JP2613448B2 - Pneumatic tire - Google Patents

Pneumatic tire

Info

Publication number
JP2613448B2
JP2613448B2 JP63241833A JP24183388A JP2613448B2 JP 2613448 B2 JP2613448 B2 JP 2613448B2 JP 63241833 A JP63241833 A JP 63241833A JP 24183388 A JP24183388 A JP 24183388A JP 2613448 B2 JP2613448 B2 JP 2613448B2
Authority
JP
Japan
Prior art keywords
tire
land portion
step region
tread
circumferential
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
JP63241833A
Other languages
Japanese (ja)
Other versions
JPH0288311A (en
Inventor
隆 久木元
直人 山岸
伸二 臼井
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Bridgestone Corp
Original Assignee
Bridgestone Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Bridgestone Corp filed Critical Bridgestone Corp
Priority to JP63241833A priority Critical patent/JP2613448B2/en
Publication of JPH0288311A publication Critical patent/JPH0288311A/en
Application granted granted Critical
Publication of JP2613448B2 publication Critical patent/JP2613448B2/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Classifications

    • 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
    • B60C11/04—Tread patterns in which the raised area of the pattern consists only of continuous circumferential ribs, e.g. zig-zag
    • B60C11/042—Tread patterns in which the raised area of the pattern consists only of continuous circumferential ribs, e.g. zig-zag further characterised by the groove cross-section
    • 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
    • B60C11/0306—Patterns comprising block rows or discontinuous ribs
    • B60C11/0309—Patterns comprising block rows or discontinuous ribs further characterised by the groove cross-section
    • 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
    • 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
    • B60C11/1236—Tread patterns characterised by the use of narrow slits or incisions, e.g. sipes with special arrangements in the tread pattern
    • B60C2011/1254—Tread patterns characterised by the use of narrow slits or incisions, e.g. sipes with special arrangements in the tread pattern with closed sipe, i.e. not extending to a groove

Description

【発明の詳細な説明】 産業上の利用分野 この発明は、踏面に主溝および陸部を有し、車両に対
する装着側に規定されている空気入りタイヤに関する。Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire having a main groove and a land on a tread surface and defined on a mounting side with respect to a vehicle.

従来の技術 一般に空気入りタイヤに生じる摩耗現象については、
路面状況に依存するが、最近の著しく整備が進められた
高速自動車道などにおける長時間走行の下では、タイヤ
の踏面接地域において路面から作用する外力（タイヤ入
力）の如何によって踏面形状に変化が生じ、これによっ
て摩耗に遅速差が発生し、摩耗の速い部分で加速度的な
累加促進が進展してリバーウェア、リブパンチ等の偏摩
耗となるのである。2. Description of the Related Art Generally, regarding the wear phenomenon that occurs in a pneumatic tire,
Although it depends on the road surface conditions, under long-term driving on a high-speed expressway, etc., which has been significantly improved recently, the tread shape changes depending on the external force (tire input) acting from the road surface in the area where the tires contact the tread. As a result, a difference in the speed of the wear is generated, and accelerating accumulative acceleration progresses in the fast-wearing portion, resulting in uneven wear of the riverware, the rib punch, and the like.

このような偏摩耗を低減させるため、従来、種々の提
案がされており、例えば、クラウン形状を変化させて偏
摩耗を低減させるものとしては米国特許第4155392号明
細書に記載されているものがあり、また、リブの両端に
サイプを配列して偏摩耗を低減させるものとしては米国
特許第3550665号明細書に記載されているものがある。In order to reduce such uneven wear, conventionally, various proposals have been made, for example, those described in U.S. Pat. There is an arrangement in which sipes are arranged at both ends of a rib to reduce uneven wear, as described in US Pat. No. 3,550,665.

発明が解決しようとする課題 しかしながら、このような従来のタイヤは、偏摩耗自
身を阻止することができず、単にその発生を遅延させる
に過ぎないため、走行後ほどなく偏摩耗が発生するとい
う問題点がある。また、前述のような提案を実施する
と、タイヤ入力の負担が他の部位に移り、該部位に偏摩
耗が生じることもあるという問題点がある。Problems to be Solved by the Invention However, such a conventional tire cannot prevent uneven wear itself and merely delays its occurrence, so that uneven wear occurs soon after traveling. There is. Further, when the above-described proposal is implemented, there is a problem in that the burden of the tire input is transferred to another part, and uneven wear may occur in the part.

課題を解決するための手段 このような問題点を解決すべく鋭意研究を重ねた結
果、有効な偏摩耗防止対策を確立することができたた
め、本出願人は特願昭62−265248号（昭和62年10月22日
出願）において、タイヤの踏面上でそのまわりに沿って
連続してのびる主溝とこの主溝によって区分された陸部
を有する重荷重用空気入りタイヤであって、上記陸部
に、踏面の断面輪郭線に対し段下りをなし、踏面のまわ
りに沿い連続する一対の細溝又はサイプによって陸部を
二分してそれから独立する段差領域からなり、この段差
領域の表面はタイヤに作用する荷重の支持を司る踏面接
地域内で路面とすべり接触する、偏摩耗犠牲部を設けて
成ることを特徴とする、偏摩耗を防止した重荷重用空気
入りタイヤ、を提案した。このものは、タイヤ走行時、
段差領域の表面が踏面接地域内で路面とすべり接触する
ため、該段差領域に極めて大きな制動方向剪断力が発生
し、結果として、段差領域の両側の陸部における剪断力
が駆動側へシフトアップされ、この結果、全ての陸部に
駆動方向剪断力が作用するようになるのである。ここ
で、駆動方向剪断力を受けている踏面の摩耗速度は制動
方向剪断力を受けている踏面の摩耗速度より著しく遅い
ため、制動方向剪断力を受けている段差領域のみが犠牲
となって摩耗し、陸部の摩耗が防止されるのである。Means for Solving the Problems As a result of intensive studies to solve such problems, effective countermeasures for preventing uneven wear have been established, and the present applicant has filed Japanese Patent Application No. 62-265248 (Showa 1). A heavy-duty pneumatic tire having a main groove extending continuously on the tread of the tire along the circumference thereof and a land portion divided by the main groove, In addition, the cross section contour of the tread is stepped down, the land is divided into two parts by a pair of narrow grooves or sipes continuous along the circumference of the tread, and the step part is composed of a step area independent of the step area. A heavy-duty pneumatic tire with uneven wear prevention, characterized in that it is provided with an uneven wear sacrificial portion that comes into sliding contact with a road surface in a tread contact area that controls an applied load. This is for tire running
Since the surface of the step area makes sliding contact with the road surface in the tread contact area, an extremely large braking force in the braking direction is generated in the step area, and as a result, the shear force on the land portions on both sides of the step area shifts up to the driving side. As a result, the driving direction shear force acts on all land portions. Here, the wear speed of the tread subjected to the shear force in the driving direction is significantly lower than the wear speed of the tread subjected to the shear force in the braking direction. The wear of the land is prevented.

ところで、車両の旋回時には旋回外側に装着された空
気入りタイヤに路面から装着内方側（旋回内側）に向か
う大きな横力が作用することが知られているが、このよ
うな大きな横力が空気入りタイヤに作用すると、装着外
方側のショルダー端近傍の陸部に大きな曲げ力が作用す
る。ここで、該ショルダー端近傍の陸部の軸方向幅が狭
い場合には、前記大きな曲げ力によって大きな変形が生
じ、これにより、該部位の陸部の接地圧が他の部位に比
較して高くなる。この結果、車両の旋回時に該部位の陸
部に摩耗が容易に発生するが、このようにして摩耗が僅
かでも発生すると、直進時にこの摩耗した部位が引き摺
られてさらに摩耗を促進し、遂には偏摩耗へと発展する
のである。By the way, it is known that a large lateral force from the road surface toward the inside (the inside of the turn) acts on the pneumatic tire mounted on the outside of the turn during turning of the vehicle. When acting on the entering tire, a large bending force acts on the land portion near the shoulder end on the outer side of mounting. Here, when the axial width of the land portion near the shoulder end is small, a large deformation occurs due to the large bending force, and as a result, the contact pressure of the land portion of the portion is higher than other portions. Become. As a result, when the vehicle turns, abrasion easily occurs on the land portion of the portion. If the abrasion occurs even in such a manner, the abraded portion is dragged when the vehicle goes straight ahead, and further promotes abrasion. It develops into uneven wear.

この発明は、このような装着外方側のショルダー端近
傍の陸部に生じる偏摩耗を、前述した段差領域を用いて
効果的に阻止することを目的とするもので、踏面に主溝
および陸部を有し、車両に対する装着側が規定されてい
る空気入りタイヤにおいて、軸方向最外側に位置する主
溝より軸方向外側で装着外方側のショルダー端と該ショ
ルダー端から踏面幅の1/3だけ離れた点との間の陸部
に、周方向に連続して延び該陸部を二分する一対の周溝
を形成してこれら周溝間に陸部から独立した段差領域を
画成するとともに、該段差領域の半径方向外端面を前記
陸部の断面輪郭線より半径方向内側に位置させ、かつ、
前記一対の周溝のうち軸方向外側に位置する周溝を狭幅
にし、走行時に踏面接地域に位置する段差領域の半径方
向外端面を路面にすべり接触させて該段差領域を偏摩耗
犠牲部として機能させるとともに、タイヤが受ける荷重
に対する比が0.1に相当する装着内方側に向かう横力を
路面から受けたとき該軸方向外側の周溝の側面同士を接
触させて段差領域より軸方向外側に位置する陸部の曲げ
変形を抑制するようにした空気入りタイヤである。An object of the present invention is to effectively prevent uneven wear generated on a land portion near the shoulder end on the outer side of the mounting by using the above-described step region, and a main groove and a land are provided on a tread surface. In the pneumatic tire having a portion, the mounting side to the vehicle is defined, in the axial direction outside the main groove located on the outermost in the axial direction, the shoulder end on the mounting outer side and 1/3 of the tread width from the shoulder end. A pair of circumferential grooves extending continuously in the circumferential direction and bisecting the land portion are formed in a land portion between the points only apart from each other to define a step region independent of the land portion between the circumferential grooves. Positioning the radially outer end face of the step region radially inward from the cross-sectional contour of the land portion, and
Of the pair of circumferential grooves, the circumferential groove located on the outside in the axial direction is made narrower, and the radially outer end face of the step region located in the tread contact area is brought into sliding contact with the road surface during traveling to make the step region an uneven wear sacrificial portion. When a lateral force directed toward the inner side of the mounting is received from the road surface, the ratio of the load received by the tire to the load received by the tire is equal to 0.1. This is a pneumatic tire that suppresses bending deformation of a land portion located in a pneumatic tire.

ここで、前記軸方向外側の周溝の開口端における幅を
1.5mmから3.0mmまでの範囲内にすることが好ましく、ま
た、該周溝の幅を開口側より溝底側において広くすると
よい。Here, the width at the open end of the axially outer circumferential groove is
It is preferable that the width be in the range of 1.5 mm to 3.0 mm, and the width of the peripheral groove be wider on the groove bottom side than on the opening side.

さらに、前記段差領域の半径方向外端面を軸方向外側
に向かうに従い半径方向内側へ傾斜させるとよい。Further, the radially outer end face of the step region may be inclined inward in the radial direction toward the outside in the axial direction.

作用 今、前述したような空気入りタイヤが車両に段差領域
が装着外方側に位置するよう、即ち規定通りの装着側で
装着されているとする。この状態で、車両を旋回させる
と、旋回外側に装着されている空気入りタイヤには摩擦
によって路面から装着内方側（旋回内側）に向かう大き
な横力が作用し、該空気入りタイヤが軸方向に曲げ変形
する。そして、このような曲げ変形は装着外方側のショ
ルダー端近傍の陸部において最大となる。しかしなが
ら、この発明においては装着外方側のショルダー端と該
ショルダー端から踏面幅の1/3だけ離れた点との間の陸
部、即ち、前記最大曲げ変形が生じる部位近傍の陸部
に、一対の周溝を形成して前述したような段差領域を画
成するとともに、前記周溝のうち軸方向外側に位置する
周溝を狭幅としたので、該周溝より軸方向横外側に位置
する陸部が、タイヤが受ける荷重に対する比が0.1に相
当する横力を路面から受けて曲げ変形すると、軸方向外
側の周溝が潰れてその側面同士が接触、即ち前記周溝よ
り軸方向外側に位置する陸部が段差領域に接触する。こ
こで、この段差領域は、その半径方向外端面が陸部の断
面輪郭線より半径方向内側に位置し、しかも、ある程度
の曲げ剛性を有しているため、前記陸部に対する突っ張
りとして機能し、該陸部の曲げ変形を抑制する。このよ
うに曲げ変形が抑制されると、該陸部の接地圧はさほど
高くならず、偏摩耗の発生が阻止される。ここで、軸方
向最外側に位置する主溝より軸方向外側の陸部に周溝を
配置したのは、仮に周溝より軸方向外側に主溝が配置さ
れていると、横力を受けても該主溝の側面同士は接触し
ないので、曲げ変形は抑制されないからである。Operation Now, it is assumed that the above-described pneumatic tire is mounted on the vehicle such that the step region is located on the outer side of mounting, that is, on the mounting side as specified. In this state, when the vehicle is turned, a large lateral force is applied to the pneumatic tire mounted on the outside of the turn from the road surface toward the inside (the inside of the turn) from the road surface by friction, and the pneumatic tire is axially moved. Bending deformation. Such bending deformation becomes maximum in the land portion near the shoulder end on the outer side of mounting. However, in the present invention, a land portion between the shoulder end on the outer side of mounting and a point separated by 1/3 of the tread width from the shoulder end, that is, a land portion near the portion where the maximum bending deformation occurs, A pair of circumferential grooves are formed to define the step region as described above, and the circumferential groove located on the outside in the axial direction among the circumferential grooves has a narrow width. When the land portion is subjected to bending deformation by receiving a lateral force equivalent to 0.1 from the road surface with respect to the load received by the tire, the outer circumferential grooves are crushed and their side surfaces are in contact with each other, that is, the outer circumferential grooves are outer than the circumferential grooves. The land located at the point contacts the step area. Here, the step region has a radially outer end face located radially inward of the cross-sectional contour of the land portion, and has a certain degree of bending rigidity, so that it functions as a tension for the land portion, Bending deformation of the land is suppressed. When the bending deformation is suppressed in this manner, the contact pressure of the land does not become so high, and the occurrence of uneven wear is prevented. Here, the circumferential groove is arranged on the land portion axially outside of the main groove located on the outermost side in the axial direction. If the main groove is arranged on the axially outer side of the circumferential groove, a lateral force is applied. This is also because the side surfaces of the main groove do not contact each other, so that bending deformation is not suppressed.

そして、軸方向外側の周溝の開口端における幅を前述
の範囲内にすれば、陸部の曲げ変形抑制効果が確実にな
り、また、周溝の幅を開口側より溝底側において広くす
ると、周溝の断面積が増大するため、前記抑制効果を維
持しつつウェット性能を向上させることができる。さら
に、段差領域の半径方向外端面を軸方向外側に向かうに
伴い半径方向内側へ傾斜させれば、陸部と接触する段差
領域のエッジが鈍角となり、突っ張り効果が向上する。When the width at the opening end of the circumferential groove on the outer side in the axial direction is in the above range, the effect of suppressing the bending deformation of the land portion is ensured, and when the width of the circumferential groove is wider at the groove bottom side than at the opening side. Since the cross-sectional area of the circumferential groove increases, the wet performance can be improved while maintaining the above-described suppression effect. Furthermore, if the radially outer end face of the stepped region is inclined radially inward as going outward in the axial direction, the edge of the stepped region that comes into contact with the land portion becomes obtuse, and the stretching effect is improved.

実施例 以下、この発明の第１実施例を図面に基づいて説明す
る。Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.

第１、２図において、１はバス、トラック等の従動輪
または遊輪に装着される重荷重用の空気入りラジアルタ
イヤであり、このタイヤ１はトロイダル状をしたラジア
ルカーカス２と、ラジアルカーカス２の半径方向外側に
配置された複数層のベルト３と、このベルト３の半径方
向外側に配置されたトレッド４とを有する。このタイヤ
１の一方のショルダー端５から他方のショルダー端（図
示していない）までの外表面、即ち踏面６には周方向に
延びる連続した主溝７が複数本（この実施例では２本）
形成されている。この結果、踏面６はこれら主溝７によ
り周方向に延びる３本の陸部８、即ち、タイヤ赤道面９
上に位置する中央リブ8aと、中央リブ8aの両側に位置す
る側方リブ8bとに区分される。ここで、前記主溝７はタ
イヤ赤道面９と平行なジグザグ状溝であるが、この主溝
７は公知の周方向直溝であってもよい。また、前記陸部
８はここでは周方向に連続したリブであるが、この陸部
８は横溝または補助溝などによってさらに区分された、
いわゆるブロックあるいはこれを含むリブーブロック複
合のものでもよい。また、装着外方側、即ち車両の中心
から離隔した側のショルダー端５と該ショルダー端５か
ら踏面幅Ｗの1/3だけ離れた点Ｐとの間の陸部８、ここ
では側方リブ8bには、周方向に連続して延びる一対の周
溝10、11が形成されている。ここで、周溝10、11をショ
ルダー端５と点Ｐとの間の陸部８に形成するようにした
のは、第１に、横力を受けたとき、前記領域の陸部に大
きな曲げ力が作用して接地圧が他の領域より高くなるた
めであり、第２に、前記点Ｐより軸方向内側に周溝10、
11を形成すると、該周溝10、11より軸方向外側に位置す
る陸部８の幅がかなり広くなってタイヤ１に横力が作用
したときにも該陸部８が殆ど曲げ変形しなくなるからで
ある。また、これら周溝10、11は、主溝７が複数本形成
されている場合には、軸方向最外側に位置する主溝７よ
り軸方向外側の陸部８に形成される。その理由は、周溝
10、11より軸方向外側の陸部８に主溝が存在している
と、タイヤ１が横力を受けて主溝より軸方向外側の陸部
が曲げ変形しても、主溝はその側面同士が接触するまで
は潰れないため、前記陸部の曲げ変形を阻止することが
できないからである。そして、前述のような周溝10、11
は陸部８（側方リブ8b）に形成されることで、該陸部８
（側方リブ8b）を当該位置において外側リブORと内側リ
ブIRとに軸方向に二分割する。ここで、各周溝10、11は
同一位相のジグザグ状溝であるが、これら周溝10、11は
タイヤ赤道面９と平行な周方向直溝であってもよい。こ
のように陸部８に周溝10、11を形成すると、対をなす周
溝10、11間の踏面６に前記陸部８（側方リブ8b）から独
立した段差領域12が画成される。ここで、各段差領域12
は周方向に連続して延びるジグザグ状の細リブである
が、この段差領域12は直線状の細リブであってもよく、
また、軸方向に延びる横溝、サイプ等によりブロックに
分割されていてもよい。また、前記周溝のうち軸方向外
側に位置する周溝10は少なくとも開口端において狭幅で
あり、その開口端における軸方向幅Ａは1.5mmから3.0mm
までの範囲内であることが好ましい。その理由は、軸方
向幅Ａが1.5mm未満であると、タイヤの横力が零であっ
ても、接地時、常に段差領域12と外側リブORとが接触す
るため、タイヤが周方向の変形をしたとき、外側リブOR
と段差領域12とが一体的に変形し、段差領域12が摩耗犠
牲部としての機能を充分に果さないからであり、一方、
3.0mmを超えると、タイヤ１に過大な横力が作用したと
きのみ周溝10の側面13、14同士が接触することになるの
で、段差領域12が突っ張りとしての機能を充分果し得な
いからである。このように周溝10を少なくとも開口端に
おいて狭幅としたので、路面からタイヤ１に、該タイヤ
１が受ける荷重に対する比が0.1に相当する装着内方側
に向かう横力、換言すれば、車両が0.1Gを受けていると
きタイヤ１が受ける横力が作用すると、該周溝10の側面
13、14同士、換言すれば外側リブORの軸方向内側面13お
よび段差領域12の軸方向外側面14同士が開口端において
接触し、該段差領域12が外側リブORに対する突っ張りと
して機能する。また、この周溝10はその軸方向幅Ａが半
径方向（深さ方向）に一定であるが、周溝のうち軸方向
内側に位置する周溝11は、その開口端における軸方向が
前記周溝10の軸方向幅Ａより広く、また、その軸方向幅
は溝底、即ち半径方向内側に向かうに従い狭くなってい
る。この結果、前記段差領域12は半径方向内側に向かう
に従いその軸方向幅が広くなっている。これにより、段
差領域12の曲げ剛性が高くなり、外側リブORの曲げ変形
に対する突っ張り効果が増大する。また、前記段差領域
12はその半径方向外端面15が前記陸部８の断面輪郭線よ
り半径方向内側に位置し、前記タイヤ１に正規荷重の50
％〜200％の荷重が作用したとき、前記段差領域12の半
径方向外端面15は路面に接触する。ここで前記半径方向
外端面15と断面輪郭線との間の距離ａは１〜5mmが好ま
しい。そして、タイヤ１が通常の荷重を受けていると
き、この半径方向外端面15は踏面接地域に到達すると、
陸部８と同様に路面と接触するが、この半径方向外端面
15における１周長は陸部８の外面における１周長より短
いため、該半径方向外端面15は路面にすべり接触し、大
きな制動方向の剪断力を受ける。また、段差領域12の半
径方向外端面15は前記陸部８の断面輪郭線より半径方向
内側に位置しているため、外側リブORが曲げ変形したと
き、段差領域12は該外側リブORの半径方向中央部におい
て接触することになり、この結果、該段差領域12は外側
リブORと一体となって変形せず突っ張りとして機能する
のである。また、前記段差領域12の半径方向外端面15か
らは、軸方向外側（装着外方側）に向かうに従い半径方
向内側に傾斜しており、この結果、該段差領域12の軸方
向外端エッジは90度以上の鈍角となる。ここで、前記外
側リブORが曲げ変形したとき、該外側リブORは段差領域
12にその軸方向外端エッジにおいて接触するが、前述の
ように該軸方向外端エッジは鈍角であるため段差領域12
は押し潰されにくく、この結果、外側リブORの曲げ変形
を効果的に抑制することができる。1 and 2, reference numeral 1 denotes a heavy-duty pneumatic radial tire mounted on a driven wheel or a free wheel such as a bus or a truck. The tire 1 has a toroidal radial carcass 2 and a radius of the radial carcass 2. The belt 3 includes a plurality of layers of belts 3 arranged on the outside in the direction, and a tread 4 arranged on the outside of the belt 3 in the radial direction. The outer surface from one shoulder end 5 to the other shoulder end (not shown) of the tire 1, that is, the tread surface 6, has a plurality of (two in this embodiment) continuous main grooves 7 extending in the circumferential direction.
Is formed. As a result, the tread surface 6 has three land portions 8 extending circumferentially by the main grooves 7, that is, the tire equatorial surface 9.
It is divided into a central rib 8a located above and side ribs 8b located on both sides of the central rib 8a. Here, the main groove 7 is a zigzag groove parallel to the tire equatorial plane 9, but the main groove 7 may be a known circumferential straight groove. Further, the land portion 8 is a rib continuous in the circumferential direction here, but the land portion 8 is further divided by a lateral groove or an auxiliary groove.
A so-called block or a rib-block composite containing the same may be used. Further, a land portion 8 between the shoulder end 5 on the outer side of the mounting, that is, the side separated from the center of the vehicle and a point P separated from the shoulder end 5 by 1/3 of the tread width W, here a side rib A pair of circumferential grooves 10, 11 extending continuously in the circumferential direction are formed in 8b. Here, the circumferential grooves 10 and 11 are formed in the land portion 8 between the shoulder end 5 and the point P because, first, when a lateral force is applied, the land portion in the region has a large bending. Secondly, the contact pressure is higher than that of the other areas due to the action of the force.
When the tire 11 is formed, the land portion 8 located axially outside the circumferential grooves 10 and 11 becomes considerably wide, so that even when a lateral force acts on the tire 1, the land portion 8 hardly bends and deforms. It is. When a plurality of main grooves 7 are formed, these peripheral grooves 10 and 11 are formed on land portions 8 that are axially outside the main groove 7 that is located on the outermost side in the axial direction. The reason is the circumferential groove
If the main groove exists in the land portion 8 that is axially outside of the main grooves 10 and 11, even if the tire 1 receives a lateral force and the land portion that is axially outside the main groove bends and deforms, the main groove remains on the side surface. This is because they are not crushed until they come into contact with each other, so that bending deformation of the land portion cannot be prevented. And the circumferential grooves 10 and 11 as described above
Is formed on the land portion 8 (side rib 8b) so that the land portion 8
The (lateral rib 8b) is axially divided into two at the position, an outer rib OR and an inner rib IR. Here, the circumferential grooves 10 and 11 are zigzag grooves having the same phase, but the circumferential grooves 10 and 11 may be circumferential straight grooves parallel to the tire equatorial plane 9. When the circumferential grooves 10 and 11 are formed in the land portion 8 as described above, a step region 12 independent of the land portion 8 (side rib 8b) is defined on the tread surface 6 between the pair of circumferential grooves 10 and 11. . Here, each step region 12
Is a zigzag thin rib extending continuously in the circumferential direction, but the step region 12 may be a linear thin rib,
Further, it may be divided into blocks by lateral grooves or sipes extending in the axial direction. The circumferential groove 10 located on the axially outer side of the circumferential groove has a narrow width at least at the opening end, and the axial width A at the opening end is 1.5 mm to 3.0 mm.
It is preferable to be within the range up to. The reason is that when the axial width A is less than 1.5 mm, even when the lateral force of the tire is zero, the step region 12 and the outer rib OR always contact at the time of contact with the ground, so that the tire is deformed in the circumferential direction. The outer rib OR
This is because the step region 12 and the step region 12 are integrally deformed, and the step region 12 does not sufficiently function as a wear sacrificial portion.
If it exceeds 3.0 mm, the side surfaces 13 and 14 of the circumferential groove 10 come into contact with each other only when an excessive lateral force acts on the tire 1, so that the step region 12 cannot sufficiently function as a tension. It is. Since the circumferential groove 10 has a narrow width at least at the opening end, the lateral force from the road surface to the tire 1 toward the inside of the mounting, where the ratio of the load applied to the tire 1 to the load is 0.1, in other words, the vehicle When the tire receives the 0.1G and the lateral force received by the tire 1 acts, the side surface of the circumferential groove 10
The axially inner surfaces 13 of the outer ribs OR and the axially outer surfaces 14 of the step region 12 contact each other at the open end, and the step region 12 functions as a tension against the outer rib OR. The circumferential groove 10 has an axial width A that is constant in the radial direction (depth direction). Among the circumferential grooves 10, the circumferential groove 11 located on the inner side in the axial direction has the axial direction at the open end thereof. The axial width of the groove 10 is wider than the axial width A, and the axial width is narrower toward the groove bottom, that is, toward the radially inner side. As a result, the width of the step region 12 in the axial direction increases toward the inside in the radial direction. Accordingly, the bending rigidity of the step region 12 is increased, and the effect of stretching the outer rib OR against bending deformation is increased. Further, the step region
Reference numeral 12 denotes a tire whose radial outer end face 15 is located radially inward of the cross-sectional contour line of the land portion 8 and has a normal load of 50 on the tire 1.
When a load of% to 200% is applied, the radially outer end surface 15 of the step region 12 comes into contact with the road surface. Here, the distance a between the radial outer end face 15 and the cross-sectional contour is preferably 1 to 5 mm. Then, when the tire 1 is under normal load, when this radial outer end face 15 reaches the tread contact area,
It comes into contact with the road surface in the same way as the land part 8, but this radial outer end face
Since one circumference at 15 is shorter than one circumference on the outer surface of the land portion 8, the outer radial end surface 15 comes into sliding contact with the road surface and receives a large shearing force in the braking direction. Further, since the radially outer end face 15 of the step region 12 is located radially inward of the cross-sectional contour line of the land portion 8, when the outer rib OR is bent and deformed, the step region 12 has the radius of the outer rib OR. The contact is made at the central portion in the direction, and as a result, the step region 12 functions as a tension without being deformed integrally with the outer rib OR. In addition, from the radially outer end surface 15 of the step region 12, it is inclined radially inward toward the outside in the axial direction (outward of the mounting). As a result, the axially outer end edge of the step region 12 is It becomes an obtuse angle of 90 degrees or more. Here, when the outer rib OR is deformed by bending, the outer rib OR is in a step region.
The outer edge 12 contacts the outer edge 12 in the axial direction.
Is hardly crushed, and as a result, bending deformation of the outer rib OR can be effectively suppressed.

次に、この発明の第１実施例の作用について説明す
る。Next, the operation of the first embodiment of the present invention will be described.

前述したタイヤ１をトラック、バス等にその段差領域
12が装着外方側に位置するよう、即ち規定通りの装着側
に装着して走行させると、該タイヤ１は路面と接地する
領域において押し潰され、大略矩形の踏面接地域が形成
されるが、この踏面接地域内においては前記陸部８の外
面および段差領域12の半径方向外端面15は共に路面に接
地する。ここで、前記段差領域12の半径方向外端面15は
陸部８の断面輪郭線より半径方向内側に位置しているた
め、段差領域12の半径方向外端面15における１周長は陸
部８の外面における１周長より短いが、前述のように段
差領域12の半径方向外端面15および陸部８の外面は踏面
接地域に到達したとき共に接地するため、この段差領域
12の半径方向外端面15は路面に引き摺られながらすべり
接触することになる。この結果、段差領域12にタイヤ１
の転動を制動する向きの、即ち制動方向の極めて大きな
剪断力が発生する。ここで、タイヤ１の陸部８全体に発
生する剪断力の合計値は各タイヤ１において一定である
と考えられるため、タイヤ１の踏面６の一部に、即ち段
差領域12に大きな制動方向剪断力が偏在すると、残りの
タイヤ１の踏面６、即ち段差領域12の両側の陸部８の剪
断力が結果として駆動側にシフトアップされる。この結
果、陸部８に作用する剪断力は陸部８のいずれの部分に
おいても駆動方向のものとなる。ここで、駆動方向剪断
力を受けている踏面６の摩耗速度は制動方向剪断力を受
けている踏面６の摩耗速度より著しく遅いため、前述の
ように制動方向剪断力を受けている段差領域12のみが犠
牲となって摩耗し、陸部８の偏摩耗が防止されるのであ
る。The above-mentioned tire 1 is used for trucks, buses and the like in the step area thereof.
When the tire 12 is located on the outer side of the mounting, that is, when the tire 1 is mounted on the mounting side as specified, the tire 1 is crushed in a region where the tire 1 comes into contact with the road surface, and a substantially rectangular tread contact area is formed. In the tread contact area, the outer surface of the land portion 8 and the outer end face 15 in the radial direction of the step region 12 both contact the road surface. Here, since the radially outer end face 15 of the step region 12 is located radially inward from the cross-sectional contour of the land portion 8, one circumferential length of the radially outer end surface 15 of the step region 12 is equal to that of the land portion 8. Although it is shorter than one circumference on the outer surface, as described above, the radially outer end surface 15 of the stepped region 12 and the outer surface of the land portion 8 come into contact with each other when reaching the tread contact area.
The outer end face 15 in the radial direction of 12 comes into sliding contact with the road surface while being dragged. As a result, the tire 1
An extremely large shear force is generated in a direction for braking the rolling of the motor, that is, in the braking direction. Here, since the total value of the shearing force generated in the entire land portion 8 of the tire 1 is considered to be constant in each tire 1, a large amount of shearing force in the braking direction is formed on a part of the tread surface 6 of the tire 1, that is, on the step region 12. When the force is unevenly distributed, the shear force of the tread surface 6 of the remaining tire 1, that is, the land portion 8 on both sides of the step region 12 is shifted up to the driving side as a result. As a result, the shearing force acting on the land portion 8 is in the driving direction in any portion of the land portion 8. Here, since the wear speed of the tread surface 6 receiving the driving direction shearing force is significantly lower than the wear speed of the tread surface 6 receiving the braking direction shearing force, the step region 12 receiving the braking direction shearing force as described above. Only at the expense of abrasion, uneven wear of the land portion 8 is prevented.

次に、車両を走行させながら旋回させると、旋回外側
に装着されているタイヤ１には摩擦によって路面から装
着内方側（旋回内側）に向かう大きな横力が作用し、該
タイヤ１が軸方向に曲げ変形する。そして、このような
曲げ変形は陸部８の軸方向幅が狭いとき、例えば踏面幅
Ｗの1/3以下であるときには大きくなり、また、装着外
方側のショルダー端５に近付くほど大きくなる。しかし
ながら、この発明においては、装着外方側のショルダー
端５と該ショルダー端５から踏面幅Ｗの1/3だけ離れた
点Ｐとの間の陸部８に一対の周溝10、11を形成して前述
したような段差領域12を画成するとともに、前記周溝の
うち軸方向外側に位置する周溝10を少なくとも開口端に
おいて狭幅としたので、外側リブORがタイヤが受ける荷
重に対する比が0.1に相当する横力より大きい力を路面
から受けて軸方向内側に曲げ変形すると、前記周溝10が
潰れてその側面13、14同士が接触、即ち外側リブORが段
差領域12に接触する。ここで、この段差領域12は、その
半径方向外側面15が該陸部８の断面輪郭線より半径方向
内側に位置し、しかも、ある程度の曲げ剛性を有してい
るため、前記接触時、外側リブORに対する突っ張りとし
て機能し、該外側リブORの曲げ変形を抑制する。このよ
うに曲げ変形が抑制されると、該外側リブORの接地圧は
さほど高くならず、偏摩耗の発生が阻止される。また、
このとき、段差領域12の半径方向外端面15は軸方向外側
に向かうに伴い半径方向内側へ傾斜しているため、段差
領域12の軸方向外端エッジが鈍角となり、前記外側リブ
ORの曲げ変形を効果的に抑制することができる。Next, when the vehicle is turned while the vehicle is running, a large lateral force is applied to the tire 1 mounted on the outside of the turn from the road surface toward the inside (the inside of the turn) from the road surface due to friction. Bending deformation. Such bending deformation increases when the axial width of the land portion 8 is small, for example, when it is equal to or less than 1/3 of the tread width W, and increases as the distance from the shoulder end 5 closer to the outer side of the mounting increases. However, in the present invention, a pair of circumferential grooves 10 and 11 are formed in the land portion 8 between the shoulder end 5 on the outer side of mounting and the point P separated from the shoulder end 5 by 1/3 of the tread width W. As described above, the step region 12 is defined as described above, and the circumferential groove 10 located on the axially outer side among the circumferential grooves is made to have a narrow width at least at the open end. When receiving a force greater than the lateral force equivalent to 0.1 from the road surface and bending inward in the axial direction, the circumferential groove 10 is crushed and the side surfaces 13 and 14 contact each other, that is, the outer rib OR contacts the step region 12. . Here, the stepped region 12 has a radially outer surface 15 located radially inward of the cross-sectional contour of the land portion 8 and has a certain degree of bending rigidity. It functions as a tension against the rib OR, and suppresses bending deformation of the outer rib OR. When the bending deformation is suppressed in this way, the contact pressure of the outer rib OR does not increase so much, and the occurrence of uneven wear is prevented. Also,
At this time, since the radially outer end face 15 of the step region 12 is inclined inward in the radial direction as going outward in the axial direction, the axially outer end edge of the step region 12 becomes obtuse, and the outer rib
The bending deformation of OR can be effectively suppressed.

次に、第１試験例を説明する。この試験を開始するに
当って、第３、４図に示すような比較タイヤ１と、第
５、６図に示すような本発明を実施した供試タイヤ１
と、前述の第１実施例で説明した第１、２図に示されて
いる供試タイヤ２と、第７、８図に示すような本発明を
実施した供試タイヤ３と、第９、10図に示すような本発
明を実施した供試タイヤ４と、を準備した。前記比較タ
イヤ１は、踏面６にジグザグ状をした４本の主溝７のみ
を形成したタイヤであり、供試タイヤ１は両周溝21、22
を同一幅になすとともに、段差領域23の半径方向外端面
24を陸部８の断面輪郭線と略平行に延在させたタイヤで
ある。また、供試タイヤ３は供試タイヤ２の半径方向外
端面15を陸部８の断面輪郭線と略平行な半径方向外端面
25に変更したタイヤであり、供試タイヤ４は供試タイヤ
２の半径方向外端面15を陸部８の断面輪郭線と略平行な
半径方向外端面27に変更するとともに、周溝10をその軸
方向内側面が半径方向内側に向かうに従い軸方向内側へ
傾斜した周溝28に変更している。この結果、供試タイヤ
４にあっては、周溝28の幅は開口端から半径方向内側に
向かうに従い、即ち、溝底側に向かうに従い広くなって
おり、このため、周溝28の断面積が増大して排水能力が
向上し、ウェット性能が向上するのである。また、この
供試タイヤ４の周溝28、11は前述のような断面形状であ
るため、段差領域26は全体として半径方向外側に向かう
に従い軸方向外側（装着外方側）へ傾斜していることに
なる。このような方向に段差領域26が傾斜していると、
曲げ変形時の外側リブORに対する交差角が大きくなり、
突っ張り効果が増大する。ここで、前述した各タイヤの
サイズは11R22.5 14PRで、使用リムは8.25×22.5であ
った。次に、このような各タイヤに8.0Kg/Cm2の内圧を
充填するとともに、積載率が100％である2D−４車（平
ボディートラック）の前輪に該タイヤをそれぞれ装着し
た後、高速道路と一般道路とが７対３の走行路（全舗
装）を８万Km走行し、走行終了時点での踏面における摩
耗量を測定した。その測定結果を指数化し耐摩耗性とし
て別表１に示すが、この別表から明らかなように、この
発明を実施した供試タイヤでは耐摩耗性が向上してお
り、（指数値が大であるほど耐摩耗性が向上）特に、段
差領域の半径方向外端面の接地面積が広いほど耐摩耗性
が向上している。なお、ここで、指数100は5.7mmであ
る。また、前記走行終了時点における装着外方側ショル
ダー端での摩耗量およびタイヤ赤道面上での摩耗量を測
定し、これらの測定値から偏摩耗性、即ち、装着外方側
ショルダー端での摩耗量とタイヤ赤道面上での摩耗量と
の比を求め、別表１に示した。ここで偏摩耗性は値が１
に近くなるほど良好であり、別表１からわかるように供
試タイヤの方が偏摩耗性は良好である。また、前述した
各タイヤによってウェット時に走行し、各タイヤのウェ
ットμ指数を求めた。その結果を別表１にウェット性能
として示すが、この別表１から明らかなように供試タイ
ヤの方がウェット性能も良好であり、供試タイヤの中で
も周溝の断面積が広くなるほど良好となる。Next, a first test example will be described. In starting this test, a comparative tire 1 as shown in FIGS. 3 and 4 and a test tire 1 in which the present invention as shown in FIGS.
The test tire 2 shown in FIGS. 1 and 2 described in the first embodiment described above, the test tire 3 embodying the present invention as shown in FIGS. A test tire 4 according to the present invention as shown in FIG. 10 was prepared. The comparative tire 1 is a tire in which only four zigzag main grooves 7 are formed on the tread surface 6, and the test tire 1 has both circumferential grooves 21, 22.
Are made the same width, and the radially outer end face of the step region 23 is formed.
24 is a tire in which 24 extends substantially parallel to the cross-sectional contour of the land portion 8. Also, the test tire 3 has a radially outer end surface 15 of the test tire 2 that is substantially parallel to the cross-sectional contour of the land portion 8.
The test tire 4 has a radial outer end surface 15 which is changed to a radial outer end surface 27 which is substantially parallel to the cross-sectional contour of the land portion 8 and the circumferential groove 10 has the circumferential groove 10. The circumferential groove 28 is inclined inward in the axial direction as the inner side surface in the axial direction moves toward the inner side in the radial direction. As a result, in the test tire 4, the width of the circumferential groove 28 increases radially inward from the opening end, that is, toward the groove bottom side. , Drainage capacity is improved, and wet performance is improved. In addition, since the circumferential grooves 28 and 11 of the test tire 4 have the cross-sectional shape as described above, the step region 26 is inclined toward the outside in the axial direction (outward toward the mounting side) as a whole toward the outside in the radial direction. Will be. If the step region 26 is inclined in such a direction,
The crossing angle with the outer rib OR during bending deformation increases,
Stretching effect increases. Here, the size of each tire described above was 11R22.5 14PR, and the rim used was 8.25 × 22.5. Next, the tires are filled with an internal pressure of 8.0 kg / Cm 2 and the tires are mounted on the front wheels of a 2D-4 car (flat body truck) having a loading rate of 100%, respectively. And a general road traveled 80,000 km on a 7: 3 travel path (entire pavement), and the amount of wear on the tread at the end of the travel was measured. The measurement results are indexed and shown in Table 1 as wear resistance. As is clear from the table, the test tires according to the present invention have improved wear resistance. In particular, as the contact area of the radially outer end face of the step region is larger, the wear resistance is improved. Here, the index 100 is 5.7 mm. Further, the amount of wear at the outer shoulder side of the mounting and the amount of abrasion on the tire equatorial plane at the end of the running were measured. The ratio between the amount of wear and the amount of wear on the tire equatorial plane was determined and is shown in Table 1 below. Here, the value of uneven wear is 1
, The test tire has better uneven wear as shown in Table 1. In addition, each tire was run in a wet state, and the wet μ index of each tire was determined. The results are shown in Table 1 as wet performance. As is clear from Table 1, the test tire has better wet performance, and among the test tires, the better the cross-sectional area of the circumferential groove is, the better.

次に、第２試験例を説明する。この試験に用いる各タ
イヤのトレッドパターンは前記第１試験例で用いた各タ
イヤのトレッドパターンとほぼ同様であるが、特に、周
溝31、32の軸方向幅が供試タイヤ７を除き半径方向に一
定である点、陸部33が横溝34によってブロック状に分割
されている点および段差領域35がジグザグの１サイクル
毎に横溝36によって分割されている点で異なる。そし
て、この試験に当っては第11、12図に示すような比較タ
イヤ２と、第13、14図に示すような供試タイヤ５と、第
15、16図に示すような供試タイヤ６と、第17、18図に示
すような供試タイヤ７とを準備した。ここで、前述した
各タイヤのサイズは185SR14で使用リムは5.5JJ−14であ
った。次に、このような各タイヤに2.0Kg/Cm2の内圧を
充填するとともに、積載率が100％であるFR駆動式乗用
車の前輪に各タイヤをそれぞれ装着した後、高速道路と
一般道路とが７対３の走行路（全舗装）を８万Km走行
し、走行終了時点で踏面における摩耗量を測定した。そ
の結果を指数化し耐摩耗性として別表２に示すが、この
試験例でも耐摩耗性は供試タイヤの方が良好である。こ
こで、指数100は実際には4.8mmであった。また、前記第
１試験例と同様に装着外方側のショルダー端での摩耗量
とタイヤ赤道面上での摩耗量との比から耐偏摩耗性を求
めたが、この試験例でも別表２に示すように供試タイヤ
の方が良好である。さらに、ウェット性能についても前
記第１試験例と同様に試験を行なったが、別表２に示す
結果から明らかなように供試タイヤの方が良好である。Next, a second test example will be described. The tread pattern of each tire used in this test is almost the same as the tread pattern of each tire used in the first test example. In particular, the axial width of the circumferential grooves 31 and 32 is the same in the radial direction except for the test tire 7. The difference is that the land portion 33 is divided into blocks by the lateral grooves 34 and that the step region 35 is divided by the lateral grooves 36 every zigzag cycle. In this test, a comparative tire 2 as shown in FIGS. 11 and 12, a test tire 5 as shown in FIGS.
A test tire 6 as shown in FIGS. 15 and 16 and a test tire 7 as shown in FIGS. 17 and 18 were prepared. Here, the size of each tire described above was 185SR14 and the rim used was 5.5JJ-14. Next, while filling each such tire with an internal pressure of 2.0 kg / Cm 2 and mounting each tire on the front wheel of an FR-driven passenger car having a loading ratio of 100%, the expressway and the general road are connected. After running 80,000 km on a 7: 3 running path (entire pavement), the amount of wear on the tread was measured at the end of running. The results are indexed and shown in Table 2 as wear resistance. In this test example as well, the wear resistance of the test tire is better. Here, the index 100 was actually 4.8 mm. Also, as in the first test example, the uneven wear resistance was determined from the ratio of the wear amount at the shoulder end on the outer side of the mounting and the wear amount on the tire equatorial plane. As shown, the test tires are better. Further, the wet performance was also tested in the same manner as in the first test example. As is clear from the results shown in Table 2, the test tire was better.

第19図から28図まではこの発明の他の実施例を示す図
である。第19図に示す第２実施例は周溝46の深さを周溝
45の深さより深くした以外は第７、８図と同様のタイヤ
であり、第20図に示す第３実施例は周溝48の深さを周溝
47の深さより深くした以外は第５、６図と同様のタイヤ
であり、第21図に示す第４実施例は第20図とは逆に周溝
49の深さを周溝50の深さより深くしたタイヤである。ま
た、第22図に示す第５実施例は周溝51の軸方向外側面を
半径方向内側に向かうに従い軸方向内外側に傾斜させて
周溝51の軸方向幅を開口側より溝底側に向かうに従い広
くするようにした以外は第７、８図と同様のタイヤであ
り、第23図に示す第６実施例は、周溝52を溝底側に向か
うに従い広くした以外は第９、10図と同様のタイヤであ
る。第24図に示す第７実施例は、両周溝53、54が半径方
向外側に向かうに従い軸方向外側（装着外方側）に傾斜
している以外は第５、６図と同様のタイヤであり、第25
図に示す第８実施例は両周溝55、56が半径方向外側に向
かうに従い軸方向内側に傾斜している以外は第５、６図
と同様のタイヤである。第26図に示す第９実施例は段差
領域57の半径方向外端面58が軸方向外側に向かうに従い
半径方向内側へ傾斜している以外は第５、６図と同様の
タイヤである。さらに、第27図に示す第10実施例は、軸
方向外側の周溝59が半径方向外側に向かうに従い軸方向
内側に傾斜し、一方、軸方向内側の周溝60が半径方向外
側に向かうに従い軸方向外側に傾斜し、これにより段差
領域61の軸方向幅が半径方向内側に向かうに従い広くな
っている以外は第５、６図と同様のタイヤであり、第28
図に示す第11実施例は半径方向外端面62が軸方向外側に
向かうに従い半径方向内側へ傾斜している以外は第27図
と同様のタイヤである。19 to 28 show another embodiment of the present invention. In the second embodiment shown in FIG.
7 and 8 except that the depth is larger than the depth of the circumferential groove 48. The third embodiment shown in FIG.
The tires are the same as in FIGS. 5 and 6 except that they are deeper than the depth of 47. The fourth embodiment shown in FIG.
This is a tire in which the depth of 49 is deeper than the depth of the circumferential groove 50. In the fifth embodiment shown in FIG. 22, the axial outer side surface of the circumferential groove 51 is inclined inward and outward in the axial direction toward the inside in the radial direction so that the axial width of the circumferential groove 51 is closer to the groove bottom side than the opening side. The tire is the same as that shown in FIGS. 7 and 8 except that the circumferential groove 52 is widened toward the groove bottom except that the circumferential groove 52 is widened toward the groove bottom side. It is a tire similar to the figure. The seventh embodiment shown in FIG. 24 is a tire similar to FIGS. 5 and 6, except that both circumferential grooves 53, 54 are inclined outward in the axial direction (outward of the mounting) as going outward in the radial direction. Yes, 25th
The eighth embodiment shown in the figure is a tire similar to FIGS. 5 and 6, except that both circumferential grooves 55 and 56 are inclined inward in the axial direction toward the outside in the radial direction. The ninth embodiment shown in FIG. 26 is a tire similar to FIGS. 5 and 6, except that the radially outer end face 58 of the step region 57 is inclined inward in the radial direction toward the outside in the axial direction. Furthermore, in the tenth embodiment shown in FIG. 27, the axially outer peripheral groove 59 is inclined inward in the axial direction as it goes radially outward, while the axially inner peripheral groove 60 is inclined in the radially outward direction. The tire is similar to FIGS. 5 and 6 except that it is inclined outward in the axial direction, whereby the axial width of the step region 61 is increased toward the inside in the radial direction.
The eleventh embodiment shown in the figure is a tire similar to that of FIG. 27 except that the radially outer end face 62 is inclined radially inward toward the axially outward side.

なお、前述の第１実施例においては、装着外方側の陸
部にのみ周溝10、11および段差領域12を設けたが、この
発明においては装着内方側の陸部あるいはタイヤ赤道面
近傍の陸部に周溝および段差領域を追加形成してもよ
い。In the above-described first embodiment, the circumferential grooves 10, 11 and the step region 12 are provided only on the land portion on the outer side of the mounting. However, in the present invention, the land portion on the inner side of the mounting or the vicinity of the tire equatorial plane is provided. A circumferential groove and a stepped region may be additionally formed in the land portion of.

発明の効果 以上説明したように、この発明によれば、既に提案し
た偏摩耗防止用の段差領域を用いて、装着外方側のショ
ルダー端近傍の陸部に生じる偏摩耗を効果的に防止する
ことができる。Advantageous Effects of the Invention As described above, according to the present invention, uneven wear generated on a land portion near the shoulder end on the outer side of mounting is effectively prevented using the uneven region for uneven wear prevention already proposed. be able to.

【図面の簡単な説明】[Brief description of the drawings]

第１図はこの発明の第１実施例を示す踏面の展開図、第
２図は第１実施例の子午線断面図、第３図は試験に用い
た比較タイヤ１を示すその踏面の展開図、第４図は比較
タイヤ１の子午線断面図、第５図は試験に用いた供試タ
イヤ１を示すその踏面の展開図、第６図は供試タイヤ１
の子午線断面図、第７図は試験に用いた供試タイヤ３を
示すその踏面の展開図、第８図は供試タイヤ３の子午線
断面図、第９図は試験に用いた供試タイヤ４を示すその
踏面の展開図、第10図は供試タイヤ４の子午線断面図、
第11図は試験に用いた比較タイヤ２を示すその踏面の展
開図、第12図は比較タイヤ２の子午線断面図、第13図は
試験に用いた供試タイヤ５を示すその踏面の展開図、第
14図は供試タイヤ５の子午線断面図、第15図は試験に用
いた供試タイヤ６を示すその踏面の展開図、第16図は供
試タイヤ６の子午線断面図、第17図は試験に用いた供試
タイヤ７を示すその踏面の展開図、第18図は供試タイヤ
７の子午線断面図、第19図はこの発明の第２実施例を示
すその一部子午線断面図、第20図はこの発明の第３実施
例を示すその一部子午線断面図、第21図はこの発明の第
４実施例を示すその一部子午線断面図、第22図はこの発
明の第５実施例を示すその一部子午線断面図、第23図は
この発明の第６実施例を示すその一部子午線断面図、第
24図はこの発明の第７実施例を示すその一部子午線断面
図、第25図はこの発明の第８実施例を示すその一部子午
線断面図、第26図はこの発明の第９実施例を示すその一
部子午線断面図、第27図はこの発明の第10実施例を示す
その一部子午線断面図、第28図はこの発明の第11実施例
を示すその一部子午線断面図である。 １……空気入りタイヤ、５……ショルダー端 ６……踏面、７……主溝 ８……陸部、10、11……周溝 12……段差領域、13、14……周溝の側面 15……半径方向外端面 Ｗ……踏面幅、Ｐ……点FIG. 1 is a development view of a tread showing a first embodiment of the present invention, FIG. 2 is a meridian sectional view of the first embodiment, FIG. 3 is a development view of a tread showing a comparative tire 1 used for a test, FIG. 4 is a meridional sectional view of the comparative tire 1, FIG. 5 is a developed view of a tread showing the test tire 1 used in the test, and FIG.
7, FIG. 7 is a developed view of the tread showing the test tire 3 used in the test, FIG. 8 is a meridian cross-sectional view of the test tire 3, and FIG. 9 is the test tire 4 used in the test. FIG. 10 is a development view of the tread, and FIG.
FIG. 11 is a developed view of the tread showing the comparative tire 2 used in the test, FIG. 12 is a meridian sectional view of the comparative tire 2, and FIG. 13 is a developed view of the tread showing the test tire 5 used in the test. ,
14 is a meridional section of the test tire 5, FIG. 15 is a development view of a tread showing the test tire 6 used in the test, FIG. 16 is a meridian cross section of the test tire 6, and FIG. FIG. 18 is a meridian sectional view of the test tire 7 showing the test tire 7 used in Example 1, FIG. 19 is a partial meridian sectional view of the test tire 7 showing the second embodiment of the present invention, FIG. The figure is a partial meridian sectional view showing a third embodiment of the present invention, FIG. 21 is a partial meridian sectional view showing a fourth embodiment of the present invention, and FIG. 22 is a fifth embodiment of the present invention. FIG. 23 is a partial meridian sectional view showing the sixth embodiment of the present invention, and FIG.
24 is a partial meridian sectional view showing a seventh embodiment of the present invention, FIG. 25 is a partial meridian sectional view showing an eighth embodiment of the present invention, and FIG. 26 is a ninth embodiment of the present invention. FIG. 27 is a partial meridian sectional view showing a tenth embodiment of the present invention, and FIG. 28 is a partial meridian sectional view showing an eleventh embodiment of the present invention. . 1 ... pneumatic tire, 5 ... shoulder end 6 ... tread surface, 7 ... main groove 8 ... land portion, 10, 11 ... circumferential groove 12 ... stepped area, 13, 14 ... side surface of circumferential groove 15: Radial outer end face W: Tread width, P: Point

───────────────────────────────────────────────────── フロントページの続き (56)参考文献 特開 昭55−22534（ＪＰ，Ａ) 特開 昭63−291703（ＪＰ，Ａ) 特開 昭55−44028（ＪＰ，Ａ) 特開 昭61−196806（ＪＰ，Ａ) 特開 昭47−44502（ＪＰ，Ａ) 特開 昭63−291703（ＪＰ，Ａ) 米国特許4155392（ＵＳ，Ａ) 米国特許3550665（ＵＳ，Ａ) ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-55-22534 (JP, A) JP-A-63-291703 (JP, A) JP-A-55-44028 (JP, A) 196806 (JP, A) JP-A-47-44502 (JP, A) JP-A-63-291703 (JP, A) US Patent 4,155,392 (US, A) US Patent 3,550,665 (US, A)

Claims (4)

(57)【特許請求の範囲】(57) [Claims] 【請求項１】踏面に主溝および陸部を有し、車両に対す
る装着側が規定されている空気入りタイヤにおいて、軸
方向最外側に位置する主溝より軸方向外側で装着外方側
のショルダー端と該ショルダー端から踏面幅の1/3だけ
離れた点との間の陸部に、周方向に連続して延び該陸部
を二分する一対の周溝を形成してこれら周溝間に陸部か
ら独立した段差領域を画成するとともに、該段差領域の
半径方向外端面を前記陸部の断面輪郭線より半径方向内
側に位置させ、かつ、前記一対の周溝のうち軸方向外側
に位置する周溝を狭幅にし、走行時に踏面接地域に位置
する段差領域の半径方向外端面を路面にすべり接触させ
て該段差領域を偏摩耗犠牲部として機能させるととも
に、タイヤが受ける荷重に対する比が0.1に相当する装
着内方側に向かう横力を路面から受けたとき該軸方向外
側の周溝の側面同士を接触させて段差領域より軸方向外
側に位置する陸部の曲げ変形を抑制するようにしたこと
を特徴とする空気入りタイヤ。1. A pneumatic tire having a main groove and a land portion on a tread surface and having a mounting side with respect to a vehicle defined, a shoulder end on an outer side in the axial direction outside the main groove located on the outermost side in the axial direction. And a pair of circumferential grooves extending continuously in the circumferential direction and bisecting the land portion are formed on a land portion between the shoulder end and a point separated by 1/3 of the tread width from the shoulder end, and a land is formed between these circumferential grooves. And defining a step region independent of the portion, and positioning a radially outer end face of the step region radially inward of the cross-sectional contour line of the land portion, and positioning the radially outer end surface axially outside of the pair of circumferential grooves. The width of the circumferential groove to be narrowed, and the radially outer end surface of the step region located in the tread contact area during sliding is brought into sliding contact with the road surface to make the step region function as an uneven wear sacrifice portion, and the ratio to the load received by the tire is reduced. Lateral force inward toward the mounting equivalent to 0.1 Pneumatic tire is characterized in that so as to suppress the bending deformation of the land portion contacting the side surfaces of the shaft outward of the circumferential groove located axially outside the step region when received from the surface. 【請求項２】前記軸方向外側の周溝の幅は開口端におい
て1.5mmから3.0mmまでの範囲内にある請求項１記載の空
気入りタイヤ。2. The pneumatic tire according to claim 1, wherein a width of the axially outer circumferential groove is in a range from 1.5 mm to 3.0 mm at an open end. 【請求項３】前記段差領域の半径方向外端面は軸方向外
側に向かうに従い半径方向内側へ傾斜している請求項１
記載の空気入りタイヤ。3. A radially outer end face of the step region is inclined radially inward toward an axially outward direction.
The pneumatic tire as described. 【請求項４】前記軸方向外側の周溝の幅は、開口側より
溝底側において広い請求項１記載の空気入りタイヤ。4. The pneumatic tire according to claim 1, wherein the width of the outer circumferential groove is wider on the groove bottom side than on the opening side.
JP63241833A 1988-09-27 1988-09-27 Pneumatic tire Expired - Lifetime JP2613448B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP63241833A JP2613448B2 (en) 1988-09-27 1988-09-27 Pneumatic tire

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP63241833A JP2613448B2 (en) 1988-09-27 1988-09-27 Pneumatic tire

Publications (2)

Publication Number Publication Date
JPH0288311A JPH0288311A (en) 1990-03-28
JP2613448B2 true JP2613448B2 (en) 1997-05-28

Family

ID=17080177

Family Applications (1)

Application Number Title Priority Date Filing Date
JP63241833A Expired - Lifetime JP2613448B2 (en) 1988-09-27 1988-09-27 Pneumatic tire

Country Status (1)

Country Link
JP (1) JP2613448B2 (en)

Families Citing this family (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH03208707A (en) * 1989-10-23 1991-09-11 Bridgestone Corp Tread of pneumatic radial tire for heavy load
US5769978A (en) * 1990-07-27 1998-06-23 Compagnie Generale Des Etablissments Michelin - Michelin & Cie Tire having a thread with lateral ribs the surface of which is radially recessed with respect to the other ribs
JP2786398B2 (en) * 1993-12-27 1998-08-13 住友ゴム工業株式会社 Heavy duty pneumatic tires
JP3706201B2 (en) * 1996-07-18 2005-10-12 富士写真フイルム株式会社 Image processing method
US7992607B2 (en) 2003-12-16 2011-08-09 Bridgestone Corporation Pneumatic tire for heavy load
US8056591B2 (en) 2004-06-23 2011-11-15 Bridgestone Corporation Pneumatic tire with tread having ground contact shape and uneven wear sacrificial protrusion
JP4665534B2 (en) * 2005-01-28 2011-04-06 横浜ゴム株式会社 Pneumatic tire
US7980281B2 (en) * 2006-10-02 2011-07-19 Toyo Tire & Rubber Co., Ltd. Pneumatic tire with tread having protruding stripe in groove bottom and tire mold for making the tire
JP5038679B2 (en) * 2006-10-12 2012-10-03 株式会社ブリヂストン Pneumatic tire
DE102008032281A1 (en) 2008-07-09 2010-01-14 Continental Aktiengesellschaft Vehicle tires
BRPI1013115A2 (en) 2009-06-15 2018-03-20 Bridgestone Corporation The tire for heavy loading
JP2019094024A (en) * 2017-11-27 2019-06-20 Ｔｏｙｏ Ｔｉｒｅ株式会社 Pneumatic tire

Also Published As

Publication number Publication date
JPH0288311A (en) 1990-03-28

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