CA2788247A1

CA2788247A1 - Pneumatic vehicle tyre

Info

Publication number: CA2788247A1
Application number: CA2788247A
Authority: CA
Inventors: Michael Seidel; Martine Blom
Original assignee: Continental Reifen Deutschland GmbH
Current assignee: Continental Reifen Deutschland GmbH
Priority date: 2010-04-19
Filing date: 2011-02-08
Publication date: 2011-10-27
Anticipated expiration: 2031-02-08
Also published as: EP2560830B1; CA2788247C; EP2560830A1; CN102844204A; DE102010016508A1; ES2603403T3; CN102844204B; WO2011131381A1; PL2560830T3

Abstract

Pneumatic vehicle tyre with a profiled tread comprising radially raised profile elements (1, 2, 3), which are delimited by grooves (4, 5), and comprising sipes (6, 7, 8), which are formed at least in some of the profile elements (1, 2, 3) and extend to a depth T, extending in a first radial outer range of extent (16) with a height h1 where (1/2)T=h1=0.9T and extending in a second radial inner range of extent (26) with a height h2 as far as the base of the sipe (12), wherein the first radially outer range of extent (16) is arranged at an angle of inclination a to the radial R where 0°=a=3°, and the second radially inner range of extent (26) is formed such that, from the first radially outer range of extent (16), it extends in a curved manner to one side as far as the base of the sipe (12).

Description

Description Pneumatic vehicle tyre The invention relates to a pneumatic vehicle tire having a profiled tread with radially elevated profile elements which are delimited by channels and having sipes, which Sipes are formed at least in some of the profile elements and have in each case two parallel sipe walls which delimit the sipe and which are formed substantially correspondingly to one another, wherein the first main direction of extent, which is formed in the ground contact surface-forming outside surface of the profile element, of the sipe has its greatest directional component in the axial direction A of the pneumatic vehicle tire, and wherein, in the section planes perpendicular to the first main direction of extent in the ground contact surface, the sipe extends from the ground contact surface-forming outside surface to the sipe base over a depth T of the sipe measured in the radial direction R, and which sipes have a first, radially outer region of extent which extends from the ground contact surface-forming outside surface radially inward over a height hl measured in the radial direction R, where (1/2)T <_ hl < 0.9T, and which sipes have a second, radially inner region of extent which is formed so as to adjoin the first region of extent inward in the radial direction R and which extends over a height h2, measured in the radial direction R, to the sipe base, wherein, in the section planes perpendicular to the first main direction of extent, the sipe, in each case in the first, radially outer region of extent, runs from the outside surface to the second, radially inner region of extent so as to be aligned along a second main direction of extent which has an angle of inclination a with respect to the radial R, wherein 0 < a < 3

- 2 - PCT/EP2011/051768 Such pneumatic vehicle tires with sipes are known.
Here, the sipes extend with a first main direction of extent substantially in the axial direction in the outside surface of the profile element, and extend perpendicular to said first main direction of extent, in a second main direction of extent, substantially rectilinearly inward in the radial direction to the sipe base. It is also known for such sipes to run, in their radial extent, in a zig-zagged or undulating manner about a second main direction of extent in the direction of the sipe base, wherein in the case of these sipes, too, the radially inner region of extent to the sipe base is formed so as to run rectilinearly in the radial direction as an elongation of the second main direction of extent.

In the case of all of said sipes, the respective opening and closing sipe action with the associated traction-improving characteristics is made possible, but results in a stress concentration at the radially inner channel sipe base, increased material loading in the radially inner region of extent of the sipe, and an increased notch effect. Said effects reduce the durability of the profile elements.
It is the object of the invention to improve the loadability and durability of such profiles in a simple manner without restriction of the advantages of the utilization of sipes.
The object is achieved according to the invention by means of the design of a pneumatic vehicle tire having a profiled tread with radially elevated profile elements which are delimited by channels and having sipes, which sipes are formed at least in some of the profile elements and have in each case two parallel sipe walls which delimit the sipe and which are formed substantially correspondingly to one another, wherein

- 3 - PCT/EP2011/051768 the first main direction of extent, which is formed in the ground contact surface-forming outside surface of the profile element, of the sipe has its greatest directional component in the axial direction A of the pneumatic vehicle tire, and wherein, in the section planes perpendicular to the first main direction of extent in the ground contact surface, the sipe extends from the ground contact surface-forming outside surface to the sipe base over a depth T of the sipe measured in the radial direction R, and which sipes have a first, radially outer region of extent which extends from the ground contact surface-forming outside surface radially inward over a height hl measured in the radial direction R, where (1/2)T < hl 5 0.9T, and which sipes have a second, radially inner region of extent which is formed so as to adjoin the first region of extent inward in the radial direction R and which extends over a height h2, measured in the radial direction R, to the sipe base, wherein, in the section planes perpendicular to the first main direction of extent, the sipe, in each case in the first, radially outer region of extent, runs from the outside surface to the second, radially inner region of extent so as to be aligned along a second main direction of extent which has an angle of inclination a with respect to the radial R, wherein 0 -< a <- 3 , as per the features of claim 1, in which, in the section planes perpendicular to the first main direction of extent, the sipe is formed, in each case in the second, radially inner region of extent, so as to run in a curved manner toward one side proceeding from the first, radially outer region of extent to the sipe base.

The design of the sipe permits full utilization of the advantages of the sipes with regard to the opening and the closing action and with regard to the traction-improving characteristics. The profile which is curved to one side in the radially inner region of extent to

- 4 - PCT/EP2011/051768 the sipe base results in a reduction of the stress in the region of the radially inner region of extent of the sipe, and a distribution of the stresses over the entire arcuately curved profile proceeding from the sipe base which is subject to the notch effect. The sipe base, which as a result of the curvature is turned out of the main direction of extent formed along the radial extent of the sipe, furthermore permits a reduction of the occurring notch effect. In this way, the material-fatiguing loadings at the sipe base are reduced, and the durability of the sipe and of the profile element is increased.

Particularly advantageous for reducing the notch effect is the design of a pneumatic vehicle tire as per the features of claim 2, wherein the sipe wall which delimits the sipe toward the outside of the curvature in the second region of extent is formed with a curvature profile with a curvature radius R1, where 2 mm S R1 -< 10 mm, about a curvature central point M1 which lies on that side of the sipe which points away from said sipe wall.

Particularly advantageous is the design of a pneumatic vehicle tire as per the features of claim 3, wherein the sipe wall which delimits the sipe toward the outside of the curvature is delimited in the radially outward direction by a transition point P, which delimits the second region of extent with respect to the first region of extent in the radially outward direction, and is delimited at the sipe base by a foot point Q, wherein the connecting path s between the transition point P and the foot point Q in the section planes perpendicular to the first main direction of extent runs with an angle of inclination (3 with respect to the radial direction R, where 15 < R S 45 , in particular 30 < (3 < 35 . This permits a particularly

- 5 - PCT/EP2011/051768 great reduction in the notch effect, and permits reliable removal from a mold.

Particularly advantageous is the design of a pneumatic vehicle tire as per the features of claim 4, wherein the sipe wall which delimits the sipe toward the outside of the curvature is delimited at the sipe base by a foot point Q, wherein the tangent t to the curvature of the ripe wall at the foot point Q runs at an. angle of inclination y with respect to the radial direction R, wherein 100 <_ y <_ 160 , in particular 1300 <_ y <_ 1400. This permits a particularly great reduction in the notch effect, and permits reliable removal from a mold.
Particularly advantageous is the design of a pneumatic vehicle tire as per the features of claim 5, wherein the sipe is formed substantially with a constant section width d over its radial extent of height h2 in the second, radially inner region of extent. This permits an improved force distribution in the second, radially inner region of extent under load, and thus a reduced notch effect.

Particularly advantageous is the design of a pneumatic vehicle tire as per the features of claim 6, wherein the two sipe walls which delimit the sipe are formed so as to be curved in the same direction along their radial extent in the second region of extent. This permits improved removability from a mold while reducing the internal mobility of the profile, as a result of which wear and rolling resistance are improved, and the forces which cause the notch effect are reduced.
Particularly advantageous is the design of a pneumatic vehicle tire as per the features of claim 7, wherein the two sipe walls which delimit the sipe are formed so

- 6 - PCT/EP2011/051768 as to be curved in opposite directions along their radial extent in the second region of extent, wherein the sipe wall which delimits the sipe in the direction of the curvature central point of the sipe has a greater curvature radius R2 than the other sipe wall.
This promotes easy insertion into and removal from a mold, and permits an optimized distribution of forces as the tire contact patch is run through, as a result of which the notch effect is reduced.
Particularly advantageous is the design of a pneumatic vehicle tire as per the features of claim 8, wherein the sipe, in the second, radially inner direction of extent, is formed with a section width which initially increases in the radially inward direction along the radial extent of said sipe proceeding from the radially outer point of extent P, and which then decreases again toward the radially inner point of extent Q. This promotes easy insertion into and removal from a mold, and permits an optimized distribution of forces as the tire contact patch is run through, as a result of which the notch effect is reduced.

Particularly advantageous is the design of a pneumatic vehicle tire as per the features of claim 9, wherein the sipe wall which inwardly delimits the sipe in the direction of the axis of curvature is delimited in the radially outward direction by a transition point P2 which delimits the second region of extent with respect to the first region of extent in the radially outward direction, and is delimited at the sipe base by a foot point Q2, and forms a rectilinear connection of the two points P2 and Q2. This promotes easy insertion into and removal from a mold, and permits an optimized distribution of forces as the tire contact patch is run through, as a result of which the notch effect is reduced.

- 7 - PCT/EP2011/051768 Particularly advantageous is the design of a pneumatic vehicle tire as per the features of claim 10, wherein, in the section planes perpendicular to the first main direction of extent, the sipe is formed in the first region of extent with a substantially constant section width along its radial extent proceeding from the second region of extent outward at least to a radial position at a distance h3 from the outside surface, wherein h3 S (1/3)T.
Particularly advantageous is the design of a pneumatic vehicle tire as per the features of claim 11, wherein the sipe is formed with a section width which increases continuously proceeding from the radial position at a distance h3 from the outside surface radially outward to the outside surface, wherein the maximum section width B is formed at the outside surface, where B < 0.5h3, wherein in particular the thickening is formed toward that side of the sipe which points away from the curvature of the second region of extent. This promotes easy insertion into and removal from a mold.
Particularly advantageous is the design of a pneumatic vehicle tire as per the features of claim 12, wherein the curvature of the sipe in the second region of extent is oriented in the direction of travel of the vehicle tire during forward travel. This permits uniform compression of the sipe under load, and a reduction of the forces acting at the sipe base.
Particularly advantageous is the design of a pneumatic vehicle tire as per the features of claim 13, wherein the curvature of the sipe in the second region of extent is orientated in the direction of travel of the vehicle tire during reverse travel. In this way, the forces acting in the sipe as the tire contact patch is run through are distributed uniformly, as a result of which the notch effect in the sipe base can be reduced.

- 8 - PCT/EP2011/051768 The invention will be explained in more detail below on the basis of the exemplary embodiments illustrated in figures 1 to 4, in which:
figure 1 shows an axial partial section of a circumferential portion of a tread profile of a pneumatic vehicle tire in plan view, figure 2 shows the tread profile of figure 1 in a sectional illustration as per section II-II
in figure 1, for explaining the depth profile of the sipes, figure 3 shows a sipe as per the illustration of figure 2, with an alternative design of the depth profile of the sipe, and figure 4 shows a sipe as per the illustration of figure 2, with a further alternative design of the depth profile of the sipe.

Figures 1 and 2 show a detail of a tread profile having a plurality of radially elevated profile ribs 1, 2, 3 which are arranged adjacent to one another in the axial direction A of the pneumatic vehicle tire and which extend in each case over the entire circumference of the pneumatic vehicle tire and which are spaced apart from one another in the axial direction A of the pneumatic vehicle tire by circumferential channels 4 and 5 which are aligned in the circumferential direction U over the entire circumference of the pneumatic vehicle tire.

For simplicity, figure 1 illustrates only the left-hand side of a tread profile from the equatorial plane A to the left-hand shoulder of the tire. The profile rib 1 is a shoulder profile rib, and the profile rib 3 is a central profile rib. The central profile rib 3 and the profile rib 2 are spaced apart axially from one another by the circumferential channel 5. The profile rib 2 and

- 9 - PCT/EP2011/051768 the shoulder profile rib 1 are spaced apart axially from one another by the circumferential channel 4. The ground contact area extends in the axial direction over its width TA into the left-hand profile rib 1. The profile rib 2 is formed in a known way with parallel sipes 7 which are arranged so as to be distributed over the circumference of the pneumatic vehicle tire and which extend from the circumferential channel 4 into the circumferential channel 5 and which is formed in a rectilinearly running manner in the outside surface 9, which delimits the tire radially to the outside, of the tire, wherein said sipes has an axial directional component and a directional component oriented in the circumferential direction, the greater of which is the axial directional component.

Parallel Sipes 8 are also formed, so as to be distributed over the circumference of the pneumatic vehicle tire, in the profile rib 3, which sipes extend in the axial direction across the entire profile rib 3 proceeding from the circumferential channel 5, and which sipes is formed in a rectilinearly running manner in the outside surface 9, which delimits the tire radially to the outside, of the tire, wherein said sipes has an axial directional component and a directional component oriented in the circumferential direction, the greater of which is the axial directional component. The shoulder profile block row 1 is formed with parallel sipes 6 which are arranged so as to be distributed over the entire circumference of the pneumatic vehicle tire and which extend outward in the axial direction A from the circumferential channel 4 into the region of extent outside the ground contact area TA and which are formed so as to extend in a rectilinearly running manner in the axial direction A
in the outside surface 9 of the pneumatic vehicle tire.

- 10 - PCT/EP2011/051768 Figure 2, taking the sipes 6 of the profile rib 1 as an example, shows the depth profile of the sipes 6. The sipes 7 and 8 in the profile ribs 2 and 3 respectively are formed with an analogous depth profile.
Here, figure 2 shows a section plane perpendicular to the main direction of extent of the sipe 6 in the outside surface 9. In the case of the sipes 6 which run rectilinearly in the outside surface 9 and which are aligned exclusively in the axial direction, said main direction of extent in the outside surface 9 is oriented in the axial direction A and the section plane is therefore the section plane perpendicular to the axial direction A.
As can be seen from figure 2, the sipe 6 is delimited laterally by the two cut walls 10 and 11 which are of corresponding form to one another. In the exemplary embodiment illustrated in figure 2, the cut walls 10 and 11 extend at a constant distance d from one another over the entire radial extent T of the sipe 6 from the outside surface 9 to the sipe base 12, which distance defines the section width.

The section width d is formed such that d < 0.6 mm, preferably d = 0.5 mm.

The Sipe 6, in a radially outer region of extent 16, extends rectilinearly radially inward from the outside surface 9 over a height of extent H1, measured in the radial direction R, so as to enclose an angle of inclination a with the radial R, wherein a <_ 3 , and defines the radial main extent 13 of the sipe. In the exemplary embodiment illustrated, in said radially outer region of extent 16, the sipe 6 extends with an angle of inclination a = 0 with respect to the radial R. The radial height of extent h1 is such that (1/2)T <-

- 11 - PCT/EP2011/051768 h1 < 0.9T. In the exemplary embodiment illustrated, hl =
(2/3)T.

Adjoining the radially outer region of extent 16, the sipe 6, in a radially inner region of extent 26, extends inward in the radial direction R over a radial height of extent h2 to the sipe base 12, wherein in the radially inner region of extent 26, the two sipe walls and 11 run in a curved fashion in circle segment 10 form about a curvature central point M1. The curvature central point M1 lies on that side of the sipe 6 in the profile rib 1 which points away from the sipe wall 10.
Here, the sipe wall 10 extends from a transition point P, which delimits the sipe wall 10 in the radially inner region of extent 26 in the radially outward direction with respect to the radially outer region of extent 16, to the point Q which delimits the sipe wall 10 in the radially inward direction at the sipe base

12, and said sipe wall 10 runs in a curved fashion with a radius R1 about the central point M1. Here, the sipe wall 11 extends from a transition point P2, which delimits the sipe wall 11 in the radially inner region of extent 26 in the radially outward direction with respect to the radially outer region of extent 16, to the point Q2 which delimits the sipe wall 11 in the radially inward direction at the sipe base 12, and said sipe wall 11 runs in a curved fashion with a radius about the central point M1. The curvature radius R1 of the sipe wall 10 is greater than the curvature radius of the sipe wall 11.

The curvature radius R1 is formed such that 2 mm < R1 <
10 mm. In the exemplary embodiment illustrated, R1 = 9 mm.

The line of intersection s which connects the two points P and Q which delimit the sipe wall 10 in the radially inner region of extent runs with an angle of inclination P with respect to the radial R, where 15 <
R < 45 . In the exemplary embodiment illustrated, (3 is selected such that 300 < (3 < 35 . In the specific embodiment illustrated, 3 = 32 .

The tangent t to the curvature contour line of the channel wall 10 at the point Q is at an angle of inclination y with respect to the radial R, where 100 < y < 160 . In particular exemplary embodiments, y is selected such that 130 < y < 140 . In the illustrated exemplary embodiment, y is selected to be 135 .

In the illustrated exemplary embodiment, the curvature central point M1 is arranged, as viewed in the circumferential direction U of the pneumatic vehicle tire, on that side of the main extent 13 of the sipe 6 in the radially outer region of extent 16 which is arranged behind the sipe 6 when the pneumatic vehicle tire rotates during forward travel of the pneumatic vehicle tire. The curvature central point M1 thus lies on that circumferential side which is situated on the pneumatic vehicle tire in front of the main extent 13 of the sipe 6 in the radially outer region of extent 16 during reverse travel, and the curvature of the sipe in the radially inner region of extent 26 is thus oriented in the direction of travel of the vehicle tire during reverse travel.

In another embodiment, the curvature central point M1 lies on that circumferential side which is situated on the pneumatic vehicle tire in front of the main extent

13 of the sipe 6 in the radially outer region of extent 16 during forward travel, and the curvature of the sipe in the radially inner region of extent 26 is thus oriented in the direction of travel of the vehicle tire during forward travel.

Figure 3 shows a design of the sipe 6 in which the sipe 6, in the radially outer region of extent 16, runs in an undulating or zig-zagged form along its main extent 13 from the outside surface 9 over the entire radial height of extent h1. The rectilinear main extent 13 of the sipe is the zero line of the undulating or zig-zagged form, and is aligned at the angle of inclination a with respect to the radial R. In this exemplary embodiment, too, the section width d, formed by the channel walls 10 and 11, of the sipe 6 is constant in the radially outer region of extent 16.

Figure 3 shows a further exemplary embodiment of the depth profile of the sipe, in which, in the radially inner region of extent 26, the channel wall 10 runs in a curved fashion about the curvature central point M1, with a curvature radius R1, between the transition point P and the point Q - as in the exemplary embodiment illustrated in figure 2. In the exemplary embodiment shown, however, the sipe wall 11 runs rectilinearly between the points P2 and Q2, parallel to the straight line s which connects the points P and Q. In the radially inner region of extent 26 of the sipe 6, the two channel walls 10 and 11 enclose a thickened opening

14 which forms a cavity and which, proceeding from the transition point P of the channel wall 10, is formed with a width d which initially increases in the radially inward direction, and which subsequently, in its radially inner region of extent, is formed with a width d of the sipe which decreases continuously again to the point Q which delimits the channel wall 10 radially to the inside.

Figure 4 shows a further exemplary embodiment of the radially inner region of extent 26 of the sipe 6, in which the channel wall 10 - as in the exemplary embodiment of figure 2 - runs in a curved fashion about the curvature central point M1, with a curvature radius R1, between the two points P and Q which delimit the channel wall 10 in the radially inner region of extent 26. In said embodiment, the channel wall 11 runs curved in circle segment form about a curvature central point M2, with a curvature radius R2, between the points P2 and Q2, wherein the curvature central point M2 is formed on that side of the sipe 6 in the profile rib 1 which points away from the sipe wall 11, and is thus formed on the opposite side of the sipe 6 in the profile rib 1 from the curvature central point M1. Here, the curvature radius R2 is such that R2 > R1. It is thus the case in this exemplary embodiment too that, in the radially inner region of extent 26, the two sipe walls 10 and 11 enclose a thickening 14, which forms a cavity, of the sipe 6, which thickening, proceeding from the transition point P which delimits the sipe wall 10 radially toward the outside, has a width d of the sipe which initially increases continuously in the radially inward direction, and which subsequently, in the radially inner region of extent of the radially inner section of extent 26, has a width d of the sipe which decreases continuously again to the point Q.

Figure 4 furthermore illustrates a further exemplary embodiment of the radially outer region of extent 16 of a sipe 6, in which, in the section planes perpendicular to the first main direction of extent, the sipe 6 is formed in the radially outer region of extent 16 with a constant section width d along its radial extent proceeding from the radially inner region of extent 26 outward to a radial position at a distance h3 from the outside surface 9, where h3 < (1/3)T. Proceeding in the radially outward direction from the radial position at a distance h3 from the outside surface 9, the sipe 6 is formed with a section width d which increases continuously to the outside surface 9, wherein the maximum section width B is formed at the outside surface 9, where B < (1/2)h3. For this purpose, the sipe

- 15 - PCT/EP2011/051768 wall 10 is formed, in the radially outward direction proceeding from the position at a distance h3 from the outside surface 9, and in the circumferential direction U which points away from the curvature central point M1, such that its distance from the main extent 13 of the sipe 6 in the radially outer region of extent 16 increases continuously. In the exemplary embodiment illustrated, in the radial region of extent proceeding from the position at a distance h3 from the outside surface 9, the sipe wall 16 is curved about a curvature central point which is formed on that circumferential side of the sipe 6 which points away from the curvature central point M1. In this way, in the region of extent of the height h3, the sipe walls 10 and 11 enclose a radially outwardly widening or thickening opening 15 which is arranged on that circumferential side of the main extent 13 of the sipe which points away from the curvature central point M1. In another embodiment which is not illustrated, the channel wall 10 is of rectilinear form in the radial region of extent h3.

Even though the sipes 6, 7 and 8 are in each case of rectilinear form in the outside surface 9 in figure 1, it is provided in another embodiment (not illustrated) that the sipes run in an undulating or zig-zagged form in the outside surface 9, wherein the zero line of the zig-zagged or undulating form in the outside surface 9 forms the main direction of extent of the sipe in the outside surface 9.
The tread profile illustrated in figure 1 is a rib profile with sipes. In another embodiment (not illustrated), at least one of the circumferential ribs is replaced by a profile block row which is formed from profile block elements arranged in series in the circumferential direction, which profile block elements are spaced apart from one another in the circumferential direction by transverse channels, and

- 16 - PCT/EP2011/051768 the sipes are formed in the profile block elements of the profile block row.

In the exemplary embodiment illustrated, the tread profile is a tread profile of a passenger motor vehicle tire. In another embodiment, the tread profile is a tread profile of a utility vehicle tire. In a further alternative embodiment, the tread profile is a tread profile of a van tire or of a tire for light transporters.

- 17 - PCT/EP2011/051768 List of reference numerals (Part of the description) 1 Profile rib 2 Profile rib 3 Profile rib 4 Circumferential channel Circumferential channel 6 Sipe 7 Sipe 8 Sipe 9 Outside surface Sipe wall 11 Sipe wall 12 Sipe base 13 Main extent 14 Thickened opening Thickened opening 16 Outer region of extent 26 Inner region of extent

Claims

1. A pneumatic vehicle tire having a profiled tread with radially elevated profile elements (1, 2, 3) which are delimited by channels (4, 5) and having sipes (6, 7, 8), which sipes are formed at least in some of the profile elements (1, 2, 3) and have in each case two parallel sipe walls (10, 11) which delimit the sipe (6) and which are formed substantially correspondingly to one another, wherein the first main direction of extent, which is formed in the ground contact surface-forming outside surface (9) of the profile element (1), of the sipe (6) has its greatest directional component in the axial direction A of the pneumatic vehicle tire, and wherein, in the section planes perpendicular to the first main direction of extent in the ground contact surface, the sipe (6) extends from the ground contact surface-forming outside surface (9) to the sipe base (12) over a depth T of the sipe (6) measured in the radial direction R, and which sipes have a first, radially outer region of extent (16) which extends from the ground contact surface-forming outside surface (9) radially inward over a height h1 measured in the radial direction R, where (1/2)T
<= h1 <= 0.9T, and which sipes have a second, radially inner region of extent (26) which is formed so as to adjoin the first region of extent (16) inward in the radial direction R and which extends over a height h2, measured in the radial direction R, to the sipe base (12), wherein, in the section planes perpendicular to the first main direction of extent, the sipe (6), in each case in the first, radially outer region of extent (16), runs from the outside surface (9) to the second, radially inner region of extent (26) so as to be aligned along a second main direction of extent (13) which has an angle of inclination .alpha. with respect to the radial R, wherein 0° <= .alpha. <= 3°, characterized in that, in the section planes perpendicular to the first main direction of extent, the sipe (6) is formed, in each case in the second, radially inner region of extent (26), so as to run in a curved manner toward one side proceeding from the first, radially outer region of extent (16) to the sipe base (12).

2. The pneumatic vehicle tire as per the features of claim 1, wherein the sipe wall (10) which delimits the sipe (6) toward the outside of the curvature in the second region of extent (26) is formed with a curvature profile with a curvature radius R1, where 2 mm <= R1 <= 10 mm, about a curvature central point M1 which lies on that side of the sipe (6) which points away from said sipe wall (10).

3. The pneumatic vehicle tire as per the features of claim 1 or 2, wherein the sipe wall (10) which delimits the sipe (6) toward the outside of the curvature is delimited in the radially outward direction by a transition point P, which delimits the second region of extent (26) with respect to the first region of extent (16) in the radially outward direction, and is delimited at the sipe base (12) by a foot point Q, wherein the connecting path s between the transition point P and the foot point Q in the section planes perpendicular to the first main direction of extent runs with an angle of inclination .beta. with respect to the radial direction R, where 15° <= .beta. <= 45°, in particular 30° <= .beta. <=
35°.

4. The pneumatic vehicle tire as per the features of one or more of the preceding claims, wherein the sipe wall (10) which delimits the sipe (6) toward the outside of the curvature is delimited at the sipe base (12) by a foot point Q, wherein the tangent t to the curvature of the sipe wall (10) at the foot point Q runs at an angle of inclination .gamma. with respect to the radial direction R, where 100° <= .gamma. <= 160°, in particular 130° <= .gamma. <=
140°.

5. The pneumatic vehicle tire as per the features of one or more of the preceding claims, wherein the sipe (6) is formed substantially with a constant section width d over its radial extent of height h2 in the second, radially inner region of extent (26).

6. The pneumatic vehicle tire as per the features of one or more of claims 1 to 4, wherein the two sipe walls (10, 11) which delimit the sipe (6) are formed so as to be curved in the same direction along their radial extent in the second region of extent (26).

7. The pneumatic vehicle tire as per the features of one or more of claims 1 to 4, wherein the two sipe walls (10, 11) which delimit the sipe (6) are formed so as to be curved in opposite directions along their radial extent in the second region of extent (26), wherein the sipe wall (11) which delimits the sipe in the direction of the curvature central point of the sipe has a greater curvature radius R2 than the other sipe wall (10).

8. The pneumatic vehicle tire as per the features of one or more of claims 1 to 4, wherein the sipe (6), in the second, radially inner direction of extent (26), is formed with a section width d which initially increases in the radially inward direction along the radial extent of said sipe proceeding from the radially outer point of extent P, and which then decreases again toward the radially inner point of extent Q.

9. The pneumatic vehicle tire as per the features of claim 6, wherein the sipe wall (11) which inwardly delimits the sipe (6) in the direction of the axis of curvature is delimited in the radially outward direction by a transition point P2 which delimits the second region of extent (26) with respect to the first region of extent (16) in the radially outward direction, and is delimited at the sipe base (12) by a foot point Q2, and forms a rectilinear connection of the two points P2 and Q2.

10. The pneumatic vehicle tire as per the features of one or more of the preceding claims, wherein, in the section planes perpendicular to the first main direction of extent, the sipe (6) is formed in the first region of extent (16) with a substantially constant section width d along its radial extent proceeding from the second region of extent (26) outward at least to a radial position at a distance h3 from the outside surface (9), where h3 <= (1/3)T.

11. The pneumatic vehicle tire as per the features of claim 10, wherein the sipe (6) is formed with a section width d which increases continuously proceeding from the radial position at a distance h3 from the outside surface (9) radially outward to the outside surface (9), wherein the maximum section width B is formed at the outside surface, where B
< 0.5h3, wherein in particular the thickening (15) is arranged to that side of the sipe (6) which points away from the curvature of the second region of extent (26).

12. The pneumatic vehicle tire as per the features of one or more of the preceding claims, wherein the curvature of the sipe (6) in the second region of extent (26) is oriented in the direction of travel of the vehicle tire during forward travel.

13. The pneumatic vehicle tire as per the features of one or more of claims 1 to 11, wherein the curvature of the sipe (6) in the second region of extent (26) is orientated in the direction of travel of the vehicle tire during reverse travel.