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: VEHICLE TYRE
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 tyres
and, in particular, to a vehicle tyre with low rolling resistance.
BACKGROUND
[0002] Tyres support load of a vehicle and facilitate steerability,
drivability, and safety of the vehicle. Generally, a tyre has a tread area and a pair of sidewalls located on either side of the tread area. The tread area is an outer region of the tyre that is formed along a circumference thereof and spreads along a width of the tyre. Also, the tread area is the portion of the tyre that contacts a surface during rotation of the tyre. The tyre generally also has a pair of beads to mount the tyre on a rim of a wheel. Therefore, each of the pair of beads are connected to each of the pair of sidewalls which is further connected to either side of the tread area, thereby forming an outer surface of the tyre.
[0003] The tread area further includes a tread pattern formed on an
outer surface thereof to provide traction. As per the usage of the vehicle and a type of terrain where the vehicle is to be used, the tread pattern of the tyre may be carved in diverse configurations. For instance, a vehicle that has to be used on a unmetalled roads may have tyres with large tread blocks in the tread pattern to allow the load of the vehicle to be distributed over a large surface area, thereby ensuring a smoother drive.
BRIEF DESCRIPTION OF FIGURES
[0004] Figure 1 illustrates a cross-sectional view of a tyre along a
longitudinal direction of the tyre, in accordance with an example of the present subject matter, and
[0005] Figure 2 illustrates a cross-sectional view of tread area of the
tyre, in accordance with another example 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 drawing.
DETAILED DESCRIPTION
[0007] Generally, a number of forces act on a tyre in motion. Amongst
other forces, rolling friction or rolling resistance is the force that resists the motion of the tyre when the tyre rolls on a surface. Various factors contribute to the rolling resistance of the tyre, such as tyre pressure, tyre diameter, tyre construction, and tyre tread pattern.
[0008] While certain factors, such as tyre pressure and tyre tread are
dynamic in nature and may vary during prolonged usage of the tyre, other factors, such as tyre construction are static and play a major role in determining rolling resistance of the tyre.
[0009] Typically, the rolling resistance of the tyre is varied by varying
various constructional parameters of the tyre such as, weight, tread pattern width, and skid depth. However, any significant variance in the constructional parameters to reduce the rolling resistance leads to a deviation from certain minimum safety and load requirements for the tyre, thereby making the tyre unsafe for use in vehicles.
[00010] According to examples of the present subject matter, a tyre with
low rolling resistance is disclosed.
[00011] In an example, the rolling resistance of the tyre may be varied
by altering contact patch parameters of the tyre along with alterations in a profile of a tyre cavity. The contact patch parameters may be understood as dimensions of a contact patch of the tyre, where the contact patch is a portion of the tread area that is in contact with a surface at a particular instance during the rotation of the tyre. Further, the tyre cavity may be understood as a hollow portion of the tyre existing between a rim of the wheel and an innermost layer of the tyre.

[00012] In the above-mentioned example, the alterations are done in a
manner, such that, any significant changes to the factors affecting the safety and usability of the tyre such as, weight, tread pattern width, or skid depth are avoided. As a result, the rolling resistance of the tyre is reduced while meeting the safety and load requirements. Further, the use of such a tyre reduces wear and tear along with a substantial increase in fuel efficiency of the vehicle.
[00013] The above aspects are further described in conjunction with the
figures, and in associated description below. It should be noted that the description and the figures merely illustrate principles of the present subject matter. Therefore, various arrangements that encompass the principles of the present subject matter, although not explicitly described or shown herein, may be devised from the description and are included within its scope.
[00014] Figure 1 illustrates a cross-sectional view of a tyre 100 along x-
y plane, in accordance with an example of the present subject matter. In an example, the tyre 100 is a pneumatic tyre. Further, the tyre 100 may be made of the materials including, but not limited to, synthetic rubber and natural rubber.
[00015] In an example, the tyre 100 comprises a tread area having a
tread pattern. As discussed earlier, the tread area may be understood as an outer portion of the tyre that contacts a surface during rotation of the tyre 100. In said example, the tread pattern may include multiple tread blocks that may be formed on the tread area to provided traction to a surface in contact with the tyre 100 during rotation. Accordingly, the tread blocks are formed on an outer surface of the tyre 100and provides traction to the surface in contact with the tyre 100 in rotation. Further, in an example, the tyre 100 may have a tread width (TW) that may indicate a width of the tread pattern.
[00016] Apart from the tread pattern, the tyre 100 has a pair of beads
6,6 that may facilitate mounting of the tyre 100 onto a rim of a wheel. The tyre 100 further has a pair of bead fillers 6a, 6a, disposed on a periphery

of each of the pair of beads 6a, 6a in a tyre radial direction to reinforce
portions of the tyre 100 having the each of the pair of beads 6a, 6a.
[00017] The tyre 100 further has a pair of sidewalls 5,5 connected to the
tread pattern at one end and to the pair of beads 6a,6a on another end. In
an example, the tyre 100 may have a section width (SW) that may be
indicated as maximum distance between each of the pair of sidewalls 5,5.
[00018] Referring to Figure 1, the tread pattern has a first tread block 1
and a second tread block 2 formed on either side of a circumferential
center CL of the tread area. The circumferential center CL may be
understood as a continuous axis that circumferentially divides the tread
area into two portions. In an example, the tyre 100 may have an outer
diameter (OD) that may be indicated as a distance between two points
arranged diagonally opposite on the circumferential center of the tyre 100.
[00019] Further, in an example, the first tread block 1 and the second
tread block 2 may be separated by a section. In said example, the section may be a continuous axis having a depth equal to a non-skid depth of the tyre 100. In said example, the first tread block 1 is arranged at a first distance from the circumferential center CL and the second tread block 2 is arranged at a second distance from the circumferential center CL, where the first distance is smaller than the second distance. Moreover, in an example, the tyre 100 may have a tread length (L1) that indicates a distance between the circumferential center CL of the tyre 100 and the second tread block 2.
[00020] Referring to Figure 2, an exemplary cross-sectional view of the
tread area 200 of the tyre 100 along x-z plane is illustrated. The tread area 200 has the first tread blocks 1,1 and second tread blocks 2,2 on either side of the circumferential center CL. Further, the first tread block 1 and the second tread block 2 are arranged at respectively the first distance d1 and the second distance d2 from the circumferential center CL. Further, as it is evident from the figure, the first distance d1 is smaller than the second distance d2.

[00021] Returning to Figure 1, the tyre 100 may have a first tread radius
(TR1) that indicates a distance between a center of the tyre and an outermost surface of the first tread block. Further, the tyre 100 may have a second tread radius (TR2) that indicates a distance between the center of the tyre and an outermost surface of the first tread block.
[00022] In an example, the tyre 100 may further have a reference height
(RH) that indicates a distance between a bead from amongst the pair of beads 6,6 and a mid-point of a sidewall from amongst the pair of sidewalls 5,5.
[00023] The tyre 100 further has a carcass layer 4 formed as an
innermost layer of the tyre 100 that stretches between each of the pair of beads 6,6, thereby forming a frame for the tyre 100. In an example, the carcass layer 4 is formed to define a tyre cavity, where the tyre cavity may be understood as the hollow portion of the tyre existing between a rim of the wheel and the innermost layer of the tyre 100. Further, ends of the carcass layer 4 may be folded to form a loop for accommodating the each of the beads 6,6 therein.
[00024] Moreover, the tyre 100 has a belt layer 7 that is formed on the
carcass layer 4. In an example, the belt layer 7 is formed by lamination of a plurality of belt pipes 7a to 7c over the carcass layer 4. In said example, the belt layer 7 is formed above the carcass layer 4 and below the tread area. The belt layer 7 serves to provide stability to the tread area of the tyre and is generally made of steel.
[00025] Further, the tyre 100 may have a first inner radius (IR1) that
indicates a distance between the center of the tyre and an innermost surface of the first tread block 1. In an example, the innermost surface of the first tread block 1 is a surface of the first tread block that abuts the outermost belt pipe 7c of the belt layer 7. Similarly, the tyre may have a second inner radius (IR2) that indicates a distance between the center of the tyre and an innermost surface of the second tread block 2. In an example, the innermost surface of the second tread block 2 is the surface

of the second tread block 2 that abuts the outermost belt pipe 7c of the belt layer 7.
[00026] In an example, as discussed earlier, the tyre may have a
contact patch is a portion of the tread area that is in contact with a surface
at a particular instance during the rotation of the tyre 100. In an example,
the tread pattern including the first tread block 1 and the second tread
block 2 may be formed to be within the contact patch of the tyre 100.
Accordingly, the parameters associated with the contact patch such as,
TW, L1, TR1, TR2, and OD may be considered to be the contact patch
parameters of the tyre 100. In said example, the parameters such as, IR1,
IR2, SW, SH, and RH, whose alteration may, directly or indirectly, affect a
shape of the tyre cavity may be considered to affect a profile of tyre cavity.
[00027] In an example of the present subject matter, the rolling
resistance of the tyre may be varied by altering contact patch parameters of the tyre along with alterations in a profile of the tyre cavity. In an example, to reduce the rolling resistance, the tyre 100 may be molded in a way, such that, a ratio of the TR1 to the OD may be set to at least about 1.50 and at most about 1.60. Further, a ratio of the TR2 to the TR1 may be set to be at least about 0.12 and at most about 0.18. Furthermore, a ratio of the IR1 to the OD may be set to be at least about 3.00 and at most about 3.20. Moreover, a ratio of the IR2 to the IR1 may be set to be at least about 9.10 and at most about 10.20.
[00028] In said example, during the molding of the tyre 100, a ratio of
the TW to the SW may be set to be at least about 0.74 and at most about
0.77. Further, a ratio of the L1 to the TW may be set to be about 0.53.
Moreover, a ratio of the SH to the RH may be set to be about 0.50.
[00029] Generally, to achieve uniformity in distribution of weight on the
surface of the contact patch, the contact patch parameters of the tyre are altered to attain a square shape for the contact patch of the tyre. In an example, the contact patch having a substantially square shape translates to a relatively uniform distribution of weight than a contact patch of any other shape, thereby exerting relatively lower pressure on the ground

while the tyre is in motion. An extent of uniformity in the distribution of
weight over the contact patch is indicated in terms of a contact patch
squareness index. Accordingly, a tyre having a higher contact patch
squareness index is considered to have relatively uniform distribution of
weight over the contact patch. In an example, the tyre 100 has a contact
patch squareness index of about 102.
[00030] Further, the tyre 100 may have a rolling resistance coefficient of
about 94, where the rolling resistance coefficient indicates an amount of
rolling resistance being applied on the tyre in motion. Accordingly, a higher
value of rolling resistance coefficient translates to a higher rolling
resistance.
[00031] Moreover, the tyre 100 may have a wear index of about 105,
where the wear index indicates an extent of wear that the tyre 100
undergoes in prolonged usage. In an example, a higher value of wear
index for the tyre translates to a higher mileage of the tyre 100.
[00032] Table 1 indicates an exemplary comparative analysis of the
various parameters described in the afore-mentioned paragraphs for a
conventional tyre and a tyre 100 molded in accordance with examples of
the present subject matter, is provided herein.

Parameters used in the present subject matter Conventional Tyre Tyre molded in accordance with an example of the present subject matter
TW/SW 0.74 - 0.77 0.74 - 0.77
TR1/OD 1.00 - 1.10 1.50 - 1.60
TR2/TR1 0.25-0.35 0.12 - 0.18
L1/TW 0.53 0.53
IR1/OD 1.00 - 1.10 3.00 - 3.20
IR2/IR1 1.30-1.50 9.10 - 10.20
RH/SH 0.50 0.50
Table 1

[00033] In said example, the alterations made to the various parameters
described above alters the various factors affecting the rolling resistance of the tyre 100. Accordingly, Table 2 an exemplary comparison of such factors for a conventional tyre and a tyre 100 molded in accordance with examples of the present subject matter, is provided herein.

Results
Tyre Details Conventional Tyre molded in
Tyre accordance with an
example of the present
subject matter
Contact Patch 100 106
Squareness index
Rolling resistance 100 94
coefficient
Wear Index 100 105
Table 2
[00034] In an example, an increase in the contact patch squareness
index of the tyre 100 may relatively exert a lower pressure on the ground while the tyre is in motion. Accordingly, the rolling resistance coefficient of the tyre may reduce along with an increase in the wear index, thereby reducing the wear and tear of the tyre in prolonged usage and increasing the fuel efficiency of the vehicle.
[00035] Although examples of the present subject matter have been
described in language specific to methods and/or structural features, it is to be understood that the present subject matter is not limited to the specific methods or features described. Rather, the methods and specific features are disclosed and explained as examples of the present subject matter.

I/We Claim:
1. A tyre comprising:
a tread pattern comprising a first tread block and a second tread block, the first tread block being arranged at a first distance from a circumferential center of the tyre and the second tread block being arranged at a second distance from the circumferential center of the tyre, wherein the first distance is smaller than the second distance;
a pair of beads to secure the tyre onto a rim of a wheel; and
a pair of sidewalls connecting the tread pattern and the pair of beads;
wherein,
an outer diameter (OD) of the tyre indicates a distance between two points arranged diagonally opposite on the circumferential center of the tyre;
a first tread radius (TR1) of the tyre indicates a distance between the center of the tyre and an outermost surface of the first tread block;
a first inner radius (IR1) of the tyre indicates a distance between the center of the tyre and an innermost surface of the first tread block;
a second tread radius (TR2) of the tyre indicates a distance between the center of the tyre and an outermost surface of the first tread block; and
a second inner radius (IR2) of the tyre indicates a distance between the center of the tyre and an innermost surface of the second tread block,
wherein
a ratio of the TR1 and the OD is at least about 1.50 and at
most about 1.60;
a ratio of the TR2 and the TR1 is at least about 0.12 and at
most about 0.18;
a ratio of the IR1 and the OD is at least about 3.00 and at
most about 3.20; and

a ratio of the IR2 and the IR1 is at least about 9.10 and at most about 10.20.
2. The tyre as claimed in claim 1, wherein a tread width (TW) of the
tyre indicates a width of the tread pattern and a section width (SW) of the
tyre indicates a maximum distance between each of the pair of sidewalls,
and wherein a ratio of the TW and the SW is at least about 0.74 and at
most about 0.77.
3. The tyre as claimed in claim 2, wherein a tread length (L1) of the
tyre indicates a distance between the circumferential center of the tyre and
the second tread block, and wherein a ratio of the L1 and the TW is about
0.53.
4. The tyre as claimed in claim 1, wherein a section height (SH) of the tyre indicates a distance between a bead from amongst the pair of beads and the outermost surface of the first tread block and a reference height (RH) of the tyre indicates a distance between the bead from amongst the pair of beads and a mid-point of a sidewall from amongst the pair of sidewalls, and wherein a ratio of the SH and the RH is about 0.50.
5. The tyre as claimed in claim 1, wherein a contact patch squareness index of the tyre is about 106.
6. The tyre as claimed in claim 1, wherein a rolling resistance coefficient of tyre is about 94.
7. The tyre as claimed in claim 1, wherein a wear index of the tyre is about 105.

8. The tyre as claimed in claim 1, wherein the tyre is a pneumatic tyre.