FORM 2
THE PATENTS ACT, 1970 (39 of 1970) & THE PATENTS RULES, 2003
COMPLETE SPECIFICATION (See section 10, rule 13)
1. Title of the invention: PNEUMATIC TIRE
2. Applicant(s)
NAME NATIONALITY ADDRESS
CEAT LIMITED Indian CEAT Ltd At: Get Muwala Po: Chandrapura Ta: Halol - 389 350 Dist: Panchmahal, Gujarat, India
3. Preamble to the description
COMPLETE SPECIFICATION
The following specification particularly describes the invention and the manner in which it
is to be performed.

TECHNICAL FIELD
[0001] The present subject matter relates, in general, to vehicle tires and,
particularly but not exclusively, to vehicle tires having treads blocks.
BACKGROUND
[0002] Tires support a load of a vehicle and impact handling, drivability, and
safety of the vehicle.
[0003] A tire has a crown or center region, a shoulder region, and beads on
either side of the center region. The center region may be understood as an outer region of the tire formed along a complete circumference of the tire and spreads along a width of the tire, which contacts with a surface during rotation. The beads may be understood as the edges of the tire. The beads contact with a wheel during the mounting of the tire. The shoulder region is a portion of the tire joining the center region and the beads of the tire.
[0004] Vulcanized and treated rubber that is applied on the center region
and shoulder region of the tire is called a tread of the tire. In some tires, the tread amongst other constituents, such as tread blocks, includes sipes. The sipes are small, thin slots molded into the tire’s tread block that create additional tread surface area for increased grip in wet, icy, and snowy conditions. In other words, the sipes improve the tires' grip on wet, snow, and ice-covered surfaces, optimizing the braking, handling, overall performance, and lifespan. Hence, the sipes’ configuration has a crucial role in tire life, vehicle maneuvering, safety, and ease of driving.
BRIEF DESCRIPTION OF DRAWINGS
[0005] The detailed description is described with reference to the
accompanying figures. The left-most digit(s) of a reference number identifies the figure in which the reference number first appears in the figures. The same

numbers are used throughout the drawings to reference like features and
components.
[0006] Figure 1 illustrates a front view of a pneumatic tire, in accordance
with an implementation of the present subject matter;
[0007] Figure 2 illustrates a front cross-sectional view of a three
dimensional (3D) sipe, in accordance with an implementation of the present
subject matter;
[0008] Figure 3 illustrates a cross-sectional view of the 3D sipe extending
in a radial direction of the pneumatic tire, in accordance with an implementation
of the present subject matter;
[0009] Figure 4 illustrates a cross-sectional view of the 3D sipe extending
in a width direction of the pneumatic tire, in accordance with an implementation
of the present subject matter;
[0010] Figure 5 illustrates a cross-sectional view of the 3D sipe extending
in a circumferential direction of the pneumatic tire, in accordance with an
implementation of the present subject matter;
[0011] Figure 6 illustrates an isometric view of the 3D sipe, in accordance
with an implementation of the present subject matter; and
[0012] Figure 7 illustrates a sectional view of the 3D sipe, in accordance
with an implementation of the present subject matter.
DETAILED DESCRIPTION OF DRAWINGS
[0013] Generally, commercial tires, such as truck and bus radial tires,
include finely carved tread patterns as well as a plurality of sipes formed on a portion of a tire that contacts the road or the ground. The sipes enable to improve the acceleration performance, braking performance, and steering stability performance of the tires under harsher conditions, for example in wet, icy, and snowy conditions. While smaller, individual tread blocks in tires do

increase traction, they also increase the risk of tread block distortion which reduces fuel efficiency, handling performance, and tread life. Sipes are more effective for increasing traction and surface area of the tire without negatively affecting these areas.
[0014] Often, under the dynamic loading, two-dimensional (2D) sipes in
conventional commercial tires may lead to deformation of the tread blocks,
thereby creating an uneven surface which may consequently make the tread
blocks unstable, and, hence, the tire performance may get compromised. Also,
as the conventional tire wears down its tread, the volume of grooves between
the tread blocks is reduced, which can lead to poor hydroplaning performance.
[0015] Thus, there exists a need for a technique that counters deformation
in tread blocks of a tire and also enables improved worn hydroplaning performance of the tire without adversely affecting other performance parameters.
[0016] To this end, the present subject matter provides for a pneumatic tire
that showcases improved rigidity of tread blocks and addresses the deficiencies of conventional tire treads, in particular, worn hydroplaning performance.
[0017] In accordance with an embodiment of the present subject matter,
the pneumatic tire comprises one or more three-dimensional (3D) sipes that are disposed of laterally in one or more tread blocks. Each of the one or more 3D sipes of the tire has a zig-zag shape in radial, width, and circumferential directions. The 3D sipes also have a circular cross-section towards its bottom portion in the radial direction. Further, each of the one or more 3D sipes has a first side and a second side on either side of the width direction. The first side has a pattern that is defined by a protrusion and a recess. The second side has a pattern that corresponds to the pattern formed on the first side.

[0018] When pressure is applied on the tread blocks, the protrusions
located on the first side of the 3D sipe advance towards the recesses on the second side of the 3D sipe until they are on in contact with one another. Once in contact, protrusions and the recesses get into an interlocking position and oppose any further deformation of the tread blocks, thereby increasing the stiffness of the tread blocks and hence enabling the tread blocks to be more stable under the dynamic loading.
[0019] Also, the circular cross-section of the 3D sipe directs the water
droplets trapped inside the 3D sipes towards a land portion of the tire for expulsion when driving on wet roads, thereby providing for the improved worn hydroplaning performance of the tire.
[0020] The above and other features, aspects, and advantages of the
subject matter will be better explained with regard to the following description and accompanying figures. It should be noted that the description and figures merely illustrate the principles of the present subject matter along with examples described herein and should not be construed as a limitation to the present subject matter. It is thus understood that various arrangements may be devised that, although not explicitly described or shown herein, embody the principles of the present disclosure. Moreover, all statements herein reciting principles, aspects, and examples thereof, are intended to encompass equivalents thereof. Further, for the sake of simplicity, and without limitation, the same numbers are used throughout the drawings to reference like features and components.
[0021] Figure 1 illustrates schematics of a pneumatic tire 100, in
accordance with an implementation of the present subject matter. In an implementation of the present subject matter, the tire 100 has a center region 102 and shoulder regions on either side of the center region 102. More specifically, the tire may have two shoulder regions 104-1, 104-2 with a center

region 102 between the two shoulder regions 104-1, 104-2. As shown in an exploded view of a tread portion of the tire 100 in Figure 1, the center and the shoulder regions include a plurality of tread blocks 106. Each of the plurality of tread blocks 106 comprises one or more three-dimensional (3D) sipes 108 that are disposed of laterally in tread block 106. As will be explained hereinafter in detail, the 3D sipes 108 of the present invention improve the rigidity and stability of the tread blocks 106, thereby improving the stiffness and mileage of the tire 100.
[0022] Figure 2 depicts the 3D sipe 108 in detail by illustrating a front cross-
sectional view of the 3D sipe 108, according to an example implementation of the present subject matter. In an implementation of the present subject matter, 3D sipe 108 has a zig-zag shape in radial, width, and circumferential directions of the tire 100, as shown in Figures 3, 4, and 5, respectively. Specifically in the radial direction, in the present embodiment, the zig-zag shape of the 3D sipe 108 in the radial direction resembles the geometry of the teeth of a hacksaw blade. In an example embodiment of the present subject matter, the zig-zag shape, from a top portion 112, that extends in the radial direction starts from a position that is at a predefined distance E from a land portion of the tread block 106. This predefined distance E may lie in a range of 0.8-2.5 mm.
[0023] It would be appreciated that although Figure 1 depicts an example
implementation of the tire 100 with the tread block 106 comprising only one 3D sipe 108, other implementations of the tread block 106 are also possible. For instance, although it is not shown in the figure, the tread block 106 with two or more 3D sipes 108 may also be implemented.
[0024] Further, the 3D sipe 108 has a circular cross-section 110 towards a
bottom portion 124 in the radial direction. In an example embodiment of the present subject matter, a radius C of the circular cross-section 110 may lie in a range of 0.3-1 mm. As shown in Figure 2, the circular cross-section 110 at

the bottom portion 124 of the 3D sipe 108 forms a structure resembling the structure of a bucket, wherein this bucket structure provides improved hydroplaning resistance to the tire. Specifically, the circular cross-section 110 that is provided in a form of an undercut surface allows storing of the water droplets when the tire 100 rolls over a wet surface and pushes the stored water droplets out of the circular cross-section 110 as the tire rotates, thereby providing for an improved worn hydroplaning performance of the tire 100. As a result, 3D sipe 108 is more effective and efficient for expelling water out of the footprint of the tire 100 when driving on wet roads. Hence, the tread block 106 in the worn condition would have improved hydroplaning performance, as compared with conventional treads blocks.
[0025] It is to be understood that the shape of the 3D sipe 108 shown in the
figures of the present embodiment is a shape of a blade included in a mold used for manufacturing the 3D sipe 108 and that the present shape of the 3D sipe 108 is formed by removing tire forming materials by the blade from the tread block 106.
[0026] Furthermore, the 3D sipe 106 has a first side 114 and a second side
116. The first side 114 has a pattern defined by a protrusion 118 and a recess 120. The second side 116 has a pattern that corresponds to the pattern of the first side 114. In an example embodiment of the present subject matter, a distance D between the two consecutive protrusions may lie in a range of 0.7-1.5 mm. As shown in Figure 2, the protrusion 118 formed on the first side 114 of the 3D sipe 108 faces the corresponding recess 122 that is formed on the second side 116 of the 3D sipe 108. The protrusion 118 and the corresponding recess 122 are formed in such a manner that they together form an interlocking shape. In an example embodiment of the present subject matter, the interlocking shape may be sinusoidal.

[0027] In another example embodiment of the present subject matter, the
protrusion 118 makes an angle of inclination O with respect to the width and
radial directions of the tire 100, and the value of said angle lies in a range of
45°-75°. In yet another example embodiment of the present subject matter, the
recess 120 makes an angle of inclination N with respect to the width and radial
directions of the tire 100, and the value of said angle lies in a range of 14°-45°.
[0028] In another example, a maximum distance A between the first side
114 and the second side 116 towards a top portion 112 of the 3D sipe 108 may lie in a range of 1.0-1.5 mm. In yet another example embodiment of the present subject matter, a maximum distance F between the first side 114 and the second side 116 towards the bottom portion 124 may lie in a range of 1.1-2.0 mm.
[0029] Thus, when the tire 100 is under the dynamic load condition, the
interlocking of both sides of the 3D sipe 108 may help in increasing the
stiffness of the plurality of tread blocks 106. The increase in stiffness means
that each of the plurality of tread blocks 106 would resist lateral movement,
thereby keeping the 3D sipes 108 open in the dynamic load conditions. This
provides a wide surface area to the tire 100 when in use that keeps tread
blocks 106 stable and enables them to support each other effectively.
[0030] In an example embodiment of the present subject matter, a length J
of the 3D sipe 108 in the radial direction may lie in a range of 35%-70% of the non-skid depth of the tire 100. In another example embodiment of the present subject matter, the 3D sipe 108 may further include a plurality of embossings 126 formed towards the bottom portion 124 in the radial direction. Each of the plurality of embossing 126 may have an end radius B in a range of 0.1-0.7 mm. Further, each of the plurality of embossing 126 may have a radius H in a range of 0.4-1.0 mm.

[0031] Figure 6 illustrates an isometric view of the 3D sipe 108, in
accordance with an implementation of the present subject matter. As shown in
Figure 6, each of the plurality of embossings 126 is provided along the width
direction at alternate positions. These embossings support hydroplaning.
[0032] Figure 7 illustrates a sectional view of the 3D sipe 108, in
accordance with an implementation of the present subject matter. As shown in Figure 7, a distance G between each of the plurality of embossings 126 and a lowest point 402 of the bottom portion 124 may lie in a range of 2.0-3.0 mm. Whereas a length S of the 3D sipe 108 in the width direction may lie in a range of 40.0 to 50.0 mm. Further, a distance K between two consecutive embossings 126 may lie in a range of 2.0-7.0 mm. Furthermore, as shown in Figure 7, each of the embossing 126 which is extruded either towards a start side 702 or an end side 704 of the 3D sipe 108, is at a predefined distance M from the corresponding side, wherein the predefined distance M may lie in a range of 0.8-2.5 mm.
[0033] As a result of an example implementation of the present subject
matter, the tire incorporated in a vehicle, when rolled over a road surface along with the movement of the vehicle, exhibits improved tangential and lateral stiffness, thereby significantly increasing the rigidity of the tread blocks. This improves the overall steering stability performance of the tire in harsh conditions. Also, the bucket structure towards the bottom portion of the 3D sipe improves the wet steering performance of the tire by providing adequate water channeling as discussed above. Additionally, the present shape of the 3D sipes is designed in such a way that facilitates the ejection of the tire from the mold during manufacturing.
[0034] Although implementations of a tire are described, it is to be
understood that the present subject matter is not necessarily limited to the

specific features of the systems described herein. Rather, the specific features are disclosed as implementations for the tire.

I/We claim:
1. A pneumatic tire (100) comprising:
one or more three-dimensional (3D) sipes (108) disposed of laterally in at least one tread block (106), wherein each of the one or more 3D sipes (108) has a zig-zag shape in radial, width, and circumferential directions of the pneumatic tire (100),
wherein each of the one or more 3D sipes (108) has a circular cross-section (110) towards a bottom portion (124) in the radial direction; and
wherein each of the one or more 3D sipes has a first side (114) and a second side (116) on either side of the width direction, the first side (114) has a pattern defined by a protrusion (118) and a recess (120), and the second side (116) has a pattern corresponding to the pattern of the first side (114).
2. The pneumatic tire (100) as claimed in claim 1, wherein a length of each of the one or more 3D sipes (108) in the radial direction lies in a range of 35%-70% of the non-skid depth of the pneumatic tire (100).
3. The pneumatic tire (100) as claimed in claim 1, wherein a maximum distance between the first side (114) and the second side (116) towards a top portion (112) of each of the one or more 3D sipes (108) lies in a range of 1.0-1.5 mm.
4. The pneumatic tire (100) as claimed in claim 1, wherein a maximum distance between the first side (114) and the second side (116) towards the bottom portion (124) lies in a range of 1.1-2.0 mm.
5. The pneumatic tire (100) as claimed in claim 1, wherein a distance between the two consecutive protrusions lies in a range of 0.7-1.5 mm.

6. The pneumatic tire (100) as claimed in claim 1, wherein the zig-zag shape extending in the radial direction is formed towards the top portion (112) at a predefined distance from a land portion of the tread block (106).
7. The pneumatic tire as claimed in claim 6, wherein the predefined distance lies in a range of 0.8-2.5 mm.
8. The pneumatic tire as claimed in claim 1, wherein a radius of the circular cross-section (110) lies in a range of 0.3-1 mm.
9. The pneumatic tire as claimed in claim 1, wherein each of the one or more 3D sipes (108) further comprises a plurality of embossings (126) formed towards the bottom portion (124) in the radial direction.
10. The pneumatic tire as claimed in claim 9, wherein an end radius of each of the plurality of embossings (126) lies in a range of 0.1-0.7 mm.
11. The pneumatic tire as claimed in claim 1, wherein a distance between each of the plurality of embossings (126) and a lowest point (402) of the bottom portion (124) lies in a range of 2.0-3.0 mm.
12. The pneumatic tire as claimed in claim 1, wherein the protrusion (118) makes an angle of inclination with respect to the width and radial directions that lie in a range of 45°-75°.

13. The pneumatic tire as claimed in claim 1, wherein the recess (120)
makes an angle of inclination with respect to the width and radial directions that lie in a range of 14°-45°.