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: TRANSITION LAYER IN TIRES
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
[001] The present subject matter relates, in general, to vehicle tires
and, particularly but not exclusively, to a transition layer in the tires.
BACKGROUND
[002] A tire has numerous components assembled together such as a
tread portion and sidewalls on either side of the tread region. The tread portion contacts with a surface on which the tire is moving during rotation and provides necessary grip or traction for driving, braking and cornering. Sidewalls offer structural support and flexibility to the tire. The tire also has a bead portion connected to lower portions of the sidewalls. Each of the bead portion have a bead core that may be understood as an edge of the tire that anchors the tire to a wheel rim of the vehicle on which the tire is mounted. The bead portion also has a bead filler or apex between the lower end of the sidewall and the bead core providing stability to the lower sidewall and bead portion. The bead core contacts with wheel during mounting of the tire.
[003] The tread portion, sidewalls and the bead portion are supported
by one or more layers of reinforcing fabric, known as body ply which wraps around bead portion enhancing strength. An inner liner is applied on the inner surface of the tire and acts as a barrier. Certain tires also have a pair of abrasion gum strips (AGS) located externally below the sidewalls and at the bead core, above the inner liner. The AGS has the function of protecting the bead from the abrasion action exerted by the rim. A transition layer comprising natural rubber may also be disposed between the body ply and the inner liner.
BRIEF DESCRIPTION OF DRAWINGS
[004] The detailed description is described with reference to the
accompanying figure. In the figure, 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.

[005] Figure 1 illustrates a cross sectional view of a conventional design
of a tire, in accordance with prior art.
[006] Figure 2 illustrates a cross sectional view of a tire, in accordance
with an implementation of the present subject matter.
[007] Figure 3 illustrates a scatter plot depicting a change in bead
endurance of the tire with respect to a varying width of a transition layer of
the tire, in accordance with an implementation of the present invention.
[008] Figure 4 illustrates a bar chart depicting a change in bead
endurance of the tire with respect to a varying width of the transition layer
of the tire, in accordance with an implementation of the present subject
matter.
[009] The figure is 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
[0010] In conventional tires, components, namely, bead apex, transition
Layer (TL) and abrasive gum strip (AGS), are located in sidewall portions of the tires. The bead apex is located above the bead core in a bead portion of the tire while the TL is positioned between an outermost body ply of one or more body plies of the tire and inner liner of the tire and the AGS is positioned below the sidewall and surrounding a bead core of the bead portion.
[0011] At either sidewall, the ending of bead apex, TL and AGS are
located nearly at same location which leads to a junction formation at apex end of the tire. Reference is made to Figure 1 to explain the apex end, its location and the junction formation at the apex end.
[0012] Figure 1 illustrates a cross sectional view of a conventional design
of a tire 100. As illustrated in Figure 1, the tire 100 comprises a tread region 102 and sidewalls 104 on either side of the tread region 102. The tire 100

also comprises a pair of bead portions. A bead portion is positioned at a lower end of respective sidewall 104. The bead portion comprises a bead core 106 at an edge of the tire 100 and a bead apex or bead filler 108 above the bead core 106. The point where the bead apex 108 ends is generally called an apex end 110 of the tire 100.
[0013] One or more layers of body plies 112 supports the tread portion
102, sidewalls 104 and the bead portions. The body plies 112 turn up around the bead portions enclosing the bead portions. A layer of inner liner 114 which may be made of made of an air-impermeable rubber compound, such as butyl rubber is applied on an outermost body ply of the one or more body plies 112 to improve air retention in the tire 100. Thickness of the inner liner 114 may be substantially about 1 mm.
[0014] The tire 100 further comprises a pair of abrasion gum strips AGS
116 surrounding the bead core 106 and ending below the sidewall 104 and near the apex end 110. The pair of AGSs 116 is arranged to be in contact with edges of a wheel rim and protect the bead core 106 from the abrasion action exerted by the wheel rim when the tire 100 is mounted on the wheel rim. The AGS 116 is generally made of a mixture of hard gum having a high resistance to abrasion.
[0015] A transition layer 118 which is generally made of natural rubber
is interposed between the outermost body ply of the tire 100 and the inner liner 114. Because of high tensile strength, the transition layer 118 of natural rubber offers resistance to fatigue from wear, such as chipping, cutting or tearing. Also, natural rubber has a property to adhere to itself and any other material. This allows the transition layer 118 to strongly adhere to the outermost body ply and the inner liner. Generally, thickness of the transition layer 118 may be substantially about 0.5 mm.
[0016] In conventional design of tires 100, transition layer 118 also ends
near the apex end 110 of the tire 100, i.e., above the respective bead portion. Thus, at an inner surface of the tire 100, only the inner liner 114 made of rubber compound and having a thickness of 1 mm is present from

the apex end 110 to bead core 106. Therefore, the rubber compound may get penetrated during rotation of tire at heavy load which may cause separation of the sidewalls 104. Further, each of the bead apex 108, transition layer 118 and the AGS 116 ends nearly at the same location, i.e., near to the apex end 110 which cause a junction of the endings of these three components to form at the apex end 110. The apex end 110 is generally at high flexing zone of tires which results in sidewall 104 separation during heavy load operation.
[0017] This compromised adhesion of the sidewall 104 may lead to a
range of performance issues, such as reduced stability, handling problems, and diminished overall tire integrity.
[0018] One of the critical consequences of separation of sidewall 104 is
the potential for air leaks and loss of tire pressure. The separation allows air to escape, leading to underinflation, which, if not addressed promptly, may result in decreased fuel efficiency, uneven tire wear, and compromised vehicle safety. If the separation issue persists, it may escalate to more severe problems, including the risk of tire failure. A separated sidewall 104 may weaken the overall tire structure, making it susceptible to blowouts or tread separation, posing a significant safety hazard to the driver and passengers.
[0019] The separation problem poses notable safety concerns, as it may
affect the tire's ability to respond predictably to steering inputs and road
conditions. This may result in decreased vehicle control and an increased
risk of accidents, especially during high-speed or emergency maneuvers.
[0020] The present invention addresses the sidewall separation issue
owing to the above-described separation issues caused by separation of
sidewalls in the high flexing zone of the tires for ensuring optimal tire
function and preventing potential safety hazards associated with tire failure.
[0021] According to an aspect of the present invention, a tire is provided
that comprises a tread portion and a pair of sidewalls arranged on either side of the tread portion. The tire may also comprise a pair of bead

assemblies. A bead assembly is located at an end of a respective sidewall
of the pair of sidewalls. Each of the tread portion, the pair of sidewalls and
the pair of bead assemblies are supported by one or more body plies turned
up around each bead assembly. The tire may further comprise a transition
layer which may be interposed between an inner liner of the tire and an
outermost body ply of the one or more body plies. The transition layer may
comprise at least natural rubber and extends upto a heel of the tire.
[0022] The tire disclosed in the present invention addresses the sidewall
separation issue by optimization of the transition layer ending at heel of tire.
Ending of transition layer is optimized to increase a width of rubber
compound at the bead assemblies. Particularly, the width of the transition
layer is increased up to the heel area. The increase of width of the transition
layer up to the heel area avoids forming ending of the bead apex, transition
layer (TL) and abrasive gum strip (AGS), at same point or location. Thus,
the risk of separation of sidewall during the tire operation may be reduced.
Notably, only the transition layer can be optimized because any change in
AGS and bead apex would impact other performance parameters of the tire.
Further, by increasing width of transition layer upto the heel of the tire, an
overall thickness of layers of rubber compounds, i.e., inner liner and the
transition layer inside and below the bead area is increased. Thus,
optimization of transition layer ending avoids excessive stress at bead area,
thereby eliminating the problem of sidewall separation and increasing the
durability of tire. The overall performance, safety, and durability of the tire
are improved by addressing challenges associated with sidewall separation.
[0023] 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.
[0024] Figure 2 illustrates a cross sectional view of a tire, in accordance
with an implementation of the present subject matter.
[0025] In accordance with an implementation of the present subject
matter, the tire 200 comprises a tread portion 202 and a pair of sidewalls 204 arranged on either side of the tread portion 202. As will be understood, this arrangement of the tread portion 202 and the pair of sidewalls 204 is the same as that of the conventional tire 100 as illustrated in Figure 1. More specifically, the tread portion 202 may comprise a center region and a shoulder region on each side of the center region connected to upper portions of corresponding sidewalls 204 of the tire 200. The center region is formed along complete circumference of the tire, spreads along a width of the tire 200 and contacts with a surface during rotation.
[0026] The tread portion 202 is designed to provide traction and resist
wear, and its design can vary depending on the specific requirements of tire 200, such as whether it is intended for use on dry, wet, or snowy surfaces. The sidewalls 204 extends circumferentially and continuously on either side of the tread portion 202. The sidewalls 204 provide lateral stability to the tire 200 and also contribute to the tire's 200 overall strength and flexibility. Tire 200 may comprise a pair of bead assemblies. A bead assembly is located at a lower or distal end of a respective sidewall of the pair of sidewalls. A bead assembly comprises a bead core 206 located at an edge of the tire and interfaces with the wheel rim during mounting of the tire on the wheel rim. The bead core 206 may be a bundle of specified diameter made of high tensile steel wires. The steel wires may be copper, brass, or bronze-plated to protect steel from corrosion. The coated steel wires may further be encased in a rubber compound. The bead core holds the tire to the wheel

rim. The bead core 206 extends from a toe 208 to a heel 210 in an axial direction with respect to a center of the tire 200. Thus, the toe 208 of the tire 200 may be understood as an inner edge of the bead core 206, while the heel 210 of the tire 200 may be understood as an outer edge of the bead core 206. The bead assembly may further comprise a bead apex or bead filler 212 extending radially above the bead core 206 upto the respective sidewall 204 of the tire 200 or an apex tip 214 of the tire 200. The end of bead apex 212 may be understood as an apex tip 214 of the tire 200. The bead apex 212 or may be a rubber compound inside the bead assembly, providing stability to lower portion of the sidewall 204 and bead core 206. Density, height and hardness of the bead filler 212 affects a tire’s performance characteristics.
[0027] In an example, each of the tread portion 202, the pair of sidewalls
204 and the pair of bead assemblies are supported by one or more body plies 216 turned up around each bead assembly. A body ply 216 generally comprises polyester, rayon, or nylon fabric cords within a rubber layer. The body plies 216 function as the structure of the tire 200 and provide the strength to contain the inflation pressure. The one or more body plies 216 extend radially across the tire 200 and wraps around each bead assembly. The tire 200 may further comprise a layer of inner liner 218 forming an inner surface of the tire 200 to improve air retention by lowering permeation outwards through the tire 200. The inner liner 218 may be made of made of an air-impermeable rubber compound such as a butyl rubber and may be applied on an outermost body ply of the one or more body plies 216 to improve air retention in the tire. In an example, a thickness of the inner liner 218 may be 1 mm. Further, the tire 200 may comprise a pair of abrasion gum strips AGS 220. Each AGS 220 may be located externally below the respective sidewall 204 and surrounding the bead core 206. The abrasion gum strips 220 met with the edges of the wheel rim during mounting of the tire 200 on the rim. The AGS 220 protects the bead core 206 from the abrasion action exerted by the rim and consequently, the abrasion gum

strips 220 are made of a mixture of hard gum having a high resistance to abrasion. More specifically, the AGS 220 provides a layer of rubber between the body plies 216 and the wheel rim for resistance against chafing. A joining surface between each sidewall 204 and the corresponding abrasion gum strip 220 is slanted such that a thickness of sidewall 204 decreases on moving towards the lower end of the sidewall 204.
[0028] In an example, a transition layer 222 comprising at least natural
rubber is interposed between an inner liner 218 of the tire 200 and an outermost body ply of the one or more body plies 216. A width of the transition layer 222 extends upto the heel 210 of the tire 200. In an example, the width of transition layer is 103% of the toe to toe length of the tire. In another example, the width of transition layer may be in a range of 101% to 105% of the toe to toe length of the tire. In an example embodiment, a tire having a specification of 195R15 comprises a transition layer of a width of 450 mm, wherein 195 representing width in mm, R representing radial tire and 15 representing diameter of wheel rim in inches. To increase the width of the transition layer 222 upto the heel 210 of the tire 200, setting of corresponding knife or cutter in calendering process may be modified accordingly. In an example, the transition layer 222 may comprise at least a natural rubber compound to avoid air permeability. In an example, a thickness of the transition layer 222 may be in a range of about 0.6 mm to 1.2 mm. Since, the transition layer 222 extends radially across the tire 200 and ends at the heel 210 of the tire 200, the thickness of the rubber compound at the axially inside bead portion and at the edge of the tire 200 increases. This results in more cushioning being provided to the bead core 206 against the chafing between the wheel rim and the bead core 206. Further, since transition layer 222 does not end at the apex tip 214 of the tire 200, as opposed to the convention design of tires formation of junction of transition layer, AGS and the bead apex in high flexing zone, i.e., apex tip of the tire may be avoided. This further prevents the excessive stress at the bead assemblies and consequently the sidewall 204 separation from the

body ply 216. Additionally, the optimization in width of the transition layer 222 aids in maintaining consistent tire performance by preventing air leaks that could result from sidewall 204 separation. This contributes to sustained tire pressure, optimizing fuel efficiency, and ensuring safe and reliable operation.
[0029] Figure 3 illustrates a scatter plot depicting a change in bead
endurance of the tire 200 with respect to a varying width or ending points of the transition layer 222 with respect to time, in accordance with an implementation of the present invention. Figure 4 illustrates a bar chart depicting a change in bead endurance of the tire 200 with respect to a varying width or ending points of the transition layer 222 with respect to time, in accordance with an implementation of the present invention. The scatter plot of Figure 3 and bar chart of Figure 4 present the results of the bead endurance report conducted by the inventors of the present invention, evaluating the impact of varying the widths of the transition layer 222 on the endurance of the tire 200. Initially, endurance of a conventional tire having the transition layer ending axially inside at the apex tip of the tire. The endurance of the conventional or regular tire as depicted in bar chart of Figure 4 comes out to be 40.5 hrs. Further, three more tires with different ending points of the transition layer are tested. In a first variant of the tire, i.e., Variant1, being tested, the transition layer 222 ends axially inside at a mid point of bead apex 212. With Variant1, an endurance of 57.05 hrs is achieved. In a second variant of the tire, i.e., Variant2, the transition layer going through heel of the tire ends substantially at a midpoint of bead core with tighter section. With Variant2, an endurance of 67.61 hrs is achieved. In a third variant of the tire, i.e., Variant3, the transition layer 222 extends upto the heel 210 of the tire 200. Figure 3 illustrates that maximum endurance is achieved at a width of 450 mm of the transition layer 222. A width of 450 mm represents the transition layer 222 extending upto the heel 210 of the tire 200. It is evident from Figure 3 and Figure 4 that a maximum endurance of 80.08 hrs is achieved in case of Variant3. Thus, it is found that

the transition layer 222 extending upto the heel 210 of the tire 200 exhibits the highest improvement in the bead endurance of the tire as per the aspect of the present invention.
[0030] Although implementations of a tire 200 are described, it is to be
understood that the present subject matter is not necessarily limited to the specific features of the apparatus described herein. Rather, the specific features are disclosed as implementations for the tire 200.

I/We Claim:
1. A tire 200 comprising:
a tread portion 202 and a pair of sidewalls 204 arranged on either side of the tread portion 202;
a pair of bead assemblies, wherein a bead assembly is located at an end of a respective sidewall of the pair of sidewalls 204,
wherein each of the tread portion 202, the pair of sidewalls 204 and the pair of bead assemblies are supported by one or more body plies 216 turned up around each bead assembly, and
a transition layer 222 comprising at least natural rubber is interposed between an inner liner 218 of the tire and an outermost body ply of the one or more body plies 216, and wherein the transition layer 218 extends upto a heel 210 of the tire.
2. The tire 200 as claimed in claim 1, wherein the bead assembly comprises a bead core 206 at an edge of the tire 200 that interfaces with a wheel rim and a bead apex 212 extending radially above the bead core 206 upto an apex tip 214 of the tire 200.
3. The tire 200 as claimed in claim 1, wherein a thickness of the transition layer 222 is in a range of 0.6 mm to 1.2 mm.
4. The tire 200 as claimed in claim 1, wherein a width of transition layer 222 is substantially about 103 % of a toe 208 to toe 208 length of the tire 200.
5. The tire 200 as claimed in claim 1, wherein a width of transition layer 222 is in the range of about 101 % to105 % of a toe 208 to toe 208 length of the tire 200.

6. The tire 200 as claimed in claim 1, wherein the tire comprises a pair of abrasion gum strips (AGS) 220, an AGS 220 being located externally below the respective sidewall 204 and surrounding the bead core 206, wherein the AGS 220 ends at the apex tip 214 of the tire 200.
7. The tire 200 as claimed in claim 1, wherein the transition layer 222 does not end at the apex tip 214 of the tire 200.