JP3597006B2 - Pneumatic radial tire for heavy loads - Google Patents

Pneumatic radial tire for heavy loads Download PDF

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Publication number
JP3597006B2
JP3597006B2 JP954397A JP954397A JP3597006B2 JP 3597006 B2 JP3597006 B2 JP 3597006B2 JP 954397 A JP954397 A JP 954397A JP 954397 A JP954397 A JP 954397A JP 3597006 B2 JP3597006 B2 JP 3597006B2
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tire
groove
inclination angle
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JPH10203119A (en
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博功 丸山
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Yokohama Rubber Co Ltd
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Yokohama Rubber Co Ltd
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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
    • B60C11/12—Tread patterns characterised by the use of narrow slits or incisions, e.g. sipes
    • B60C11/1204—Tread patterns characterised by the use of narrow slits or incisions, e.g. sipes with special shape of the sipe
    • B60C2011/1213—Tread patterns characterised by the use of narrow slits or incisions, e.g. sipes with special shape of the sipe sinusoidal or zigzag at the tread surface

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Description

【０００１】
【発明の属する技術分野】
本発明は、ブロック基調のトレッドパターンを有する重荷重用空気入りラジアルタイヤに関し、さらに詳しくは、排水性を実質的に低下させることなく、ヒールアンドトウ摩耗の発生を抑制するようにした重荷重用空気入りラジアルタイヤに関する。
【０００２】
【従来の技術】
重荷重用空気入りラジアルタイヤにおいて、ブロックパターンを基調とする全天候パターンでは、排水性及び浅雪時の走行性能を向上するために、タイヤ周方向に延びる主溝やタイヤ幅方向に延びるサブ溝の溝幅を大きくして溝面積を広くし、またブロックの形状をほぼ矩形としたものが主流になっている。
【０００３】
しかしながら、上述のように主溝やサブ溝の溝幅を拡大し、かつブロックの形状を矩形化すると、個々のブロックが独立して配置されることになり、ブロック１個当たりに負荷される接地圧力が大きくなるため、接地時のブロック変形量が大きくなり、ヒールアンドトウ摩耗を発生しやすくな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、排水性を実質的に低下させることなく、ヒールアンドトウ摩耗の発生を抑制することを可能にした重荷重用空気入りラジアル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ための本発明の重荷重用空気入りラジアルタイヤは、トレッド面に、タイヤ周方向に延びる複数本の主溝と、タイヤ幅方向に延びる複数本のサブ溝及び該サブ溝よりも溝幅が狭い切溝とを設け、前記主溝及びサブ溝によってセンター部に複数のブロックからなる２列のブロック列を分割形成し、前記主溝及び切溝によって左右のショルダー部にそれぞれ複数のブロックからなるブロック列を分割形成した重荷重用空気入りラジアルタイヤにおいて、前記サブ溝及び切溝をタイヤ赤道側から両外側へタイヤ反回転側に傾斜させた方向性を有するトレッドパターンにすると共に、前記サブ溝のタイヤ周方向に対する傾斜角度をタイヤ赤道側から外側に向けて徐々に減少させ、タイヤ赤道側の主溝に対してタイヤ反回転側に測った傾斜角θ０ を７０°≦θ０ ≦９０°の範囲にし、タイヤ外側の主溝に対してタイヤ反回転側に測った傾斜角θ１ を３０°≦θ１ ＜θ０ の関係にし、かつ前記切溝のタイヤ周方向に対する傾斜角度をタイヤ赤道側から外側に向けて徐々に増加させ、タイヤ赤道側の主溝に対してタイヤ反回転側に測った傾斜角θ２ を２０°≦θ２ ≦５０°の範囲にし、タイヤ外側のショルダーエッジに対してタイヤ反回転側に測った傾斜角θ３ を３０°＜θ３ ＜９０°の範囲にしたことを特徴とするものである。
【０００６】
このようにサブ溝のタイヤ周方向に対する傾斜角度を上記範囲でタイヤ赤道側から外側に向けて徐々に減少させ、サブ溝をタイヤの回転方向に向けて凸となる円弧状にすることにより、センター部においてブロックの踏込側端部における剛性を確保しながら、互いに前後に位置するブロックのタイヤ幅方向の重複量を増加させてブロックの相互補助作用により接地圧力を分散し、ブロックの変形を抑制するので、センター部のブロック列に発生するヒールアンドトウ摩耗を抑制することができる。
【０００７】
また、切溝のタイヤ周方向に対する傾斜角度を上記範囲でタイヤ赤道側から外側に向けて徐々に増加させ、切溝をタイヤの回転方向とは反対方向に向けて凸となる円弧状にすることにより、ショルダー部においてブロックの蹴出側端部における剛性を確保しながら、互いに前後に位置するブロックのタイヤ幅方向の重複量を増加させてブロックの相互補助作用により接地圧力を分散し、ブロックの変形を抑制するので、ショルダー部のブロック列に発生するヒールアンドトウ摩耗を抑制することができる。
【０００８】
なお、上記切溝はサブ溝に比べて溝幅が狭くなっているが、切溝を円弧状にすることにより、直線状のものに比べて総長さを延長して大きな溝体積を確保するので、排水性の低下を最低限に抑えることができる。
【０００９】
【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て詳細に説明する。
図１は、本発明の実施形態からなる重荷重用空気入りラジアルタイヤのトレッドパターンを例示するものである。このトレッドパターンは矢印Ｒの方向をタイヤ回転方向として指定された方向性パターンになっている。
【００１０】
図１において、トレッド面Ｔには、タイヤ周方向に延びる３本の主溝１が設けられており、これら主溝１によってセンター部に２列のブロック列５が、両ショルダー部にそれぞれブロック列７が形成されている。３本の主溝１の間には、複数本のサブ溝２がブロック列５をタイヤ幅方向に横切るように設けられ、これらサブ溝２はタイヤ赤道ＣＬ側の主溝１から両外側の主溝１へ向けてそれぞれタイヤ反回転方向へ傾斜するように設けられている。これら複数本のサブ溝２によってブロック列５が複数のブロック４に分割されている。なお、サブ溝２はタイヤ赤道ＣＬの両側で互いにタイヤ周方向にオフセットするように配置されているが、必ずしも左右のサブ溝２がオフセットすることは必要ではない。
【００１１】
また、両外側の主溝１の外側には、サブ溝２よりも溝幅が狭い複数本の切溝３がブロック列７をタイヤ幅方向に横切るように設けられ、これら切溝３もサブ溝２と同様にタイヤ赤道ＣＬ側の主溝１からショルダーエッジへ向けてタイヤ反回転方向へ傾斜するように設けられている。これら複数本の切溝３によってブロック列７が複数のブロック６に分割されている。
【００１２】
上述したように、サブ溝２は、タイヤ赤道ＣＬ側の主溝１から左右両側の主溝１へそれぞれタイヤ反回転方向へ傾斜すると共に、その傾斜角度が図２に示すようにタイヤ赤道ＣＬ側から外側に向けて徐々に減少するようになっている。すなわち、サブ溝２はタイヤの回転方向に向けて凸となる半径Ｒ１ の円弧状に湾曲している。更に、サブ溝２は、タイヤ赤道ＣＬ側の主溝１に対してタイヤ反回転側に測った傾斜角θ０ が７０°≦θ０ ≦９０°の範囲に設定され、タイヤ外側の主溝１に対して同じくタイヤ反回転側に測った傾斜角θ１ が３０°≦θ１ ＜θ０ の関係となるように設定されている。
【００１３】
このようにサブ溝２の傾斜方向と傾斜角度を設定することにより、センター部に位置するブロック４の踏込側端部における剛性を確保しながら、互いに前後に位置するブロック４のタイヤ幅方向の重複量を増加させてブロック４の相互補助作用により接地圧力を分散させるので、ヒールアンドトウ摩耗に対する耐偏摩耗性を向上することができる。
【００１４】
サブ溝２のタイヤ赤道ＣＬ側の傾斜角θ０ が７０°未満であると、ブロック４の踏込側端部における剛性が不十分になるので、耐偏摩耗性を向上させる効果を得られなくなる。一方、サブ溝２のタイヤ外側の傾斜角θ１ が３０°未満になると、ブロック４の蹴出側端部の剛性が不十分になって蹴出側にヒールアンドトウ摩耗を生じるようになる。また、傾斜角θ１ を傾斜角θ０ 以上にすると、サブ溝２を挟む前後のブロック４のタイヤ幅方向の重複量を増加させて接地圧を分散させる効果が得られなくなる。
【００１５】
また、サブ溝２の傾斜角θ０ と傾斜角θ１ との角度差（θ０ −θ１ ）は２０°〜５０°となるように設定することが好ましい。角度差（θ０ −θ１ ）が２０°未満であると、前後のブロック４のタイヤ幅方向の重複量を増加させて接地圧を分散させる効果が得られなくなり、逆に５０°を超えると、ブロック４の蹴出側端部における剛性が不十分になる。
【００１６】
一方、切溝３は、タイヤ赤道ＣＬ側から両外側へそれぞれタイヤ反回転方向へ傾斜すると共に、その傾斜角度が図２に示すようにタイヤ赤道ＣＬ側から外側に向けて徐々に増加するようになっている。すなわち、切溝３はタイヤの反回転方向に向けて凸となる半径Ｒ２ の円弧状に湾曲している。更に、切溝３は、タイヤ赤道ＣＬ側の主溝１に対してタイヤ反回転側に測った傾斜角θ２ が２０°≦θ２ ≦５０°の範囲に設定され、タイヤ外側のショルダーエッジに対して同じくタイヤ反回転側に測った傾斜角θ３ が３０°＜θ３ ＜９０°の範囲となるように設定されている。
【００１７】
このように切溝３の傾斜方向と傾斜角度を設定することにより、両ショルダー部に位置するブロック６の蹴出側端部における剛性を確保しながら、互いに前後に位置するブロック６のタイヤ幅方向の重複量を増加させてブロック６の相互補助作用により接地圧力を分散させるので、ヒールアンドトウ摩耗に対する耐偏摩耗性を向上することができる。
【００１８】
切溝３のタイヤ赤道ＣＬ側の傾斜角θ２ が２０°未満であると、ブロック６の踏込側端部における剛性が不十分になって踏込側にヒールアンドトウ摩耗を生じるようになり、逆に５０°を超えると、切溝３を挟む前後のブロック６のタイヤ幅方向の重複量を増加させて接地圧を分散させる効果を得られなくなる。一方、切溝３のタイヤ外側の傾斜角θ３ が３０°以下になると、ブロック６の蹴出側端部における剛性が不十分になるので、耐偏摩耗性を向上させる効果を得られなくなる。
【００１９】
また、切溝３の傾斜角θ２ と傾斜角θ３ との角度差（θ３ −θ２ ）は１０°〜４０°となるように設定することが好ましい。角度差（θ３ −θ２ ）が１０°未満であると、前後のブロック６のタイヤ幅方向の重複量を増加させて接地圧を分散させる効果が得られなくなり、逆に４０°を超えると、ブロック６の踏込側端部における剛性が不十分になる。
【００２０】
上述のサブ溝２の幅は例えば３〜１０ｍｍとし、切溝３の溝幅は例えば０．５〜３ｍｍにするとよい。切溝３の溝幅は、サブ溝２に比べて溝幅が狭くなっているが、切溝３を円弧状にすることにより、直線状のものに比べて総長さを延長して大きな溝体積を確保するので、排水性の低下を最低限に抑えることができる。また、切溝３の溝幅ｗは、サブ溝２の溝幅Ｗに対して０．１Ｗ≦ｗ≦０．５Ｗの関係にすることが好ましい。切溝３の溝幅ｗを上記範囲に設定することにより、互いに前後に位置するブロック６を近接させてブロック列７において相互補助作用を得るようにする。この切溝３の溝幅ｗが０．１Ｗ未満であると、排水性が不十分になり、逆に０．５Ｗを超えると、耐偏摩耗性を向上させる効果を得られなくなる。
【００２１】
【実施例】
タイヤサイズを１１Ｒ２２．５とし、図３に示すトレッドパターンを有する従来タイヤと、図１に示すトレッドパターンを有し、切溝３の傾斜角θ２ を４０°とし、傾斜角θ３ だけを種々異ならせた比較タイヤ１，２及び本発明タイヤ１〜４を製作した。なお、従来タイヤにおいて、切溝３はタイヤ周方向に対する角度を８０°として直線状に延長させたものである。
【００２２】
これら試験タイヤについて、下記試験方法により耐偏摩耗性を評価し、その結果を表１に示した。
耐偏摩耗性：
各試験タイヤを空気圧７００ｋＰａとしてトレーラーに装着し、１万ｋｍ走行後のヒールアンドトウ摩耗の発生量を測定した。評価結果は、従来タイヤの測定値の逆数を１００とする指数で示した。この指数値が大きいほど、耐偏摩耗性が優れている。
【００２３】

Figure 0003597006
この表１から明らかなように、切溝３の傾斜角θ２ を４０°とする一方で傾斜角θ３ を５０°〜８０°の範囲にした本発明タイヤ１〜４は、従来タイヤに比べて耐偏摩耗性が優れていた。一方、切溝３の傾斜角θ３ をそれぞれ４０°，９０°にした比較タイヤ１，２は、従来タイヤに比べて耐偏摩耗性の向上が見られなかった。
【００２４】
次に、タイヤサイズを１１Ｒ２２．５とし、図１に示すトレッドパターンを有し、切溝３の傾斜角θ３ を７０°とし、傾斜角θ２ だけを種々異ならせた比較タイヤ３，４及び本発明タイヤ５〜８を製作した。これら試験タイヤについて、上記試験方法により耐偏摩耗性を評価し、その結果を表２に示した。
【００２５】
Figure 0003597006
【００２６】
この表２から明らかなように、切溝３の傾斜角θ３ を７０°とする一方で傾斜角θ２ を２０°〜５０°の範囲にした本発明タイヤ５〜８は、従来タイヤに比べて耐偏摩耗性が優れていた。一方、切溝３の傾斜角θ２ を１０°にした比較タイヤ３は、従来タイヤに比べて耐偏摩耗性の向上が見られなかった。
【００２７】
【発明の効果】
以上説明したように本発明によれば、サブ溝及び切溝をタイヤ赤道側から両外側へタイヤ反回転方向へ傾斜させた方向性を有するトレッドパターンにすると共に、サブ溝のタイヤ周方向に対する傾斜角度をタイヤ赤道側から外側に向けて徐々に減少させ、タイヤ赤道側の傾斜角θ０ を７０°≦θ０ ≦９０°の範囲にし、タイヤ外側の傾斜角θ１ を３０°≦θ１ ＜θ０ の関係にし、かつ切溝のタイヤ周方向に対する傾斜角度をタイヤ赤道側から外側に向けて徐々に増加させ、タイヤ赤道側の傾斜角θ２ を２０°≦θ２ ≦５０°の範囲にし、タイヤ外側の傾斜角θ３ を３０°＜θ３ ＜９０°の範囲にしたから、排水性を実質的に低下させることなく、ヒールアンドトウ摩耗の発生を抑制することができる。
【図面の簡単な説明】
【図１】本発明の重荷重用空気入りラジアルタイヤのトレッドパターンを例示する平面図である。
【図２】図１のブロック近傍の部分拡大平面図である。
【図３】従来の重荷重用空気入りラジアルタイヤのトレッドパターンを例示する平面図である。
【符号の説明】
Ｔ トレッド面
１ 主溝
２ サブ溝
３ 切溝
４，６ ブロック
５，７ ブロック列[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a heavy-duty pneumatic radial tire having a block-based tread pattern, and more particularly to a heavy-duty pneumatic tire designed to suppress the occurrence of heel and toe wear without substantially reducing drainage. Related to radial tires.
[0002]
[Prior art]
In heavy-duty pneumatic radial tires, in the all-weather pattern based on the block pattern, in order to improve drainage and running performance at the time of shallow snow, main grooves extending in the tire circumferential direction and sub-grooves extending in the tire width direction are used. The mainstream is to increase the groove area by increasing the width and to make the shape of the block substantially rectangular.
[0003]
However, if the widths of the main groove and the sub-groove are increased and the shape of the blocks is made rectangular as described above, the individual blocks are arranged independently, and the ground applied to each block is grounded. Since the pressure is increased, the amount of deformation of the block at the time of contact with the ground is increased, and there has been a problem that heel and toe wear is likely to occur.
[0004]
[Problems to be solved by the invention]
It is an object of the present invention to provide a pneumatic radial tire for heavy loads that is capable of suppressing the occurrence of heel and toe wear without substantially reducing drainage.
[0005]
[Means for Solving the Problems]
The pneumatic radial tire for heavy load of the present invention for achieving the above object has a plurality of main grooves extending in the tire circumferential direction, a plurality of sub-grooves extending in the tire width direction, and a plurality of sub-grooves extending on the tread surface. A groove having a narrow groove width is provided, and two block rows composed of a plurality of blocks are dividedly formed in the center portion by the main groove and the sub-groove, and a plurality of blocks are respectively formed on left and right shoulder portions by the main groove and the groove. In a heavy-duty pneumatic radial tire formed by dividing a block row composed of blocks, a tread pattern having a direction in which the sub-grooves and the kerfs are inclined from the tire equator side to both outer sides toward the anti-rotation side of the tire, The inclination angle of the sub-groove with respect to the tire circumferential direction is gradually reduced from the tire equator side to the outside, and measured on the tire anti-rotation side with respect to the main groove on the tire equator side. The inclination angle theta 0 and in a range of 70 ° ≦ θ 0 ≦ 90 ° , and the inclination angle theta 1 measured in the tire reverse rotation side with respect to the major groove of the tire outside the relationship 30 ° ≦ θ 1 <θ 0 , and The inclination angle of the kerf with respect to the tire circumferential direction is gradually increased from the tire equator side to the outside, and the inclination angle θ 2 measured on the tire anti-rotation side with respect to the tire equatorial side main groove is 20 ° ≦ θ 2 ≦ the range of 50 °, is characterized in that the inclination angle theta 3 measured in the tire reverse rotation side with respect to the shoulder edge of the tire outside the range of 30 ° <θ 3 <90 ° .
[0006]
As described above, the inclination angle of the sub-groove with respect to the tire circumferential direction is gradually decreased from the tire equator side to the outside in the above range, and the sub-groove is formed in an arc shape that is convex in the tire rotation direction, thereby obtaining the center. While securing the rigidity at the stepping side end of the block in the part, the overlapping amount in the tire width direction of the blocks located before and after each other is increased, the ground pressure is dispersed by the mutual assisting action of the blocks, and the deformation of the blocks is suppressed. Therefore, heel and toe wear generated in the block row at the center can be suppressed.
[0007]
In addition, the inclination angle of the kerf with respect to the tire circumferential direction is gradually increased from the tire equator side to the outside in the above range, and the kerf is formed in an arc shape that is convex in a direction opposite to the tire rotation direction. Thereby, while securing rigidity at the kick-out side end of the block at the shoulder portion, the amount of overlap in the tire width direction of the blocks located before and after each other is increased to disperse the contact pressure by the mutual assisting action of the blocks, Since the deformation is suppressed, the heel and toe wear generated in the block row of the shoulder portion can be suppressed.
[0008]
In addition, the groove width of the above-mentioned kerf is narrower than that of the sub-groove.However, by making the kerf arc-shaped, the total length is extended as compared with the straight groove, so that a larger groove volume is secured. In addition, it is possible to minimize a decrease in drainage.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 illustrates a tread pattern of a pneumatic radial tire for heavy loads according to an embodiment of the present invention. This tread pattern is a directional pattern in which the direction of arrow R is designated as the tire rotation direction.
[0010]
In FIG. 1, three main grooves 1 extending in the tire circumferential direction are provided on a tread surface T, and two rows of block rows 5 are provided at a center portion by these main grooves 1, and block rows are provided at both shoulder portions. 7 are formed. A plurality of sub-grooves 2 are provided between the three main grooves 1 so as to cross the block row 5 in the tire width direction, and these sub-grooves 2 are arranged on the outer side of the main groove 1 on the tire equator CL side. The tires are provided so as to be inclined toward the groove 1 in the tire anti-rotation direction. The block row 5 is divided into a plurality of blocks 4 by the plurality of sub-grooves 2. The sub-grooves 2 are arranged on both sides of the tire equator CL so as to be offset from each other in the tire circumferential direction, but it is not always necessary that the left and right sub-grooves 2 be offset.
[0011]
Outside the main grooves 1 on both outer sides, a plurality of incisions 3 having a narrower groove width than the sub-grooves 2 are provided so as to cross the block row 7 in the tire width direction. Similarly to 2, the tire is provided so as to be inclined in the tire anti-rotation direction from the main groove 1 on the tire equator CL side toward the shoulder edge. The block row 7 is divided into a plurality of blocks 6 by the plurality of cut grooves 3.
[0012]
As described above, the sub-groove 2 is inclined from the main groove 1 on the tire equator CL side to the main grooves 1 on the left and right sides in the anti-rotation direction of the tire, and the angle of inclination is as shown in FIG. From the outside gradually decreases. That is, the sub groove 2 is curved in an arcuate shape of radius R 1 that is convex toward the rotation direction of the tire. Further, the sub-groove 2 is set such that the inclination angle θ 0 measured on the anti-rotation side of the tire with respect to the main groove 1 on the tire equator CL side is in the range of 70 ° ≦ θ 0 ≦ 90 °, and the main groove 1 outside the tire is set. It is set as also the inclination angle theta 1 measured in the tire reverse rotation side a relationship of 30 ° ≦ θ 1 <θ 0 with respect.
[0013]
By setting the inclination direction and the inclination angle of the sub-groove 2 in this manner, the rigidity at the stepping-side end of the block 4 located at the center is ensured, and the blocks 4 located at the front and rear are overlapped in the tire width direction. Since the contact pressure is dispersed by increasing the amount by the mutual assisting action of the blocks 4, uneven wear resistance against heel and toe wear can be improved.
[0014]
If the inclination angle θ 0 of the sub-groove 2 on the tire equator CL side is less than 70 °, the rigidity at the stepping-side end of the block 4 becomes insufficient, so that the effect of improving the uneven wear resistance cannot be obtained. On the other hand, the inclination angle theta 1 of the tire outer sub-grooves 2 is less than 30 °, will produce a heel and toe wear on the delivery side of the kick becomes insufficient rigidity of kick outlet end of the block 4. Further, when the inclination angle theta 1 with the inclination angle theta 0 or more, not the effect of dispersing the ground contact pressure by increasing the amount of overlap in the tire width direction of the front and rear of the block 4 to sandwich the sub-grooves 2 are obtained.
[0015]
Further, it is preferable that the angle difference (θ 0 −θ 1 ) between the inclination angle θ 0 and the inclination angle θ 1 of the sub-groove 2 is set to be 20 ° to 50 °. If the angle difference (θ 0 −θ 1 ) is less than 20 °, the effect of increasing the overlapping amount of the front and rear blocks 4 in the tire width direction and dispersing the contact pressure cannot be obtained. Conversely, if the angle difference exceeds 50 °, In addition, the rigidity of the end of the block 4 on the ejection side becomes insufficient.
[0016]
On the other hand, the kerfs 3 are inclined from the tire equator CL side to both outer sides in the tire anti-rotation direction, and the inclination angle is gradually increased outward from the tire equator CL side as shown in FIG. Has become. That is, kerfs 3 is curved in an arcuate shape of radius R 2 that is convex toward the reverse rotation direction of the tire. Further, the kerf 3 is set such that the inclination angle θ 2 measured on the anti-rotation side of the tire with respect to the main groove 1 on the tire equator CL side is in the range of 20 ° ≦ θ 2 ≦ 50 °, and against it is set as also the inclination angle theta 3 measured in the tire reverse rotation side is in a range of 30 ° <θ 3 <90 ° .
[0017]
By setting the inclination direction and the inclination angle of the incision 3 in this way, the rigidity at the kick-out side ends of the blocks 6 located at both shoulder portions is ensured, and the tires in the tire width direction of the blocks 6 located forward and backward to each other are secured. Is increased and the contact pressure is dispersed by the mutual assistance of the blocks 6, so that the uneven wear resistance against heel and toe wear can be improved.
[0018]
If the inclination angle theta 2 of the tire equator CL side of the kerf 3 is less than 20 °, will produce a heel and toe wear in the depression side rigidity becomes insufficient in the depression side end portion of the block 6, the reverse If the angle exceeds 50 °, the effect of increasing the overlapping amount of the blocks 6 before and after the kerf 3 in the tire width direction and dispersing the contact pressure cannot be obtained. On the other hand, when the inclination angle theta 3 of the tire outer kerf 3 becomes 30 ° or less, the rigidity of the kick outlet end of the block 6 is insufficient, can not be obtained an effect of improving the uneven wear resistance.
[0019]
Further, it is preferable that the angle difference (θ 3 −θ 2 ) between the inclination angle θ 2 and the inclination angle θ 3 of the kerf 3 is set to be 10 ° to 40 °. If the angle difference (θ 3 −θ 2 ) is less than 10 °, the effect of increasing the overlapping amount of the front and rear blocks 6 in the tire width direction and dispersing the contact pressure cannot be obtained. In addition, the rigidity at the step-side end of the block 6 becomes insufficient.
[0020]
The width of the sub-groove 2 is, for example, 3 to 10 mm, and the width of the cut groove 3 is, for example, 0.5 to 3 mm. The groove width of the cut groove 3 is smaller than that of the sub-groove 2, but by forming the cut groove 3 in an arc shape, the total length is extended as compared with a straight groove to increase the groove volume. Therefore, a decrease in drainage can be minimized. Further, the groove width w of the cut groove 3 is preferably set to have a relationship of 0.1 W ≦ w ≦ 0.5 W with respect to the groove width W of the sub-groove 2. By setting the groove width w of the incision 3 within the above range, the blocks 6 located before and after each other are brought close to each other so that a mutual assisting action is obtained in the block row 7. If the groove width w of the cut groove 3 is less than 0.1 W, drainage becomes insufficient, and if it exceeds 0.5 W, the effect of improving uneven wear resistance cannot be obtained.
[0021]
【Example】
The tire size and 11R22.5, various and conventional tire, has a tread pattern shown in FIG. 1, the inclination angle theta 2 kerf 3 and 40 °, only the inclination angle theta 3 having a tread pattern shown in FIG. 3 Different comparative tires 1 and 2 and inventive tires 1 to 4 were produced. In the conventional tire, the kerf 3 is linearly extended at an angle of 80 ° with respect to the tire circumferential direction.
[0022]
For these test tires, uneven wear resistance was evaluated by the following test method, and the results are shown in Table 1.
Uneven wear resistance:
Each test tire was mounted on a trailer at an air pressure of 700 kPa, and the amount of heel and toe wear generated after traveling 10,000 km was measured. The evaluation results are shown as indices with the reciprocal of the measured value of the conventional tire being 100. The larger the index value, the better the uneven wear resistance.
[0023]
Figure 0003597006
As is clear from Table 1, the present invention tires 1 to 4 the inclination angle theta 3 was in the range of 50 ° to 80 ° angle of inclination theta 2 while a 40 ° kerf 3, compared with the conventional tire And excellent uneven wear resistance. On the other hand, the inclination angle theta 3 each 40 ° kerf 3, comparison tires 1 and 2 was 90 °, the improvement of uneven wear resistance was observed as compared with the conventional tire.
[0024]
Next, the tire size and 11R22.5, has a tread pattern shown in FIG. 1, the inclination angle theta 3 kerf 3 and 70 °, compared tires 3, 4 and was variously different by the inclination angle theta 2 Inventive tires 5 to 8 were produced. For these test tires, uneven wear resistance was evaluated by the test method described above, and the results are shown in Table 2.
[0025]
Figure 0003597006
[0026]
As is clear from Table 2, the present invention tires 5-8 the inclination angle theta 2 While the inclination angle theta 3 kerf 3 and 70 ° and in a range of 20 ° to 50 ° as compared with the conventional tire And excellent uneven wear resistance. On the other hand, Comparative tire 3 in which the inclined angle theta 2 kerf 3 to 10 °, the improvement of uneven wear resistance was observed as compared with the conventional tire.
[0027]
【The invention's effect】
As described above, according to the present invention, a sub-groove and a kerf are formed in a tread pattern having a direction in which the sub-groove is inclined from the tire equator side to both outer sides in the tire anti-rotation direction, and the sub-groove is inclined with respect to the tire circumferential direction. angle gradually decreases outward from the tire equator side, the inclination angle theta 0 of the tire equator side to the range of 70 ° ≦ θ 0 ≦ 90 ° , the inclination angle theta 1 of 30 ° ≦ θ 1 of the tire outer < θ 0 , and the inclination angle of the kerf with respect to the tire circumferential direction is gradually increased from the tire equator side to the outside, so that the tire equatorial side inclination angle θ 2 is in the range of 20 ° ≦ θ 2 ≦ 50 °. since the inclination angle theta 3 of the tire outside the range of 30 ° <θ 3 <90 ° , substantially without reducing the drainage performance, it is possible to suppress the occurrence of heel and toe wear.
[Brief description of the drawings]
FIG. 1 is a plan view illustrating a tread pattern of a pneumatic radial tire for heavy loads according to the present invention.
FIG. 2 is a partially enlarged plan view in the vicinity of a block in FIG. 1;
FIG. 3 is a plan view illustrating a tread pattern of a conventional pneumatic radial tire for heavy loads.
[Explanation of symbols]
T Tread surface 1 Main groove 2 Sub groove 3 Cut groove 4, 6 Block 5, 7 Block row

Claims (4)

トレッド面に、タイヤ周方向に延びる複数本の主溝と、タイヤ幅方向に延びる複数本のサブ溝及び該サブ溝よりも溝幅が狭い切溝とを設け、前記主溝及びサブ溝によってセンター部に複数のブロックからなる２列のブロック列を分割形成し、前記主溝及び切溝によって左右のショルダー部にそれぞれ複数のブロックからなるブロック列を分割形成した重荷重用空気入りラジアルタイヤにおいて、前記サブ溝及び切溝をタイヤ赤道側から両外側へタイヤ反回転側に傾斜させた方向性を有するトレッドパターンにすると共に、前記サブ溝のタイヤ周方向に対する傾斜角度をタイヤ赤道側から外側に向けて徐々に減少させ、タイヤ赤道側の主溝に対してタイヤ反回転側に測った傾斜角θ０ を７０°≦θ０ ≦９０°の範囲にし、タイヤ外側の主溝に対してタイヤ反回転側に測った傾斜角θ１ を３０°≦θ１ ＜θ０ の関係にし、かつ前記切溝のタイヤ周方向に対する傾斜角度をタイヤ赤道側から外側に向けて徐々に増加させ、タイヤ赤道側の主溝に対してタイヤ反回転側に測った傾斜角θ２ を２０°≦θ２ ≦５０°の範囲にし、タイヤ外側のショルダーエッジに対してタイヤ反回転側に測った傾斜角θ３ を３０°＜θ３ ＜９０°の範囲にした重荷重用空気入りラジアルタイヤ。On the tread surface, a plurality of main grooves extending in the tire circumferential direction, a plurality of sub-grooves extending in the tire width direction and a cut groove having a groove width narrower than the sub-grooves are provided, and a center is formed by the main grooves and the sub-grooves. A heavy-load pneumatic radial tire in which two rows of blocks each composed of a plurality of blocks are divided and formed in a portion, and a block row composed of a plurality of blocks is formed in each of the left and right shoulder portions by the main groove and the cut groove. A sub-groove and a kerf are formed in a tread pattern having a direction inclining from the tire equator side to both outer sides to the tire anti-rotation side, and the inclination angle of the sub-groove with respect to the tire circumferential direction is directed outward from the tire equator side. gradually decreased, the inclination angle theta 0 measured in the tire reverse rotation side with respect to the major groove of the tire equator side to the range of 70 ° ≦ θ 0 ≦ 90 ° , against the major groove of the tire outer The inclination angle theta 1 measured in the tire reverse rotation side to the relationship 30 ° ≦ θ 1 <θ 0 Te, and gradually increased toward the outer side of the inclination angle with respect to the tire circumferential direction of the notch from the tire equator side, the inclination angle theta 2 measured in the tire reverse rotation side with respect to the major groove of the tire equator side to the range of 20 ° ≦ θ 2 ≦ 50 ° , the inclination angle measured in the tire reverse rotation side with respect to the shoulder edge of the tire outer heavy duty pneumatic radial tire in which the theta 3 in the range of 30 ° <θ 3 <90 ° . 前記サブ溝の傾斜角θ０ と傾斜角θ１ との角度差（θ０ − θ１ ）を２０°〜５０°の範囲にした請求項１に記載の重荷重用空気入りラジアルタイヤ。2. The pneumatic radial tire for heavy load according to claim 1 , wherein an angle difference (θ 0 −θ 1 ) between the inclination angle θ 0 and the inclination angle θ 1 of the sub-groove is in a range of 20 ° to 50 °. 前記切溝の傾斜角θ２ と傾斜角θ３ との角度差（θ３ −θ２ ）を１０°〜４０°の範囲にした請求項１に記載の重荷重用空気入りラジアルタイヤ。 2. The pneumatic radial tire for heavy load according to claim 1, wherein an angle difference (θ 3 −θ 2 ) between the inclination angle θ 2 and the inclination angle θ 3 of the kerf is in a range of 10 ° to 40 °. 前記切溝の溝幅ｗを、前記サブ溝の溝幅Ｗに対して０．１Ｗ≦ｗ≦０．５Ｗの関係にした請求項１に記載の重荷重用空気入りラジアルタイヤ。The pneumatic radial tire for heavy loads according to claim 1, wherein a groove width w of the cut groove is set to a relation of 0.1W ≦ w ≦ 0.5W with respect to a groove width W of the sub groove.
JP954397A 1997-01-22 1997-01-22 Pneumatic radial tire for heavy loads Expired - Fee Related JP3597006B2 (en)

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JP954397A JP3597006B2 (en) 1997-01-22 1997-01-22 Pneumatic radial tire for heavy loads
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