Tyre tread

Abstract

It is provided a pneumatic tyre, the tyre having a circumferential direction, an axial direction and an equatorial plane, and the tyre comprising: a tread extending in a tyre circumferential direction, said tread comprising at least one circumferential groove running continuously in the circumferential direction, and a plurality of axial grooves or transverse grooves running at an angle to the axial direction, and a plurality of blocks defined by the circumferential groove and the axial grooves or transverse grooves, said blocks extending radially between an inner surface of the tread and a tread surface to come into contact with the ground, wherein at least some of the blocks comprise at least one wavy groove that extends from a circumferential groove inwardly into the block, and wherein the wavy groove has a depth extending radially from the tread surface to come into contact with the ground towards the inner surface that ends above the inner surface (26) of the tread.

Claims

1. A pneumatic tyre, the tyre having a circumferential direction, an axial direction and an equatorial plane, and the tyre comprising: a tread extending in a tyre circumferential direction, said tread comprising at least one circumferential groove running continuously in the circumferential direction, and a plurality of axial grooves or transverse grooves running at an angle to the axial direction, and a plurality of blocks defined by the circumferential groove and the axial grooves or transverse grooves, said blocks extending radially between an inner surface of the tread and a tread surface to come into contact with a ground, wherein at least some of the blocks comprise at least one wavy groove that extends from a circumferential groove inwardly into the block, and wherein the wavy groove has a depth extending radially from the tread surface to come into contact with the ground towards the inner surface that ends above the inner surface of the tread, wherein at least a portion of one or more longitudinal side walls of blocks of a middle tread row comprises a step, wherein the wavy groove is arranged on said portion of the longitudinal side wall comprising the step and has a depth at the longitudinal side wall extending in the radial direction from the tread surface to the step, and wherein the step has a height extending in a radial direction from the inner surface of the tread to a bottom of the groove at the longitudinal side wall, and wherein the depth of the wavy groove decreases along its length inwardly into the block.

2. The tyre according to claim 1, wherein the tread comprises on each side of the equatorial plane a central circumferential groove running continuously in a zigzag manner in the circumferential direction, and a lateral circumferential groove running continuously in a zigzag manner in the circumferential direction, wherein the lateral circumferential groove is arranged outwardly of the central circumferential groove in the tyre axial direction; and a center tread row delimited by the central circumferential grooves, a middle tread row arranged on each lateral side of the center tread row and delimited by the central circumferential groove and the lateral circumferential groove, and a shoulder tread row arranged on the lateral side of the of the middle tread row in the tyre axial direction; each of the tread rows comprising a plurality of blocks, said blocks in each tread row being separated from each other by axial grooves or transverse grooves running at an angle to the axial direction; wherein the blocks of the middle tread row comprise a wavy groove, and wherein the wavy grooves alternatingly extend from the central circumferential groove or the lateral circumferential groove inwardly into the blocks.

3. The tyre according to claim 1, wherein center blocks of a center tread row comprise at least one multi-step area on a longitudinal block side wall, the multi-step area protruding into the central circumferential grooves and comprising at least two or three steps above the inner surface.

4. The tyre according to claim 1, wherein center blocks of a center tread row, middle blocks of a middle tread row and shoulder blocks of a shoulder tread row comprise a plurality of zigzag shaped 3D sipes, wherein the sipe density in the middle tread row is configured to be larger than the sipe density in the shoulder tread row.

5. The tyre according to claim 1, wherein a sipe density in a middle tread row of the tyre is configured to be larger than a sipe density in a center tread row of the tyre.

6. The tyre according to claim 1, wherein center blocks of a center tread row are arranged in pairs of adjacent tread blocks, wherein each pair of center blocks in longitudinal direction is separated from the following pair by an axial groove and each single center block is separated from the other block of the pair by a transverse groove, wherein the transverse groove has a segmented Z-shaped form.

7. The tyre according to claim 1, wherein middle blocks of a middle tread row are arranged in pairs of adjacent tread blocks, wherein each pair of middle blocks in longitudinal direction is separated from the following pair by a transverse groove and each single middle block is separated from the other block of the pair by a transverse groove, wherein the transverse groove has a segmented Z-shaped form.

8. The tyre according to claim 1, wherein at least some blocks of a shoulder tread row of the tyre comprises a recess along the tread edge, wherein the recess has a length l.sub.r extending longitudinally from the block edge ranging from 30% to 70%, relative to the longitudinal length l.sub.b of the block.

9. The tyre according to claim 1, wherein at least some blocks of a shoulder tread row of the tyre comprise a recess on a tread shoulder of the tyre, the recess extending inwardly from the surface of the tread shoulder.

10. The tyre according to claim 1, wherein at least some blocks of a shoulder row of the tyre comprise a protrusion on a tread shoulder of the tyre, the protrusion extending outwardly from the surface of the tread shoulder.

11. The tyre according to claim 1, wherein at least some blocks of a shoulder row of the tyre comprises a recess along a tread edge, wherein the recess has a length l.sub.r extending longitudinally from a block edge ranging from 40% to 60%, relative to the longitudinal length l.sub.b of the block.

12. The tyre according to claim 1, wherein said portion of the longitudinal side wall at which the wavy groove is arranged has a single step.

13. The tyre according to claim 1, wherein the wavy grooves extend at an angle of from 10° to 50° to the axial direction.

Description

(1) In the following the invention is explained in detail by the examples and drawings showing preferred embodiments of the present invention, wherein each feature can constitute solely or in combination an aspect of the invention. In the drawings:

(2) FIG. 1: is a simplified schematic view of a pneumatic tyre for an all-terrain vehicle.

(3) FIG. 2: is a schematic perspective view of a pneumatic tyre for an all-terrain vehicle.

(4) FIG. 3: is a schematic view of a pair of blocks of shoulder, middle and center row of a tread for a passenger car tyre.

(5) FIG. 4: is a schematic view of a pair of blocks of shoulder, middle and center row of a tread for a light truck tyre.

(6) The FIG. 1 illustrates a tyre tread 2 for an all-terrain vehicle having a circumferential direction, an axial direction and an equatorial plane E. The tread has first lateral tread edge 5 and a second lateral tread edge 6. The tyre comprises a tread 2 extending in a tyre circumferential direction. The tread 2 comprises on each side of the equatorial plane E a central circumferential groove 14 running continuously in a zigzag manner in the circumferential direction, and a lateral circumferential groove 16 running continuously in a zigzag manner in the circumferential direction. The lateral circumferential groove 16 is arranged outwardly of the central circumferential groove 14 in the tyre axial direction. The pitch of the central circumferential groove 14 is higher than the pitch of the lateral circumferential groove 16. Central and lateral circumferential grooves 14 and 16 have a maximum profile depth extending radially between an inner surface 26 of the tread 2 and a tread surface 33 to come into contact with the ground.

(7) A center tread row 17 is delimited by the central circumferential grooves 14. A middle tread row 18 arranged on each lateral side of the center tread row 17 is delimited by the central circumferential groove 14 and the lateral circumferential groove 16. A shoulder tread row 19 is arranged on the lateral side of the of the middle tread row 18 in the tyre axial direction. Each of the tread rows 17, 18, 19 comprises a plurality of blocks 20a, 20b, 22a, 22b, 24a, 24b. The plurality of blocks 20a, 20b, 22a, 22b, 24a, 24b is defined by the circumferential groove 14, 16 and the axial grooves 34 or transverse grooves 35, 36. The blocks 20a, 20b, 22a, 22b, 24a, 24b in each tread row 17, 18, 19 are separated from each other by axial grooves 34 or transverse grooves 35, 36 running at an angle of from 5° to 50° to the axial direction.

(8) The blocks 20a, 20b, 22a, 22b, 24a, 24b extend radially between an inner surface 26 of the tread 2 and a tread surface 33 to come into contact with the ground. The blocks 22a, 22b of the middle tread row 18 comprise a wavy groove 30 that extends from the circumferential groove 14, 16 inwardly into the block 22a, 22b, whereby the wavy groove 30 narrows along its length. The wavy grooves 30 alternatingly extend from the central circumferential groove 14 or the lateral circumferential groove 16 inwardly into the blocks 22a, 22b. The wavy groove 30 has a depth decreases along its length inwardly into the block 22a, 22b. The wavy groove 30 is less deep at the tip 52 than at the base 50. The wavy grooves 30 extend in transverse direction at an angle of from 10° to 50° to the axial direction.

(9) Each block comprises a ground contact surface 33 and a leading side wall 42 and a trailing side wall 44 and at least two longitudinal side walls 40 facing the circumferential grooves. The leading side wall 42, or the trailing side wall 44 and at least a portion of one or two of the longitudinal side walls 40 of the middle blocks 22a, 22b comprise a step 31. The steps 31 on the leading side wall 42 and trailing side wall 44 protrude into the transverse grooves 36. The steps 31 on the longitudinal side walls 40 protrude into the central circumferential grooves 14 or lateral circumferential grooves 16. Also the shoulder blocks 20a, 20b comprise a step 31 protruding into the lateral circumferential grooves 16. The wavy groove 30 is arranged on a portion of the longitudinal side wall 40 and has a depth extending in radial direction from the tread surface 33 to the step 31.

(10) The center blocks 24a, 24b each comprise a multi-step area 32 on a longitudinal block side wall 40. The multi-step area 32 protrudes into the central circumferential grooves 14 and comprises three steps above the inner surface 26.

(11) The center blocks 24a, 24b are arranged in pairs of adjacent tread blocks, wherein each pair of center blocks 24a, 24b in longitudinal direction is separated from the following pair 24a, 24b by an axial groove 34 and each single center block 24a, 24b is separated from the other block of the pair by a transverse groove 35. Also the middle blocks 22a, 22b are arranged in pairs of adjacent tread blocks, wherein each pair of middle blocks 22a, 22b in longitudinal direction is separated from the following pair 22a, 22b by a transverse groove 36 and each single middle block 22a, 22b is separated from the other block of the pair by a transverse groove 35. The transverse grooves 35 have a segmented Z-shaped form.

(12) The FIG. 2 illustrates a schematic perspective view of a pneumatic tyre for an all-terrain vehicle. The tyre 1 comprises a tread 2 extending in a tyre circumferential direction. The tread 2 comprises a center tread row 17, a middle tread row 18 arranged on each lateral side of the center tread row 17 and a shoulder tread row 19 arranged on the lateral sides of the of the middle tread rows 18 in the tyre axial direction. The center blocks 24a, 24b are arranged in pairs of adjacent tread blocks, wherein each pair of center blocks 24a, 24b in longitudinal direction is separated from the following pair 24a, 24b by an axial groove 34 and each single center block 24a, 24b is separated from the other block of the pair by a transverse groove 35. The axial grooves separating the block pairs of the central tread row have a tie bar 46 therein. The center blocks 24a, 24b, the middle blocks 22a, 22b and the shoulder blocks 22a, 22b comprise zigzag shaped 3D sipes 29.

(13) Some of the blocks 20a of the shoulder row 19 comprise a recess 39 along the tread edge 6, wherein the recess 39 has a length l.sub.r extending longitudinally from the block edge 46 of about 40% to 50%, relative to the longitudinal length l.sub.b of the block 20a. Some of the blocks 20a, 20b of the shoulder row 19 comprise a triangular recess 37 on the tread shoulder 4, the triangular recess 37 extending inwardly from the surface of the block 20a, 20b. Some of the blocks 20a, 20b of the shoulder row 19 comprise a triangular protrusion 38 on the tread shoulder 4, the triangular protrusion 38 extending outwardly from the surface of the block 20a, 20b. The tread 2 has a substantially uniform exterior block surfaces in the axial direction.

(14) Illustrated in FIG. 3 is a schematic view of a pair of blocks of shoulder, middle and center row of a tread for a passenger car tyre. The center blocks 24a, 24b, the middle blocks 22a, 22b and the shoulder blocks 22a, 22b comprise a plurality of zigzag shaped 3D sipes 29. The sipe density in the blocks 22a, 22b of the middle tread row 18 is larger than the sipe density in the blocks 20a, 20b of the shoulder tread row 19. Particularly, the sipe density of the blocks 22a, 22b of middle tread row 18 is larger than the sipe density in the blocks 24a, 24b of the center tread row 17.

(15) Illustrated in FIG. 4 is a schematic view of a pair of blocks of shoulder, middle and center row of a tread for a light truck tyre. The center blocks 24a, 24b, the middle blocks 22a, 22b and the shoulder blocks 22a, 22b comprise a plurality of zigzag shaped 3D sipes 29. The sipe density in the blocks 22a, 22b of the middle tread row 18 is larger than the sipe density in the blocks 20a, 20b of the shoulder tread row 19. Further, the sipe density of the blocks 22a, 22b of middle tread row 18 is larger than the sipe density in the blocks 24a, 24b of the center tread row 17.

EXAMPLES

(16) Sample sets of prototype pneumatic tyres 265/70R17 light truck tyres (LT 1, 2, 3, 4) and passenger car tyres (PCT 1, 2, 3, 4) having the basic tread pattern as illustrated in FIG. 4 and FIG. 3, respectively, were manufactured and outdoor performance was tested. Typical depth values for wavy grooves in the examples were from 19% to 43%. Outdoor testing included the following performance tests: R117 noise testing measuring noise values in dB(A) measured by instrument, testing of in cabin noise rated by expert assessment, dry handling rated by expert assessment, off road sand and mud performance rated by expert assessment, snow braking determining the objective braking distance, stone release tests rating the stone count after transit on gravel based on visual control, off road traction on gravel rated by expert assessment, aquaplaning determining the speed, wet breaking determining the objective braking distance, and wet handling rated by expert assessment.

Example 1: Outdoor Testing On-Road Evaluation

(17) A sample set of four prototype light truck tyres 265/70R17 (LT 1) were mounted on a rim and fitted on a vehicle. A set of four prior art tyres size 265/70R17 (Ref 1) were mounted on a rim fitted on a vehicle and used as control and outdoor performance was tested for both tyre sets under identical conditions. For this experiment, the tyres were tested on an outdoor proving ground using the above test procedures. The table 1 below shows the test results of the tyres LT 1 in comparison to the reference tyres Ref 1. For the subjective ratings, the higher the score, the better the performance is.

(18) TABLE-US-00001 TABLE 1 on-road evaluation of light truck tyres Pattern/Construction Ref 1 LT 1 Size LT 265/70R17 LT 265/70R17 Spec LT - Reference set LT Subjective Noise Rating 6.75 7.00 Lateral Hydroplane Rating 7.00 7.25 Lateral Hydroplane Speed 88.51 90.12 (kph) Wet Handling Rating 6.75 7.25 Wet Handling Lap Time 61.20 60.30 (avg) Wet Lateral Circle G 0.56 0.60 Lane Change Speed (kph) 90 93 Lane Change Rating 7.00+ 7.5 Dry Max Handling Rating 7.00+ 7.5

(19) As apparent from the test results as shown in Table 1, the example tyres showed improved levels of noise, wet performance, dry performance and limit handling capacity.

Example 2: Outdoor Testing Off Road Evaluation

(20) A sample set of four prototype light truck tyres 265/70R17 (Proto 1) were mounted on a rim and fitted on a vehicle. A set of four prior art tyres size 265/70R17 (Ref 1) were mounted on a rim fitted on a vehicle and used as control and outdoor performance was tested for both tyre sets under identical conditions. For this experiment, the tyres were tested on an outdoor proving ground using the above test procedures.

(21) The table 2 below shows the test results of the tyres LT 2 in comparison to the reference tyres 2. For the subjective ratings, the higher the score, the better the performance is.

(22) TABLE-US-00002 TABLE 2 off road evaluation of light truck tyres Pattern/Construction Ref 2 LT 2 Size LT 265/70R17 LT 265/70R17 Spec LT - Reference set LT Loose Hill Climb Ability 6.75 7 Side Slip/Side Slope Traction 7 7 Gravel Bin Traction 6.5 6.75 Sand Bin Traction 7 7.25 Steering ability/side-bite ability 7 7 Front path stability 7 7.25 Forward traction/acceleration 7 7 traction (Rock Surface) Mechanical Envelopment/Lug 6.75 7.25 Engagement Overall Rating 6.75 7.00

(23) As apparent from the test results as shown in Table 2, the example tyres showed a noticeable increase in tread lug engagement on irregular rock/boulder surfaces, with increased outboard shoulder traction availability. The example tyres further showed lightly higher front path stability and lateral holding ability using smaller sections of contact patch than the reference tyres.

Example 3: Outdoor Testing of Mud Acceleration and Steering

(24) A sample set of four prototype light truck tyres 265/70R17 (LT 3) were mounted on a rim and fitted on a vehicle. A set of four prior art tyres size 265/70R17 (Ref 3) were mounted on a rim fitted on a vehicle and used as control. Outdoor performance was tested for both tyre sets under identical conditions. For this experiment, the tyres were tested on an outdoor proving ground using the above test procedures.

(25) The table 3 below shows the test results of the tyres LT 3 in comparison to the reference tyres Ref 3. For the subjective ratings, the higher the score, the better the performance is.

(26) TABLE-US-00003 TABLE 3 mud acceleration and steering of light truck tyres Pattern/Construction Ref 3 LT 3 Size LT 265/70R17 LT 265/70R17 Spec LT - Reference set LT Initial Forward Acceleration 6.5 7 (Low Wheel Speed) Forward Acceleration 6.75 7 (High Wheel Speed) Steering Response & Precision 7 7 Controllability 6.75 7 Overall Rating 6.75 7.00

(27) As apparent from the test results as shown in Table 3, the example tyres showed a noticeable increase in initial forward acceleration/material moving capability at low wheel speed, providing for higher longitudinal acceleration from standstill. The example tyres further showed an improved overall controllability compared to the prior art group, with reduced rear axle yaw movement/lateral movement during initial acceleration.

Example 4: Outdoor Testing of Snow Performance

(28) A sample set of four prototype light truck tyres 265/70R17 (LT 4) were mounted on a rim and fitted on a vehicle. A set of four prior art tyres size 265/70R17 (Ref 4) were mounted on a rim fitted on a vehicle and used as control. Outdoor performance was tested for both tyre sets under identical conditions. For this experiment, the tyres were tested on an outdoor proving ground using the above test procedures.

(29) The table 4 below shows the test results of the tyres LT 4 in comparison to the reference tyres Ref 4. For the subjective ratings, the higher the score, the better the performance is.

(30) TABLE-US-00004 TABLE 4 snow performance of light truck tyres Pattern/Construction Ref 4 LT 4 Size LT 265/70R17 LT 265/70R17 Spec LT - Ref. set LT Braking snow ABS 100% 105% Acc snow with ESP 100% 110%

(31) As apparent from the test results as shown in Table 4, the example tyres showed improved levels of snow braking and acceleration compared to the reference.

Example 5: Outdoor Testing On-Road Evaluation

(32) A sample set of four prototype passenger car tyres 265/70R17 (PCT 1) were mounted on a rim and fitted on a vehicle. A set of four prior art tyres size 265/70R17 (Ref 5) were mounted on a rim fitted on a vehicle and used as control and outdoor performance was tested for both tyre sets under identical conditions. For this experiment, the tyres were tested on an outdoor proving ground using the above test procedures.

(33) The table 5 below shows the test results of the tyres PCT 1 in comparison to the reference tyres Ref 5. For the subjective ratings, the higher the score, the better the performance is.

(34) TABLE-US-00005 TABLE 5 on-road evaluation of passenger car tyres Pattern/Construction Ref 5 PCT 1 Size P 265/70R17 P 265/70R17 Spec PCT - Ref. set PCT Ride 7.00 7.25− Steering/Light Handling 6.75 7.50+ Lateral Hydroplane Rating 7.00+ 7.25 Lateral Hydroplane Speed 85.30 86.90 (kph) Wet Handling Rating 6.75 7.25+ Wet Handling Lap Time (avg) 60.63 59.53 Wet Lateral Circle G 0.62 0.62 Lane Change Speed (kph) 92 100 Lane Change Rating 7 7.5 Dry Max Handling Rating 7 7.5

(35) As apparent from the test results as shown in Table 5, the example tyres showed improved levels of ride, steering, wet performance, dry performance and limit handling capacity.

Example 6: Outdoor Testing Off Road Evaluation

(36) A sample set of four prototype passenger car tyres 265/70R17 (PCT 2) were mounted on a rim and fitted on a vehicle. A set of four prior art tyres size 265/70R17 (Ref 6) were mounted on a rim fitted on a vehicle and used as control and outdoor performance was tested for both tyre sets under identical conditions. For this experiment, the tyres were tested on an outdoor proving ground using the above test procedures.

(37) The table 6 below shows the test results of the tyres PCT 2 in comparison to the reference tyres 6. For the subjective ratings, the higher the score, the better the performance is.

(38) TABLE-US-00006 TABLE 6 off road evaluation of passenger car tyres Pattern/Construction Ref 6 PCT 2 Size P 265/70R17 P 265/70R17 Spec PCT - Ref. set PCT Loose Hill Climb Ability 6.75 7 Side Slip/Side Slope Traction 7 7.25 Gravel Bin Traction 6.5 6.75 Sand Bin Traction 7.25 7.25 Steering ability/side-bite ability 7 7.25 Front path stability 7 7 Forward traction/acceleration 7 7 traction (Rock Surface) Mechanical Envelopment/Lug 6.75 7.25 Engagement Overall Rating 6.75 7.00

(39) As apparent from the test results as shown in Table 6, the example tyres showed increased mechanical edge envelopment compared to prior art group, showing reduced tread lug skipping, and higher loose hill climbing ability, gravel bin traction showing some improvement compared to control tyre group, with higher forward grip and equal sand acceleration performance.

Example 7: Outdoor Testing of Mud Acceleration and Steering

(40) A sample set of four prototype passenger car tyres 265/70R17 (PCT 3) were mounted on a rim and fitted on a vehicle. A set of four prior art tyres size 265/70R17 (Ref 7) were mounted on a rim fitted on a vehicle and used as control. Outdoor performance was tested for both tyre sets under identical conditions. For this experiment, the tyres were tested on an outdoor proving ground using the above test procedures.

(41) The table 7 below shows the test results of the tyres PCT 3 in comparison to the reference tyres Ref 7. For the subjective ratings, the higher the score, the better the performance is.

(42) TABLE-US-00007 TABLE 7 mud acceleration and steering of passenger car tyres Pattern/Construction Ref 7 PCT 3 Size P 265/70R17 P 265/70R17 Spec PCT - Ref. set PCT Initial Forward Acceleration 6.75 7.25 (Low Wheel Speed) Forward Acceleration 6.75 7.25 (High Wheel Speed) Steering Response & Precision 7 7 Controllability 6.75 7 Overall Rating 6.75 7.25

(43) As apparent from the test results as shown in Table 7, the example passenger car tyres showed a large increase in initial forward acceleration, generating higher longitudinal grip at lower wheel speeds than prior art group. Improved cleaning ability at high & low speeds, with improved generating of forward grip.

Example 8: Outdoor Testing of Snow Performance of Passenger Car Tyres

(44) A sample set of four prototype passenger car tyres 265/70R17 (PCT 4) were mounted on a rim and fitted on a vehicle. A set of four prior art tyres size 265/70R17 (Ref 8) were mounted on a rim fitted on a vehicle and used as control. Outdoor performance was tested for both tyre sets under identical conditions. For this experiment, the tyres were tested on an outdoor proving ground using the above test procedures.

(45) The table 8 below shows the test results of the tyres PCT 4 in comparison to the reference tyres Ref 8. For the subjective ratings, the higher the score, the better the performance is.

(46) TABLE-US-00008 TABLE 8 snow performance of passenger car tyres Pattern/Construction Ref 8 PCT 4 Size P 265/70R17 P 265/70R17 Spec PCT - Ref. set PCT Braking snow ABS 100% 102.5% Acc snow with ESP 100% .sup. 102%

(47) As apparent from the test results as shown in Table 8, the example passenger car tyres showed improved levels of snow braking and acceleration compared to benchmark.

Example 9: Determination of Sipe Density

(48) The sipe density D.sub.R for each pair of blocks (pitch) 20a, 20b of the shoulder tread row, 22a, 22b of the middle tread row, and 24a, 24b of the center tread row, of the tread of a passenger car tyre as illustrated in FIG. 3 and a light truck tyre as illustrated in FIG. 4 was determined according to the equation (1):
D.sub.R=(ΣL.sub.i(A.sub.a+A.sub.b))×100, for i={1,2, . . . ,n}  (1).

(49) TABLE-US-00009 TABLE 9 sipe densities of a passenger car tyre as illustrated in FIG. 3 blocks i n Σ Li A.sub.a + A.sub.b D.sub.R 20a, 20b integer 1 to n 4 131.2 mm 1701.6 mm.sup.2 7.71 mm.sup.−1 22a, 22b integer 1 to n 6 153.1 mm 1804.6 mm.sup.2 8.48 mm.sup.−1 24a, 24b integer 1 to n 4 105.9 mm 1609.3 mm.sup.2 6.58 mm.sup.−1

(50) This example illustrates a small pitch size of a pitch P1 of a passenger car tyre.

(51) TABLE-US-00010 TABLE 10 sipe densities of a light truck tyre as illustrated in FIG. 4 blocks i n Σ Li A.sub.a + A.sub.b D.sub.R 20a, 20b integer 1 to n 4 143.8 mm 2872.8 mm.sup.2 5 mm.sup.−1 22a, 22b integer 1 to n 7 207.6 mm 3315 mm.sup.2 6.26 mm.sup.−1 24a, 24b integer 1 to n 6 182.6 mm 2969.2 mm.sup.2 6.15 mm.sup.−1

(52) This example illustrates a large pitch size of a pitch P4 of a light truck tyre.

LIST OF REFERENCE SIGNS

(53) 1 tyre 2 tread 4 tread shoulder 5 tread edge 6 tread edge 14 central circumferential groove 16 lateral circumferential groove 17 center tread row 18 middle tread row 19 shoulder tread row 20a, b shoulder blocks 22a, b middle blocks 24a, b center blocks 26 inner surface 29 3D sipe 30 wavy groove 31 step 32 multiple step area 33 ground contacting surface 34 axial groove 35 transverse groove 36 transverse groove 37 recess 38 protrusion 39 shoulder edge recess 40 longitudinal block side wall 42 leading block side wall 44 trailing block side wall 46 block edge 48 tie bar 49 side wall edge 50 base of wavy groove 52 tip of wavy groove