LU506708B1

LU506708B1 - Pneumatic tyre with blocks and sipes

Info

Publication number: LU506708B1
Application number: LU506708A
Authority: LU
Inventors: Zuilekom Frits Van; Antonius Theodore Folkert Aelberts
Original assignee: Apollo Tyres Global R & D Bv
Priority date: 2024-03-27
Filing date: 2024-03-27
Publication date: 2025-10-01
Also published as: WO2025202407A1

Abstract

The invention relates to a pneumatic tyre for a vehicle comprising a tread portion (10) for contacting the ground and a pair of opposing sidewall portions, wherein the tread portion (10) comprises circumferential grooves (16) generating at least one outermost row (18a) adjacent to the shoulder (12) on a vehicle inner side region (20) and at least one outermost row (18b) adjacent to the shoulder (12) on a vehicle outer side region (22), wherein the outermost rows (18a, 18b) each comprise multiple blocks (24a, 24b) and at least one block (24a, 24b) in each of the outermost rows (18a, 18b) comprises at least one sipe (36a, 36b), wherein a number of blocks (24a) over the circumference of the tyre for the outermost row (18a) on the vehicle inner side region (20) is greater than the number of blocks (24b) over the circumference of the tyre for the outermost row (18b) on the vehicle outer side region (22), and wherein a number of sipes (36a) over the circumference of the tyre along the outermost row (18a) on the vehicle inner side region (20) is lower than the number of sipes (36b) over the circumference of the tyre along the outermost row (18b) on the vehicle outer side region (22). The invention further relates to a corresponding wheel for a vehicle.

Description

APOLLO TYRES GLOBAL R&D B.V. 27 March, 2032°°798 our Reference: AD 43035 / AL; P.175-AST-T

PNEUMATIC TYRE WITH BLOCKS AND SIPES

FIELD OF THE INVENTION

The present invention relates to pneumatic tyre for a vehicle comprising a tread portion with blocks and sipes for improving the running performance on snow and on dry road surface.

The present invention further relates to a corresponding wheel.

BACKGROUND OF THE INVENTION

Tyres are meant for commuting purpose, are subjected to varying speed operation, road conditions, and driver expertise. In particular, pneumatic tyres in the all-season segment need to perform well on very different road conditions ranging for example from snowy roads at low winter temperatures, over wet roads at ambient temperatures, to dry roads at high summer temperatures.

Tyres having a tread portion extending between a pair of shoulders in a circumferential direction of the tyre, and with a tread pattern where the tread portion comprises circumferential grooves generating at least one outermost row adjacent to the shoulder on a vehicle inner side region and at least one outermost row adjacent to the shoulder on a vehicle outer side region, wherein the outermost rows each comprise multiple blocks at least partially spaced apart from each other in the circumferential direction by lateral grooves, and wherein at least one block in each of the outermost rows comprises at least one sipe are known in prior art.

For example US 5,660,651 A relates to a vehicle tyre for use in winter driving conditions whose tread pattern includes a circumferentially extending row in each of the shoulder regions, wherein the profile or pattern is asymmetrically shaped and includes, relative to the vehicle, an inner tread portion and an outer tread portion, with the shoulder block row of the inner tread portion being provided with sipes having good LU506708 opening characteristics, with reference to the circumferential direction of the tire, and the shoulder block row of the outer tread portion is provided with sipes that assure high block rigidity during lateral force loading.

In these types of tyres, increasing the number of lateral grooves and sipes generally increases the snow traction and improves the running performance on snow. However, an excessive number of lateral grooves and sipes also decreases the running performance on dry road surfaces due to a decrease in block rigidity.

There is a permanent need for providing a tyre with an optimized transfer of driving forces on snowy or icy surfaces or roads and good driving properties on dry as well as wet surfaces.

The present invention has the objective to provide a tyre with a well-balanced performance on snow and dry road surface.

SUMMARY OF THE INVENTION

This and other objects are achieved by providing a tyre according to claim 1 as well as a wheel according to claim 14. Preferred embodiments of the invention are given by the dependent claims, which can constitute each solely or in combination an aspect of the invention.

In a first aspect, the invention provides a pneumatic tyre for a vehicle comprising a tread portion for contacting the ground and a pair of opposing sidewall portions, the tread portion extending between a pair of shoulders in a circumferential direction of the tyre, the sidewall portions extending essentially in a radial direction from the shoulders, wherein the tread portion comprises circumferential grooves generating at least one outermost row adjacent to the shoulder on a vehicle inner side region and at least one outermost row adjacent to the shoulder on a vehicle outer side region, wherein the outermost rows each comprise multiple blocks least partially spaced apart from each other in the circumferential direction by lateral grooves, wherein a number of blocks over the circumference of the tyre for the outermost row on the vehicle inner side region is greater than the number of blocks over the circumference of the tyre for the outermost LU506708 row on the vehicle outer side region, wherein at least one block in each of the outermost rows comprises at least one sipe, and wherein a number of sipes over the circumference of the tyre along the outermost row on the vehicle inner side region is lower than the number of sipes over the circumference of the tyre along the outermost row on the vehicle outer side region.

One aspect of the invention is that the number of blocks over the circumference of the tyre for the outermost rows is not the same for the vehicle inner side region and for the vehicle outer side region. Instead, the number of blocks of the outermost row on the vehicle inner side region is greater than the number of blocks of the outermost row on the vehicle outer side region.

A further aspect of the invention is that the number of sipes over the circumference of the tyre for the outermost rows is not the same for the vehicle inner side region and for the vehicle outer side region. Instead, the number of sipes over the circumference for the outermost row on the vehicle inner side region is lower than the number of sipes over the circumference for the outermost row on the vehicle outer side region.

It was surprisingly determined that the inventive combination of unequal numbers of blocks and sipes in the outermost rows as described, create a stiffening and rigidity effect that leads to a good driving performance on dry road surface and still provides good gripping on snow. For handling on dry road and in particular for lane changing, it is of importance that in the outermost rows the pattern stiffness is high during lateral force loading. On the other hand, for improving snow performance, a reduced block rigidity is advantageous, which can be achieved for example by a greater number of blocks. However, a highly increased number of blocks on the vehicle inner side region may negatively affect the dry road performance, which is according to the invention compensated by the lower number of sipes on the vehicle inner side region. Thus, the tyre has a good running performance both on dry road surfaces as well as on snow.

The circumferential direction of the tyre is preferably the direction along the tyre rolling movement. As used herein, the terms “radial direction” and/or “radially” refer to a direction orthogonal to the circumferential direction and can either mean towards an axis of rotation of the tyre or away from the axis of rotation of the tyre. The terms “axial LU506708 direction” and/or “axially” refer to the axis of rotation of the tyre. In a situation where the tyre is mounted to the vehicle, the terms “axial direction” and/or “axially” can either mean towards a longitudinal axis of a vehicle or away from a longitudinal axis of the vehicle.

The term “vehicle inner side region” specifies the region of the tyre that is closer to the longitudinal axis of the vehicle than the “vehicle outer side region” when the tyre is mounted on the vehicle. In other words, the outermost row adjacent to the shoulder on the vehicle inner side region faces towards the longitudinal axis of the vehicle, while the outermost row adjacent to the shoulder on the vehicle outer side region faces away from the longitudinal axis of the vehicle.

The term “groove” means an elongated void area in the tyre that may extend in the circumferential direction, axial direction, or any combination thereof in the tread portion in a straight, curved, wavy, stepped, or zigzag manner. Grooves may be of varying depths in the radial direction in the tyre.

As used herein, the term “circumferential groove” refers to a continuous groove which is oriented in the circumferential direction of the tyre. Preferably the circumferential groove is a straight groove extending parallel to the circumference of the tyre.

The term “lateral groove” refers to a groove which is essentially oriented in the axial direction of the tyre. The lateral groove may not extend parallel to the rotation axis of the tyre but may be inclined with regard to the rotation axis. Furthermore, the lateral groove may not be a continuous groove, meaning it does not necessarily extend over the whole tread portion in the axial direction. Furthermore, the lateral groove may be straight, curved, wavy, stepped or zigzagged.

The term “sipe” defines a very small groove or cut having a width of between 0.3 mm and 0.8 mm, and preferably about 0.5 mm. The sipe extends essentially in the axial direction of the tyre. The sipe may not extend parallel to the rotation axis but may be inclined with regard to the rotation axis The sipe may be shaped as a straight line.

Alternatively, the sipe may have a zigzag or wavy shape. As the sipes assure good gripping properties on snow-covered and/or ice-covered covered surfaces the tread LU506708 portion provides sufficient traction and braking capacity.

Furthermore, the term “tyre” preferably means all types of elastic bandages subjected to 5 internal pressure. The tyre is a pneumatic tyre. Further preferably the tyre is configured as a tyre suitable for a vehicle. The tyre preferably comprises, a pair of opposing bead portions, a carcass and at least one reinforcing ply, the sidewall portions extending essentially in a radial direction from the bead portion, the carcass extending between the pair of bead portions, and the reinforcing ply being sandwiched between the tread portion and the carcass. Further preferably an inner liner for holding air pressure is arrange on an inner side of the carcass.

The tread portion of the tyre is preferably formed by a quantity of rubber material delimited by the sidewall portions and is intended to come into contact with the ground when the tyre is rolling. The tread pattern of the tyre is such that the tread portion comprises the circumferential grooves that generate at least one outermost row adjacent to the shoulder on the vehicle inner side region and at least one outermost row adjacent to the shoulder on the vehicle outer side region. It is preferred that the tread portion comprises more than one circumferential groove such that in addition to the outermost row on the vehicle inner side region and the outermost row on the vehicle outer side region, the tread portion preferably comprises additional centre rows in between the outermost rows.

The outermost rows each comprise multiple blocks, the blocks within the outermost rows being at least partially separated from each other by the lateral groove in the circumferential direction. The blocks have a width along the axial direction, which corresponds to the width of the outermost row. Within the outermost rows, the blocks are at least partially separated from the corresponding neighbouring block in the circumferential direction by the lateral groove. The lateral groove may have a length along the axial direction that is shorter than the width of the row. Thus, the blocks may not be completely separated from the corresponding neighbouring block, meaning that the blocks may not be separated in the circumferential direction over the whole width of the row. Instead, the blocks may only be partially separated from each other in the circumferential direction. In other words, the blocks within the outermost row may be partly connected to the neighbouring block in the circumferential direction, in cases LU506708 where the length of the lateral groove is shorter than the width of the outermost row.

Preferably, the length of the lateral groove separating to neighbouring blocks from each other in the circumferential direction is at least half of the width of the outermost row.

Furthermore, the blocks have a length along the circumferential direction. The length of a specific block is defined by the distance between the beginning and the end of the block, which is specified by the lateral groove that lies in the circumferential direction directly before and directly after the specific block. The multiple blocks within the outermost row on the vehicle inner side region may all have the same length.

Alternatively, the multiple blocks within the outermost row on the vehicle inner side region may have different lengths. This is also the case for the multiple blocks within the outermost row on the vehicle outer side region. These blocks may all have the same length or may have different lengths.

Particularly preferably and in order to avoid dominant frequencies in the emitted noise when the tyre is rolling over the ground, the blocks within the outermost row are arranged and have lengths such that a number of lateral grooves in the outermost row on the vehicle outer side region that are placed in the same circumferential position as a corresponding lateral groove in the outermost row on the vehicle inner side region is minimized. Such an arrangement of blocks with potentially different block lengths can be found via a suitable computer program.

In a preferred embodiment of the invention, a tyre is provided wherein the number of sipes within one block is dependent on the length of the block along the circumferential direction. Preferably, blocks being longer comprise more sipes than blocks being shorter. As the outermost row on the vehicle outer side region comprises less blocks than on the inner side region, the blocks in the outermost row on the vehicle outer side region are on average longer. Thus, this is an easy way to provide a tyre wherein the number of sipes over the circumference of the tyre along the outermost row on the vehicle outer side region is higher than the number of sipes over the circumference of the tyre along the outermost row on the vehicle inner side region. In this regard it is particularly preferred that the number of sipes within one block is in between L/6.4 and

L/5.6, with L being the length of the block along the circumferential direction.

It is possible that the distance between two sipes within one block is different for blocks in the outermost row for the vehicle inner side region and for the vehicle outer side region. However, in a preferred embodiment of the invention, a tyre 1s provided wherein a distance between two adjacent sipes within one block is the same + 10 % for the vehicle inner side region and for the vehicle outer side region, wherein the distance refers to the distance between two adjacent sipes in the circumferential direction. In other words, it is preferred that the higher number of sipes over the circumference of the tyre in the outermost row on the vehicle outer side region, compared to the vehicle inner side region, is not due to a lower distance between two adjacent sipes within the respective blocks. Instead, the higher number of sipes over the circumference of the tyre in the outermost row on the vehicle outer side region is preferably due to a higher average length of the blocks in the outermost row on the vehicle outer side region, and thus to a higher average number of sipes per block in the outermost row on the vehicle outer side region, compared to the outermost row on the vehicle inner side region.

According to another preferred embodiment of the invention, a ratio of the number of sipes over the circumference along the row on the vehicle inner side region to the number of sipes over the circumference along the row on the vehicle outer side region is in the range of 0.82 to 0.96. It was found that such a ration provides an improved handling on snow as well as on dry road.

According to another preferred embodiment of the invention a tyre is provided, wherein a ratio of the number of blocks over the circumference along the outermost row on the vehicle inner side region to the number of blocks over the circumference along the outermost row on the vehicle outer side region, is in the range of 1.09 to 1.29. For example, the number of blocks within the outermost row on the vehicle inner side region may be 72, while a number of blocks within the outermost row on the vehicle outer side region may be 60. In this example the ration would be 1.2. Independent of the size of the tyre and thus the length of the circumference a ratio in the range of 1.09 to 1.29 provides a well-balanced performance on snow and dry road.

According to another preferred embodiment of the invention, a ratio of an air-ratio of the outermost row on the vehicle inner side region to the air-ratio of the outermost row on the vehicle outer side region is in the range of 1.03 to 1.18, and wherein the air-ratio LU506708 specifies a quotient of a surface area of the outermost row coming in contact to the ground to a footprint area of the outermost row coming in contact to the ground, as per

E.-TR.T.O. standards. The air-ratio is an indication for the proportion of the two- dimensional area occupied by void-space instead of tread compound in a specific two- dimensional area of tread. The surface area of the outermost row that comes in contact to the ground is the area that consists exclusively of the tread compound, while the footprint area of the outermost row that comes in contact to the ground is the area that consists of the tread compound and the voids. The air-ratio can be given in percent and may for example be for the outermost row on the vehicle inner side region 33 % and for the outermost row on the vehicle outer side region 30 %.

According to a further embodiment of the invention a tyre is provided wherein the width of the lateral groove on the vehicle inner side region is lower than the width of the lateral groove on the vehicle outer side region. The width of the lateral groove is the width of the groove in the circumferential direction. It was found that both running performance on dry road surfaces and running performance on snow can be improved when the width of the lateral groove on the vehicle inner side region is lower than the width of the lateral groove on the vehicle outer side region. Further preferably the width of the lateral groove is the same for all grooves within the outermost row on the vehicle inner side region. Also, preferably the width of the lateral groove is the same for all grooves within the outermost row on the vehicle outer side region.

According to another preferred embodiment of the invention and in connection to the different numbers of blocks over the circumference of the tyre for the outermost rows, a tyre is provided wherein an average length of the block along the circumference on the vehicle inner side region is smaller than the average length of the block along the circumference on the vehicle outer side region. The higher number of blocks over the circumference of the tyre for the outermost row on the vehicle inner side region, compared to the outermost row on the vehicle outer side region, is preferably achieved by a smaller average length of the blocks for the outermost row on the vehicle inner side region, compared to the outermost row on the vehicle outer side region. As the blocks are on average shorter, more blocks fit into the outermost row on the vehicle inner side region around the circumference of the tyre.

As already mentioned, the tread portion may comprise more than one circumferential groove such that in addition to the outermost row on the vehicle inner side region and the outermost row on the vehicle outer side region, the tread portion comprises additional centre rows in between the outermost rows. In connection to this and according to another preferred embodiment of the invention, a tyre is provided wherein the circumferential grooves in the tread portion generate an uneven number of rows across the axial direction of the tread portion. This preferably means that the tread portion comprises an even number of circumferential grooves. In other words, the centre rows — also comprise (as do the outermost rows) multiple blocks at least partially spaced apart from each other in the circumferential direction by lateral grooves.

Regarding the number of blocks over the circumference of the tyre for the centre rows, it is further preferred that the number of blocks for each of the centre rows either corresponds to the number of blocks for the outermost row on the vehicle inner side region or corresponds to the number of blocks for the outermost row on the vehicle outer side region.

According to another preferred embodiment of the invention, a tyre is provided wherein the tread portion comprises in between the outermost rows several centre rows each comprising multiple blocks at least partially spaced apart from each other in the circumferential direction by further lateral grooves, and wherein a first group of centre rows adjacent to the outermost row on the vehicle inner side region comprises a number of blocks over the circumference of the tyre that corresponds to the number of blocks in the outermost row on the vehicle inner side region, and a second group of centre rows adjacent to the outermost row on the vehicle outer side region comprises a number of blocks over the circumference of the tyre that corresponds to the number of blocks in the outermost row on the vehicle outer side region.

In connection to the above and according to another preferred embodiment of the invention, a circumferential groove delimiting the first group of centre rows from the second group of centre rows, is arranged with an axial offset to a circumferential centre line of the tyre. The circumferential centre line of the tyre, also called equatorial centre line, divides the tread portion along the axial direction in two halves of the same size.

Furthermore, it is preferred that the axial offset to the circumferential centre line by which the circumferential groove delimiting the first group of centre rows from the LUS06708 second group of centre rows is arranged, is an axial offset towards the vehicle outer side region. In other words, the tread portion comprises more rows — outermost row and middle rows — having a number of blocks that corresponds to the number of blocks in the outermost row on the vehicle inner side region, than rows that have a number of blocks that corresponds to the number of blocks in the outermost row on the vehicle outer side region.

According to another preferred embodiment of the invention, the tyre comprises an asymmetrical tread pattern. As used herein an asymmetrical tread pattern is a tread pattern that does not comprises a mirror plane arranged such that the circumferential centre line lies within said mirror plane, or that does not have two identical patterns on each halve. Due to the asymmetrical tread pattern, the tyre may have improved performance. For example, the tread pattern on the inner vehicle region pushes water away, and can thus keep the vehicle from hydroplaning, while the tread pattern on the vehicle outer side region has higher rigidity and provide a higher grip while cornering.

According to another preferred embodiment of the invention, the tyre is an all-season tyre. Compared to summer tyres that are optimized for high temperatures and dry road condition, and compared to winter tyres that are optimized for low temperatures and snow, all-season tyres need to have good performance on different road conditions.

Preferably the width of the lateral groove for all-season tyres is lower than for snow tyres and larger than conventional tires.

In connection to this and according to a further preferred embodiment of the invention, a tread compound of the tread portion has a glass-transition temperature T, below -20 °C, preferably below -25 °C, more preferably from -40 °C to -30 °C, and even more preferably from -40 °C to -36 °C. Not only the tread pattern of summer, winter, and all- season tyres may be different to each other, but also the physical properties of the tread compound making up the tread portion. A tread compound for a summer tyre typical has a glass-transition temperature Tg between -20 °C to -8 °C, while a tread compound for a winter tyre has a glass-transition temperature Tg below-40 °C. In other words, the glass-transition temperature Tg of the tread compound is preferably in between typical values for summer and winter tyres. The values for the glass-transition temperature Tg can be determined by recording a DMA curve according to ISO 4664-1, with a LU506708 frequency of 10 Hz, a dynamic strain of 0.1 % and a temperature range from -80 °C to +25 °C, where the glass transition temperatures Ts corresponds to the temperature at the maximum of the tan 6 curve.

The invention also relates to a wheel for a vehicle, comprising a tyre rim for being connected to an axle of the vehicle and the above-described tyre mounted to the tyre rim. Such a wheel has well-balanced performance on snow and dry road surface.

Further preferably, the wheel is configured such that when the rim 1s connected to the axles of the vehicle, the outermost row on the vehicle inner side region faces towards the longitudinal axis of the vehicle, while the outermost row on the vehicle outer side region faces away from the longitudinal axis of the vehicle.

BRIEF DESCRIPTION OF THE DRAWING

The invention will now be described by way of example and with reference to the accompanying drawing in which:

Fig. 1 is a schematic view of a tread portion of a tyre according to a preferred embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawing, so as to assist those having ordinary skill in the art in a comprehensive understanding of the invention, and the present invention is not limited to the embodiments disclosed below.

Figures 1 shows a tread portion 10 of a tyre for contacting the ground, according to a preferred embodiment of the invention. The tread portion 10 extends between a pair of shoulders 12 in a circumferential direction 14 of the tyre.

Tread portion 10 comprises circumferential grooves 16 — in this embodiment four circumferential grooves — generating at least one outermost row 18a adjacent to the shoulder on a vehicle inner side region 20 and at least one outermost row 18b adjacent LU506708 to the shoulder on a vehicle outer side region 22.

The outermost rows 18 each comprise multiple blocks 24a, 24b at least partially spaced apart from each other in the circumferential direction 14 by lateral grooves 26a, 26b. In this embodiment for outermost rows 18a and18b a length 28a, 28b of the lateral groove 26a, 26b is equal to the width 30a, 30b of the outermost row 18a, 18b.

Furthermore, the blocks 24a, 24b have a length 32a, 32b along the circumferential direction 14. The length 32a, 32b of a specific block 24a, 24b is defined by the distance between the beginning and the end of the block 24a, 24b, which is specified by the lateral groove 26a, 26b that lies in the circumferential direction 14 directly before and directly after the specific block 26a, 26b.

The lateral grooves 26a, 26b have different widths 34a, 34b in the circumferential direction 14 on the vehicle inner side region 20 and the vehicle outer side region 22.

The width 34a of the lateral groove 26a on the vehicle inner side region 20 is lower than the width 34b of the lateral groove 26b on the vehicle outer side region 22.

Furthermore, a number of blocks 24a over the circumference of the tyre for the outermost rowl8a on the vehicle inner side region 20 is greater than the number of blocks 24b over the circumference of the tyre for the outermost row 18b on the vehicle outer side region 22. In this embodiment the number of blocks 24a in the outermost row 18a on the vehicle inner side region 20 is seventy-two, while the number of blocks 24b inthe outermost row 18b on the vehicle outer side region 22 is sixty.

As is also visible on figure 1, is that the blocks 24a, 24b of the outermost rows 18a, 18b each comprise multiple sipes 36a 36b. The number of sipes 36a over the circumference of the tyre along the outermost row 18a on the vehicle inner side region 20 is lower than the number of sipes 36b over the circumference of the tyre along the outermost row 18b on the vehicle outer side region 22. In this embodiment the number of sipes 36a in the outermost row 18a on the vehicle inner side region 20 is two-hundred-and-eight, while the number of sipes 36b in the outermost row 18b on the vehicle outer side region 22 is two-hundred-and-thirty-two.

Furthermore, as the tread portion 10 comprises in this embodiment four circumferential grooves 16, the tread portion 10 comprises in addition to the outermost row 18a on the vehicle inner side region 20 and the outermost row 18b on the vehicle outer side region 22, additional centre rows 38a, 38b in between the outermost rows 18a, 18b.

Similar to the outermost rows 18a, 18b, the centre rows 38a, 38b each comprising multiple blocks 40a, 40b at least partially spaced apart from each other in the circumferential direction. A first group of centre rows 38a adjacent to the outermost row 18a on the vehicle inner side region 20 — in this embodiment two centre rows 38a — comprises the same number of blocks 40a over the circumference of the tyre as the outermost row 18a on the vehicle inner side region 20.

Furthermore, second group of centre rows 38b adjacent to the outermost row 18b on the vehicle outer side region 22 — in this embodiment one centre row 38b — comprises the same number of blocks 40b over the circumference of the tyre as the outermost row 18b on the vehicle outer side region 22.

Additionally, as can be seen in figure 1, the circumferential groove 16* delimiting the first group of centre rows 38a from the second group of centre rows 38b, is arranged with an axial offset 42 to a circumferential centre line 44 of the tyre. The circumferential centre line 44 divides the tread portion 10 along the axial direction 46 in two halves of the same size. In this embodiment the axial offset 42 to the circumferential centre line 44 by which the circumferential groove 16* is arranged, is an axial offset 42 towards the vehicle outer side region 22.

EXAMPLE

An example of the present invention will be described below, but the present invention isnot limited to the following example.

A tyre Il according to the invention is a 245/45R19 102Y XL tyre. For the tyre Il the number of blocks over the circumference of the tyre for the outermost row on the vehicle inner side region is greater than the number of blocks over the circumference of the tyre for the outermost row on the vehicle outer side region. Furthermore, for the tyre LUS06708

I1 the number of sipes over the circumference of the tyre along the outermost row on the vehicle inner side region is lower than the number of sipes over the circumference of the tyre along the outermost row on the vehicle outer side region.

The tyre Il is compared to a tyre according to prior art called reference 1. Reference 1 comprises equal amounts of blocks in the outermost row on the vehicle inner side region and the vehicle outer side region. Furthermore, reference 1 comprises equal amounts of sipes on in the outermost row on the vehicle inner side region and the vehicle outer side region.

The parameters regarding number of blocks, number of sipes as well as the glass- transition temperature Tg of the tread compound of the tread portion of the tyre I1 and for the reference 1 are summarized in table 1: mem eee [7 w

The tyres were assembled on wheels having a rim size of 18x81/2J, mounted on a test vehicle having a 2000 cc displacement, and under conditions of 230 kPa air pressure, an evaluation was performed by a test driver for handling and braking on dry road, for handling and braking on wet road, and for handling and braking on snow. The handling was determined based on the performance of the vehicle particularly during cornering and on the vehicle’s steering stability. Furthermore, snow acceleration was determined.

The evaluation results were expressed as an index with the reference tyre 1 as being 100%. A larger index value indicates superior performance. Table 2 summarizes the evaluation results:

er wm

The evaluation results show that the tyre Il has a slightly improved dry handling and braking ability and a strongly improved snow handling ability. The wet handling, wet braking, as well as snow braking and snow acceleration are in principle comparable to the reference tyre.

REFERENCE SIGNS LU506708 10 tread portion 12 shoulder 14 circumferential direction 16 circumferential groove 16* circumferential groove delimiting first group of centre row from second group of centre row 18a outermost row on vehicle inner side region 18b outermost row on vehicle outer side region 20 vehicle inner side region 22 vehicle outer side region 24a block within row 18a 24b block within row 18b 26a lateral groove within row 18a 26b lateral groove within row 18b 28a length of lateral groove 26a 28b length of lateral groove 26b 30a width of outermost row 18a 30b width of outermost row 18b 32a length of block 24a 32b length of block 24b 34a width of lateral groove 26a 34b width of lateral groove 26b 36a sipein block 24a 36b sipe in block 24b 38a centre row of first group 38b centre row of second group 40a block in centre row of first group 40b block in centre row of second group 42 axial offset 44 circumferential centre line 46 axial direction

Claims

CLAIMS LU506708

1. À pneumatic tyre for a vehicle comprising a tread portion (10) for contacting the ground and a pair of opposing sidewall portions, the tread portion (10) extending between a pair of shoulders (12) in a circumferential direction (14) of the tyre, the sidewall portions extending essentially in a radial direction from the shoulders, wherein the tread portion (10) comprises circumferential grooves (16) generating at least one outermost row (18a) adjacent to the shoulder (12) on a vehicle inner side region (20) and at least one outermost row (18b) adjacent to the shoulder (12) on a vehicle outer side region (22), wherein the outermost rows (18a, 18b) each comprise multiple blocks (24a, 24b) at least partially spaced apart from each other in the circumferential direction (14) by lateral grooves (26a, 26b), wherein a number of blocks (24a) over the circumference of the tyre for the outermost row (18a) on the vehicle inner side region (20) is greater than the number of blocks (24b) over the circumference of the tyre for the outermost row (18b) on the vehicle outer side region (22), wherein at least one block (24a, 24b) in each of the outermost rows (18a, 18b) comprises at least one sipe (36a, 36b), and wherein a number of sipes (36a) over the circumference of the tyre along the outermost row (18a) on the vehicle inner side region (20) is lower than the number of sipes (36b) over the circumference of the tyre along the outermost row (18b) on the vehicle outer side region (22).

2. The pneumatic tyre according to claim 1, wherein the number of sipes (36) within one block (24) is dependent on a length (32) of the block (24) along the circumferential direction (14), and preferably is in between L/6.4 and L/5.6, with L being the length (32) of the block (24) along the circumferential direction (14).

3. The pneumatic tyre according to claim 1 or 2, wherein a distance between two adjacent sipes (36) within one block (24) is the same + 10 % for the vehicle inner side region (20) and for the vehicle outer side region (22), wherein the distance refers to the distance between two adjacent sipes (36) in the LU506708 circumferential direction (14).

4. The pneumatic tyre according to any of the previous claims, wherein a ratio of the number of sipes (36a) over the circumference along the outermost row (18a) on the vehicle inner side region (20) to the number of sipes (36b) over the circumference along the outermost row (18b) on the vehicle outer side region (22) is in the range of 0.82 to 0.96.

5. The pneumatic tyre according to any of the previous claims, wherein a ratio of the number of blocks (24a) over the circumference along the outermost row (18a) on the vehicle inner side region (20) to the number of blocks (24b) over the circumference along the outermost row (18b) on the vehicle outer side region (22), is in the range of 1.09 to 1.29.

6. The pneumatic tyre according to any of the previous claims, wherein a ratio of an air-ratio of the outermost row (18a) on the vehicle inner side region (20) to the air-ratio of the outermost row (18b) on the vehicle outer side region (22) is in the range of 1.03 to 1.18, and wherein the air-ratio specifies a quotient of a surface area of the outermost row (18) coming in contact to the ground to a footprint area of the outermost row (18) coming in contact to the ground, as per

E.T.R.T.O. standards.

7. The pneumatic tyre according to any of the previous claims, wherein a width (34a) of the lateral groove (26a) on the vehicle inner side region (20) is lower than the width (34b) of the lateral groove (26b) on the vehicle outer side region (22).

8. The pneumatic tyre according to any of the previous claims, wherein an average length (32a) of the block (24a) along the circumference on the vehicle inner side region (20) is smaller than the average length (32b) of the block (24a) along the circumference on the vehicle outer side region (22).

9. The pneumatic tyre according to any of the previous claims, wherein the LU506708 circumferential grooves (16) in the tread portion (10) generate an uneven number of rows (18, 38) across an axial direction (46) of the tread portion (10).

10. The pneumatic tyre according to any of the previous claims, wherein the tread portion (10) comprises in between the outermost rows (18a, 18b) several centre rows (38a, 38b) each comprising multiple blocks (40a, 40b) at least partially spaced apart from each other in the circumferential direction (14) by further lateral grooves, and wherein a first group of centre rows (38a) adjacent to the outermost row (18a) on the vehicle inner side region (20) comprises a number of blocks (40a) over the circumference of the tyre that corresponds to the number of blocks (24a) in the outermost row (18a) on the vehicle inner side region (20), and a second group of centre rows (38b) adjacent to the outermost row (18b) on the vehicle outer side region (22) comprises a number of blocks (40b) over the circumference of the tyre that corresponds to the number of blocks (24b) in the outermost row (18b) on the vehicle outer side region (22).

11. The pneumatic tyre according to the previous claim, wherein a circumferential groove (16%) delimiting the first group of centre rows (38a) from the second group of centre rows (38b), is arranged with an axial offset (42) to a circumferential centre line (44) of the tyre.

12. The pneumatic tyre according to any of the previous claims, wherein the tyre comprises an asymmetrical tread pattern.

13. The pneumatic tyre according to any of the previous claims, wherein the tyre is an all-season tyre.

14. The pneumatic tyre according to any of the previous claims, wherein a tread compound of the tread portion has a glass-transition temperature Tg below -20 °C, preferably below -25 °C, further preferably from -40 °C to -30 °C, and even more preferably from -40 °C to -36 °C.

15. Wheel for a vehicle comprising a tyre rim for being connected to an axle of the LU506708 vehicle and a tyre according to any of claims 1 to 14 mounted to the tyre rim.