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 WITH TIE BAR
2. Applicant(s)

NAME NATIONALITY ADDRESS
CEAT LIMITED Indian RPG HOUSE, 463, Dr. Annie Besant Road, Worli, Mumbai, Maharashtra 400 030, 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 invention relates to a pneumatic tire with a tie bar.
BACKGROUND
[0002] Tires enable movement of automobile on road surfaces. In an
automobile, the tires may be responsible for a plurality of functions, such as braking, to maintain steering, transfers weight of the automobile, etc. In view of its function, tire design is essential for ensuring safe driving on different types of road surface conditions, such wet, dry and snow. In general, tires have a toroidal structure with a circumferential outer surface containing plurality of treads. The treads are the grooved outer surface of tire that is in direct contact with the road. The groove defined on the surface, accommodates water to expel it from beneath the tire during rotation of tire on any wet surface and prevent phenomenon of aquaplaning.
BREIF DESCRIPTIONOF THE DRAWINGS
[0003] 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.
[0004] FIG. 1 illustrates schematics of tire with a tie bar configuration, in
accordance with an implementation of the present subject matter.
[0005] FIG. 2 illustrates schematic of a tie bar configuration, in accordance
with an implementation of the present subject matter.
[0006] Throughout the drawings, identical reference numbers designate
similar, but not necessarily identical elements. The figures are not necessarily

to scale, and the size of some parts may be exaggerated to more clearly illustrate the example shown. Moreover, the drawings provide examples and/or implementations consistent with the description; however, the description is not limited to the examples and/or implementations provided in the drawings.
DETAILED DESCRIPTION
[0007] As described previously, automobile tires have a tread pattern
which extends circumferentially about the outer surface of the tire. The tread pattern is designed in such a manner that the plurality of treads is spaced apart from each other by defining circumferentially and laterally extending grooves. These grooves divide the plurality of treads into either continuous or discontinuous tread blocks. The groove between the adjacent tread blocks provide free passage for expelling water backwards to provide better traction on wet surfaces and overcome adverse road phenomenon, such as hydroplaning. In some cases, extra wide grooves provide increased flexibility to the tread blocks which in turn reduces stiffness of the tread block and results in twisting of the tread blocks. To increase the stiffness of the tread block, a tie bar of same material as that of the tread block is extruded along the laterally extending grooves.
[0008] The tie bars are arranged in such a manner that the longitudinally
extending parallel sides of the tie bars are in close contact with the sidewalls of the adjacent tread blocks. These tie bars extend orthogonally from the bottom surface of the groove up to a certain height as compared to the height of the tread blocks. In an example, tie bars extend from 0% to 75% of the height of the tread blocks so that a top surface of the tie bar may not create disturbance and only comes into contact with the road as the tire wears. In addition to the increased stiffness, tie bar provides noise reduction, wear reduction, decreased rolling resistance and increased handling and traction for the tire. As may be understood, the main purpose of the tie bar is to

increase stiffness of the tread block, but it may reduce the capacity of the groove to accommodate water during movement on wet surfaces or snowy surface.
[0009] As may be understood, road surface covered with rain water or
snow provide greater challenges from gripping to the stability of the steering. Rain on a road surface may lead to an automobile experiencing hydroplaning particularly at higher speeds. In general hydroplaning occurs when the tire begins to push water in front of the tire as it travels down the road surface. One of the techniques to maintain hydroplaning at an acceptable level is, by increasing dimension of the grooves provided on the tire tread pattern which lead to increased groove capacity. The increase in groove dimension may causes reduction in the dry grip of the tire because the ground contact area is reduced. In addition, the increased groove capacity reduces steering stability as the stiffness of the tread block is reduced.
[0010] Still further, when the tire is in contact with the ground, a kind of air
column may be formed between the road surface and the circumferentially extending grooves. Such air column then generates a noise of specific intensity caused by airflow within the air column during movement. The intensity of the generated noise may increase with increase in the groove capacity. Conventionally, different tie bar configurations have been designed to overcome above mentioned problems. However, conventional tie bar configuration result in improving certain tire performance parameter but at the same time results in deterioration of other performance parameter. Therefore, considering above raised problems, there is a need of a tie bar configuration with increased groove capacity to enhance wet performance and still maintain other performance parameter in safety limit.
[0011] A pneumatic tire with a tie bar for tread pattern, is described herein.
As per an implementation of the present subject matter, the tie bar configuration enhances performance parameter of the pneumatic tire. As may be understood, tie bars are used to provide stiffness to the adjacent tread

blocks while rotating on a wet as well as on a dry road surface. The type of performance parameters which are to be enhanced, as well as which are to be deteriorate, may account to the factors for designing tie bar. The tie bar, as described in the present subject matter, may not only increase the wet performance and wear appearance of the pneumatic tire, but may also reduce weight of the tire and cost of production of tire as well. For example, the material used for molding pneumatic tire decreases and subsequently cost of manufacturing also reduces. Further, the tie bar in addition with increasing wet performance may result in consistent cornering capability and noise generation as compared with the conventional tie bar configuration. For example, the generated noise is directly proportional to the groove dimension, as dimension of the groove remains constant, so the generated noise is not affected.
[0012] In one example, a pneumatic tire having toroidal shape with a
circumferential outer surface includes plurality of tread protruded and extended orthogonally from the circumferential outer surface of the pneumatic tire. The treads are the component which make direct contact with the road surface and these are extruded on outer surface to impart wear resistance and traction to the tire. The material used for compounding tread is such selected that it has long wear characteristics and good traction capability.
[0013] Continuing with the present example, the treads on the outer
surface of pneumatic tire are such that the plurality of treads are spaced apart from each other to form a circumferentially and laterally extending grooves between the adjacent treads amongst the plurality of treads. The grooves may allow water to be expelled from beneath the tire and preventing aquaplaning. The grooves are defined in such manner that they provide a hollow space between a bottom surface and a spaced sidewall of adjacent treads. In some cases, the grooves may also include wear limit indicators in the form of small raised bridges within the grooves. When the top surface of the wear limit indicators and the adjacent treads coincides, indicates that the tire is worn out

and exceeded beyond its safety limit.
[0014] Returning to the present example, the pneumatic tire may further
include a tie bar extending from the bottom surface of the groove. The tie bar is extruded along the laterally extending grooves. The tie bars connect adjacent treads circumferentially to reduce treads squirm when rolling, as well as during acceleration and braking. The tie bar includes a pair of lateral flanged walls parallel to one another. The pair of lateral flanged walls extend from the bottom surface of the groove up to a certain height which is less than the height of the adjacent treads. The tie bar further includes a connecting stem portion extending from one lateral flanged wall to the other parallel lateral flanged wall. In one example, the connecting stem portion connects the pair of lateral flanged wall and forms an I-shaped tie bar. In another example, the orthogonal extension of the connecting stem portion from the bottom surface of the groove is same as that of the pair of lateral flanged walls.
[0015] Thus, the present subject matter discloses a tie bar with enhanced
wet performance, wear appearance and reduced weight and cost of the pneumatic tire. The tie bar configuration disclosed by the present subject matter has a I-shaped structure, such that it increases capacity of the laterally extending groove to accommodate higher volume of water. Thus, aquaplaning of the tire on wet surfaces is prevented using this tie bar configuration. Further, the pair of lateral flanged walls are making a closed contact with the sidewalls of the adjacent treads to provide appropriate stiffness to the adjacent tread blocks during rotation on the wet as well as dry surface. Further, tie bar configuration amounts to increased wear appearance of the tire as well.
[0016] These and other advantages of the present subject matter would
be described in greater detail in conjunction with the following figures, without limiting the scope of the invention. While configuration of the tie bar of the pneumatic tire may be implemented in any number of different configurations.
[0017] Fig. 1 illustrates schematics of a pneumatic tire 100 with a tread
portion 102 for automobiles, such as utility vehicles (UVR), crossover utility

vehicles (CUV), passenger buses, bicycles, heavy equipment automobiles, aircrafts etc., in accordance with an implementation of the present subject matter. The pneumatic tire 100 may include a pair of shoulder portions 104 with the tread portion 102 placed between the pair of shoulder portions 104. In an example, the tread portion 102 may be represented as a crown shaped portion, located between the pair of shoulder portion 104. In another example, the tread portion 102 may be considered as a circumferential outer surface of the pneumatic tire 100. The circumferential outer surface may include the tread portion 102 which contacts directly with the surface of the road during rotation. Further, the shoulder portions 104 join the circumferential outer surface to the rim of the pneumatic tire 100. The tread portion 102 as shown in FIG. 1 may be designed as per any possible pattern, without deviating from the scope of the invention, such that the designed pattern reliably provides wear resistance and traction with the road surface.
[0018] As may be understood, the tread portion 102 on the circumferential
outer surface includes plurality of treads 106. The plurality of treads 106 are to make close contact with the surface of the road while rotation. In general, any tire may include a plurality of circumferentially extending grooves along the outer surface. The circumferentially extending grooves may be considered as a recess in between treads extending along the circumference of the tire. In an example, the tire may further include transversely extending grooves. The transversely extending groove may be result in a hollow channel extending laterally in the solid tread portion of the tire along the width of tire. Therefore, the transverse groove may be considered as the grooves defined in tread portion branching from the one of the circumferential grooves and extending towards another circumferential groove. In an example, the transverse grooves may be through grooves, reaching from one circumferential groove to another circumferential groove. In another example, the transverse grooves may be formed at an angle less than or equal to 90 degrees with respect to circumference of the tire. In one example, these set of circumferential and transverse grooves provide channel for expelling water

during rotation on a wet surface.
[0019] Continuing with the present example, the tread portion 102 on the
circumferential outer surface of the pneumatic tire 100 may include a plurality of tread blocks 108-1, 2..., N (collectively referred to as tread blocks 108) formed by defining recess between the plurality of treads 106. The tread blocks 108 extending along the circumferential outer surface of the pneumatic tire 100 may be separated by either type of the grooves, as described above. Thus, the circumferential and transverse grooves in the solid tread portion form tread blocks 108 and these multiple tread blocks in a row forms a circumferential tread row. Number of tread blocks 108 in a circumferential tread row is known as pitch of the pneumatic tire 100. In an example, pitch of the tire may vary for a tire with same tread width and tire radius. In an example, the pneumatic tire 100 may further include a sipe 110 along the circumferential outer surface. The sipe 110 may be considered as thin slits molded into smooth tread surface to improve traction of the tire in wet, snowy or icy road conditions. Such sipe 110 essentially subdivide tread blocks 108 into smaller elements to provide additional biting edges for foul-weather traction.
[0020] Returning to the present example, the pneumatic tire 100 may
include a groove 112, such as a laterally extending groove, extending between the adjacent tread blocks 108 from amongst the plurality of treads 106. The groove 112 is designed in such a manner that it allows water to be expelled from beneath the pneumatic tire 100 and provide better traction on wet surfaces and overcome adverse road phenomenon, such as hydroplaning or aquaplaning. The groove 112 extending along the circumference or width of the pneumatic tire 100 are defined between a bottom surface 114 of the groove 112 and an opposing sidewall 116 of adjacent tread blocks 108. In some cases, the groove 112 may also include a wear limit indicator in the form of small raised bridges at regular intervals around the tire within the groove 112. When the top surface of the wear limit indicators coincides with the top surface of the tread blocks 108, it indicates that the tire is worn to its safety

limit.
[0021] Continuing with the present example, the pneumatic tire 100 may
further include a tie bar 118 extending from the bottom surface 114 of the groove 112. In an example, the tie bar 118 may extends orthogonally from the bottom surface 114 of the groove 112 up to a certain height less than the height of the tread blocks 108. The tie bar 118 may be extruded along the laterally extending groove 112 (referred to as groove 112). In an example, tie bar 118 may be considered as a short rubber links molded across groove 112 between adjacent tread blocks 108. In one example, the tie bar 118 may maintain a close contact with the sidewall 116 of the adjacent tread blocks 108. The tie bar 118 connect tread blocks 108 circumferentially to reduce tread squirm when rolling, as well as during acceleration and braking. Tie bar 118 extruded along the groove 112 opposes tread blocks 108 movement to resist irregular wear.
[0022] The tie bar 118 includes a pair of lateral flanged walls i.e. an upper
lateral flanged wall 120 (referred to as upper flanged wall 120) and a lower lateral flanged wall 122 (referred to as lower flanged wall). The upper flanged wall 120 and the lower flanged wall 122 extends from the bottom surface 114 of the groove 112 along the opposing sidewall 116 of the adjacent tread blocks 108. In an example, both the flanged wall makes a close contact with the opposing sidewall 116 of the adjacent tread blocks 108. The tie bar 118 may further includes a connecting stem portion 124 extending from upper flanged wall 120 to the lower flanged wall 122. In an example, the connecting stem portion 124 extends orthogonally from one of the flanged walls to the other flanged wall. In another example, similar to the pair of lateral flanged walls (120, 122), the connecting stem portion 124 may extends up to a certain height with respect to the height of the adjacent tread blocks 108. The connecting stem portion 124 may acquire any possible dimensions, without limiting the scope of the invention, to connect the pair of lateral flanged wall. In one example, the connecting stem portion 124 rigidly connects the pair of

lateral flanged wall, to oppose tread blocks 108 movement.
[0023] The above described configuration of the tie bar 118 increases
capacity of the laterally extending groove to accommodate higher volume of water, owing to which, increased amount of water is expelled beneath the tires and prevents phenomenon of aquaplaning. In addition to improvement in wet performance of the tire, tie bar 118 lead to reduced weight, as lesser amount of rubber material is utilized during manufacturing and cost of manufacturing of the pneumatic tire 100 also reduced. Further, the tie bar 118 maintains relatively similar level of consistency in other additional tire performance parameters as provided by the conventional tie bar configuration. Examples of such additional performance parameters include, but are not limited to, tangential and lateral stiffness, cornering capability, shear stress, unidirectional bending and noise level. Further, due to the I-shaped structure of the tie bar 118, it provides better wear appearance as well. The dimensions of the tie bar 118 may be such selected that it increases the overall capacity of the groove and still providing same level of stiffness to the adjacent tread blocks 108. Certain example tie-bar dimensions and associated groove dimensions are provided in Table 1 below:
Table 1

Tie Bar Dimensions Groove Dimension
A ≥ E
B ≥ F
C ≥ (F-1)
D ≥ (E-1)
[0024] Table 1 provides a relationship between the dimensional
parameters of the tie bar 118 and dimension of the groove 112. In table 1, ‘A’ represents flanged wall length, ‘B’ represents outer tie bar width, ‘C’ represents inner tie bar width and ‘D’ represents longitudinally extending

hollow part width. Further, ‘E’ represents groove length and ‘F’ represents groove width. As mentioned in table 1, to provide appropriate stiffness between the adjacent tread blocks 108, flanged wall length ‘A’ may be greater than or equal to the groove length ‘E’. In an example, a single tie bar 118 may extend all along the groove 112, owing to which, sidewall 116 is fully supported by the pair of flanged walls. Similarly, outer tie bar width ‘B’ is greater than or equal to the groove width ‘F’. In an example, larger outer tie bar width ‘B’ provides required stiffness to the adjacent tread blocks 108, owing to which, tread blocks 108 may not squirm while rotation. Further, inner tie bar width ‘C’ and longitudinally extending hollow part width ‘D’ are greater than or equal to the one unit less than the groove length E and groove width F, respectively. It may be noted that any given tire having certain dimensions may be provided with the tie bar 118, as per the relation indicated in Table 1.
[0025] Fig. 2 illustrates schematics of a tie bar 118 extruded along the
groove 112 of the pneumatic tire 100, in accordance with an implementation of the present subject matter. As may be understood, the pneumatic tire 100 include plurality of tread blocks 108 separated by circumferentially or laterally extending groove 112. The groove 112 provide hollow channel for expelling water from beneath the tire on wet surfaces and prevents aquaplaning. Due to these grooves 112, adjacent tread blocks 108 may experience squirm on wet as well on dry surface while rotating. To overcome this problem, tie bar 118 are extruded along the groove 112 to circumferentially connecting adjacent tread blocks 108.
[0026] As shown in FIG. 2, the tie bar 118 include the upper lateral flanged
wall 120 and the lower lateral flanged wall 122 making close contact with the opposing sidewall 116 of the adjacent tread blocks 108. These flanged walls oppose movement of the adjacent tread block s108 and provide appropriate stiffness to the tread blocks 108 while rotation of the pneumatic tire 100 on any surface. In an example, the pair of lateral flanged wall (120, 122) extends from the bottom surface 114 of the groove 112 while making close contact

with the sidewall 116 of the adjacent tread blocks 108. The tie bar 118 may further include the connecting stem portion 124 extending from upper flanged wall 120 to the lower lateral flanged wall 122. In an example, the connecting stem portion 124 extends orthogonally from one flanged wall to another flanged wall. In another example, the connecting stem portion 124 rigidly connects the pair of lateral flanged wall (120, 122), to oppose tread blocks 108 movement while tire rotation.
[0027] Returning to the present example, the proposed configuration of
the tie bar 118 results in an increase in the capacity of the laterally extending groove to hold higher volume of water as compared to the conventional tie bar configurations. The increase in holding capacity of groove 112 results in preventing aquaplaning phenomenon while rotation of the pneumatic tire 100 on the wet surface. As may be understood, in conventional approaches, in order to improve one performance parameter, other performance parameter deteriorates and results in an overall degradation tire performance. However, the tie bar 118 results in enhanced tire performance in wet condition, increased wear performance, reduced tire weight and reduced cost of manufacturing and other performance parameter still maintain the same safety level. The comparison of the conventional tie bar configuration with the claimed tie bar configuration based on the tire performance parameter is listed in the below table- 2 to 4.
[0028] Table 2

Conventional Tie Bar Presently
Claimed Tie
Bar % Reduction in Tie bar Volume Through claimed tie bar
Total
Volume
Occupied in
tyre 6134 4579 25.35%
[0029] Table 2 provides comparison of conventional tie bar with the
claimed tie bar 118 based on the volume occupied by the tie bar 118 in the

pneumatic tire 100. As mentioned in table 2, the volume occupied by the tie bar 118 reduces by 25.35% as compared to the conventional tie bar. In an example, this reduced volume is a result of the I-shaped structure with openings present on the tie bar 118.
[0030] Table 3

S. No Measured Parameter Conventional Tie Bar Claimed tie bar Conclusion /remarks
1 Aqua performance Index 3.3 4.2 I block resistor is 1.25 times Better than Conventional
2 Tangential Stiffness (Kxx) 1727 1721 At Same Level
3 Lateral Stiffness (Kyy) 1780 1778 At Same Level
[0031] Table 3 provides comparison of the conventional tie bar with the
claimed example tie bar, such as tie bar 118, based on the measured performance parameter of the pneumatic tire 100. As mentioned in table, aqua performance index of the claimed tie bar 118 increased 1.25 times as
compared to the index value of the conventional tie bar. In an example, the aqua performance index may be represented by below formula.

[0032] Further, the tangential and lateral stiffness level in case of claimed
tie bar 118 maintain the same level as that of the conventional tie bar.
[0033] Table 4

S. No
1 2 Influenced performance Conventional Tie Bar Claimed tie bar Conclusion /remarks

Aqua planning 100 103 better than Conventional Tie bar

Cornering Capability 100 100 At Same Level

3
5 6 7 Wear Appearance 100 105 Improved Wear Appearance

Tire Weight 100 99 Weight reduction

Noise 100 100 At Same Level

Cost Saving 100 99 Material Cost saving Through innovative shape
[0034] Table 4 provides comparison of the conventional tie bar with the
claimed tie bar 118 based on the influenced performance parameter of the pneumatic tire 100. As mentioned in table, the aquaplaning and wear appearance of the pneumatic tire 100 improves as compared to the conventional tie bar. Further, the weight and cost of manufacturing of the pneumatic tire 100 reduces substantially to improve tire performance. Similarly, the noise level generated during rotation of the pneumatic tire 100 maintains the same level as that of the conventional tie bar.
[0035] Thus, based on various experimental results and data obtained
from the tires, the tie bar configuration provides improved wet performance and wear appearance. Additionally, a reduction in tire weight and cost of manufacturing is also obtained with other performance parameter remains in their respective safety limits.
[0036] Although examples for the present disclosure have been described
in language specific to structural features and/or methods, it should be understood that the appended claims are not necessarily limited to the specific features or methods described. Rather, the specific features and methods are disclosed and explained as examples of the present disclosure.

I/We Claim:
1. A pneumatic tire (100) having a toroidal shape with a circumferential
outer surface, wherein the outer surface comprises:
a tread portion (102) having plurality of treads (106) protruded, and extended orthogonally from the circumferential outer surface, wherein the plurality of tread (106) is spaced apart from each other with a defined distance to form plurality of tread blocks (108);
a groove (112) extending between the adjacent tread blocks (108) from amongst the plurality of treads (106), wherein the groove (112) is defined between a bottom surface (114) and an opposing sidewall (116) of adjacent tread blocks (108), wherein the groove (112) comprises:
a tie bar (118) extending from the bottom surface (114) of groove (112), wherein the tie bar (118) comprises:
a pair of lateral flanged walls (120,122) provided on opposing sidewall (116) of the adjacent tread blocks (108); and
a connecting stem portion (124) extending between the pair of the lateral flanged walls (120, 122).
2. The pneumatic tire (100) as claimed in claim 1, wherein the tread blocks (108) includes a top surface, a pair of lateral sidewalls and a pair of longitudinal sidewalls.
3. The pneumatic tire (100) as claimed in claim 1, wherein the connecting stem portion (124) extends orthogonally from an upper lateral flanged wall (120) to the lower lateral flanged wall (122).

4. The pneumatic tire (100) as claimed in claim 3, wherein the pair of lateral fanged walls (120, 122) and connecting stem portion (124) defines a I-shaped structure of the tie bar (118).
5. The pneumatic tire (100) as claimed in claim 1, wherein the pair of lateral flanged walls (120, 122) of the tie bar (118) makes a close contact with the opposing sidewall (116) of the adjacent tread blocks (108).
6. The pneumatic tire (100) as claimed in claim 1, wherein the tie bar (118) extends orthogonally up to a certain height of the adjacent tread blocks (108).
7. The pneumatic tire (100) as claimed in claim 1, wherein the length of the pair of the lateral flanged walls (120, 122) is greater than or equal to the length of the groove (112).
8. The pneumatic tire (100) as claimed in claim 1, wherein the outer width of the tie bar (118) is greater than or equal to the width of the groove (112).
9. The pneumatic tire (100) as claimed in claim 1, wherein the inner width of the tie bar (118) is greater than or equal to one unit less than the length of the groove (112).
10. The pneumatic tire (100) as claimed in claim 1, wherein the distance from the distal end of the lateral flanged walls (120, 122) to the intersection with the connecting stem portion (124) is greater than or equal to one unit less than the width of the groove (112).