ｂの外周端９a₁，９b₁がタイヤ断面高さＨの４５％よりも低いと、操縦安定性を改善することが困難になり、逆に６５％を越えると、外周端９a₁，９b₁における歪み変形が大きくなり、剥離故障を招き易くなる。
本発明では、上記補強層９Ａ，９Ｂの補強コードの傾斜角度θとしては、タイヤ周方向に対し４０°＜θ＜６５°にすることができる。傾斜角度θが４０°以下であっても６５°以上になっても、補強効果が小さく、操縦安定性を改善することが難しくなる。
【００２３】
外側の補強層９Ｂの内周端９b₂の位置としては、側面視においてビードコア５の外周端５ａ近傍に位置させるのがよく、また、内側の補強層９Ａの外周端９a₁の位置は、ビードフィラー６の外周端６ａからタイヤ外径側に８〜１５mmの範囲に位置させることができる。
【００２４】
図３は、本発明の他の例を示し、上述した芳香族ポリアミド繊維からなる補強コードを有する補強層９Ａ，９Ｂに代えて、スチールコードからなる補強コードをタイヤ周方向に対し傾斜して配列した１層の補強層１０Ａと、芳香族ポリアミド繊維からなる補強コードをタイヤ周方向に対し傾斜して配列した１層の補強層１０Ｂとをその補強コードが交差するように配置したものである。
【００２５】
スチールコードからなる補強コードを配列した補強層１０Ａがタイヤ内側となり、その外側に芳香族ポリアミド繊維からなる補強コードを配列した補強層１０Ｂを配置した構成になっている。
その外側の補強層１０Ｂの外周端１０b₁は、内側のスチールコードを配した補強層１０Ａの外周端１０a₁を越えてタイヤ外径側に延在し、補強層１０Ａ，１０Ｂの外周端１０a₁，１０b₁の位置をずれるようにしている。補強層１０Ａ，１０Ｂの内周端１０a₂，１０b₂は、内側の補強層１０Ａの内周端１０a₂の方がタイヤ内径側に位置し、端末をずれるようにしている。
【００２６】
このように補強層をスチールコードからなる補強コードを配列した補強層１０Ａと芳香族ポリアミド繊維からなる補強コードを配列した補強層１０Ｂとから構成しても、それらをタイヤ外側から内側に巻き下げた外側のカーカス層４Ｂの両端部４ｂとタイヤ内側から外側に巻き上げた内側のカーカス層４Ａの両端部との間で、しかも、芳香族ポリアミド繊維からなる補強コードを有する補強層１０Ｂの外周端１０b₁をスチールコード補強層１０Ａの外周端１０a₁よりもタイヤ外径側にずらして配置することにより、スチールコード補強層１０Ａの外周端１０a₁を外側のカーカス層４Ｂと外側の補強層１０Ｂの２層で二重に保護するようにしたので、スチールコードの補強コードを配列した補強層１０Ａを共に用い、それらの補強層１０Ａ，１０Ｂをタイヤ断面高さＨの４５％を越えてタイヤ外径側に延在させ、高荷重負荷走行しても、その外周端が容易にゴムと剥離することがなく、従来と同等レベルの荷重耐久性を確保することができる。
【００２７】
また、両補強層１０Ａ，１０Ｂをその補強コードが交差するように設け、その両補強層１０Ａ，１０Ｂの外周端１０a₁，１０b₁をタイヤ断面高さＨの４５〜６５％となる位置まで延在させたので、サイドウォール部の曲げ剛性を従来よりも広い範囲にわたって大きくすることができ、操縦安定性を一層改善することができる。
【００２８】
上記補強層１０Ａの補強コードの傾斜角度αとしては、タイヤ周方向に対し１０°＜α＜３０°にすることができる。傾斜角度αが１０°以下であると、曲げ剛性が小さすぎるため、補強効果が低減し、操縦安定性の改善効果を得ることができない。逆に３０°以上になると、曲げ剛性が高くなりすぎるため、カーカス層との剛性差を大きくなり、高荷重負荷走行時にカーカスコードの切断故障が発生する。補強層１０Ｂの補強コードの傾斜角度θとしては、上述と同様にすることができる。
【００２９】
補強層１０Ｂの内周端１０b₂よりもタイヤ内径側となるスチールコード配列の補強層１０Ａの内周端１０a₂の位置としては、側面視においてビードコア５の外周端５ａ近傍に位置させるのがよく、また、芳香族ポリアミド繊維からなる補強コードを有する補強層１０Ｂの外周端１０b₁は、ビードフィラー６の外周端６ａからタイヤ外径側に８〜１５mmの範囲に位置させることができる。
【００３０】
【実施例】
実施例１
タイヤサイズを２２５／４５ＺＲ１７（前輪用）、２４５／４０ＺＲ１７（後輪用）で共通にし、図１に示す構成の乗用車用空気入りタイヤにおいて、図２のように芳香族ポリアミド繊維からなる補強コードを有する補強層を２層配置し、その外周端の位置（高さｈ）をタイヤ断面高さＨに対して表１のように変えた本発明タイヤ１〜３とその比較タイヤ１，２、図３のようにスチールコードの補強コードを有する補強層と芳香族ポリアミド繊維からなる補強コードを有する補強層とを配置し、その外周端の位置（高さｈ）をタイヤ断面高さＨに対して表１のように変えた本発明タイヤ４〜６とその比較タイヤ３，４、及びスチールコードを配列した補強層を１層配置した従来タイヤとをそれぞれ作製した。なお、芳香族ポリアミド繊維として、ケブラーを使用した。
【００３１】
これら各試験タイヤを以下に示す測定条件により、操縦安定性及び荷重耐久性の評価試験を行ったところ、表１に示す結果を得た。
操縦安定性
各試験タイヤをリムサイズ１７×７1/2-JJ（前輪）と１７×８1/2-JJ（後輪）のリムに装着し、２８０HPを越える車両に取付け、ドライ時のテストコースにおいて、パネラーによるフィーリングテストを実施し、その結果を従来タイヤを１００とする指数値で評価した。この値が大きい程、操縦安定性が優れている。
荷重耐久性
【００３２】
２２５／４５ＺＲ１７を代表とし、試験タイヤをドラム径１７０７mmのドラム試験機に取り付け、ＪＩＳ−Ｄ４２３０，ＪＡＴＭＡイヤーブック（１９９８年度版）を準用し、内圧２００ｋＰａ，荷重６２０ｋｇを常用荷重とし、荷重耐久性試験終了後、荷重を２０％／5hr 毎ステップアップし、タイヤが破壊するまで試験を続行した。その結果を従来タイヤを１００とする指数値で評価した。この値が大きい程、荷重耐久性に優れている。
【００３３】
【表１】

【００３４】
表１から明らかなように、本発明タイヤは、荷重耐久性を従来タイヤと同レベル以上に確保しながら、操縦安定性を改善することができるのが判る。上記指数値は１０５以上であることが好ましい。
実施例２
タイヤサイズを上記と同様にし、図２の補強層の芳香族ポリアミド繊維（ケブラー）からなる補強コードの傾斜角度θを表２のように変えた試験タイヤ１〜３と、図３の補強層のスチールコードの傾斜角度αを表２のように変えた試験タイヤ４〜６、及び図３の補強層の芳香族ポリアミド繊維の傾斜角度θを表２のように変えた試験タイヤ７〜９とをそれぞれ作製した。
【００３５】
試験タイヤ１〜３の補強層高さｈは０．５２Ｈ、試験タイヤ４〜６の補強層高さｈは０．４５Ｈ、試験タイヤ７〜９の補強層高さｈは０．４８Ｈである。また、試験タイヤ１〜３は傾斜角度θが逆向きで共に同じ角度、試験タイヤ４〜６の傾斜角度θは５０°で一定、試験タイヤ７〜９の傾斜角度αは２０°で一定である。
【００３６】
これら各試験タイヤを上述と同様にして操縦安定性と荷重耐久性の評価試験を行ったところ、表２に示す結果を得た。
【００３７】
【表２】

【００３８】
表２から、芳香族ポリアミド繊維からなる補強コードを配列した２層の補強層を用いた本発明タイヤにおいて、該補強層の補強コードの傾斜角度θをタイヤ周方向に対し４０°＜θ＜６５°にするのがよいことが判る。
【００３９】
また、スチールコードからなる補強コードを配列した補強層と芳香族ポリアミド繊維からなる補強コードを配列した補強層を用いた本発明タイヤにおいて、スチールコード補強層の補強コードの傾斜角度αをタイヤ周方向に対し１０°＜α＜３０°、芳香族ポリアミド繊維補強層の補強コードの傾斜角度θをタイヤ周方向に対し４０°＜θ＜６５°にするのがよいことが判る。
実施例３
【００４０】
タイヤサイズを上記と同様にし、図１に示す構成の乗用車用空気入りタイヤにおいて、図２のように芳香族ポリアミド繊維からなる補強コードを有する補強層を２層配置した本発明タイヤ７と、カーカス層両端部を共にタイヤ内側から外側に巻き上げ、その両端部間に本発明タイヤ７と同じ補強層を配置した比較タイヤ５とをそれぞれ作製した。
【００４１】
これら各試験タイヤを上記と同様にして荷重耐久性の評価試験を行ったところ、表３に示す結果を得た。なお、表３では、比較タイヤ５を１００とする指数値で評価した。この値が大きい程、荷重耐久性が優れている。
【００４２】
【表３】

【００４３】
表３から、内周側のカーカス層両端部をビードコアの周りにタイヤ内側から外側に巻き上げる一方、外周側のカーカス層両端部を内周側のカーカス層両端部の外側でビードコアの周りにタイヤ外側から内側に巻き下げた本発明タイヤは、カーカス層両端部を共にタイヤ内側から外側に巻き上げたものよりも荷重耐久性が大幅に優れていることが判る。
【００４４】
【発明の効果】
上述したように本発明は、ビードコアを埋設した左右のビード部間に２層のカーカス層を配置した乗用車用空気入りタイヤにおいて、内周側のカーカス層両端部を前記ビードコアの周りにタイヤ内側から外側に巻き上げる一方、外周側のカーカス層両端部を前記内周側のカーカス層両端部の外側にして前記ビードコアの周りにタイヤ外側から内側に巻き下げ、前記内周側及び外周側のカーカス層両端部の間に芳香族ポリアミド繊維からなる補強コードをタイヤ周方向に対し傾斜して配列した２層の補強層を、その補強コードが交差するように設けると共に、それら補強層の外周端及び内周端をずらして配置し、かつその外周端をタイヤ断面高さＨの４５〜６５％となる位置まで延在させる、或いは、上記２層の補強層に代えて、スチールコードからなる補強コードをタイヤ周方向に対し傾斜して配列した１層の補強層とその外側の芳香族ポリアミド繊維からなる補強コードをタイヤ周方向に対し傾斜して配列した１層の補強層とを、その補強コードが交差するように設けると共に、芳香族ポリアミド繊維からなる補強コードを有する補強層の外周端をスチールコードからなる補強コードを有する補強層のそれよりもタイヤ外径側となるようにずらして配置することにより、荷重耐久性を従来レベル以上に維持しながら操縦安定性を一層高めることができる。
【図面の簡単な説明】
【図１】本発明の乗用車用空気入りタイヤの一例を示すタイヤ子午線断面説明図である。
【図２】図１の要部断面説明図である。
【図３】本発明の乗用車用空気入りタイヤに用いられる補強層の他の例を示す断面説明図である。
【符号の説明】
２ビード部４Ａ，４Ｂカーカス層
４ａ，４ｂ端部４a' エッジ
５ビードコア５ａ外周端
６ビードフィラー６ａ外周端
９Ａ，９Ｂ，１０Ａ，１０Ｂ補強層
９a₁，９b₁，１０a₁，１０b₁ 外周端
９a₂，９b₂，１０a₂，１０b₂ 内周端[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pneumatic tire for a passenger car, and more particularly, to a pneumatic tire for a passenger car that is intended to improve steering stability while ensuring a load durability equal to or higher than a conventional level.
[0002]
[Prior art]
Conventionally, in a pneumatic tire for a passenger car having two carcass layers, a reinforcing layer is provided adjacent to both ends of the carcass layer that is folded around the bead core. The durability and handling stability are improved.
[0003]
For example, there is a proposal to use a reinforcing layer in which steel cords are arranged as the reinforcing layer as described above. However, in the reinforcing layer using the steel cord as described above, in order to further improve the handling stability, if the outer peripheral end of the reinforcing layer extends to the tire outer diameter side exceeding 45% of the tire cross-section height, a high load load is applied. There is a problem in that the outer peripheral end easily causes a peeling failure during traveling and the load durability deteriorates.
[0004]
[Problems to be solved by the invention]
An object of the present invention is to provide a pneumatic tire for a passenger car that can further improve the handling stability while maintaining the load durability at or above the conventional level.
[0005]
[Means for Solving the Problems]
The pneumatic tire for a passenger car of the present invention that achieves the above object is the pneumatic tire for a passenger car in which two carcass layers are arranged between the left and right bead parts in which bead cores are embedded, and both end portions of the carcass layer on the inner peripheral side are disposed at the ends. Winding from the tire inner side to the outer side around the bead core, while the both ends of the carcass layer on the outer peripheral side are outside the both ends of the carcass layer on the inner peripheral side, the inner peripheral side is wound down around the bead core from the tire outer side to the inner side. In addition, two reinforcing layers in which reinforcing cords made of aromatic polyamide fibers are inclined and arranged with respect to the tire circumferential direction are provided between both ends of the carcass layer on the outer peripheral side so that the reinforcing cords intersect with each other, and the reinforcement the outer peripheral edge and inner peripheral edge of the layer and staggered to each other and extend its outer peripheral end to a position where the 45 to 65% of the tire section height H, the inner reinforcement layer of While allowing the outer peripheral edge is positioned on the tire outer diameter side than the outer reinforcing layer, characterized in that is positioned in the tire radially inner side than that of the inner peripheral end of the outer reinforcing layer inner reinforcing layer.
[0006]
Another passenger car pneumatic tire according to the present invention is a passenger car pneumatic tire in which two carcass layers are arranged between left and right bead portions in which bead cores are embedded, and both end portions of the carcass layer on the inner peripheral side are connected to the bead core. The carcass layer both ends on the outer peripheral side are wound outward from the both ends of the carcass layer on the inner peripheral side, and the inner peripheral side and the inner peripheral side A reinforcing cord made of a steel cord between the both ends of the carcass layer on the outer peripheral side is arranged so as to be inclined with respect to the tire circumferential direction, and a reinforcing cord made of an aromatic polyamide fiber on the outer side is arranged with respect to the tire circumferential direction. A single reinforcing layer arranged in an inclined manner is provided so that the reinforcing cords intersect with each other, and the outer peripheral end and the inner peripheral end of the reinforcing layers are shifted from each other. The outer peripheral end of the reinforcing layer having a reinforcing cord made of aromatic polyamide fiber is arranged to be closer to the tire outer diameter side than that of the reinforcing layer having a reinforcing cord made of steel cord, and the outer peripheral ends of both reinforcing layers are arranged It extends to the position which becomes 45 to 65% of tire cross-section height H, It is characterized by the above-mentioned.
[0007]
As described above, according to the present invention, the reinforcing layer in which the reinforcing cords made of aromatic polyamide fibers are arranged is arranged between both end portions of the carcass layer, so that the reinforcing layer exceeds 45% of the tire cross-section height H. Even if it extends to the tire outer diameter side, it is not a stiff reinforcing layer in which steel cords are arranged. Therefore, it does not cause a peeling failure in which the outer peripheral end easily peels off from the rubber during traveling under a heavy load. Therefore, not only does load durability deteriorate, but the improvement can be performed.
[0008]
Further, two reinforcing layers in which reinforcing cords made of aromatic polyamide fibers are arranged to be inclined with respect to the tire circumferential direction are provided so that the reinforcing cords intersect with each other, and the outer peripheral ends thereof are 45 to 45 in tire cross-section height H. By extending the position to 65%, it is possible to increase the bending rigidity of the sidewall portion over a high range, thereby further improving the steering stability.
[0009]
In addition, since both the outer peripheral edge and the inner peripheral edge of the reinforcing layer are shifted, it is possible to avoid stress concentration at a large step due to the end matching of the two reinforcing layers. Terminal peeling does not easily occur.
Also, among the two carcass layers arranged, both ends of the inner carcass layer are wound around the bead core from the inside of the tire to the outside, while both ends of the outer carcass layer are wound from the outside of the tire to the inside. Since both ends of the inner carcass layer are covered with the outer carcass layer and both layers are rolled up from the inside of the tire to the outside, the edge of the carcass layer is not covered and is not located on the outside of the tire. Effectively restrains the end of the carcass layer from peeling from the rubber of the sidewall due to the large shearing force generated between both ends of the carcass and the rubber of the sidewall due to the stunt wave phenomenon during high-speed running be able to.
[0010]
On the other hand, instead of the two reinforcing layers in which reinforcing cords made of aromatic polyamide fibers are arranged, both ends of the outer carcass layer wound down from the outer side of the tire and both ends of the inner carcass layer wound up from the inner side of the tire A single reinforcing layer in which reinforcing cords made of steel cords are arranged is arranged on the inner side of the tire, and a single reinforcing layer in which reinforcing cords made of aromatic polyamide fibers are arranged on the outside. The outer end of the reinforcing layer having the reinforcing cord made of aromatic polyamide fiber is shifted so as to be on the tire outer diameter side of the reinforcing layer having the reinforcing cord made of steel cord, and the inner steel cord reinforcing layer is arranged. Since the outer peripheral edge of the steel is protected by two layers of an outer carcass layer and an outer reinforcing layer, even if a steel cord reinforcing layer is used, The outer circumferential end of the reinforcing layer extends beyond the tire cross-section height H over 45% of the tire cross-section height H, and the outer peripheral edge does not easily peel off from the rubber even when traveling under a heavy load. Load durability can be obtained.
[0011]
Further, since both reinforcing layers are provided so that the reinforcing cords intersect, and the outer peripheral ends of both reinforcing layers are extended to a position that is 45 to 65% of the tire cross-section height H, the bending rigidity of the sidewall portion Can be increased over a wide range, and steering stability can be further improved.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 shows an example of a pneumatic tire for passenger cars according to the present invention, wherein 1 is a tread portion, 2 is a bead portion, and 3 is a sidewall portion. The left and right sidewall portions 3 are connected to the left and right bead portions 2 on the tire outer diameter side, and the tread portion 1 extending in the tire circumferential direction is provided between the left and right sidewall portions 3.
[0013]
Inside the tire, two

carcass layers

4A and 4B in which textile cords such as nylon cords and rayon cords are arranged in the tire radial direction are arranged between the left and right bead portions 2. A bead core 5 is embedded in each of the left and right bead portions 2, and a bead filler 6 is disposed on the outer periphery of the bead core 5.
A plurality of belt layers 7 are embedded in the tread portion 1 on the outer periphery side of the carcass layer, and a belt cover layer 8 for protecting the belt layer 7 over the entire surface is provided on the belt layer 7. CL is a tire center line.
[0014]
In the present invention, in the pneumatic tire having the above-described configuration, both end portions 4a of the carcass layer 4A on the inner peripheral side are folded back from the tire inner side to the outer side so as to sandwich the bead filler 6 around the bead core 5. The tire extends along the sidewall portion 3 to the center portion thereof toward the tire outer diameter side.
Both end portions 4b of the outer peripheral side carcass layer 4B are wound down from the outer side of the tire around the bead core 5 on the outer side of the inner peripheral side carcass layer end portions 4a, and the edges 4b 'are formed on the inner end side of the bead core 5. And it extends to the inside of the tire.
[0015]
Two reinforcing layers 9A and 9B in which reinforcing cords made of aromatic polyamide fibers are arranged are interposed between the inner and outer carcass layer opposite

ends

4a and 4b outside the bead filler 6 tire. ing. The reinforcing layers 9A and 9B formed in an annular shape are provided so that reinforcing cords arranged to be inclined with respect to the tire circumferential direction intersect.
[0016]
The outer peripheral ends 9a ₁ and 9b ₁ of the reinforcing layers 9A and 9B extend beyond the outer peripheral end 6a of the bead filler 6 to the tire outer diameter side, but more than the edges 4a ′ of the carcass layer both ends 4a on the inner peripheral side. On the tire inner diameter side, it extends to a position that is 45 to 65% of the tire cross-section height H that is the length in the tire radial direction from the bead heel a to the tread surface top (height of the reinforcing layer h). = 0.45-0.65H).
[0017]
Further, the outer peripheral ends 9a ₁ and 9b ₁ and the inner peripheral ends 9a ₂ and 9b ₂ of the reinforcing layers 9A and 9B are shifted from each other. In FIGS. 1 and 2, the outer peripheral end 9a ₁ of the inner reinforcing layer 9A is the outer side. While the outer peripheral end 9b ₁ of the reinforcing layer 9B is positioned on the tire outer diameter side, the inner peripheral end 9b ₂ of the outer reinforcing layer 9B is positioned closer to the tire inner diameter side than the inner peripheral end 9a ₂ of the inner reinforcing layer 9A. is doing.
[0018]
Thus, the present invention uses a reinforcing layer in which reinforcing cords made of aromatic polyamide fibers are arranged instead of a hard reinforcing layer in which steel cords are arranged between the two

end portions

4a and 4b of the carcass layers 4A and 4B. Even if the reinforcing layer extends beyond 45% of the tire cross-section height H to the tire outer diameter side, the outer peripheral edge does not easily cause a peeling failure during traveling under a heavy load, and the load durability is not lowered. It can also be improved.
[0019]
Further, two layers of reinforcing layers 9A and 9B in which reinforcing cords made of aromatic polyamide fibers are arranged inclined with respect to the tire circumferential direction are provided so that the reinforcing cords intersect with each other, and the outer peripheral ends 9a ₁ and 9b ₁ thereof. Is extended to a position that is 45 to 65% of the tire cross-section height H, so that the bending rigidity of the sidewall portion 3 can be increased over a wider range than before, thereby further improving the steering stability. Can do.
[0020]
Moreover, since the outer peripheral ends 9a ₁ and 9b ₁ and the inner peripheral ends 9a ₂ and 9b ₂ of the reinforcing layers 9A and 9B are shifted from each other, the ends of the _two reinforcing layers 9A and 9B are large. It is possible to avoid stress concentration caused by the steps and to suppress the end peeling of the reinforcing layers 9A and 9B.
[0021]
Of the two

carcass layers

4A and 4B arranged, both end portions 4a of the inner carcass layer 4A are wound around the bead core 5 from the inner side of the tire to the outer side, and both end portions 4b of the outer carcass layer 4B are turned from the outer side of the tire to the inner side. The both ends 4a of the inner carcass layer 4A are protected by the carcass layer 4B by so-called 1-1PL (ply lock) structure, and both layers are wound from the tire inner side to the outer side, so-called 2-0PL ( Since the edge of the carcass layer is not protected and is not positioned outside the tire unlike the ply-lock structure, the carcass layer end portion and the rubber of the sidewall portion 3 are caused by the stunt wave phenomenon during high-speed driving. Even when a shearing force acts between them, a peeling failure in which the end portion of the carcass layer peels from the rubber of the sidewall portion 3 does not easily occur.
[0022]
If the outer peripheral ends 9a ₁ and 9b _{1 of the} reinforcing layers 9A and 9B are lower than 45% of the tire cross-section height H, it becomes difficult to improve the steering stability. The strain deformation at 9a ₁ and 9b ₁ is increased, and peeling failure is likely to occur.
In the present invention, the inclination angle θ of the reinforcing cords of the reinforcing layers 9A and 9B can be set to 40 ° <θ <65 ° with respect to the tire circumferential direction. Even if the inclination angle θ is 40 ° or less or 65 ° or more, the reinforcing effect is small and it is difficult to improve the steering stability.
[0023]
The position of the inner peripheral end 9b ₂ of the outer reinforcing layer 9B is preferably located in the vicinity of the outer peripheral end 5a of the bead core 5 in a side view, and the position of the outer peripheral end 9a ₁ of the inner reinforcing layer 9A is The filler 6 can be positioned in the range of 8 to 15 mm from the outer peripheral end 6a to the tire outer diameter side.
[0024]
FIG. 3 shows another example of the present invention. Instead of the reinforcing layers 9A and 9B having the reinforcing cord made of the aromatic polyamide fiber, the reinforcing cord made of the steel cord is arranged so as to be inclined with respect to the tire circumferential direction. The one reinforcing layer 10A and the one reinforcing layer 10B in which reinforcing cords made of aromatic polyamide fibers are arranged to be inclined with respect to the tire circumferential direction are arranged so that the reinforcing cords intersect each other.
[0025]
A reinforcing layer 10A in which reinforcing cords made of steel cords are arranged is the inside of the tire, and a reinforcing layer 10B in which reinforcing cords made of aromatic polyamide fibers are arranged is arranged on the outer side.
The outer peripheral end 10b ₁ of the outer reinforcing layer 10B extends beyond the outer peripheral end 10a ₁ of the reinforcing layer 10A provided with the inner steel cord to the tire outer diameter side, and the outer peripheral ends 10a ₁ of the reinforcing layers 10A and 10B. , 10b ₁ is shifted. The inner peripheral ends 10a ₂ and 10b ₂ of the reinforcing layers 10A and 10B are arranged such that the inner peripheral end 10a ₂ of the inner reinforcing layer 10A is located closer to the tire inner diameter side and the terminal is displaced.
[0026]
In this way, even if the reinforcing layer is composed of the reinforcing layer 10A in which the reinforcing cords made of steel cords are arranged and the reinforcing layer 10B in which the reinforcing cords made of aromatic polyamide fibers are arranged, they are unwound from the outside to the inside of the tire. The outer peripheral edge 10b _{1 of the} reinforcing layer 10B having a reinforcing cord made of an aromatic polyamide fiber, between the both ends 4b of the outer carcass layer 4B and both ends of the inner carcass layer 4A wound outward from the inside of the tire. Are arranged so as to be shifted to the tire outer diameter side from the outer peripheral end 10a ₁ of the steel cord reinforcing layer 10A, so that the outer peripheral end 10a ₁ of the steel cord reinforcing layer 10A is two layers of the outer carcass layer 4B and the outer reinforcing layer 10B. Thus, the reinforcing

layers

10A, 1 are used together with a reinforcing layer 10A in which reinforcing cords of steel cords are arranged. Even if B is extended to the tire outer diameter side exceeding 45% of the tire cross-section height H and running at a high load load, the outer peripheral edge does not easily peel off from the rubber, and the load is equal to the conventional level. Durability can be ensured.
[0027]
Further, both the reinforcing layers 10A and 10B are provided so that the reinforcing cords intersect with each other, and the outer peripheral ends 10a ₁ and 10b ₁ of both the reinforcing layers 10A and 10B are extended to a position that is 45 to 65% of the tire cross-section height H. Therefore, the bending rigidity of the sidewall portion can be increased over a wider range than before, and the steering stability can be further improved.
[0028]
The inclination angle α of the reinforcing cord of the reinforcing layer 10A can be 10 ° <α <30 ° with respect to the tire circumferential direction. When the inclination angle α is 10 ° or less, the bending rigidity is too small, so that the reinforcing effect is reduced and the improvement effect of the steering stability cannot be obtained. On the other hand, if the angle is 30 ° or more, the bending rigidity becomes too high, the rigidity difference from the carcass layer becomes large, and the carcass cord breaks down when traveling under a heavy load. The inclination angle θ of the reinforcing cord of the reinforcing layer 10B can be the same as described above.
[0029]
The position of the inner peripheral edge 10a ₂ of the reinforcing layer 10A of the steel cord array of the tire radially inner side than the inner peripheral end 10b ₂ of the reinforcing layer 10B, may that be located on the outer peripheral edge 5a vicinity of the bead core 5 in a side view Moreover, the outer peripheral end 10b ₁ of the reinforcing layer 10B having a reinforcing cord made of an aromatic polyamide fiber can be positioned in the range of 8 to 15 mm from the outer peripheral end 6a of the bead filler 6 to the tire outer diameter side.
[0030]
【Example】
Example 1
The tire size is the same for 225 / 45ZR17 (for front wheels) and 245 / 40ZR17 (for rear wheels). In the pneumatic tire for passenger cars having the configuration shown in FIG. 1, a reinforcing cord made of an aromatic polyamide fiber is used as shown in FIG. The present invention tires 1 to 3 and comparative tires 1 and 2 thereof, in which two reinforcing layers are arranged and the position (height h) of the outer peripheral edge is changed as shown in Table 1 with respect to the tire cross-section height H, A reinforcing layer having a steel cord reinforcing cord and a reinforcing layer having a reinforcing cord made of an aromatic polyamide fiber as shown in FIG. 3 are arranged, and the position (height h) of the outer peripheral end with respect to the tire cross-section height H The tires 4 to 6 of the present invention that were changed as shown in Table 1, comparative tires 3 and 4 thereof, and a conventional tire in which one reinforcing layer in which steel cords were arranged were arranged. In addition, Kevlar was used as an aromatic polyamide fiber.
[0031]
When each of these test tires was subjected to a steering stability and load durability evaluation test under the measurement conditions shown below, the results shown in Table 1 were obtained.
Steering stability Each test tire is mounted on a rim with a rim size of 17 × 71 / 2-JJ (front wheel) and 17 × 81 / 2-JJ (rear wheel), mounted on a vehicle exceeding 280HP, and on a dry test course. A feeling test by a paneler was performed, and the result was evaluated by an index value with a conventional tire as 100. The larger this value, the better the steering stability.
Load durability 【0032】
225 / 45ZR17 as a representative, the test tire is mounted on a drum testing machine with a drum diameter of 1707 mm, JIS-D4230, JATMA Yearbook (1998 version) is applied mutatis mutandis, internal pressure is 200 kPa, load is 620 kg, load durability test After completion, the load was stepped up by 20% / 5hr and the test was continued until the tire broke down. The result was evaluated by an index value where the conventional tire was 100. The larger this value, the better the load durability.
[0033]
[Table 1]

[0034]
As is clear from Table 1, it can be seen that the tire of the present invention can improve the steering stability while ensuring the load durability at the same level or higher as that of the conventional tire. The index value is preferably 105 or more.
Example 2
Test tires 1 to 3 in which the tire size is the same as described above, and the inclination angle θ of the reinforcing cord made of aromatic polyamide fiber (Kevlar) in the reinforcing layer in FIG. 2 is changed as shown in Table 2, and the reinforcing layer in FIG. Test tires 4 to 6 in which the inclination angle α of the steel cord is changed as shown in Table 2, and test tires 7 to 9 in which the inclination angle θ of the aromatic polyamide fiber of the reinforcing layer in FIG. Each was produced.
[0035]
Test tires 1 to 3 have a reinforcing layer height h of 0.52H, test tires 4 to 6 have a reinforcing layer height h of 0.45H, and test tires 7 to 9 have a reinforcing layer height h of 0.48H. Further, the test tires 1 to 3 have the same inclination angle θ, and the test tires 4 to 6 have a constant inclination angle θ of 50 °, and the test tires 7 to 9 have a constant inclination angle α of 20 °. .
[0036]
When these test tires were subjected to an evaluation test of steering stability and load durability in the same manner as described above, the results shown in Table 2 were obtained.
[0037]
[Table 2]

[0038]
From Table 2, in the tire of the present invention using the two reinforcing layers in which the reinforcing cords made of aromatic polyamide fibers are arranged, the inclination angle θ of the reinforcing cord of the reinforcing layer is set to 40 ° <θ <65 with respect to the tire circumferential direction. It turns out that it is good to make it into °.
[0039]
Further, in the tire of the present invention using the reinforcing layer in which the reinforcing cords made of steel cords are arranged and the reinforcing layer in which the reinforcing cords made of aromatic polyamide fibers are arranged, the inclination angle α of the reinforcing cords of the steel cord reinforcing layer is set in the tire circumferential direction. In contrast, it can be seen that 10 ° <α <30 ° and the inclination angle θ of the reinforcing cord of the aromatic polyamide fiber reinforcing layer should be 40 ° <θ <65 ° with respect to the tire circumferential direction.
Example 3
[0040]
In the pneumatic tire for a passenger car having the configuration shown in FIG. 1 with the tire size similar to the above, the tire 7 of the present invention in which two reinforcing layers having reinforcing cords made of aromatic polyamide fibers are arranged as shown in FIG. Both ends of the layer were rolled up from the inside to the outside of the tire, and comparative tires 5 in which the same reinforcing layer as that of the tire 7 of the present invention was disposed between the both ends were produced.
[0041]
When each of these test tires was subjected to a load durability evaluation test in the same manner as described above, the results shown in Table 3 were obtained. In Table 3, the evaluation was performed using an index value where the comparative tire 5 was 100. The larger this value, the better the load durability.
[0042]
[Table 3]

[0043]
From Table 3, both ends of the carcass layer on the inner peripheral side are wound around the bead core from the inside of the tire to the outside, while both ends of the carcass layer on the outer peripheral side are outside the ends of the carcass layer on the inner peripheral side and around the bead core. It can be seen that the tire of the present invention, which has been wound inwardly from the inside, has significantly higher load durability than those in which both ends of the carcass layer are wound up from the inside of the tire to the outside.
[0044]
【The invention's effect】
As described above, the present invention provides a pneumatic tire for a passenger car in which two carcass layers are arranged between left and right bead portions in which bead cores are embedded, and both end portions of the carcass layer on the inner peripheral side are disposed around the bead core from the inside of the tire. While winding up outside, both ends of the carcass layer on the outer peripheral side are outside the both ends of the carcass layer on the inner peripheral side, and the both ends of the carcass layers on the inner peripheral side and the outer peripheral side are wound around the bead core from the outer side of the tire. Two reinforcing layers in which reinforcing cords made of aromatic polyamide fibers are inclined and arranged with respect to the tire circumferential direction are provided between the portions so that the reinforcing cords intersect with each other, and the outer peripheral ends and inner peripheries of the reinforcing layers Displace the ends and extend the outer peripheral end to a position that is 45 to 65% of the tire cross-section height H, or replace the two reinforcing layers with a steel coat. And a reinforcing layer made of aromatic polyamide fibers on the outer side thereof and arranged in an inclined manner with respect to the tire circumferential direction. The reinforcing cords are provided so as to intersect with each other, and the outer peripheral end of the reinforcing layer having the reinforcing cord made of aromatic polyamide fiber is located on the outer diameter side of the tire with respect to the reinforcing layer having the reinforcing cord made of steel cord. By disposing them, the steering stability can be further enhanced while maintaining the load durability at or above the conventional level.
[Brief description of the drawings]
FIG. 1 is a tire meridian cross-sectional explanatory view showing an example of a pneumatic tire for a passenger car of the present invention.
FIG. 2 is a cross-sectional explanatory view of a main part of FIG.
FIG. 3 is an explanatory cross-sectional view showing another example of a reinforcing layer used in the pneumatic tire for passenger cars of the present invention.
[Explanation of symbols]
2

bead portions

4A,

4B carcass layer

4a, 4b end 4a 'edge 5 bead core 5a outer peripheral edge 6 bead filler 6a outer

peripheral end

9A, 9B, 10A, 10B reinforcing layer _{_{_{9a 1, 9b 1, 10a 1}}} , 10b 1 outer peripheral edge 9a _{_{_{2, 9b 2, 10a 2,}}} 10b 2 inner circumferential edge

Claims

In a pneumatic tire for a passenger car in which two carcass layers are arranged between left and right bead portions in which bead cores are embedded,
The both ends of the carcass layer on the inner peripheral side are rolled up around the bead core from the inside of the tire to the outside, while the both ends of the carcass layer on the outer peripheral side are outside the both ends of the carcass layer on the inner peripheral side, and the outer side of the tire around the bead core. A two-layer reinforcing layer in which reinforcing cords made of an aromatic polyamide fiber are arranged at an inclination with respect to the tire circumferential direction between both ends of the inner and outer carcass layers. Are provided so as to intersect with each other, and the outer peripheral ends and inner peripheral ends of the reinforcing layers are shifted from each other, and the outer peripheral ends are extended to a position that is 45 to 65% of the tire cross-section height H , Air for passenger cars in which the outer peripheral end of the reinforcing layer is positioned closer to the tire outer diameter side than that of the outer reinforcing layer, while the inner peripheral end of the outer reinforcing layer is positioned closer to the tire inner diameter side than that of the inner reinforcing layer Enter Tire.

The pneumatic tire for a passenger car according to claim 1, wherein an inclination angle θ of the reinforcing cord of the reinforcing layer is set to 40 ° <θ <65 ° with respect to the tire circumferential direction.

While the inner peripheral end of the outer reinforcing layer is positioned near the outer peripheral end of the bead core, the outer peripheral end of the inner reinforcing layer is 8 on the tire outer diameter side from the outer peripheral end of the bead filler provided on the outer periphery of the bead core. The pneumatic tire for passenger cars according to claim 1 or 2, which is located in a range of -15 mm .

The pneumatic tire for a passenger car according to any one of claims 1 to 3 , wherein the outer peripheral ends of the two reinforcing layers are both arranged closer to the tire inner diameter side than the edges of both ends of the inner peripheral carcass layer.

In a pneumatic tire for a passenger car in which two carcass layers are arranged between left and right bead portions in which bead cores are embedded,
The both ends of the carcass layer on the inner peripheral side are rolled up around the bead core from the inside of the tire to the outside, while the both ends of the carcass layer on the outer peripheral side are outside the both ends of the carcass layer on the inner peripheral side, and the outer side of the tire around the bead core. One reinforcing layer in which reinforcing cords made of steel cords are arranged inclining with respect to the tire circumferential direction between both ends of the inner and outer carcass layers, and an outer aromatic polyamide A reinforcing layer made of fibers and arranged in a slanted manner with respect to the tire circumferential direction is provided so that the reinforcing cords intersect with each other, and the outer peripheral end and the inner peripheral end of the reinforcing layers are arranged to be shifted from each other. In addition, the outer peripheral end of the reinforcing layer having a reinforcing cord made of an aromatic polyamide fiber is closer to the tire outer diameter side than that of the reinforcing layer having a reinforcing cord made of a steel cord. Arrangement, and the extended passenger car pneumatic tires was the outer peripheral edge of the two reinforcing layers to a position where the 45 to 65% of the tire section height H to.

The inclination angle θ of the reinforcement cord of the reinforcement layer having the reinforcement cord made of aromatic polyamide fiber is 40 ° <θ <65 ° with respect to the tire circumferential direction, and the inclination angle of the reinforcement cord of the reinforcement layer having the reinforcement cord made of steel cord The pneumatic tire for passenger cars according to claim 5, wherein α is 10 ° <α <30 ° with respect to the tire circumferential direction .

The inner peripheral end of the reinforcing layer having the reinforcing cord made of the steel cord is positioned in the vicinity of the outer peripheral end of the bead core, while the outer peripheral end of the reinforcing layer having the reinforcing cord made of the aromatic polyamide fiber is provided on the outer periphery of the bead core. The pneumatic tire for a passenger car according to claim 5 or 6, wherein the pneumatic tire is located within a range of 8 to 15 mm from an outer peripheral end of the bead filler to a tire outer diameter side .

The pneumatic tire for a passenger car according to any one of claims 5 to 7 , wherein both outer peripheral ends of the two reinforcing layers are disposed closer to a tire inner diameter side than edges of both ends of the inner circumferential carcass layer.