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: NOISE REDUCTION IN VEHICLE TIRE
2. Applicant(s)
NAME NATIONALITY ADDRESS
CEAT LIMITED Indian RPG HOUSE, 463, Dr. Annie Besant Road, Worli, Mumbai, Maharashtra 400030, 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.
BACKGROUND [0002] Tires support load of a vehicle and impact handling, drivability, and safety of the vehicle. A tire has a crown or center region, a shoulder region and beads on either side of the center region. In an example, the center region may be understood as outer region of the tire formed along complete circumference of the tire and spreads along width of the tire. Further, the center region contacts with surface during rotation. The beads may be understood as edges of the tire. The beads contact with wheel during mounting of the tire. The shoulder region is portion of the tire joining the center region and the beads of the tire.
[0003] Vulcanized and treated rubber on the center region and shoulder region of the tire is a tread of the tire. The tread is often carved in diverse configuration by way of tread blocks, tread grooves, tread voids, wear bar, and the like. The configuration the tread affects contact and interaction of the tire with road and thus affects traction of the vehicle and noise generated during the interaction of the tire with road surface. Hence, the tread configuration has a crucial role in tire life, vehicle maneuvering, noise-free driving, safety, and ease of driving.
BRIEF DESCRIPTION OF DRAWINGS [0004] The detailed description is described with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the drawings to reference like features and components.
[0005] Figure 1 illustrates a conventional design of a tread pattern of a tire depicting alignment of a tread block in a circumferential tread row of a center tread

region with respect to a tread block in a circumferential tread row of a shoulder tread
region of the tire.
[0006] Figure 2 illustrates schematics of a tire with a tread pattern, in accordance
with an implementation of the present subject matter.
[0007] Figure 3 illustrates a design of a tread pattern of a tire depicting alignment
of a tread block in a first circumferential tread row of a center tread region with respect
to a tread block in a second circumferential tread row of a shoulder tread region of the
tire, according to an example implementation of the present subject matter.
DETAILED DESCRIPTION
[0008] In vehicles, there are two major sources of noise generated during motion
of a tire incorporated in a vehicle along a surface or road. One is a propulsion system of the vehicle, such as a combustion engine along with a power transmission shaft attached to it. Second, during motion of the vehicle, tread region of the tire contacts with surface of the motion. Upon contact with the surface ambient air gets trapped between grooves of the tire and the surface. The trapping of the air and improper air channeling generates noise in the tire during motion. In case of electric and hybrid vehicles, the propulsion system produces less noise, thus, less sound emission is expected. The presence of an electric motor in combination with a battery for e-vehicles tends to produce very low noise than a conventional internal combustion engine, so for a quiet ride for drive and passengers it is desirable to have a tire with lower noise as compared to the conventional tire.
[0009] Noise generated from tire significantly depends on tire tread pattern design,
tread compound, tire construction or sidewall structure. In this context, tire design parameters are very critical and any deviation from any of them may lead to trade off in other performance parameters which is not acceptable in some cases. Conventionally, diverse tread patterns have been designed. However, conventional tread patterns amount to generation of noise in the tire. Some tread patterns are designed with multiple grooves to enhance air channeling. However, with increase in

grooves, surface of the tire in contact with the surface during motion is reduced, amounting to poor braking of the vehicle. Thus, affecting maneuvering and safety of the vehicle.
[0010] A tire tread pattern is formed by plurality of circumferential tread rows
separated by circumferential grooves. A circumferential tread row comprises multiple
transverse grooves. Circumferential and transverse grooves formed along a
circumference of a tire forms tread blocks or pitches. Thus, a circumferential tread row
includes multiple tread blocks or pitches. Generally, if every tread block or pitch has
same pitch length, an unpleasant harmonic and monotonous sound may be generated
through all tires of the vehicle, as they rolled over the road surface. To avoid such
monotonous sound, pitches along a circumferential tread row of a tire have varying
lengths and are arranged in a particular sequence of these varying pitch lengths.
[0011] For example, if the circumferential tread row comprises pitches small S,
medium M and large L of three different lengths in increasing order, than the pitches in the circumferential tread row may be arranged in a particular sequence of these pitches S, M and L such as S, M, S, L, M, S, M, S, L, M,….and so on all along the circumference of the tire. Conventionally, a tire has a single optimized pitch sequence in a circumferential tread row formed in a center tread region of the tire and in a circumferential tread row formed in a shoulder tread region of the tire.
[0012] For instance, referring to Figure 1, a conventional design of a tire tread
pattern illustrating alignment of a tread block in a circumferential tread row of a center tread region with respect to a tread block in a circumferential tread row of a shoulder tread region of the tire is illustrated. According to the conventional design of tread pattern as illustrated in Figure 1, a pitch length of a smallest pitch of pitches in the center tread region of the tire is equal to a pitch length of a smallest pitch S of pitches in the shoulder tread region of the tire. For example, if pitch length of the smallest pitch S is C in the center tread region, then pitch length of the smallest pitch in the shoulder tread region would also be C. Similarly, medium and large pitches in both

of the center and the shoulder tread regions also have the same length. Further, as stated above, pitches in both of the center and the shoulder tread regions of the tire are arranged in a same pitch sequence of pitches S, M and L. Since, the pitches in both of the center and shoulder tread region are arranged in a same sequence of pitches S, M and L and length of the pitches for both the tread regions are also same, the grooves in the center tread region and in the shoulder tread region or in the adjacent circumferential tread row will be aligned with each other to form a channel. However, as mentioned above, pitches arranged in such synchronous pitch sequence in both of the center and the shoulder tread region lead to an irritating harmonic and monotonous sound during the motion of tire on a road surface.
[0013] To this end, the present subject matter provides a tire for a vehicle which
produces less noise during movement over a road surface, the tire may be modified to overcome the above-described problem associated with air channeling and consequent noise generation during motion of the vehicle on the road surface.
[0014] In accordance with an embodiment of the present subject matter, a tire
having a center tread region and a shoulder tread region on either side of the center tread region is disclosed. The tire includes at least one first circumferential tread row in the center tread region having plurality of pitches. The plurality of pitches of the at least one first circumferential tread row is arranged in a first pitch sequence. The tire also comprises at least one second circumferential tread row in the shoulder tread region having plurality of pitches. The plurality of pitches of the at least one second circumferential tread row is arranged in a second pitch sequence. Each of the first pitch sequence and the second pitch sequence comprises sequence of pitches of at least four different lengths. Further, the first pitch sequence is different from the second pitch sequence.
[0015] Thus, the present subject matter discloses the tire tread configuration with
reduced tire noise. The tread configuration disclosed by the present subject matter has an asynchronous pitch sequence in both of the center and the shoulder tread regions of

the tire, such that the sound is distributed over the spectrum in a more suitable way. Further, by applying different pitch sequences harmonics of the center and the shoulder tread regions are avoided. Hence, the tire generates reduced noise including cabin noise and pass by noise when rolled over a road surface.
[0016] 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.
[0017] Figure 2 illustrates schematics of a tire 100 with a tread pattern, in
accordance with an implementation of the present subject matter. While Figure 3 illustrates a design of a tread pattern of a tire depicting alignment of a tread block in a circumferential tread row of a center tread region with respect to a tread block in a circumferential tread row of a shoulder tread region of the tire, according to an example implementation of the present subject matter. For sake of ease of explanation, Figures 2 and 3 are explained together.
[0018] In an implementation of the present subject matter, the tire 100 has a center
tread region 102 and a shoulder tread region 104 on either side of the center tread region 102. More specifically, the tire may have two shoulder regions 104 with a center tread region 102 between the two shoulder regions 104. The center and the shoulder tread regions may include different tread patterns as illustrated in Figure 2. At least one first circumferential tread row 106 is included in the center tread region 102 having

plurality of pitches and at least one second circumferential tread row 108 in the shoulder tread region 104 having plurality of pitches. As illustrated, the tire tread pattern is formed by plurality of circumferential tread rows separated by circumferential grooves. The circumferential grooves 110 may be understood as groove in solid tread portion of the tire 100 along circumference of the tire 100. The tire tread pattern 100 may also include transverse grooves 112. The transverse grooves may be understood as grooves in the solid tread portion of the tire 100 along tread width of the tire 100. A transverse groove 112 extends from a circumferential groove to another circumferential groove along a width of the tire 100.
[0019] In an implementation of the present subject matter, the shoulder tread
region 104 is formed on both sides of the center tread region 102 and comprises at least one second circumferential tread row 108 on each side of the center tread region 102. Thus, the first circumferential tread row 106 is formed between the second circumferential tread rows 108 formed in the shoulder tread regions 104 on either side of the center tread region 102. In an example, circumferential grooves 110 may be formed between the at least first circumferential tread row 106 and the at least second circumferential tread row 108.
[0020] As stated above, each of the at least one first circumferential tread row 106
in the center tread region 102 and at least one second circumferential tread row 108 in the shoulder tread region 104 has plurality of pitches. The pitches in a circumferential tread row may be separated by transverse grooves 112. A tread block is formed between two adjacent transverse grooves 112 in a circumferential tread row formed between two adjacent circumferential grooves 110. Thus, circumferential 110 and transverse grooves 112 in the solid tread portion form pitches or tread blocks and multiple pitches together form a circumferential tread row. The plurality of pitches of the at least one first circumferential tread row 106 corresponds to a plurality of first tread blocks and the plurality of pitches of the at least one second circumferential tread row 108 corresponds to a plurality of second tread blocks.

[0021] The plurality of pitches of the at least one first circumferential tread row
106 is arranged in a first pitch sequence. Similarly, the plurality of pitches of the at least one second circumferential tread row 108 is arranged in a second pitch sequence. Further, each of the first pitch sequence and the second pitch sequence comprises sequence of pitches of at least four different lengths. For example, the first sequence of pitches comprises pitches SS1, S1, M1 and L1 of four different lengths, while the second sequence of pitches comprises pitches SS2, S2, M2 and L2 of four different lengths. Pitch SS1 is of a smallest length and pitch L1 is of a longest length in the first pitch sequence. Similarly, pitch SS2 is of a smallest length and pitch L2 is of a longest length in the second pitch sequence.
[0022] As opposed to the conventional tread pattern illustrated in Figure 1, the
four different lengths of pitches in the first pitch sequence is different from that of the pitches in the second pitch sequence. For example, pitch lengths of pitches SS1, S1, M1, and L1 are different from the pitch lengths of pitches SS2, S2, M2 and L2. Further, contrary to the conventional tread pattern, wherein pitches in both of the center 102 and the shoulder tread regions 104 of the tire are arranged in a same pitch sequence of pitches S, M and L, the first pitch sequence is different from the second pitch sequence. For instance, as illustrated in Figure 2, the plurality of pitches in the second circumferential tread row 108 of the shoulder tread region 104 of the tire 100 are arranged in a second pitch sequence of SS2, SS2, S2, S2, M2, M2, L2, L2, SS2, SS2, S2, S2, M2, M2, L2, L2,….
[0023] In an example, while forming the first pitch sequence, a first predefined
ratio of pitch length to a number of pitches is maintained in the at least one first circumferential tread row 106. In an example, the pitch length in the first predefined pitch ratio corresponds to a pitch length C of a smallest pitch of the pitches of the at least four different lengths in the first pitch sequence. In an example, while forming the second pitch sequence, a second predefined ratio of pitch length to a number of pitches is maintained in the at least one second circumferential tread row 108. In an

example, the pitch length in the second predefined pitch ratio corresponds to a pitch length D of a smallest pitch of the pitches of the at least four different lengths in the second pitch sequence.
[0024] In an example, a number of first tread blocks A may be in a range of 65 to
85. That is, the first circumferential tread row 106 in the center tread region 102 may comprise tread blocks ranging from 65 to 85. In another example, a number of second tread blocks B is in a range of 1.05*A to 1.42*A. That is, the second circumferential tread row 108 may comprise tread blocks ranging from 1.05*(number of tread blocks in the first circumferential tread row) to 1.42*(number of tread blocks in the first circumferential tread row). For example, if the number of first tread blocks are 72, then the number of second tread blocks may vary in the range ranging from 1.05*72(=75.6) to 1.42*72(=102.24).
[0025] In another example, a pitch length C of a smallest pitch of the pitches of
the at least four different lengths in the first pitch sequence is in a range of 20 mm to 26 mm. For instance, pitch SS1, which is the smallest pitch in the first pitch sequence in the above described example, may have a length C in a range ranging from 20 mm to 26 mm. In an example, the pitch length C of the smallest pitch SS1 of the pitches of the at least four different lengths in the first pitch sequence is 21.50 mm. In an example, a pitch length D of a smallest pitch of the pitches of the at least four different lengths in the second pitch sequence is in a range of 0.70*C mm to 0.95*C mm. For example, if a pitch length C of a smallest pitch of the pitches of the four different lengths in the first pitch sequence is 24, pitch SS2, which is the smallest pitch in the second pitch sequence in the above described example, may have a length D in a range ranging from 0.70*24(=16.8) mm to 0.95*24(=22.8) mm. In an example, the pitch length D of the smallest pitch SS2 of the pitches of the at least four different lengths in the second pitch sequence is 17.0 mm.

[0026] Contrary to the conventional design of tread pattern illustrated in Figure 1,
wherein a ratio of the pitch length of the smallest pitch in the center tread region to the
pitch length of the smallest pitch in the shoulder tread region is 1:1, a ratio of the pitch
length C of a smallest pitch of the pitches of the at least four different lengths in the
first pitch sequence to the pitch length D of the smallest pitch of the pitches of the at
least four different lengths in the second pitch sequence may be in the range ranging
from 1:0.70 to 1:0.95. This difference between the pitch length of the pitches in the
center tread region and the pitch length of pitches in the shoulder tread region results
in significant noise reduction, during motion of the tire on a road surface.
[0027] Figure 3 illustrates a design of a tread pattern of a tire 100 depicting
alignment of a tread block in a first circumferential tread row 106 of a center tread region 102 with respect to a tread block in a second circumferential tread row 108 of a shoulder tread region 104 of the tire 102, according to an example implementation of the present subject matter. As opposed to the conventional tread pattern design illustrated in Figure 1, according to the present subject matter, the pitch length C of the smallest pitch of the pitches of the at least four different lengths in the first pitch sequence is different from the pitch length D of the smallest pitch of the pitches of the at least four different lengths in the second pitch sequence.
[0028] 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 the movement of the vehicle, in cabin noise and pass by noise are significantly reduced by 6 % and 5 % respectively as compared to the conventional tires. Further, because of reduced noise, less vibration are produced resulting in a more comfortable ride for the passengers which is improved approximately by 5 %. However, there is no impact on the wear appearance of the tire when compared with the conventional tire.
[0029] 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 tire 100 having a center tread region 102 and a shoulder tread region 104 on
either side of the center tread region 102, the tire 100 comprising:
at least one first circumferential tread row 106 in the center tread region 102 having plurality of pitches, the plurality of pitches of the at least one first circumferential tread row 106 being arranged in a first pitch sequence; and
at least one second circumferential tread row 108 in the shoulder tread region 104 having plurality of pitches, the plurality of pitches of the at least one second circumferential tread row 108 being arranged in a second pitch sequence;
wherein each of the first pitch sequence and the second pitch sequence comprises sequence of pitches of at least four different lengths, and
wherein the first pitch sequence is different from the second pitch sequence.
2. The tire as claimed in claim 1, wherein a first predefined ratio of pitch length to a number of pitches is maintained in the at least one first circumferential tread row 106.
3. The tire as claimed in claim 1, wherein a second predefined ratio of pitch length to a number of pitches is maintained in the at least one second circumferential tread row 108.
4. The tire as claimed in claim 1, wherein the plurality of pitches of the at least one first circumferential tread row 106 corresponds to a plurality of first tread blocks and the plurality of pitches of the at least one second circumferential tread row 108 corresponds to a plurality of second tread blocks.
5. The tire as claimed in claim 1, wherein a number of first tread blocks A is in a range of 65 to 85.

6. The tire as claimed in claim 1, wherein a number of second tread blocks B is in a range of 1.05*A to 1.42*A.
7. The tire as claimed in claim 1, wherein a pitch length C of a smallest pitch of the pitches of the at least four different lengths in the first pitch sequence is in a range of 20 mm to 26 mm.
8. The tire as claimed in claim 1, wherein a pitch length D of a smallest pitch of
the pitches of the at least four different lengths in the second pitch sequence is in a
range of 0.70*C mm to 0.95*C mm.