JP3563468B2 - Studless pneumatic tires for heavy loads - Google Patents

Studless pneumatic tires for heavy loads Download PDF

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Publication number
JP3563468B2
JP3563468B2 JP00781195A JP781195A JP3563468B2 JP 3563468 B2 JP3563468 B2 JP 3563468B2 JP 00781195 A JP00781195 A JP 00781195A JP 781195 A JP781195 A JP 781195A JP 3563468 B2 JP3563468 B2 JP 3563468B2
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Prior art keywords
tread
land portion
block
grooves
blocks
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JPH08197911A (en
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能武木 荒牧
直也 越智
裕章 西川
徹 福岡
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Bridgestone Corp
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Bridgestone Corp
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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
    • 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
    • B60C11/1218—Three-dimensional shape with regard to depth and extending direction
    • 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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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Tires In General (AREA)

Description

【０００１】
【産業上の利用分野】
本発明は、氷雪路面での優れた走行性能を有する重荷重用スタッドレス空気入りタイヤに関するものである。
【０００２】
【従来の技術】
トレッド部の表面に突出したスパイク、またはスタッドによる粉塵公害をなくすため、スパイクタイヤの使用が禁止されて以来、スパイクを備えない、氷雪路面での走行性能に優れるタイヤを目差し種々の開発がなされてきた。これらはスタッドレスタイヤと総称されている。このスタッドレスタイヤにほぼ共通する特徴として、そのトレッド表面が多数のブロックに区画され、更に多数のサイプが施されていることが挙げられる。このサイプには様々な態様が可能であって、これまでにも各種提案されてきているが、何れもサイプによるブロック角部のエッジ効果によって氷上摩擦係数を高めることを狙いとしている。
【０００３】
図２はスタッドレスタイヤの一例として示すトレッドの平面図である。
図２においてトレッド１は、赤道面Ｏ上とその両側に２対周方向に向かって変形クランク状、または変形ジグザグ状に延びる主溝２を設け、これら主溝２およびトレッド端Ｅによって６本の陸部３を区画し、更にそれらを横断する多数のラグ溝４によって独立ブロック５に区分し、この場合、雪上走行に備えネガティブ率（トレッド面積に対する溝部分の合計面積の比率）を大きく与えられている。一方氷上走行のために、ブロック５は駆動・制動、およびコーナリング時に作用する外力に備え、これら力が作用する方向と実質上直交する方向のエッジ効果を付与すべく横向き、並びに縦向きサイプ６、７が多数設けられている。
【０００４】
【発明が解決しようとする課題】
このような構造のトレッドは、走行を通じてほぼ一定荷重を受ける乗用車用タイヤの場合は問題ないが、重荷重用タイヤは、荷重積載条件に対応する必要性から高内圧が適用されるが、空車時には荷重が著しく軽減し、積載時と空車時とでタイヤの荷重負担の変動が甚だしい。その結果、積載時において全幅に亙り接地するトレッドは、空車時には僅かしか撓まないため、それに伴い接地長と共に接地幅が短くなって接地面積が著しく減少することとなる。
【０００５】
このような空車時においては、接地領域が減少することによってトレッドは部分的に機能するに止まり、特に氷上性能を効果的に発揮することができない。この点につき発明者等が積載時と空車時とで荷重変動が取り分け著しい小型トラック用タイヤの場合を調べたところによると、荷重積載時には接地したトレッドのブロックが受ける接地圧は、総ての列に亙りほぼ均等な分布がみられたところ、空車時においてはトレッド端に近接するショルダーブロックと、これに隣合った中間ブロックの軸方向外側部分は全く接地せず、トレッド中央部の限られた領域の接地面を通じ機能していることが分かった。このような状態では雪上ではともかく氷上走行において、ネガティブ率が大きいスタッドレスタイヤは到底予期した性能を発揮することはできない。またこのような接地状態のため中間ブロックにヒールアンドトウ摩耗（偏摩耗）が多発する。
本発明は、上記知見に基づきなされたもので、優れた氷雪路走行性能を有すると共に、ヒールアンドトウ摩耗を低減したスタッドレス空気入りタイヤを提供することを目的とする。
【０００６】
【課題を解決するための手段】
本発明の重荷重用スタッドレス空気入りタイヤは、円筒状の踏面部に少なくとも４本の周方向主溝によって区画された、中央陸部、踏面の両端に近接する一対のショルダー陸部、および、これらの陸部間の中間陸部を夫々有するトレッドを備えたタイヤにおいて、それぞれの周方向主溝を、直線的に引いた溝中心線を越えない左右の振り幅で延在させ、上記トレッドの中央並びにショルダー陸部に、これらを横切る多数のラグ溝によって区分されたブロックの列を形成する一方、上記中間陸部を、接地面内で前後方向の力が作用したときに閉じる程度の細溝によって見掛け上のブロックに区分したリブとするとともに、その細溝を、長手方向の中央部で屈曲させて軸方向に延在させ、これらブロックおよびリブに、ジグザグ状に延びる複数の横向きサイプを形成し、リブに形成した全てのサイプの両端を周方向主溝に開口させるとともに、中央陸部のブロックに、一端が周方向主溝に開口し、他端がブロック内に終端する複数のサイプを周方向に互い違いに配置したことを特徴とするものである。
【０００８】
【作用】
本発明における重荷重用スタッドレスタイヤは、直線的に引いた溝中心線を越えない左右の振り幅で延在させたそれぞれの周方向主溝によって区画された中央並びにショルダー陸部に、これらを横切る多数のラグ溝によって区分されたブロックの列を形成する一方、上記中間陸部を、接地面内で細溝が閉じることによって周方向に機能的に連なるリブとするとともに、その細溝を、長手方向の中央部で屈曲させて軸方向に延在させ、これらブロックおよびリブに、ジグザグ状に延びる複数の横向きサイプを形成し、リブに形成した全てのサイプの両端を周方向主溝に開口させるとともに、中央陸部のブロックに、一端が周方向主溝に開口し、他端がブロック内に終端する複数のサイプを周方向に互い違いに配置したことを構造上の特徴とする。
ここでは、中間陸部は周方向に向かって機能的に連なるリブをなしているため、ラグ溝で区分されたブロックと異なり横向きサイプを多用しても、懸念される陸部剛性の低下を来すことが少ない。そのため空車状態での走行においてもトレッドの有効接地面積、即ち氷面に実際に接する陸部の面積が横向きサイプを伴って増加し、その結果増加したサイプによるエッジ効果によって、特に駆動・制動性能が著しく向上するのである。
一方雪上空車走行においては、雪面が軟弱なためラグ溝によって区分されたショルダーブロックが機能し、ロードホールディングの点では従来通り発揮することができ走行に支障を来すことはない。
【０００９】
中間陸部は接地面内で前後方向の力が作用したとき閉じる程度の細溝によって見掛け上ブロックに区分した場合、互いに独立したブロックの機能と、前後方向の力に対してはこれらブロックの協働によりリブとしての機能を併せもつこととなり、また設けた細溝によるエッジ効果を得ることができる。
また中間陸部がエンドレスリブの場合は、横向きサイプを多用しても不所望な剛性の低下が少ないため、増加したサイプの分陸部のエッジ効果が向上する訳である。
中間陸部の上記リブとしての機能は、接地面内での不要な動き、またはこの動きに惹起される滑りが制限されるため、ヒールアンドトウ摩耗が効果的に低減する。
【００１０】
【実施例】
以下図面に基づき説明する。図１は本発明における一実施例を示すトレッドの平面図である。
本発明におけるスタッドレスタイヤは、円筒状の踏面部に少なくとも４本の周方向主溝２によって区画された、中央陸部３Ｃ、踏面部の両端Ｅに近接する一対のショルダー陸部３Ｓ、および、これらの陸部３Ｃ、３Ｓ間の中間陸部３Ｍを有するトレッド１を備えている。そして上記中央陸部３Ｃならびにショルダー陸部３Ｓ に、これらを横切る多数のラグ溝４によって区分されたブロック５の列を形成する一方、中間陸部３Ｍは、周方向に機能的に連なるリブ８をなし、これらブロック５およびリブ８を、ジグザグ状に延びる複数の横向きサイプ６を有するものとする。
【００１１】
中間陸部３Ｍは、前後方向の力が作用したとき閉じる程度に幅が狭い細溝９によって見掛け上ブロックに区分したり、細溝９を横向きまたは類似のサイプに置き換えることにより、接地面内において作用する力の方向次第では少なくともリブとして機能する必要がある。
なお、図示を省略しているが本発明におけるスタッドレスタイヤは、左右サイドウォールと、両サイドウォール間に跨がってトレッド１を備えるクラウン部がトロイダルに連なり、一方のサイドウォールからクラウン部を通り他方のサイドォール間に亙ってナイロン、ポリエステルで代表される繊維コードラジアルプライの少なくとも１枚（通常２枚）、或はスチールコードラジアルプライの１枚から成るカーカスによって、またスチールコード層の複数枚を含む非伸長性ベルト層をカーカスとトレッド１間に配置した補強構造を適用することができる。
【００１２】
図１に示す実施例においてトレッド１は、赤道面Ｏを挟み左右一対、その外側に一対周方向に連なる主溝２を設け、赤道面Ｏ上に中央部陸部３Ｃ、その両側にこれとほぼ幅が等しい中間陸部３Ｍ、更にその両側に、端Ｅに近接する広幅のショルダー陸部３Ｓを区画している。中央部陸部３Ｃに隣合った主溝２は、その中心線ｊを越えることなく左右に出入りが小さい変形クランク状をなし周方向に延びている。ショルダー陸部３Ｓに隣合った主溝２も、左右の振り幅が比較的大きいとは云え溝の中心線ｋを越えることなく同様に延びている。主溝２の幅はトレッドの踏面部幅の２〜６％の範囲が適当である。
なお中央陸部は、中間陸部間に１列に限ることなく複数列設けることもできる。
【００１３】
中央部およびショルダー陸部３Ｃ、３Ｓは、ほぼ中央で屈曲し軸方向を横切る多数のラグ溝４によって、陸部３Ｃ位置では多少縦長の、陸部３Ｓでは多少横長のブロック５に区分している。一方中間陸部３Ｍは、同様に長手方向のほぼ中央で屈曲し軸方向に延びる、幅１．５ｍｍの細溝９によって見掛け上のブロック５’に区分している。細溝９の幅は、本発明の目的に照らし０．７〜２．０ｍｍ、また深さは主溝２の深さの６０〜７５％の範囲が夫々好ましい。
【００１４】
細溝によって区分されたブロック５’は、細溝と同様に両主溝間をジグザグに横断する横向きサイプ６１を６本ずつ実質上等間隔に設け、７つの部分１０に細分している。ブロック５’はこのように細分されても、ジグザグ成分によって走行時に作用する外力、特に横力に対しては部分１０は互いに影響し合い対応し得るよう配慮している。
【００１５】
中央陸部のブロック５は、軸方向両端からジグザグに延びブロック内に終端する横向きサイプ６２を等間隔に、且つ互い違いに４本設けている。またショルダー陸部の広幅ブロック５には、その軸方向両端から内側へジグザグに延びる横向きサイプ６２を４本ずつ配置し、中央部に残されたスペースにブロックを縦断する縦向きのジグザグサイプ７を２本お互い平行に設けている。
【００１６】
【効果】
このようにして成る本発明のタイヤの効果を確かめるため、６５０Ｒ１６ １０ＰＲサイズのラジアル構造を適用し、図１に示す実施例のタイヤと図２に示す比較例のタイヤとの間で小型トラックによる空車条件での氷雪上実車テスト、とアスファルト舗装路上の１３，０００粁走行（速度８０ｋｍ／ｈ）によるヒールアンドトウ摩耗テストを行い評価した。
これら両種タイヤのトレッド上に形成された横力に対するエッジ成分の長さの合計を表１に、前後力に対するエッジ成分の長さの合計を表２に夫々指数にて示している。
【００１７】
【表１】

Figure 0003563468
【００１８】
【表２】
Figure 0003563468
【００１９】
テスト条件として、タイヤは夫々１６×５．５０Ｆリムに組み、５．５Ｋｇｆ／ｃｍ２の内圧を充填した。
テスト方法は次の通りである。
氷上（雪上）操縦安定性：
氷結フィールド（雪上の場合は圧雪フィールド）にコーナリング性、旋回性にポイントを置き設定した特設コースをパネラーの運転技量に応じて走行（２０〜６０Ｋｍ／ｈ）し、決められた区間の通過タイムを測定した。
氷上（雪上）加速性：
氷結路上（雪上の場合は圧雪路上）で加速がスムーズに行えるかどうか、またその時のふらつきの度合いをフィーリングで評価した。
氷上（雪上）制動性：
氷結路上（雪上の場合は圧雪路上）において直進初速３０Ｋｍ／ｈでタイヤにブレーキをかけ、その地点から停止地点までの距離を測定した。
【００２０】
【表３】
Figure 0003563468
【００２１】
ヒールアンドトウ摩耗は、比較例のタイヤが中間ブロックを中心に著しく発生したのに対し、実施例のタイヤには殆ど認められなかった。
【００２２】
このように、中央陸部並びにショルダー陸部につき多数のラグ溝によって区分されたブロックの列を形成する一方、中間陸部は周方向に機能的に連なるリブをなし、これらブロックおよびリブに、ジグザグ状に延びる複数の横向きサイプを備えた本発明の重荷重用スタッドレス空気入りタイヤは空車時における、特に氷上性能を有利に発揮することができる。
【図面の簡単な説明】
【図１】本発明の実施例を示すトレッド平面図。
【図２】比較例のトレッド平面図。
【符号の説明】
１ ドレッド
２ 周方向主溝
３ 陸部
４ ラグ溝
５ ブロック
６ 横向きサイプ
８ リブ[0001]
[Industrial applications]
The present invention relates to a heavy duty studless pneumatic tire having excellent running performance on ice and snowy road surfaces.
[0002]
[Prior art]
To eliminate dust pollution caused by spikes or studs, projecting on the surface of the tread portion, since the use of spiked tires is prohibited, without the spike, various developments have been made aiming a tire which is excellent in running performance on snowy and icy road surfaces Have been. These are collectively referred to as studless tires. A feature that is substantially common to this studless tire is that its tread surface is divided into a number of blocks and a number of sipes are provided. This sipe can take various forms, and various proposals have been made so far, but all aim to increase the friction coefficient on ice by the edge effect of the corner of the block by the sipe.
[0003]
FIG. 2 is a plan view of a tread shown as an example of a studless tire.
In FIG. 2, the tread 1 is provided with two main grooves 2 extending on the equatorial plane O and on both sides thereof in a circumferentially deformed crank shape or a deformed zigzag shape. The land 3 is partitioned and further divided into independent blocks 5 by a large number of lug grooves 4 crossing them. In this case, the negative rate (the ratio of the total area of the groove portion to the tread area) is large in preparation for running on snow. ing. On the other hand, for running on ice, the block 5 is prepared for driving, braking, and external forces acting during cornering, and in order to provide an edge effect in a direction substantially orthogonal to the direction in which these forces act, a horizontal and vertical sipe 6, 7 are provided.
[0004]
[Problems to be solved by the invention]
A tread having such a structure has no problem in the case of a tire for a passenger car which receives a substantially constant load during traveling, but a high internal pressure is applied to a tire for a heavy load because it is necessary to cope with a load loading condition. Is significantly reduced, and the load on the tires varies greatly between when loaded and when the vehicle is empty. As a result, the tread that touches the ground over the entire width during loading is slightly bent when the vehicle is empty, and accordingly, the tread width is shortened along with the tread length, and the tread area is significantly reduced.
[0005]
In such an empty vehicle, the tread only partially functions due to the decrease in the contact area, and in particular, performance on ice cannot be effectively exhibited. Regarding this point, the inventors and others have examined the case of light truck tires in which the load fluctuation is remarkable when loaded and when the vehicle is empty. When the vehicle was empty, the shoulder block close to the tread edge and the axially outer portion of the intermediate block adjacent to the shoulder block did not touch the ground at all, and the center of the tread was limited. It was found to work through the ground plane of the area. In such a state, the studless tire having a large negative rate cannot exhibit the expected performance when traveling on ice anyway on snow. Further, heel and toe wear (uneven wear) frequently occurs in the intermediate block due to such a ground contact state.
The present invention has been made based on the above findings, and has as its object to provide a studless pneumatic tire having excellent icy and snowy road running performance and reduced heel and toe wear.
[0006]
[Means for Solving the Problems]
The studless pneumatic tire for heavy load according to the present invention includes a central land portion, a pair of shoulder land portions proximate to both ends of the tread, and a pair of shoulder land portions defined by at least four circumferential main grooves in the cylindrical tread. In a tire provided with a tread having an intermediate land portion between land portions, each circumferential main groove is extended with a left and right swing width not exceeding a linearly drawn groove center line, and the center of the tread and On the shoulder land portion, a row of blocks separated by a large number of lug grooves crossing these are formed, while the intermediate land portion is apparently formed by a narrow groove that closes when a force in the front-rear direction acts on the ground contact surface. with a rib which is divided into the upper block, the narrow groove, is bent in the longitudinal direction of the central portion is extended in the axial direction, these blocks and ribs, a plurality of which extends in a zigzag shape Forming the orientation sipe, terminated at both ends of all of the sipe formed in the rib circumferential main grooves to is opened Rutotomoni, the blocks of the central land portion, one end opening to the circumferential main groove, the other end in the block A plurality of sipes are alternately arranged in the circumferential direction.
[0008]
[Action]
The heavy-duty studless tire of the present invention has a large number of cross-sections at the center and at the shoulder land portion defined by the respective circumferential main grooves extending at right and left swing widths not exceeding the groove center line drawn linearly. While the row of blocks divided by the lug grooves is formed, the intermediate land portion is formed as a rib functionally connected in the circumferential direction by closing the narrow groove in the ground contact surface, and the narrow groove is formed in the longitudinal direction. is bent at the central portion extend axially, these blocks and ribs, to form a plurality of lateral sipes extending in a zigzag manner, Ru is opened at both ends of all of the sipe formed in the rib in the circumferential direction main grooves Along with the central land portion, a structural feature is that a plurality of sipes having one end opening in the circumferential main groove and the other end terminating in the block are alternately arranged in the circumferential direction.
Here, since the middle land portion is formed as a rib that is functionally connected in the circumferential direction, unlike the block divided by the lug groove, even if the lateral sipe is frequently used, the land portion rigidity may be reduced. Less. Therefore, even when the vehicle is traveling in an empty state, the effective contact area of the tread, that is, the area of the land portion actually in contact with the ice surface increases with the lateral sipe, and as a result, the edge effect due to the increased sipe causes the driving and braking performance to be particularly reduced. It is significantly improved.
On the other hand, when the vehicle runs on snow, the shoulder surface divided by the lug grooves functions because the snowy surface is soft, and the vehicle can be exhibited as usual in terms of road holding and does not hinder the traveling.
[0009]
If the intermediate land portion is obtained by dividing the apparent block by narrow groove to the extent that closes when acts longitudinal force in the ground contact surface, independently of each other and function of blocks, together these blocks with respect to the longitudinal direction of the force By the action, it also has a function as a rib, and an edge effect by the provided narrow groove can be obtained.
In addition, when the middle land portion is an endless rib, undesired reduction in rigidity is small even when the lateral sipe is frequently used, so that the edge effect of the increased sipe at the landing portion is improved.
The function of the intermediate land as the rib is to limit unnecessary movement in the ground contact surface or slip caused by this movement, so that heel and toe wear is effectively reduced.
[0010]
【Example】
This will be described below with reference to the drawings. FIG. 1 is a plan view of a tread showing one embodiment of the present invention.
Studless tire of the present invention is partitioned by the circumferential main grooves 2 of at least 4 on a cylindrical tread portion, a center land portion 3 C, a pair of shoulder land portion 3 close to the opposite ends E of the tread portion S and, , and a tread 1 having a middle land portion 3 M among these land portions 3 C, 3 S. And the central land portion 3 C and shoulder land portions 3 S, while forming the rows of blocks 5 which are partitioned by a number of lug grooves 4 across these, intermediate land portion 3 M is connected to functional circumferentially A rib 8 is formed, and the block 5 and the rib 8 have a plurality of lateral sipes 6 extending in a zigzag shape .
[0011]
Intermediate land portion 3 M by replacing or divided into apparently blocked by the narrow groove 9 width is narrow extent close when acts longitudinal force, a narrow groove 9 on its side or similar sipes, ground plane It is necessary to function at least as a rib, depending on the direction of the force acting at.
Although not shown, the studless tire according to the present invention has left and right sidewalls and a crown portion provided with the tread 1 straddling between the two sidewalls in a toroidal manner, and passes through the crown portion from one sidewall. nylon over between the other Saidoru, at least one fiber cord radial ply typified by polyester (two normal), or by a carcass composed of one steel cord radial ply, and a plurality of sheets of steel cord layers The reinforcement structure in which the non-extensible belt layer including the above is disposed between the carcass and the tread 1 can be applied.
[0012]
Tread 1 in the embodiment shown in FIG. 1, right and left sandwiching the equatorial plane O, the main grooves 2 provided continuous to a pair circumferentially on the outside, and which on the equatorial plane O central land portion 3 C, on both sides approximately equal width intermediate land portion 3 M, further on both sides, and partitions the wide shoulder land portion 3 S close to the edge E. Main groove was Tonaria' in central land portion 3 C 2 extends in the circumferential direction form a rather out of the left and right small deformations crank shape exceed the center line j. Main groove 2 Tonaria' the shoulder land portion 3 S also, the left and right swing width is relatively large extend similar without exceeding the center line k of the groove be said. The width of the main groove 2 is appropriately in the range of 2 to 6% of the tread width of the tread.
The central land portion is not limited to a single line between the intermediate land portions, and may be provided in a plurality of lines.
[0013]
Central and shoulder land portion 3 C, 3 S is substantially by a number of lug grooves 4 transverse to the axial direction is bent in the middle, somewhat elongated in the land portion 3 C position, the land portions 3 block 5 somewhat oblong in S It is classified. On the other hand, the intermediate land portion 3M is similarly divided into an apparent block 5 'by a narrow groove 9 having a width of 1.5 mm, which is bent substantially at the center in the longitudinal direction and extends in the axial direction. For the purpose of the present invention, the width of the narrow groove 9 is preferably 0.7 to 2.0 mm, and the depth is preferably 60 to 75% of the depth of the main groove 2.
[0014]
Block 5 'which are separated by narrow grooves, the lateral sipes 61 crossing the zigzag between both main grooves like the narrow groove provided in substantially equally spaced by six, it is subdivided into seven parts 10. Even if the block 5 'is subdivided in this way, it is taken into consideration that the portions 10 can influence each other and respond to external forces acting on the vehicle due to zigzag components, particularly lateral forces.
[0015]
Block 5 of the central land portion, at regular intervals the transverse sipes 6 2 terminating in a block extending from both axial ends in a zigzag, are and staggered four provided. The wide block 5 of the shoulder land portion is also its axial end transverse sipe 6 2 Place One not a four extending zigzag inwardly from vertical zigzag sipes traversing the block in the space left in the central portion 7 are provided in parallel with each other.
[0016]
【effect】
In order to confirm the effect of the tire of the present invention thus constituted, a radial structure of 650R16 10PR size is applied, and an empty vehicle by a small truck is used between the tire of the embodiment shown in FIG. 1 and the tire of the comparative example shown in FIG. An actual vehicle test on ice and snow under the conditions and a heel and toe wear test by traveling at 13,000 km (speed: 80 km / h) on an asphalt pavement were evaluated.
Table 1 shows the total length of the edge components with respect to the lateral force formed on the treads of these two types of tires, and Table 2 shows the total length of the edge components with respect to the longitudinal force.
[0017]
[Table 1]
Figure 0003563468
[0018]
[Table 2]
Figure 0003563468
[0019]
As test conditions, each tire was assembled on a 16 × 5.50F rim and filled with an internal pressure of 5.5 kgf / cm 2 .
The test method is as follows.
Steering stability on ice (snow):
In the freezing field (in the case of snow, the snow compaction field), a special course with the cornering and turning points set in accordance with the driving skills of the panelists (20-60 km / h), and the passing time of the determined section It was measured.
Acceleration on ice (snow):
Feeling was used to evaluate whether acceleration could be performed smoothly on an icy road (on snowy roads in the case of snow) and the degree of wandering at that time.
On ice (on snow) braking:
The tire was braked on an icy road (on snowy roads in the case of snow) at an initial straight traveling speed of 30 km / h, and the distance from that point to the stop point was measured.
[0020]
[Table 3]
Figure 0003563468
[0021]
Heel and toe wear was remarkably generated mainly in the intermediate block in the tire of the comparative example, but hardly observed in the tire of the example.
[0022]
Thus, the central land and the shoulder land form a row of blocks separated by a number of lug grooves, while the intermediate land forms circumferentially functional ribs, which are zigzag. The heavy-duty studless pneumatic tire of the present invention, which includes a plurality of laterally extending sipes, can advantageously exhibit performance on an empty vehicle, particularly on ice.
[Brief description of the drawings]
FIG. 1 is a tread plan view showing an embodiment of the present invention.
FIG. 2 is a tread plan view of a comparative example.
[Explanation of symbols]
Reference Signs List 1 dread 2 circumferential main groove 3 land portion 4 lug groove 5 block 6 lateral sipe 8 rib

Claims (1)

円筒状の踏面部に少なくとも４本の周方向主溝によって区画された、中央陸部、踏面の両端に近接する一対のショルダー陸部、および、これらの陸部間の中間陸部を夫々有するトレッドを備えたタイヤにおいて、それぞれの周方向主溝を、直線的に引いた溝中心線を越えない左右の振り幅で延在させ、上記トレッドの中央並びにショルダー陸部に、これらを横切る多数のラグ溝によって区分されたブロックの列を形成する一方、上記中間陸部を、接地面内で前後方向の力が作用したときに閉じる程度の細溝によって見掛け上のブロックに区分したリブとするとともに、その細溝を、長手方向の中央部で屈曲させて軸方向に延在させ、これらブロックおよびリブに、ジグザグ状に延びる複数の横向きサイプを形成し、リブに形成した全てのサイプの両端を周方向主溝に開口させるとともに、中央陸部のブロックに、一端が周方向主溝に開口し、他端がブロック内に終端する複数のサイプを周方向に互い違いに配置したことを特徴とする重荷重用スタッドレス空気入りタイヤ。A tread having a central land portion, a pair of shoulder land portions adjacent to both ends of the tread surface, and an intermediate land portion between these land portions, each of which is defined by at least four circumferential main grooves in a cylindrical tread portion. In the tire provided with, the respective circumferential main grooves are extended with a right and left swing width not exceeding the linearly drawn groove center line, and a large number of lugs traversing the center of the tread and the shoulder land portion are provided. While forming a row of blocks divided by grooves, the intermediate land portions are ribs divided into apparent blocks by narrow grooves that close when a force in the front-rear direction acts on the ground contact surface , the narrow groove, is bent in the longitudinal direction of the central portion is extended axially, these blocks and ribs, to form a plurality of lateral sipes extending in a zigzag manner, all rhino formed in the rib Rutotomoni allowed both ends opened to the circumferential main grooves of the block of the center land portion, the one end opening to the circumferential main groove and the other end was placed alternately a plurality of sipes in the circumferential direction that terminates in block A studless pneumatic tire for heavy loads characterized by the following.
JP00781195A 1995-01-23 1995-01-23 Studless pneumatic tires for heavy loads Expired - Fee Related JP3563468B2 (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100680245B1 (en) 2004-08-11 2007-02-07 한국타이어 주식회사 Block kerf pattern of tire tread

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JP4860132B2 (en) * 2004-10-06 2012-01-25 株式会社ブリヂストン Pneumatic tires for snowy and snowy roads
JP2006264487A (en) * 2005-03-23 2006-10-05 Bridgestone Corp Pneumatic tire
JP4782559B2 (en) * 2005-12-14 2011-09-28 株式会社ブリヂストン Pneumatic tire
JP5798414B2 (en) * 2011-08-30 2015-10-21 住友ゴム工業株式会社 Pneumatic tire
CN106457923B (en) * 2014-05-01 2019-03-12 横滨橡胶株式会社 Pneumatic tire
JP7346277B2 (en) * 2019-12-19 2023-09-19 株式会社ブリヂストン tire

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR100680245B1 (en) 2004-08-11 2007-02-07 한국타이어 주식회사 Block kerf pattern of tire tread

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