JP4777768B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire for use in an automobile traveling on a snowy road, and more particularly to a pneumatic tire with improved on-snow handling stability.

  Conventionally, when a pneumatic tire for winter travels on a snowy road, there is a difficulty in that the tire slips on the snow surface without being able to grip the snowy road. In order to improve acceleration performance, braking performance and snow handling stability performance on snowy roads, a design has been made to provide sipe on the tire tread pattern, but when increasing sipe to secure these snow performance, There is a problem that it is impossible to ensure the stability of maneuvering on the paved road, and if the sipe edge is simply increased on the snow, the rigidity of the land will decrease and the maneuvering stability on the snow will deteriorate. At present, there is a limit to the method of improvement.

However, with respect to this difficulty, the pneumatic tires disclosed in Patent Documents 1 and 2 have improved on-snow maneuvering stability performance by appropriately arranging land portions and sipes on the tread.
JP 2000-229505 A JP 05-229310 A

By the way, since the load of the vehicle moves when the vehicle turns, there is a feature that the contact pressure increases on the outer side of the vehicle mounting with respect to the tire equator surface of the tire and decreases on the inner side of the mounting of the vehicle.
However, in conventional winter tires (for example, Patent Documents 1 and 2), circumferential grooves and lateral grooves provided in the tread are arranged substantially symmetrically with respect to the tire equatorial plane. The sipes provided on the tread portion of the block formed by the above are also arranged symmetrically.
For this reason, conventional winter tires can obtain sufficient acceleration and braking performance on snow, but it is not sufficient to secure a grip on the outside of the tire vehicle mounting where the ground pressure improves when turning, There was a risk of lack of stable handling performance on snow.

  An object of the present invention is to provide a pneumatic tire having excellent snow handling stability performance by optimizing the distribution of tread grooves and sipes in consideration of the above facts.

In order to achieve the above object, a pneumatic tire according to claim 1 of the present invention is provided with at least one on the vehicle mounting outer side and on the vehicle mounting inner side with respect to the tire equatorial plane of the tread, and extends in the tire circumferential direction. The total groove area on the tread is provided in a circumferential groove that is larger than the inner side of the vehicle mounting on the outer side of the vehicle mounting and on a plurality of land portions defined by the plurality of circumferential grooves, and in the tire width direction. A sipe extending in the tire width direction on the tread tread surface and having a larger sipe on the vehicle mounting outer side than on the vehicle mounting inner side. The distance from the outermost circumferential groove to the center of the circumferential groove is the distance from the tire equator plane to the outermost circumferential groove in the tire width direction inside the vehicle. A long time and said Ri.

Since conventional pneumatic tires for winter are designed on the assumption that the forces acting on the outside and inside of the vehicle are equally input, as described above, the distribution of grooves and the arrangement of sipes are generally left and right. It was symmetrical. For this reason, there is a possibility that the change in the ground pressure distribution due to the load movement at the time of turning, which is important for the stable driving performance on snow, cannot be handled.
Therefore, in the present invention, attention is paid to the characteristics of an asymmetric tread pattern (a tread pattern in which the front and back sides of the vehicle are specified) that can specify the outer side and the inner side of the vehicle.

  As shown in FIG. 2A, when the vehicle turns, a centrifugal force is generated in the vehicle body, and when the vehicle rolls, a load movement occurs in which the load on the inner ring decreases and the load on the outer ring increases. At this time, lateral input (input in the tire width direction) occurs due to centrifugal force on the ground contact surface of the tire, and due to load movement to the outer ring, the ground contact pressure becomes large particularly near the end portion of the ground contact surface outside the vehicle, The ground pressure becomes small especially in the vicinity of the end inside the vehicle.

  On the other hand, as shown in FIG. 4 (A), the generation mechanism of the snow μ (snow friction coefficient) is as follows: compression resistance FA as a running resistance on the front surface of the tire, surface friction force FC on the land surface (tread surface), groove (described later). The snow column shearing force FB of the horizontal groove), the edge effect FD of the sipe edge and the land edge (see FIG. 4B for the edge effect).

From these, on the outside of the vehicle where the tire has a ground contact pressure when turning (in the range surrounded by the one-dot chain line in FIG. 2 (B)), the surface pressure for stepping and solidifying the snow becomes large, and the snow column shear force is effectively exhibited. be able to.
However, in order to ensure stable driving performance on snow, there is insufficient surface pressure to step on and harden the snow on the inside of the vehicle where the ground pressure is low when turning (the area surrounded by the two-dot chain line in FIG. 2 (B)). It is necessary to compensate for the shortage of snow column shearing force by edge effect by sipe edge.
In addition, the snow column shear force said here is an effect which obtains traction using the shear stress of the snow column formed in the groove part.

Next, the effect of the pneumatic tire according to claim 1 will be described.
By increasing the total groove area of the circumferential grooves on the tread surface on the outside of the vehicle than on the inside of the vehicle, the snow column shear force of the circumferential groove against the lateral input is improved on the outside of the vehicle where the ground pressure increases. However, since the total width of the land portion is increased on the inner side of the vehicle where the contact pressure is reduced, the rigidity of the land portion with respect to the lateral input is improved. Therefore, the on-snow handling stability is improved.
In addition, by increasing the sum of the length components in the tire width direction of the sipe on the tread surface from the inside of the vehicle to the outside of the vehicle, the edge effect due to the sipe edge is improved on the outside of the vehicle, where the contact pressure increases. On the inner side of the vehicle, where the pressure is reduced, the land rigidity against lateral input is improved. Therefore, the snow handling stability is improved. The length component of the sipe in the tire width direction refers to the length of the sipe measured in the tire width direction.
Therefore, by optimizing the distribution of the tread grooves and sipes, the snow handling stability is excellent.
In addition, the distance from the tire equator surface on the tread surface to the center of the outermost circumferential groove in the tire width direction (hereinafter simply referred to as the outer shoulder circumferential groove) on the outer side of the vehicle is the tire width on the inner side of the vehicle from the tire equator surface. By making the outermost circumferential groove (hereinafter simply referred to as “inner shoulder circumferential groove”) longer than the distance to the groove center, the outer shoulder circumferential groove becomes a region where the ground pressure becomes large when turning on the outside of the vehicle. Therefore, the snow column shear force of the outer shoulder circumferential groove and the edge effect of the land portion edge with respect to the lateral input can be effectively exhibited. In addition, since the inner shoulder circumferential groove is closer to the tire equator on the inner side of the vehicle, the width of the land portion arranged in the outer region in the tire width direction than the inner shoulder circumferential groove that reduces the ground pressure during turning is reduced. Widens and improves land rigidity. Moreover, the length of the sipe provided in this land part becomes long, and the edge effect by a sipe edge can be improved.

  The pneumatic tire according to claim 2 of the present invention is the pneumatic tire according to claim 1, wherein, in the tread surface, the total groove area of the circumferential grooves on the outer side of the vehicle is AO, and the inner side of the vehicle is attached. When the sum of the groove areas of the circumferential grooves is AI, AO / AI = 1.05 to 4.0 is satisfied.

Next, the effect of the pneumatic tire of Claim 2 is demonstrated.
If AO / AI <1.05, no significant difference can be found between the inside of the tread and the outside of the vehicle, and if AO / AI> 4.0, the inside of the tread and the vehicle. Since the groove area of the circumferential groove is extremely deviated from the outside, the drainage capacity of the circumferential groove during straight traveling is deteriorated, and the steering stability performance is deteriorated. Therefore, the relationship between AO and AI preferably satisfies AO / AI = 1.05 to 4.0.

  The pneumatic tire according to a third aspect of the present invention is the pneumatic tire according to the first or second aspect, wherein the number of sipes installed on the tread surface is greater on the outer side than the inner side of the vehicle. It is characterized by.

Next, the effect of the pneumatic tire according to claim 3 will be described.
By increasing the number of sipes installed on the tread tread on the outside of the vehicle from the inside of the vehicle, the edge effect of the sipe can be further improved on the outside of the vehicle where the contact pressure becomes large.

  A pneumatic tire according to a fourth aspect of the present invention is the pneumatic tire according to the third aspect, wherein, on the tread surface, the number of installed sipes outside the vehicle mounting is PO, and the number of the sipes inside the vehicle mounting is When the installation number is PI, PO / PI = 1.05 to 2.0 is satisfied.

Next, the effect of the pneumatic tire of Claim 4 is demonstrated.
If PO / PI <1.05, no significant difference can be found between the inner side and the outer side of the tread, and if PO / PI> 2.0, The rigidity of the part is extremely lowered, and the wear performance outside the vehicle is deteriorated. Therefore, the relationship between PO and PI preferably satisfies PO / PI = 1.05 to 2.0.

The pneumatic tire according to claim 5 of the present invention is the pneumatic tire according to any one of claims 1 to 4 , wherein, in the tread surface, the outermost side in the tire width direction outside the vehicle mounted from the tire equatorial plane. LO = LI = 5, where LO is the distance from the circumferential groove to the groove center, and LI is the distance from the tire equatorial plane to the groove center of the circumferential groove at the outermost side in the tire width direction inside the vehicle. It is characterized by satisfying ˜50 mm.

Next, the effect of the pneumatic tire of Claim 5 is demonstrated.
If LO-LI <5mm, no significant difference can be found between the tread inside and outside the tread, and if LO-LI> 50mm, the tread inner shoulder circumferential groove and the outer shoulder circumferential direction. Since the position with the groove is extremely deviated, the drainage capacity in the area inside the tire width direction (tread center part on the outside of the vehicle, which will be described later) from the outer shoulder circumferential groove is deteriorated and the steering stability performance is deteriorated when going straight. Resulting in. Therefore, it is preferable that the relationship between LO and LI satisfies LO-LI = 5 to 50 mm.

Pneumatic tire according to claim 6 of the present invention is the pneumatic tire according to any one of claims 1 to 5, in the tread surface, the circumferential direction of the tire width direction outermost interior of the vehicle mounting outer The groove area of the groove is larger than the groove area of the circumferential groove on the innermost side in the tire width direction inside the vehicle.

Next, the effect of the pneumatic tire of Claim 6 is demonstrated.
The groove area of the innermost circumferential groove in the tire width direction on the outer side of the vehicle wearing the tread that will have a large contact pressure when turning is made larger than the groove area on the inner side of the tire width direction on the inner side of the vehicle in which the tread becomes smaller Thus, the snow column shear force of the circumferential groove with respect to the lateral input can be effectively exerted on the vehicle mounting outer side, and the land portion rigidity is ensured on the vehicle mounting inner side.

The pneumatic tire according to claim 7 of the present invention is the pneumatic tire according to claim 6 , wherein, on the tread surface, the groove area of the circumferential groove on the innermost side in the tire width direction outside the vehicle is AOC, AOC / AIC = 1.05-4.0 is satisfied, where AIC is the groove area of the circumferential groove on the innermost side in the tire width direction inside the vehicle.

Next, the effect of the pneumatic tire of Claim 7 is demonstrated.
If AOC / AIC <1.05, no significant difference can be found between the inside of the tread and the outside of the vehicle, and if AOC / AIC> 4.0, the inside of the tread and the vehicle. Since the area of the circumferential groove on the innermost side in the tire width direction is extremely biased on the outer side, the drainage capacity in the circumferential groove on the innermost side in the tire width direction during straight travel deteriorates, and the steering stability performance deteriorates. Therefore, it is preferable that the relationship between AOC and AIC satisfies AOC / AIC = 1.05 to 4.0.

The pneumatic tire according to claim 8 of the present invention is the pneumatic tire according to any one of claims 1 to 7 , wherein, in the tread surface, the sum of length components in the tire width direction of the sipe is: It becomes larger in the tread center part which is the area inside the tire width direction than the circumferential groove on the outermost side in the tire width direction than the tread shoulder part which is the area between the circumferential groove on the outermost side in the tire width direction and the tread end. It is characterized by that.

Next, the effect of the pneumatic tire of Claim 8 is demonstrated.
By making the total length component of the sipe in the tire width direction larger at the tread center than at the tread shoulder, the edge effect by the sipe edge is improved at the tread center, and the land rigidity is improved at the tread shoulder. As a result, the ground contact area can be increased, and snow acceleration performance and snow braking performance can be improved in addition to snow handling stability performance. The tread end mentioned here means that a pneumatic tire is mounted on a standard rim defined in JATMA YEAR BOOK (2005 edition, Japan Automobile Tire Association Standard), and in the size and ply rating applicable to JATMA YEAR BOOK. Fills 100% of the air pressure (maximum air pressure) corresponding to the maximum load capacity (internal pressure-load capacity correspondence table) as the internal pressure, and indicates the outermost ground contact portion in the tire width direction when the maximum load capacity is loaded. In addition, when TRA standard and ETRTO standard are applied in a use place or a manufacturing place, it follows each standard.

The pneumatic tire according to claim 9 of the present invention is the pneumatic tire according to claim 8 , wherein, in the tread surface, the number of sipes installed is greater in the tread center portion than in the tread shoulder portion. Features.

Next, the effect of the pneumatic tire of Claim 9 is demonstrated.
By increasing the number of sipe installations at the tread center part than the tread shoulder part, the edge effect by the sipe edge is further improved at the tread center part, and the land part rigidity is improved at the tread shoulder part and the ground contact area is increased. As a result, the snow handling stability performance, snow acceleration performance and snow braking performance can be further improved.

A pneumatic tire according to a tenth aspect of the present invention is the pneumatic tire according to the ninth aspect , wherein the number of sipes installed in the tread shoulder portion is set to PS and the sipes in the tread center portion are arranged on the tread surface. When the installation number is PC, PS / PC = 0.5 to 0.9 is satisfied.

Next, the effect of the pneumatic tire of Claim 10 is demonstrated.
If PS / PC <0.5, the edge effect due to the sipe of the tread shoulder portion is extremely reduced. If PS / PC> 0.9, the tread shoulder portion is between the tread center portion and the tread shoulder portion. No significant difference can be found, and snow acceleration performance and snow braking performance are not improved. Therefore, the relationship between PS and PC preferably satisfies PS / PC = 0.5 to 0.9.

A pneumatic tire according to an eleventh aspect of the present invention is the pneumatic tire according to any one of the first to tenth aspects, wherein a plurality of the circumferential grooves are provided on the tread and extend in the tire width direction. And a transverse groove that divides the plurality of land portions to define a plurality of block-shaped land portions.

Next, the effect of the pneumatic tire of Claim 11 is demonstrated.
By forming a plurality of block-shaped land portions by the lateral grooves, the edge effect is improved, and snow handling stability performance, snow acceleration performance and snow braking performance are improved.

A pneumatic tire according to a twelfth aspect of the present invention is the pneumatic tire according to the eleventh aspect , wherein the groove width of the lateral groove is wider on the inner side of the vehicle than on the outer side of the vehicle. And

Next, the effect of the pneumatic tire of Claim 12 is demonstrated.
By increasing the width of the lateral groove on the tread tread from the inside of the vehicle to the outside of the vehicle, the snow column shear force is improved on the inside of the vehicle where the contact pressure is low, and the rigidity of the land is increased on the outside of the vehicle where the contact pressure is high. improves.

A pneumatic tire according to a thirteenth aspect of the present invention is the pneumatic tire according to the twelfth aspect , wherein, in the tread surface, the groove width of the lateral groove on the vehicle mounting outer side is RO, and the lateral groove on the vehicle mounting inner side is the When the groove width is RI, RI / RO = 1.05 to 5.0 is satisfied.

Next, the effect of the pneumatic tire of Claim 13 is demonstrated.
If RI / RO <1.05, no significant difference can be found between the vehicle mounting inner side and the vehicle mounting outer side of the tread. If RI / RO> 5.0, the vehicle mounting outer side and the vehicle mounting inner side are not detected. Because the lateral groove width is extremely biased, the snow column shearing force due to the lateral groove deteriorates on the outer side of the vehicle, and the snow column shearing force of the entire tire deteriorates. By reducing the height, the rigidity of the block-shaped land portion is extremely lowered, and the wear performance inside the vehicle is deteriorated. Therefore, the relationship between RI and RO preferably satisfies RI / RO = 1.05 to 5.0.

The pneumatic tire according to claim 14 of the present invention is the pneumatic tire according to any one of claims 11 to 13 , wherein the tread includes two or more circumferential grooves on the vehicle mounting outer side. The vehicle mounting outside includes a plurality of sipes on the tread surface portion that continuously extend in the tire circumferential direction between the circumferential groove on the outermost side in the tire width direction and the circumferential groove on the innermost side in the tire width direction. One or more circumferential continuous land portions are arranged.

Next, the effect of the pneumatic tire of Claim 14 is demonstrated.
A circumferential continuous land portion extending continuously in the tire circumferential direction is provided on the outer side of the tread mounted on the vehicle, and sipes are arranged at a high density on the circumferential continuous land portion, so that an edge effect due to the sipe edge on the outer side of the vehicle mounted is obtained. Further improvement.

A pneumatic tire according to a fifteenth aspect of the present invention is the pneumatic tire according to the fourteenth aspect , wherein the sum of the widths of the one or more circumferential continuous land portions is LR on the tread surface, The width of the circumferential continuous land portion or the block-shaped land portion formed between the circumferential groove on the innermost side in the tire width direction and the circumferential groove on the innermost side in the tire width direction outside the vehicle is LC. LR / LC = 0.5 to 2.0.

Next, the effect of the pneumatic tire of Claim 15 is demonstrated.
If LR / LC <0.5, the sipe length becomes extremely small with the total width of the circumferential continuous land portion, so the edge effect due to the sipe edge cannot be improved. If it is> 2.0, the total width of the circumferential continuous land portion becomes extremely large. Therefore, on the outside of the tread mounted on the vehicle, the length of the lateral groove is shortened, and the snow column shear force by the lateral groove is deteriorated. As a result, the snow column shear force of the entire tire deteriorates. Therefore, the relationship between LR and LC preferably satisfies LR / LC = 0.5 to 2.0.

The pneumatic tire according to claim 16 of the present invention is the pneumatic tire according to any one of claims 11 to 15 , wherein, in the tread surface, the groove width of the lateral groove is the outermost in the tire width direction. It is characterized in that it is narrower in the tread center portion, which is a region on the inner side in the tire width direction than the circumferential groove on the outermost side in the tire width direction, from the tread shoulder portion which is a region between the circumferential groove and the tread end.

Next, the effect of the pneumatic tire of Claim 16 is demonstrated.
By making the groove width of the lateral groove narrower at the tread center part than at the tread shoulder part, the rigidity of the land part arranged in the tread center part can be improved and the contact area can be increased. In the section, the snow column shear force can be improved by increasing the width of the lateral groove. Therefore, snow handling stability performance, snow acceleration performance and snow braking performance are improved.

A pneumatic tire according to a seventeenth aspect of the present invention is the pneumatic tire according to the sixteenth aspect , wherein a width of the lateral groove provided in the tread shoulder portion is WS and the lateral groove provided in the tread center portion. When the groove width of WC is WC, WC / WS = 0.2 to 0.95 is satisfied.

Next, the effect of the pneumatic tire of Claim 17 is demonstrated.
If WC / WS <0.2, the groove width of the lateral groove provided in the tread center portion becomes extremely small, so that the snow column shear force deteriorates in the tread center portion, and the snow column shear force of the entire tire is reduced. Getting worse. If WC / WS> 0.95, no significant difference can be found between the tread center portion and the tread shoulder portion, and the snow acceleration performance and snow braking performance are not improved. Accordingly, the relationship between WC and WS preferably satisfies WC / WS = 0.2 to 0.95.

The pneumatic tire according to claim 18 of the present invention is the pneumatic tire according to any one of claims 1 to 17 , wherein the sipe is inclined with respect to a tire width direction. .

Next, the effect of the pneumatic tire of Claim 18 is demonstrated.
By tilting the sipe with respect to the tire width direction, an edge effect in the lateral direction can be secured in addition to the edge effect in the front-rear direction.

  The pneumatic tire of the present invention is excellent in snow handling stability performance by optimizing the distribution of tread grooves and sipes.

[First Embodiment]
Next, a first embodiment of the pneumatic tire of the present invention will be described with reference to FIG. Note that the pneumatic tire 10 of the present embodiment (hereinafter simply referred to as the tire 10) has a tire size of 195 / 65R15, and its internal structure is the same as that of a general radial tire, so that the internal structure is the same. Description of is omitted.

As shown in FIG. 1, the outermost layer of the tire 10 is provided with a tread 12 having a tread surface that contacts the road surface.
The tread 12 has a tread pattern that is asymmetrical between the vehicle mounting outer side (in the arrow OUT direction) and the vehicle mounting inner side (in the arrow IN direction) with respect to the tire equator plane CL. For this reason, the front and back of the tire 10 are designated with respect to vehicle mounting.

  The tread pattern of the tread 12 is provided on both sides of the tire equatorial plane CL, and extends in the tire circumferential direction with a center circumferential groove 14 (the center circumferential groove on the vehicle mounting inner side is 14I, and the center circumferential groove on the vehicle mounting outer side is 14O. And a shoulder circumferential groove 16 provided on the outer side in the tire width direction of the center circumferential groove 14 and extending in the tire circumferential direction (shoulder circumferential groove 16I on the vehicle mounting inner side and shoulder circumferential groove on the outer side of the vehicle mounting). 16O), the center lateral groove 18 extending in the tire width direction and intersecting the center circumferential groove 14 and the shoulder circumferential groove 16I, and the tread 12 from the tread end 12E outside the vehicle to the shoulder circumferential groove 16O. A shoulder lateral groove 20A extending in the width direction and a tread end 12E on the inner side of the tread 12 mounted on the vehicle shoulder And a shoulder lateral grooves 20B extending in the tire width direction to the groove 16I.

  Further, the region between the shoulder circumferential grooves 16I and 16O of the tread 12 is defined as a region on the tire width direction outer side of the tread center portion 22 and the shoulder circumferential groove 16I (the shoulder circumferential groove 16I and the tread end 12E on the vehicle mounting inner side. The region between the shoulder circumferential groove 16O and the outer region in the tire width direction (region between the shoulder circumferential groove 16O and the tread end 12E on the vehicle mounting outer side) is referred to as a tread shoulder portion 24.

  A center block 26 defined by the center circumferential grooves 14I and 14O and the center lateral groove 18, a center circumferential groove 14I, a shoulder circumferential groove 16I, and a center lateral groove 18 extending obliquely with respect to the tire width direction. The second block 28, the shoulder block 30 defined by the shoulder circumferential groove 16I, the tread end 12E and the shoulder lateral groove 20B, and the tire circumferential direction defined by the center circumferential groove 14O and the shoulder circumferential groove 16O are continuous. The center rib groove 18 and the shoulder lateral grooves 20A and 20B are substantially flat on the respective tread surfaces of the second rib 32 extending in the same manner and the shoulder block 34 defined by the shoulder circumferential groove 16O, the tread end 12E and the shoulder lateral groove 20A. Is sipes 36 extending provided. In addition, the sipe 36 provided in the second block 28 is disposed substantially in parallel with the center lateral groove 18 extending inclined with respect to the tire width direction.

In the present embodiment, as shown in FIG. 1, the center lateral groove 18 and the shoulder lateral grooves 20A and 20B may extend along the tire width direction or may be inclined in the tire width direction.
At this time, as described above, the sipe is provided so as to extend substantially in parallel with the lateral grooves that define the ribs or blocks. However, the sipe does not have to be substantially parallel.
Further, in the present embodiment, as shown in FIG. 1, the center circumferential grooves 14I and 14O and the shoulder circumferential grooves 16I and 16O extend substantially along the tire circumferential direction, but are inclined in the tire circumferential direction. It may be configured to extend to.

Further, as shown in FIG. 1, the sipe 36 of the present embodiment is a cut that divides each block or rib, but this cut ends in the middle without dividing the block or rib. In addition, a notch that does not open in the groove that defines the block or rib may be used.
Further, the depth of the sipe 36 of the present embodiment is uniformly 6.6 mm when new, but may be other than 6.6 mm in other embodiments, and each sipe installation position may be different. Depending on the depth.
Further, the depths of the circumferential grooves and the lateral grooves in the present embodiment are each uniformly 10 mm when new, but may be other than 10 mm in other embodiments, and depending on the position of each groove. , The depth may be different.

  In the tread surface, the sum of the groove areas of the center circumferential groove 14O and the shoulder circumferential groove 16O on the outer side of the vehicle is larger than the sum of the groove areas of the center circumferential groove 14I and the shoulder circumferential groove 16I on the inner side of the vehicle. When the total groove area of the center circumferential groove 14O and the shoulder circumferential groove 16O on the outer side of the mounting is AO, and the total area of the center circumferential groove 14I and the shoulder circumferential groove 16I on the inner side of the vehicle is AI, AO / It is preferable to satisfy AI = 1.05 to 4.0.

  On the tread surface, the sum of the length components in the tire width direction of the sipe 36 outside the vehicle is larger than the sum of the length components in the tire width direction of the sipe 36 inside the vehicle. PO / PI = 1.05 where the number of installations is greater than the number of installations of the sipe 36 inside the vehicle, PO is the number of installations of the sipe 36 outside the vehicle installation, and PI is the number of installations of the sipe 36 inside the vehicle installation. It is preferable to satisfy -2.0.

  Further, on the tread surface, the distance from the tire equatorial plane CL to the center of the shoulder circumferential groove 16O is longer than the distance from the tire equatorial plane CL to the center of the shoulder circumferential groove 16I, and from the tire equatorial plane CL to the shoulder circumference. When the distance to the groove center of the directional groove 16O is LO and the distance from the tire equatorial plane CL to the groove center of the shoulder circumferential groove 16I is LI, it is preferable to satisfy LO-LI = 5 to 50 mm.

  Further, on the tread surface, the groove area of the center circumferential groove 14O is larger than the groove area of the center circumferential groove 14I, the groove area of the center circumferential groove 14O is AOC, and the groove area of the center circumferential groove 14I is AIC. At this time, it is preferable to satisfy AOC / AIC = 1.05 to 4.0.

  Further, in the tread surface, the total length component in the tire width direction of the sipe 36 of the tread center portion 22 is larger than the total length component in the tire width direction of the sipe 36 of the tread shoulder portion 24, and further, the tread center portion. When the number of installed sipes 36 of the tread shoulder portion 24 is larger than the number of installed sipes 36 of the tread shoulder portion 24, the number of installed sipes 36 of the tread shoulder portion 24 is PS, and the number of installed sipes 36 of the tread center portion 22 is PC. PS / PC = 0.5 to 0.9 is preferably satisfied.

  Further, on the tread surface, the width of the shoulder lateral groove 20A on the outer side of the vehicle is wider than the width of the shoulder lateral groove 20B on the inner side of the vehicle, and the width of the shoulder lateral groove 20A on the outer side of the vehicle is RO. It is preferable to satisfy RI / RO = 1.05 to 5.0 when the groove width of 20B is RI.

Further, on the tread surface, when the width of the second rib 32 is LR and the width of the center block 26 is LC, it is preferable to satisfy LR / LC = 0.5 to 2.0.
In the present embodiment, the width LR of the second rib 32 is smaller than the width LC of the center block 26.

  Further, on the tread surface, the groove width of the center lateral groove 18 is narrower than the groove widths of the shoulder lateral grooves 20A and 20B. When the groove width of the shoulder lateral groove 20A is WS and the groove width of the center lateral groove 18 is WC, WC / WS = It is preferable to satisfy 0.2 to 0.95.

(Function)
Next, the operation of the first embodiment will be described.
As shown in FIG. 1, on the tread surface, the total groove area of the center circumferential groove 14O and the shoulder circumferential groove 16O on the vehicle mounting outer side is the groove of the center circumferential groove 14I and the shoulder circumferential groove 16I on the vehicle mounting inner side. By making it larger than the total area, as shown in FIG. 3 (B), the snow column shearing force of the circumferential groove with respect to the lateral input is improved and the ground pressure is reduced on the vehicle mounting outside where the ground pressure increases when turning. Since the total width of the blocks is increased inside the vehicle, the block rigidity with respect to the lateral input is improved. Therefore, the on-snow handling stability is improved.
Moreover, as shown in FIG. 3 (A), the sum of the length components in the tire width direction of the sipe 36 on the tread tread surface is made larger on the outer side than the inner side of the vehicle as shown in FIG. The edge effect in the tire front-rear direction due to the sipe edge of the sipe 36 is improved on the vehicle mounting outside where the pressure is increased, and the block rigidity against the lateral input is improved on the vehicle mounting inner side where the ground pressure is reduced. Therefore, the snow handling stability is improved.
From the above, by optimizing the distribution of the groove of the tread 12 and the sipe 36, the on-snow handling stability is excellent.

  If AO / AI <1.05, no significant difference can be found between the inside of the tread 12 and the outside of the vehicle, and if AO / AI> 4.0, the inside of the tread 12 Since the groove area of the circumferential groove is extremely deviated from the outside of the vehicle, the drainage capacity of the circumferential groove during straight travel deteriorates, and the steering stability performance deteriorates. Therefore, the relationship between AO and AI preferably satisfies AO / AI = 1.05 to 4.0.

Further, by increasing the number of sipe 36 installed on the tread surface on the vehicle mounting outer side than on the vehicle mounting inner side, the edge effect in the tire front-rear direction by the sipe 36 on the vehicle mounting outer side where the contact pressure becomes large can be further improved.
Further, if PO / PI <1.05, no significant difference can be found between the inside of the tread 12 and the outside of the vehicle, and if PO / PI> 2.0, the tread 12 is mounted on the vehicle. On the outside, the rigidity of the block and the rib is extremely lowered, and the wear performance on the outside of the vehicle is deteriorated. Therefore, the relationship between PO and PI preferably satisfies PO / PI = 1.05 to 2.0.

  Further, on the tread surface, the distance from the tire equatorial plane CL to the center of the shoulder circumferential groove 16O is longer than the distance from the tire equatorial plane CL to the center of the shoulder circumferential groove 16I. The shoulder circumferential groove 16O can be disposed in a region where the contact pressure becomes large when turning, and the snow column shear force of the shoulder circumferential groove 16O and the edge effect of the edge portion of the second rib 32 with respect to the lateral input are effectively obtained. It can be demonstrated. In addition, since the shoulder circumferential groove 16I is closer to the tire equatorial plane CL on the inner side of the vehicle, the width of the shoulder block 30 that reduces the ground pressure when turning is increased, and the rigidity of the shoulder block 30 is improved. The length of the sipe 36 provided on the shoulder block 30 is increased, and the edge effect by the sipe edge can be improved.

  If LO-LI <5 mm, no significant difference can be found between the inside of the tread 12 and the outside of the vehicle, and if LO-LI> 50 mm, the shoulder circumferential groove 16I and the shoulder circumferential direction of the tread. Since the position with respect to the groove 16O is extremely biased, the drainage capacity in the region on the inner side in the tire width direction (the tread center portion 22 on the outside of the vehicle) from the shoulder circumferential groove 16O deteriorates during straight traveling, and the steering stability performance deteriorates. Resulting in. Therefore, it is preferable that the relationship between LO and LI satisfies LO-LI = 5 to 50 mm.

  Further, the groove area of the center circumferential groove 14O on the outer side of the tread 12 where the ground pressure is increased during turning is set larger than the groove area of the center circumferential groove 14I on the inner side of the tread 12 where the ground pressure is reduced. Thus, the snow column shear force of the circumferential groove with respect to the lateral input can be effectively exerted on the vehicle mounting outside, and the block rigidity is ensured on the vehicle mounting inside.

  If AOC / AIC <1.05, no significant difference can be found between the vehicle mounting inner side and the vehicle mounting outer side of the tread 12, and if AOC / AIC> 4.0, the vehicle mounting inner side of the tread 12 Since the area of the center circumferential groove 14 is extremely biased on the vehicle mounting outer side, the drainage capacity in the center circumferential groove 14 during straight traveling is deteriorated, and the steering stability performance is deteriorated. Therefore, it is preferable that the relationship between AOC and AIC satisfies AOC / AIC = 1.05 to 4.0.

  Further, as shown in FIG. 1, the sum of the length components of the sipe 36 in the tire width direction is made larger at the tread center portion 22 than at the tread shoulder portion 24, so that the contact pressure as shown in FIG. In the tread center portion 22, the edge effect in the tire front-rear direction is improved at the tread center portion 22, and the rigidity of the shoulder blocks 30 and 34 is improved at the tread shoulder portion 24, and the ground contact area is increased. In addition to steering stability performance, snow acceleration performance and snow braking performance can also be improved.

  Furthermore, by increasing the number of sipe 36 installed at the tread center portion 22 than at the tread shoulder portion 24, the tread center portion 22 further improves the edge effect in the tire front-rear direction by the sipe edge. The rigidity of the shoulder blocks 30 and 34 is further improved, and the ground contact area can be increased. Therefore, snow handling stability, snow acceleration performance and snow braking performance are further improved.

  If PS / PC <0.5, the edge effect in the tire front-rear direction due to the sipe 36 of the tread shoulder portion 24 is extremely reduced, and if PS / PC> 0.9, the tread center portion. Therefore, no significant difference can be found between the tread shoulder portion 24 and the tread shoulder portion 24, and the acceleration performance on snow and the braking performance on snow cannot be improved. Therefore, the relationship between PS and PC preferably satisfies PS / PC = 0.5 to 0.9.

  Since the plurality of blocks are partitioned by the center lateral groove 18 and the shoulder lateral grooves 20A and 20B, the edge effect in the tire front-rear direction is improved, and snow handling stability performance, snow acceleration performance, and snow braking performance are improved.

  Also, on the tread surface, the width of the shoulder lateral groove 20B on the inner side of the vehicle mounting is made wider than the width of the shoulder lateral groove 20A on the outer side of the vehicle mounting. This improves the rigidity of the shoulder block 34 on the outside of the vehicle where the contact pressure is large.

  If RI / RO <1.05, no significant difference can be found between the vehicle mounting inner side and the vehicle mounting outer side of the tread 12, and if RI / RO> 5.0, the vehicle mounting outer side and the vehicle mounting inner side are detected. Therefore, the snow column shear force in the tire longitudinal direction by the shoulder lateral groove 20A is deteriorated on the outer side of the vehicle mounting, and the snow column shearing force of the entire tire is deteriorated on the outer side of the vehicle mounting. Due to the decrease in the circumferential length of the block 30, the rigidity of the shoulder block 30 is extremely reduced, and the wear performance inside the vehicle is deteriorated. Therefore, the relationship between RI and RO preferably satisfies RI / RO = 1.05 to 5.0.

By arranging the sipe 36 on the second rib 32 at a high density, the edge effect in the tire front-rear direction due to the sipe edge on the vehicle mounting outside of the tread 12 is further improved.
If LR / LC <0.5, the length of the sipe 36 becomes extremely small with the width of the second rib 32, so that the edge effect in the tire front-rear direction by the sipe edge cannot be improved. If LC> 2.0, the width of the second rib 32 becomes extremely large. Therefore, on the outer side of the tread 12 mounted on the vehicle, the length of the shoulder lateral groove 20A is shortened and the snow column in the tire longitudinal direction by the shoulder lateral groove 20A. The shear force deteriorates and the snow column shear force of the entire tire deteriorates. Therefore, the relationship between LR and LC preferably satisfies LR / LC = 0.5 to 2.0.

  Further, by making the groove width of the center lateral groove 18 of the tread center portion 22 smaller than the groove width of the shoulder lateral groove 20A of the tread shoulder portion 24, in the tread center portion 22, the blocks disposed in the tread center portion 22 and The rigidity of the ribs can be improved and the contact area can be increased. In the tread shoulder portion 24, the snow column shearing force in the tire longitudinal direction can be improved by increasing the width of the shoulder lateral groove 20A. Therefore, snow handling stability performance, snow acceleration performance and snow braking performance are improved.

If WC / WS <0.2, since the groove width of the center lateral groove 18 provided in the tread center portion 22 becomes extremely small, the snow column shear force in the tire front-rear direction in the tread center portion 22 deteriorates, The snow column shear force of the entire tire is deteriorated. If WC / WS> 0.95, no significant difference can be found between the tread center portion 22 and the tread shoulder portion 24, and snow acceleration performance and snow braking performance are not improved. Accordingly, the relationship between WC and WS preferably satisfies WC / WS = 0.2 to 0.95.
Further, by inclining the sipe 36 with respect to the tire width direction, an edge effect in the lateral direction can be ensured in addition to the edge effect in the front-rear direction.

(Test example)
In order to confirm the performance improvement effect of the pneumatic tire of the present invention, one type of pneumatic tire of an example according to the first embodiment of the present invention and one type of conventional pneumatic tire are prepared, and a passenger car is prepared. Accelerated performance test, braking performance test, and steering stability performance test on snow. The sizes of the tires used in the tests were 195 / 65R15, and the tires were assembled to the rim 6J-15, and the inner pressure was set to 200 kpa and mounted on the passenger car. The constitution of the conventional tire and the tire of the example is shown in Table 1.

The acceleration performance test was evaluated by measuring the time (acceleration time) from the stationary state until the accelerator was fully opened and traveling 50 m.
The braking performance test was evaluated by measuring the braking distance when the full brake was applied from 30 km / h.
The driving stability performance test was evaluated with a feeling score by a test driver.
In all cases, the evaluation results of the three types of tests are shown in Table 1 as index indications when the numerical value of the conventional tire is set to 100. In addition, an evaluation numerical value shows a favorable result, so that it is large.

Example: Tire according to the first embodiment shown in FIG.
Conventional example: A tire having a tread pattern shown in FIG. The tread 102 of the tire 100 of this conventional example includes a circumferential groove 104 that is provided in two symmetrically with respect to the tire equatorial plane CL, and a lateral groove 106 that intersects the circumferential groove 104. A sipe 110 is provided on the tread surface portion of the block 108 that is defined between the horizontal groove 106 and the lateral groove 106. Note that the circumferential groove 104 has the same groove width, the lateral groove 106 has the same groove width, and the number of sipes is the same on the left and right.
Note that the depth of the grooves (circumferential grooves 104 and lateral grooves 106) of the conventional tire is 10 mm as in the tire of the embodiment, and the sipe depth is 6.6 mm as in the tire of the embodiment.

  From the results in Table 1, it can be seen that the tire of Example 1 is superior in acceleration performance, braking performance and steering stability performance on snow than the conventional tire. In particular, it can be seen that the performance on snow handling stability has been greatly improved.

It is the figure which showed the tread pattern of the pneumatic tire which concerns on 1st Embodiment. (A) It is a figure showing the force which acts on a vehicle at the time of turning. (B) It is a figure showing the contact pressure distribution in the contact surface of the tire at the time of turning of FIG. 2 (A). (A) It is a figure showing distribution of contact pressure on the contact surface of a tire at the time of going straight. (B) It is a figure showing the contact pressure distribution in the contact surface of the tire at the time of turning. (A) It is the figure which represented the generation | occurrence | production mechanism of the traction on the snow of a pneumatic tire, and a brake seeing from the tire width direction. (B) It is an enlarged view showing the generation | occurrence | production mechanism of the edge effect by the sipe edge of FIG. 4 (A). It is the figure which showed the tread pattern of the pneumatic tire of a prior art example.

Explanation of symbols

10 Pneumatic tire 12 Tread 12E Tread end 14 Center circumferential groove (circumferential groove)
16 Shoulder circumferential groove (circumferential groove)
18 Center lateral groove (horizontal groove)
20 Shoulder lateral groove (lateral groove)
22 tread center section 24 tread shoulder section 26 center block (block-shaped land section (land section))
28 Second Block (Block-shaped land (land))
30 Shoulder Block (Blocky Land (Land))
32 second rib (circumferential continuous land (land))
34 Shoulder block (Block-shaped land (land))
CL Tire equatorial plane IN Inside vehicle mounting OUT Outside vehicle mounting

Claims (18)

One or more vehicles are provided on the outer side and the inner side of the vehicle on the tread tire equatorial plane, and extend in the tire circumferential direction. The total groove area on the tread surface is larger on the outer side than on the inner side of the vehicle. Direction grooves,
The vehicle is provided on a tread surface portion of a plurality of land portions defined by a plurality of circumferential grooves, extends in the tire width direction, and the total length component of the tread tread surface in the tire width direction is from the vehicle mounting inner side to the vehicle. A large sipe on the outside,
A distance from the tire equator surface to the groove center of the circumferential groove on the outermost side in the tire width direction on the outer side of the vehicle mounted on the tread surface is the outermost side in the tire width direction on the inner side of the vehicle mounted A pneumatic tire characterized by being longer than the distance to the groove center of the circumferential groove .   On the tread surface, AO / AI = 1.05, where AO is the total groove area of the circumferential grooves outside the vehicle mounting, and AI is the total groove area of the circumferential grooves inside the vehicle mounting. The pneumatic tire according to claim 1, wherein 4.0 is satisfied.   3. The pneumatic tire according to claim 1, wherein the number of sipes installed on the tread surface is greater on the outside of the vehicle than on the inside of the vehicle. 4.   On the tread surface, PO / PI = 1.05-2.0 is satisfied, where PO is the number of sipes installed on the outside of the vehicle and PI is the number of sipes installed on the inside of the vehicle. The pneumatic tire according to claim 3. In the tread surface, the distance from the tire equator surface to the groove center of the circumferential groove on the outermost side in the tire width direction on the outer side of the vehicle is LO, and the circumference on the outermost side in the tire width direction on the inner side of the vehicle from the tire equator surface is LO. The pneumatic tire according to any one of claims 1 to 4, wherein LO-LI = 5 to 50 mm is satisfied, where LI is a distance to the groove center of the directional groove . In the tread surface, the groove area of the circumferential groove on the innermost side in the tire width direction outside the vehicle mounting is larger than the groove area of the circumferential groove on the innermost side in the tire width direction on the inner side of the vehicle mounting. The pneumatic tire according to any one of claims 1 to 5. In the tread surface, when the groove area of the circumferential groove on the innermost side in the tire width direction on the outer side of the vehicle mounting is AOC, and the groove area of the circumferential groove on the innermost side in the tire width direction on the inner side of the vehicle mounting is AIC, The pneumatic tire according to claim 6, wherein AOC / AIC = 1.05 to 4.0 is satisfied. In the tread surface, the total length component of the sipe in the tire width direction is the outermost portion in the tire width direction from the tread shoulder portion which is a region between the circumferential groove on the outermost side in the tire width direction and the tread end. The pneumatic tire according to any one of claims 1 to 7, wherein the pneumatic tire is larger at a tread center portion that is an inner region in the tire width direction than the circumferential groove. The pneumatic tire according to claim 8, wherein the number of sipes installed in the tread surface is greater in the tread center portion than in the tread shoulder portion. In the tread surface, PS / PC = 0.5 to 0.9 is satisfied, where PS is the number of sipes installed in the tread shoulder portion and PC is the number of sipes installed in the tread center portion. The pneumatic tire according to claim 9. A plurality of the treads are provided, the tire includes a transverse groove that extends in the tire width direction, intersects with the plurality of circumferential grooves, and divides the plurality of land portions to form a plurality of block-like land portions. The pneumatic tire according to any one of claims 1 to 10. The pneumatic tire according to claim 11, wherein, in the tread surface, the width of the lateral groove is wider on the inner side of the vehicle than on the outer side of the vehicle. In the tread surface, when the groove width of the lateral groove outside the vehicle mounting is RO and the groove width of the horizontal groove inside the vehicle mounting is RI, RI / RO = 1.05-5.0 is satisfied. The pneumatic tire according to claim 12. The tread includes two or more circumferential grooves on the vehicle mounting outer side, and on the vehicle mounting outer side, between the circumferential groove on the outermost side in the tire width direction and the circumferential groove on the innermost side in the tire width direction. The air according to any one of claims 11 to 13, wherein one or more circumferential continuous land portions extending continuously in the tire circumferential direction and having a plurality of sipes on the tread portion are disposed. Enter tire. In the tread surface, the sum of the widths of the one or more circumferential continuous land portions is LR, the circumferential groove on the innermost side in the tire width direction on the inner side of the vehicle and the innermost side in the tire width direction on the outer side of the vehicle. The LR / LC = 0.5 to 2.0 is satisfied, where LC is a width of the circumferential continuous land portion or the block-shaped land portion that is partitioned between the directional grooves. 14. The pneumatic tire according to 14. In the tread surface, the groove width of the lateral groove is larger than the circumferential groove on the outermost side in the tire width direction from the tread shoulder portion which is a region between the circumferential groove on the outermost side in the tire width direction and the tread end. The pneumatic tire according to any one of claims 11 to 15, wherein the pneumatic tire is narrow at a tread center portion that is a region on the inner side in the direction. When the groove width of the transverse groove provided in the tread shoulder portion is WS and the groove width of the transverse groove provided in the tread center portion is WC, WC / WS = 0.2 to 0.95 is satisfied. The pneumatic tire according to claim 16, wherein The pneumatic tire according to claim 1, wherein the sipe is inclined with respect to a tire width direction.

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