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 tread patterns.
BACKGROUND
[0002] Tires support the load of a vehicle and impact handling, drivability,
and safety of the vehicle.
[0003] Vulcanized and treated rubber on the circumference of a tire is a
tread of the tire. The tread is the critical part that grips the road. Tire treads
come in different patterns, made-up of combinations of ribs, blocks, lugs, and
other elements. The pattern of the tread affects contact and interaction of the
tire with the road and thus affects the traction of the vehicle. For example, a
rib-type tread pattern in a tire may help improve the steering and braking
effectiveness. The rib-type tread pattern, therefore, plays an important role in
the tire of a highway bus, long-distance truck, or sightseeing bus, for instance.
On the other hand, block pattern treads show good traction and water
dispersal, and therefore, are used in winter tires and off-road vehicle tires.
[0004] Different types of tread patterns help achieve different performance
parameters of the tires and hence find different applicability in different types of vehicles where they play a crucial role in tire life, vehicle handling, 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 1a illustrates a front view of a tread portion of a pneumatic
tire when the tire is at 0% wear, in accordance with an implementation of the
present subject matter;
[0007] Figure 1b illustrates a cross-section of the pneumatic tire through
five tread ribs when the tire is at 0% wear, in accordance with an
implementation of the present subject matter;
[0008] Figure 2 illustrates a cross-sectional view of a lateral groove, in
accordance with an implementation of the present subject matter;
[0009] Figure 3a illustrates a front view of the tread portion of the pneumatic
tire when the tire is at 25% wear, in accordance with an implementation of the
present subject matter;
[0010] Figure 3b illustrates a cross-section of the pneumatic tire through
the five tread ribs when the tire is at 25% wear, in accordance with an
implementation of the present subject matter;
[0011] Figure 4a illustrates a front view of the tread portion of the pneumatic
tire when the tire is at 50% wear, in accordance with an implementation of the
present subject matter;
[0012] Figure 4b illustrates a cross-section of the pneumatic tire through
four tread ribs when the tire is at 50% wear, in accordance with an
implementation of the present subject matter;
[0013] Figure 5a illustrates a front view of the tread portion of the pneumatic
tire when the tire is at 75% wear, in accordance with an implementation of the
present subject matter; and
[0014] Figure 5b illustrates a cross-section of the pneumatic tire through
the four tread ribs when the tire is at 75% wear, in accordance with an
implementation of the present subject matter.

DETAILED DESCRIPTION OF DRAWINGS
[0015] A pneumatic tire usually has a tread pattern of the lug, rib, rib-lug,
block, lug-block, or rib-block type, depending on the use of the tire, seasonal factors, road conditions, etc.
[0016] For example, a tire with a rib-type tread pattern has a plurality of ribs
defined by a plurality of circumferentially continuous grooves which divide a
tread surface across its width. The tires having the rib-type tread pattern are
considered suitable mainly for traveling on a good road under a heavy load at
a high speed as they help to improve the steering and braking effectiveness.
The tires having the rib-type tread pattern have good directional stability, and
therefore, are used for the steering wheels or front axle of trucks and buses.
[0017] A block-type tread pattern is usually composed of blocks of various
shapes defined by a multiplicity of notches on a tread surface. The edges of the notches catch the road surface firmly and enable a great improvement in the coefficient of traction power and transverse sliding resistance. They serve effectively for drainage purposes on a wet road and exhibit an excellent wet grip and a high performance on snow. Due to these advantages, a tire having a block-type tread pattern is particularly used during the rainy season or when it has snowed, replacing tires of other types whenever required.
[0018] However, due to continuous traveling at high speeds under heavily
loaded conditions on hard roads, the tires having the rib-type tread pattern tend to wear rapidly and become unusable even if these tires have not completely worn out. Due to this reason, often, users use the tires with the rib type tread pattern only up to 50% wear, post which it can neither be used in the front axle due to safety concerns nor in a drive axle of the vehicle due to the poor traction characteristics of the rib type tread pattern. In such cases, the tires having the rib-type tread pattern are generally discarded upon reaching 50% wear condition. In some cases, users shift the semi-worn-out

tires to a dummy axle because of deterioration of performance parameters like steerability, traction, maneuverability, etc. Either way, the useful life of the tire is effectively only 50%, resulting in a lower cost versus output ratio which is not only uneconomical for users but is also not environment friendly owing to the amount of wasted rubber material.
[0019] Thus, there exists a need for a technique that may be used for
prolonging the useful life of the tire without compromising its performance to any degree throughout life.
[0020] To this end, the present subject matter provides for a pneumatic tire
in which after 50% of wear, the rib type tread pattern is regenerated to a new block type tread pattern which is superior in traction, force generation similar to a block tire which is at 0% wear. Thus, the present invention addresses the deficiencies of a conventional tire having a rib-type tread pattern and extends the useful life of the tire till the end without deterioration in performance parameters.
[0021] In accordance with an embodiment of the present subject matter,
the pneumatic tire comprises a plurality of tread ribs that are disposed of circumferentially on the pneumatic tire. The pneumatic tire further comprises at least two circumferential grooves that extend circumferentially on the pneumatic tire. The pneumatic tire of the present invention also comprises a plurality of lateral grooves that are provided laterally across each of the plurality of tread ribs. Each of these pluralities of lateral grooves has a bottle-shaped cross-section in a radial and tangential direction.
[0022] The lateral groove causes the tread pattern to change from rib type
to block type after 50% wear in the tire tread. In accordance with an embodiment of the present subject matter, at about 50% wear in the tire tread, an upper cylindrical portion of a bottle-shaped lateral groove diminishes, exposing a lower cylindrical portion of the bottle-shaped lateral groove. The

depth of the upper cylindrical portion of the bottle-shaped lateral groove, being substantially equal to the depth of the at least two circumferential grooves, causes the plurality of tread ribs disposed circumferentially along the circumferential grooves to behave as a unit or a block with the lower cylindrical portion of the bottle-shaped lateral groove acting as a circumferential groove for said block.
[0023] Accordingly, the tire previously with rib type tread pattern behaves
as a tire with block type tread pattern which is capable of retaining its wet-grip performance and, hence, may be used in drive axle up to the end of the tread life.
[0024] 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.
[0025] Figure 1a illustrates schematics of a front view of a tread portion 100
of a pneumatic tire when the tire is at 0% wear, in accordance with an implementation of the present subject matter. In an implementation of the present subject matter, the tread portion 100 comprises a plurality of tread ribs. In the illustrated example embodiment, the tread portion 100 comprises five ribs 102-1,….102-5 that are disposed of circumferentially across the tread

portion 100. The tread portion 100 further comprises four circumferential grooves 104-1,…104-4 that divide the plurality of tread ribs 102-1,….102-5 into five rows, as shown in Figure 1a.
[0026] It would be appreciated that although the figures depict an example
implementation of the pneumatic tire with the tread portion 100 comprising four
circumferential grooves 104-1,…104-4 and five rows of the tread ribs 102-
1,….102-5, other implementations of the tread portion 100 are also possible.
For instance, although it is not shown in the figures, the tread portion 100 with
two circumferential grooves and three rows of ribs may also be implemented.
[0027] As shown in an exploded view of Figure 1a, the tread portion 100
also comprises a plurality of lateral grooves 106 that are disposed of laterally
across each of the plurality of tread ribs 102-1,….102-5. The lateral grooves
106 are provided in such a manner that when the tread portion 100 of the
pneumatic tire has been worn up to a predefined amount, the tread ribs change
into blocks, thereby converting the tread pattern of the tire from rib to block
type. This is achieved due to a bottle-like shape of the lateral grooves 106
comprising a narrow portion followed by a wider portion (elaborated in Fig.2).
[0028] Figure 1b illustrates a cross-section of the pneumatic tire through
five tread ribs 102-1,….102-5 when the tire is at 0% wear, in accordance with an implementation of the present subject matter. In an implementation of the present subject matter. As shown in Figure 1b, a depth of the second and third circumferential grooves 104-2, 104-3 is less than that of the first and fourth circumferential grooves 104-1, 104-4. The depth of the second and third circumferential grooves 104-2, 104-3 is substantially equal to the depth of the narrow or upper portion of the bottle-shaped lateral grooves 106, such that the wear exposes the bottom surface of the second and third circumferential grooves 104-2, 104-3 and the start of the wider portion of the bottle-shaped lateral grooves together. In other words, when the tread pattern 100 of the tire

undergoes up to 40% to 60% wear of its total depth, a depth of the second,
third, and fourth tread ribs 102-2, 102-3, 102-4 equalizes with the depth of the
second and third circumferential grooves 104-2, 104-3, respectively, thereby
forming four rows of circumferentially separated blocks. Since the wear
equalizes the depth of the ribs and the grooves and exposes the start of the
wider portion of the bottle-shaped lateral grooves at the same wear level, the
wider portion of the bottle-shaped lateral grooves provides for a groove for the
resulting combined block. The block pattern of the tread in the pneumatic tire
may provide good traction and water dispersal, thereby delivering useful life to
the tire till the end without deterioration in performance at any point of tread
life. At 0% wear, the lateral groove 106 remains at its maximum depth.
[0029] Figure 2 illustrates a cross-sectional view of the lateral groove 106
in detail, in accordance with an implementation of the present subject matter.
As shown in Figure 2, the lateral groove 106 has a bottle-shaped cross-section
that extends in a radial and tangential direction of the pneumatic tire.
[0030] It is to be understood that the shape of the lateral groove 106 shown
in the figures of the present embodiment is the shape of the bottle, other shapes of the lateral groove 106 are also possible. For instance, although it is not shown in the figures, the lateral groove 106 may also be in a shape of a jar or a bulb. In an example implementation of the present subject matter, the maximum depth C of each of the plurality of lateral grooves may lie in a range of 12-25 mm.
[0031] Further, each of the plurality of lateral grooves 106 may be divided
into an upper or narrow cylindrical region 202 and a lower or wider cylindrical region 204. In an example, a depth A of the upper cylindrical region 202 may lie in a range of 40%-60% of a maximum depth C of the lateral groove 106 which may lie in a range of 15-20 mm. Furthermore, a depth B of the lower cylindrical region 204 of the lateral groove 106 may lie in a range of 40%-60%

of its maximum depth C. Additionally, a width E of the upper cylindrical region 202 of the lateral groove 106 may lie in a range of 5%-30% of its maximum depth C. Also, a width D of the lower cylindrical region 204 of the lateral groove 106 may lie in a range of 20%-50% of its maximum depth C.
[0032] It is to be understood that the shape of the lateral groove 106 shown
in the figures of the present embodiment is in the shape of a bottle included in a mold used for manufacturing the pneumatic tire and that the present shape of the lateral groove 106 is formed by removing tire forming materials by the blade from the tread portion 100.
[0033] Figures 3a, 3b, 4a, 4b, 5a, and 5b depict the tread pattern 100 when
the tire is respectively at 25%, 50%, and 75% wear, in accordance with an implementation of the present subject matter.
[0034] Specifically, in the early stage of wear, after the tread portion 100
has undergone 50% or above wear, the third tread rib 102-3 is no longer present as illustrated clearly in Figures 4b and 5b. Initially, at 0% wear, the depth of the second and third circumferential grooves 104-2, 104-3 is equal to the depth of the upper cylindrical region 202 of the lateral groove 106. However, once the tread portion 100 of the tires touch 50% or above wear, the upper cylindrical region 202 of the lateral groove 106 vanishes completely, thereby exposing the lower cylindrical region 204 of the lateral groove 106, as depicted in Figures 4b and 5b. In such a scenario, the depth of the third tread ribs 102-3 matches with the depth of the second and third circumferential grooves 104-2, 104-3, converting the rib pattern of the tread portion 100 into a blocks 502-1,…502-4 consisting of four blocks formed by at least three circumferential grooves 504-1, 504-2, 504-3 and a plurality of lateral grooves 506, as shown in Figures 5a, 5b.
[0035] As a result of an example implementation of the present subject
matter, the tread pattern of the tire may be changed from rib to block type after

50% wear. Once done, the tire behaves as a new block tire which may then be used in the drive axle of the vehicle up to the end of tread life, thereby delivering useful life to the tire without deterioration in performance at any point of the tread life. This maximizes the cost versus output ratio of the tire. Additionally, the user is no longer required to manage the tire with multiple tread patterns. Also, the rib to block the conversion of the tread type helps in avoiding various disadvantages of the conventional off-road tires, such as slippage and an increase in noise. Additionally, the block pattern with at least three circumferential grooves provides improved wet steering performance of the tire by providing adequate water channeling, thereby delivering useful life to the tire and higher mileage till the end without deterioration in performance at any point of tread life.
[0036] 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 having a tread portion (100) comprising:
a plurality of tread ribs (102-1,….102-5) disposed of circumferentially on the pneumatic tire,
at least two circumferential grooves (104-2, 104-3) extending circumferentially on the pneumatic tire; and
a plurality of lateral grooves (106) disposed of laterally across each of the plurality of tread ribs (102-1,….102-5),
wherein each of the plurality of lateral grooves (106) has a bottle-shaped cross-section in a radial and tangential direction.
2. The pneumatic tire as claimed in claim 1, wherein each of the plurality of lateral grooves (106) has an upper cylindrical region (202) and a lower cylindrical region (204), and wherein a depth (A) of the upper cylindrical region (202) lies in a range of 40%-60% of a maximum depth (C) of the lateral groove (106).
3. The pneumatic tire as claimed in any one of claims 1-2, wherein a depth of each of the at least two circumferential grooves (104-2, 104-3) is equal to the depth of the upper cylindrical region (202).
4. The pneumatic tire (100) as claimed in any one of claims 1-3, wherein pneumatic tire comprises four circumferential grooves (104-1,…104-4) to divide the plurality of tread ribs (102-1,….102-5) into at least five rows, and
wherein the five rows of the plurality of tread ribs (102-1,….102-5) change into four circumferentially separated tread blocks (502-1,…502-4)

when each of the plurality of lateral grooves (106) is worn in a range of 40% to 60% of its maximum depth (C).
5. The pneumatic tire as claimed in any one of claims 1-4, wherein the maximum depth (C) of each of the plurality of lateral grooves (106) lies in a range of 12-25 mm.
6. The pneumatic tire (100) as claimed in any one of claims 1-5, wherein a depth (B) of the lower cylindrical region (204) lies in a range of 40%-60% of its maximum depth (C).
7. The pneumatic tire (100) as claimed in any one of claims 1-6, wherein a width (E) of the upper cylindrical region (202) lies in a range of 5%-30% of its maximum depth (C).
8. The pneumatic tire (100) as claimed in any one of claims 1-7, wherein a width (D) of the lower cylindrical region (204) lies in a range of 20%-50% of its maximum depth (C).
9. The pneumatic tire (100) as claimed in any one of claims 1-8, wherein the lower cylindrical region (204) forms a circumferential groove (504-2) when each of the plurality of lateral grooves (106) is worn in the range of 40% to 60% of its maximum depth (C).