Quality asymmetric tires

Abstract

The present invention provides a tire, which includes a tire top surrounded by side parts terminating in a bead configured to cooperate with a mounting rim, and includes at least one carcass reinforcement, wherein the at least one carcass reinforcement is covered from the top by a tire top reinforcement composed of multiple reinforcing cord layers, when the tire is mounted on its standard mounting rim and inflated with its nominal pressure, each side part has three points, namely an upper side point, a bottom side point, and an intermediate side point, and has an upper side part defined as being located on the outside of the radially outermost carcass reinforcement and bounded by a virtual line passing through the upper side point and a virtual line passing through the intermediate side point, and a bottom side part defined as being located on the outside of the radially outermost carcass reinforcement and bounded by a virtual line passing through the bottom side point and a virtual line passing through the intermediate side point, and the weight of the bottom side part on one side part is at least 15% lighter than the weight of the bottom side part on the other side part.

Description

Technical Field

[0001] The present invention relates to tires and, more particularly, to a tire having asymmetric mass from one side to the other. Background Art

[0002] In recent years, premiumization and quality improvement of vehicles have led to a desire for reduction of various noises from the perspective of passenger comfort and environmental considerations, particularly toward electrification of vehicles.

[0003] It is known that the noise from the tire includes various components, namely, a component from external noise and a component from internal noise. The internal noise includes vibrations due to the excitation of the tread portion during rolling, which are transmitted to the rim, axle, suspension and body of the vehicle and then heard as noise inside the vehicle.

[0004] In order to improve this noise, it is known that changes in tire vibration characteristics are effective. Various solutions have been proposed to improve this noise.

[0005] JPH05193310 discloses a pneumatic tire having a damping coefficient ratio (Ho / Hi), wherein Ho is the damping coefficient of the outer sidewall calculated from the average thickness Go of the outer sidewall and the loss tangent tanδo (Go×tanδo), and Hi is the damping coefficient of the inner sidewall calculated from the average thickness Gi of the inner sidewall and the loss tangent tanδi (Gi×tanδi), and the ratio is set within the range of 1.2-6.5 to improve comfort without deteriorating handling performance.

[0006] JP H05-193311 discloses a pneumatic tire having an average thickness GU of a region of each sidewall extending from a position corresponding to the widest part of the tire toward the tread and an average thickness GL of a region of the sidewall extending from the same position toward the bead. The above two average thicknesses are set to be different from each other. The average thickness GU of the tread side region is set to be not less than 2.5 mm, and the average thickness GL of the bead side region is set to be less than 2.5 mm and not less than 1.0 mm to reduce the tire mass without degrading the cut resistance of the sidewall. FR 2978083 discloses a tire having a maximum axial width SW and an axial width RW at the bead, including a crown reinforcement and a radial carcass reinforcement having a width TW. In this tire, when the tire is mounted on its mounting rim and inflated to its service (operating) pressure and equilibrium state, the following conditions are satisfied: Thy / SW = 75%, TW / RW = 85% and X / SH = 50%, where X is the radial height at the position where the tire has the maximum axial width and SH represents the radial height of the tire; Y / SH = 80%, where Y is the radial height of the carcass reinforcement at the end of the crown reinforcement; and Z / SH = 90%, where Z represents the radial height of the carcass reinforcement, and where the absolute value of the angle a between the tangent at the point of the carcass reinforcement having the same axial position as the axial end of the crown reinforcement and the axial direction is less than or equal to 22°. DE 102005044354 discloses a vehicle tire including a running strip, a carcass, (rigid) hardening elements, stabilizing elements and beads. The running strip and the carcass form a convex shoulder that extends into a concave sidewall section. The hardening elements and the stabilizing elements are embedded in the bead section. JP 2004-359042 discloses a pneumatic tire for an automobile, which is provided with an annular expansion section having an inner circumferential side surface facing the outer circumferential side curved surface of the rim flange on at least one sidewall section and is provided with at least one row of protrusions continuously provided in the circumferential direction on the inner circumferential side of the tire in the expansion section. The height R1 of the peak P1 of the expansion section with the nominal diameter NR as a reference value is 55 mm or higher, and the height H1 of the extension line of the peak P1 from the sidewall 2 is 3 mm or higher. The relationship between the height R2 at the position P2 with the nominal diameter NR as a reference value and the height HR of the upper end surface of the rim flange 21 satisfies 4 mm < R2 - HR < 10 mm. JP 2013-018345 discloses a tire-wheel assembly for an in-wheel motor, which includes a pneumatic tire and a wheel. The carcass is stretched over the bead cores at both ends through the tread portion, and both ends of the carcass are folded back at the bead cores so as to hold the bead cores and the bead fillers therebetween. The inner diameter of the bead section located at the inner side of the vehicle mounting is formed to be larger than the inner diameter of the bead section located at the outer side of the vehicle mounting to form a tire having different diameters.When the cross-sectional height of the tire installed on the inside of the vehicle is defined as Hin, the cross-sectional height of the tire installed on the outside of the vehicle is defined as Hout, the height of the bead filler installed on the inside of the vehicle is defined as Fin, the height of the bead filler installed on the outside of the vehicle is defined as Fout, and K is a coefficient, K.Hout / Hin=Fout / Fin is satisfied, where 1.0≤K≤4.0 (Expression 1). JPH04201604 discloses a tire with different sidewall heights on the inside and outside, in which a car travels with a thin tire when driving straight, and when turning, by squeezing the tire on the outside, the contact width between the road surface and the tire becomes wider, thereby increasing the grip. In addition, the inner diameter A of the wheel on which the tire is installed is made large, while the outer diameter B is made small. Therefore, it is possible to improve the grip without flattening the tire and wheel and improve the driving feel at a low fuel cost.

[0007] Citation List

[0008] Patent Literature

[0009] PTL1: JPH05193310

[0010] PTL2: JPH05193311

[0011] PTL3:FR2978083

[0012] PTL4:DE102005044354

[0013] PTL5:JP2004359042

[0014] PTL6:JP2013018345

[0015] PTL7: JPH04201604

[0016] However, with the solutions disclosed in these documents, the improvement in noise performance is not satisfactory. And at the same time, the degradation of handling performance is at an unacceptable level. Therefore, it is desirable to further improve the noise performance while maintaining a reasonable level of handling performance.

[0017] Therefore, there is a need for a tire that provides improved noise performance while maintaining a reasonable level of handling performance.

[0018] definition:

[0019] A “radial direction / orientation” is a direction / orientation perpendicular to the axis of rotation of the tire. This direction / orientation corresponds to the thickness orientation of the tread.

[0020] An "axial direction / orientation" is a direction / orientation parallel to the tire's axis of rotation.

[0021] A "circumferential direction / orientation" is a direction / orientation that is tangential to an arbitrary circle centered on the axis of rotation. This direction / orientation is perpendicular to both the axial direction / orientation and the radial direction / orientation.

[0022] “Tyre” means all types of resilient tyres, whether or not under internal pressure.

[0023] "Ply" or "reinforcement ply" means a layer of material consisting of a plurality of single and / or strands of metal or fiber filaments such as steel, polyester or nylon arranged in parallel and covered with a rubber composition. Such metal or fiber filaments may extend in a direction different from the direction of rotation of the tire.

[0024] It is therefore an object of the present invention to provide a tyre which offers an improvement in noise performance while maintaining a reasonable level of handling performance. Summary of the invention

[0025] The invention provides a tire intended to be mounted on a mounting rim, the tire comprising a bead surrounded on both sides by side portions terminating in beads, the beads being arranged to cooperate with the mounting rim, the tire comprising at least one carcass reinforcement extending in the bead and the side portions and anchored at both ends in the beads, the at least one carcass reinforcement being covered radially on the outside from the top by a bead reinforcement consisting of a plurality of reinforcing plies, the bead reinforcement being covered radially on the outside from the top by a tread intended to come into contact with the ground during rolling The tire is covered with a portion of the tire, and each side portion has three points when the tire is mounted on its standard mounting rim and inflated at its nominal pressure: an upper point, which is defined as a point on the radially outermost carcass reinforcement at which a virtual line perpendicular to the carcass reinforcement extends from a point on the contour line of the tire intersecting a virtual horizontal line extending from the axial end point of the widest reinforcing cord layer; a bottom point, which is defined as a point on the radially outermost carcass reinforcement at which a virtual line perpendicular to the carcass reinforcement extends from a point on the contour line of the tire intersecting a virtual horizontal line extending from the axial end point of the widest reinforcing cord layer. The tire is characterized in that the tire is provided with a plurality of side portions, each of which ...

[0026] This configuration (arrangement) provides improvements in noise performance while maintaining reasonable levels of handling performance.

[0027] Since the weight of the bottom side portion on one side portion is at least 15% lighter than the weight of the bottom side portion on the other side portion, the dynamic torsional rigidity (rigidity) of the tire, i.e., a component of the dynamic rigidity of the tire that transmits vibrations from the ground, can be effectively reduced. Therefore, the noise performance can be improved.

[0028] If the weight difference between the two bottom side portions is less than 15%, there is a risk that the improvement in noise performance will be insufficient due to insufficient reduction in dynamic torsional rigidity. By setting the weight difference between the two bottom side portions to at least 15%, the noise performance can be improved.

[0029] The weight of the bottom side portion on one side portion is preferably at least 20% lighter than the weight of the bottom side portion on the other side portion.

[0030] Due to the bottom side portion, which is defined as the portion of the side portion located outside the radially outermost carcass reinforcement between the bottom side point and the intermediate side point, the bottom side point being defined as a point on the radially outermost carcass reinforcement at which a virtual line perpendicular to the carcass reinforcement extends from a point on the contour line of the tire intersecting a radially outermost virtual horizontal line touching the rim flange, and the intermediate side point being defined as a point on the radially outermost carcass reinforcement at which the length along the carcass reinforcement from the bottom side point is 60% of the length along the carcass reinforcement between the upper side point and the bottom side point, the side portion can maintain a sufficient material volume in order to perform a reasonable level of handling performance. Therefore, noise performance can be improved while maintaining a reasonable level of handling performance.

[0031] If the intermediate side point is located at a position where the length along the carcass reinforcement from the bottom side point exceeds 60% of the length along the carcass reinforcement between the upper side point and the bottom side point, there is a risk that the side portion as a whole will not retain a sufficient material volume to perform a reasonable level of handling performance. By setting the intermediate side point at a position where the length along the carcass reinforcement from the bottom side point is 60% of the length along the carcass reinforcement between the upper side point and the bottom side point, noise performance can be improved while maintaining a reasonable level of handling performance.

[0032] Since the tire has a predetermined mounting side (inside-outside) and the lighter bottom side portion is located on the inside of the predetermined mounting side, the noise performance can be improved while efficiently maintaining a reasonable level of handling performance because the rigidity of the bottom side portion is more important on the outside than on the inside.

[0033] Since the upper side portion without the lighter bottom side portion is lighter than the upper side portion with the lighter bottom side portion, noise performance can be further improved because the lighter upper side portion without the lighter bottom side portion contributes to reduced dynamic torsional stiffness.

[0034] In another preferred embodiment, the weight of the bottom side portion on one side portion is at most 50% lighter than the weight of the bottom side portion on the other side portion.

[0035] If the weight of the bottom side portion on one side portion is 50% or more lighter (i.e., more than 50%) than the weight of the bottom side portion on the other side portion, there is a risk of deterioration in handling performance or deterioration in durability performance due to insufficient rubber volume at the bottom side portion. By setting the weight of the bottom side portion on one side portion to be at most 50% lighter than the weight of the bottom side portion on the other side portion, noise performance can be improved while maintaining reasonable levels of durability performance and handling performance.

[0036] The weight of the bottom side portion on one side portion is preferably at most 45% lighter than the weight of the bottom side portion on the other side portion, more preferably at most 40% lighter than the weight of the bottom side portion on the other side portion.

[0037] In another preferred embodiment, the profile of the tire is asymmetrical between the two side portions.

[0038] According to this configuration, such a tire can be manufactured with lower raw material consumption, thereby improving the cost effectiveness of the tire.

[0039] In another preferred embodiment, the profile of the tire is symmetrical between the two side portions.

[0040] According to this configuration, such a tire can be manufactured using an existing mold having a standard profile on a side portion, whereby the cost effectiveness of the tire can be improved.

[0041] Advantageous Effects of the Invention

[0042] According to the configuration described above, it is possible to provide an improvement in noise performance while maintaining a reasonable level of handling performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Other characteristics and advantages of the invention emerge from the following description made with reference to the accompanying drawings which show, by way of non-limiting example, embodiments of the invention.

[0044] In these drawings:

[0045] [ Figure 1 ] Figure 1 is a schematic cross-sectional view of a tire according to a first embodiment of the present invention;

[0046] [ Figure 2 ] Figure 2 yes Figure 1 An enlarged schematic diagram of the portion indicated as II in FIG.

[0047] [ Figure 3 ] Figure 3is a schematic cross-sectional view of a tire according to a second embodiment of the present invention;

[0048] [ Figure 4 ] Figure 4 yes Figure 3 An enlarged schematic diagram of the portion indicated as IV in FIG. DETAILED DESCRIPTION

[0049] Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

[0050] Reference Figure 1 and Figure 2 A tire 1 according to a first embodiment of the present invention is described. Figure 1 is a schematic cross-sectional view of a tire according to a first embodiment of the present invention. Figure 2 yes Figure 1 An enlarged schematic diagram of the portion indicated as II in FIG.

[0051] The tire 1 is a tire of size 235 / 45R18, which is intended to be mounted on a mounting rim W and comprises a summit 2 surrounded on both sides by side portions 3, which terminate in beads 4 arranged to cooperate with the mounting rim W. The tire 1 comprises at least one carcass reinforcement 5 extending in the summit 2 and the side portions 3 and anchored at its two ends in the beads 4. The mounting rim W is terminated on both axial sides by rim flanges RF. In this first embodiment, the tire 1 has one carcass reinforcement 5.

[0052] like Figure 1 As shown, said at least one carcass reinforcement 5 is topped radially on the outside by a top reinforcement 6 composed of a plurality of reinforcing plies 61 and the top reinforcement 6 is topped radially on the outside by a tread 7 intended to come into contact with the ground during rolling. In this first embodiment, the top reinforcement 6 consists of two reinforcing plies 61.

[0053] like Figure 1 and Figure 2As shown, when the tire 1 is mounted on its standard mounting rim and inflated with its nominal pressure, each side portion 3 has three points; namely, an upper point 33, which is defined as a point on the radially outermost carcass reinforcement 5, at which point a virtual line VU1 perpendicular to the carcass reinforcement 5 extends from a point on the contour line of the tire 1 where it intersects with a virtual horizontal line VU2 extending from the axial end point of the widest reinforcing cord layer 61; a bottom point 35, which is defined as a point on the radially outermost carcass reinforcement 5, at which point a virtual line VB1 perpendicular to the carcass reinforcement 5 extends from a point on the contour line of the tire 1 where it intersects with a radially outermost virtual horizontal line VB2 touching the rim flange RF; an intermediate point 34, which is defined as a point on the radially outermost carcass reinforcement 5, at which point the length along the carcass reinforcement 5 from the bottom point 35 is 60% of the length along the carcass reinforcement 5 between the upper point 33 and the bottom point 35. According to the ETRTO Standards Manual 2020, the standard mounting rim size is 8.0 inches and the nominal pressure is 290 kPa in the case of extra load and 250 kPa in the case of no extra load.

[0054] like Figure 1 and Figure 2 As shown, each side portion 3 comprises an upper side portion 31, which is defined as the portion of the side portion 3 located outside the radially outermost carcass reinforcement 5 bounded by an imaginary line passing through an upper side point 33 and an imaginary line passing through an intermediate side point 34, and a bottom side portion 32, which is defined as the portion of the side portion 3 located outside the radially outermost carcass reinforcement 5 bounded by an imaginary line passing through a bottom side point 35 and an imaginary line passing through an intermediate side point 34. The weight of the bottom side portion 32 on one side portion 3 is at least 15% lighter than the weight of the bottom side portion 32 on the other side portion 3.

[0055] like Figure 1 and Figure 2 As shown, the profile of the tire 1 is asymmetric between the two side portions 3 so that the weight of the bottom side portion 32 on one side portion 3 is at least 15% lighter than the weight of the bottom side portion 32 on the other side portion 3. The profile of the side portion 3 provided with the lighter (lighter) bottom side portion 32 is concave (recessed) from (relative to) the profile of the side portion 3 not provided with the lighter bottom side portion 32. The weight of the bottom side portion 32 on one side portion 3 is at most 50% lighter than the weight of the bottom side portion 32 on the other side portion 3. In addition, the weight of the upper side portion 31 without the lighter bottom side portion 32 is lighter than the weight of the upper side portion 32 provided with the lighter bottom side portion 32.

[0056] When comparing the weight of the bottom side portion 32 and / or the weight of the upper side portion 31, the upper side portion 31 should be defined by a virtual line passing through the upper point 33, a virtual line passing through the middle point 34, and the outermost carcass reinforcement 5, and the bottom side portion 32 should be defined by a virtual line passing through the bottom point 35, a virtual line passing through the middle point 34, and the outermost carcass reinforcement 5. The virtual lines passing through the upper point 33, the middle point 34, and the bottom point 35 should be identical from one side portion 3 to the other, respectively, such as a virtual line VU1 as a virtual line passing through the upper point 33, a virtual line VM perpendicular to the carcass reinforcement 5 as a virtual line passing through the middle point 34, and a virtual line VB1 as a virtual line passing through the bottom point 35.

[0057] The comparison of the weight of the bottom side portion 32 and / or the weight of the upper side portion 31 should be performed by comparing the overall weight of the bottom side portion 32 and / or the upper side portion 31. If the weight of the bottom side portion 32 and / or the weight of the upper side portion 31 can be considered uniform in the circumferential orientation, the comparison of these weights can be performed by comparing the weight of a portion extracted along the axial cross section.

[0058] like Figure 1 and Figure 2 As shown, the tire 1 has a predetermined mounting side (inside-outside), where in the case of the present example, the outside is the left side and the inside is the right side in the drawing, and the lighter bottom side portion 32 is located on the inside of the predetermined mounting side. The predetermined mounting side is usually the following case (example), which is indicated on the surface of the side portion (sidewall) by characters such as "OUTSIDE", "INSIDE" or similar indicators (not shown).

[0059] Since the weight of the bottom side portion 32 on one side portion 3 is at least 15% lighter than the weight of the bottom side portion 32 on the other side portion 3, the dynamic torsional rigidity of the tire 1, i.e., a component of the dynamic rigidity of the tire that transmits vibrations from the ground, can be effectively reduced. Therefore, the noise performance can be improved.

[0060] If the weight difference between the two bottom side portions 32 is less than 15%, there is a risk that the noise performance will be insufficiently improved due to insufficient reduction in dynamic torsional rigidity. By setting the weight difference between the two bottom side portions 32 to at least 15%, the noise performance can be improved.

[0061] The weight of the bottom side portion 32 on one side portion 3 is preferably at least 20% lighter than the weight of the bottom side portion 32 on the other side portion 3 .

[0062] Due to the bottom side portion 32, which is defined as the portion of the side portion 3 located outside the radially outermost carcass reinforcement 5 between the bottom side point 35 and the intermediate side point 34, the bottom side point 5 being defined as a point on the radially outermost carcass reinforcement 5 at which a virtual line perpendicular to the carcass reinforcement 5 extends from a point on the contour line of the tire 1 intersecting a radially outermost virtual horizontal line touching the rim flange RF, and the intermediate side point 34 being defined as a point on the radially outermost carcass reinforcement 5 at which the length along the carcass reinforcement 5 from the bottom side point 35 is 60% of the length along the carcass reinforcement 5 between the upper side point 33 and the bottom side point 35, the side portion 3 can maintain a sufficient material volume in order to perform a reasonable level of handling performance. Therefore, the noise performance can be improved while maintaining a reasonable level of handling performance.

[0063] If the intermediate side point 34 is located at a position where the length along the carcass reinforcement 5 from the bottom side point 35 exceeds 60% of the length along the carcass reinforcement 5 between the upper side point 33 and the bottom side point 35, there is a risk that the side portion 3 as a whole cannot maintain a sufficient material volume to perform a reasonable level of handling performance. By setting this intermediate side point 34 to be located at a position where the length along the carcass reinforcement 5 from the bottom side point 35 is 60% of the length along the carcass reinforcement 5 between the upper side point 33 and the bottom side point 35, the noise performance can be improved while maintaining a reasonable level of handling performance.

[0064] Since the weight of the bottom side portion 32 on one side portion is at most 50% lighter than the weight of the bottom side portion 32 on the other side portion, the noise performance can be improved while maintaining a reasonable level of durability and handling performance.

[0065] If the weight of the bottom side portion 32 on one side portion is 50% or more lighter than the bottom side portion 32 on the other side portion, there is a risk of deteriorating handling performance or durability due to insufficient rubber volume at the bottom side portion 32.

[0066] The weight of the bottom side portion 32 on one side portion 3 is preferably at most 45% lighter than the weight of the bottom side portion 32 on the other side portion 3 , more preferably at most 40% lighter than the weight of the bottom side portion 32 on the other side portion 3 .

[0067] Since the weight of the upper side portion 31 without the lighter bottom side portion 32 is lighter than that of the upper side portion 31 with the lighter bottom side portion 32, the noise performance can be further improved because the lighter upper side portion 31 without the lighter bottom side portion 32 contributes to the reduction of dynamic torsional rigidity.

[0068] Since the tire 1 has a predetermined mounting side (inside-outside) and the lighter bottom side portion 32 is located on the inside of the predetermined mounting side, the noise performance can be improved while efficiently maintaining a reasonable level of handling performance because the rigidity of the bottom side portion 32 is more important on the outside than on the inside.

[0069] Since the contour line of the tire 1 is asymmetrical between the two side parts 3 , such a tire can be produced with a lower consumption of raw materials, whereby the cost-effectiveness of the tire 1 can be increased.

[0070] When the tire 1 is mounted on the mounting rim W, it is preferred to use a mounting rim with an inner adjustment, in which the attachment plate portion of the mounting rim W is axially offset outward from the axial center of the mounting rim W, rather than using a mounting rim with a zero adjustment (the attachment plate portion of the mounting rim W is located on the same plane as the axial center of the mounting rim W) or an outer adjustment (the attachment plate portion of the mounting rim W is axially offset inward from the axial center of the mounting rim W) to obtain effective noise performance improvement.

[0071] In case a plurality of carcass reinforcements 5 are provided, the upper point 33 , the intermediate point 34 and the lower point 35 are considered to be located on the radially outermost carcass reinforcement 5 excluding the portion of the carcass reinforcement 5 turned around the bead 4 .

[0072] A similar effect can be obtained by increasing the weight of one side of the bottom side portion 32 (i.e., the bottom side portion 32 on one side) rather than reducing the weight of one side of the bottom side portion 32, but considering energy and raw material consumption, it is preferred to reduce the weight of one side of the bottom side portion 32.

[0073] In order to maintain reasonable durability performance, it may be preferred to maintain a minimum thickness at least equal to 1.0 mm for the lightened bottom side portion 32 outside the carcass reinforcement 5 .

[0074] Reference Figure 3 and Figure 4 A tire 21 according to a second embodiment of the present invention is described. Figure 3 is a schematic cross-sectional view of a tire according to a second embodiment of the present invention. Figure 4 yes Figure 3 An enlarged schematic diagram of the portion indicated as IV in FIG. Figure 3 and Figure 4 The structure of the second embodiment is similar to that of the first embodiment except for the configuration shown. Figure 3 and Figure 4 Give a description.

[0075] like Figure 3 and Figure 4As shown, the tire 21 is intended to be mounted on a mounting rim W and comprises a tread 22 surrounded on both sides by side portions 23, said side portions 23 terminating in beads 24, said beads 24 being arranged to cooperate with the mounting rim W. The tire 21 comprises at least one carcass reinforcement 25 extending in the tread 22 and the side portions 23 and anchored at its two ends in the beads 24. The mounting rim W is terminated on both axial sides by rim flanges RF. In this second embodiment, the tire 21 has one carcass reinforcement 25.

[0076] like Figure 3 As shown, said at least one carcass reinforcement 25 is topped radially on the outside by a top reinforcement 26 composed of a plurality of reinforcing plies 261 and said top reinforcement 26 is topped radially on the outside by a tread 27 intended to come into contact with the ground during rolling. In this second embodiment, the top reinforcement 26 is composed of two reinforcing plies 261.

[0077] like Figure 3 and Figure 4 As shown, when the tire 21 is mounted on its standard mounting rim and inflated at its nominal pressure, each side portion 23 has three points; namely, an upper point 233, which is defined as a point on the radially outermost carcass reinforcement 25, at which a virtual line VU1 perpendicular to the carcass reinforcement 25 extends from a point on the contour line of the tire 21 where it intersects a virtual horizontal line VU2 extending from the axial end point of the widest reinforcing cord layer 261; a bottom point 235, which is defined as a point on the radially outermost carcass reinforcement A point on the tire 25, at which point a virtual line VB1 perpendicular to the carcass reinforcement 25 extends from a point on the contour line of the tire 21 intersecting a virtual horizontal line VB2 that touches the radially outermost portion of the rim flange RF; an intermediate side point 234, which is defined as a point on the radially outermost carcass reinforcement 25, at which point the length along the carcass reinforcement 25 from the bottom side point 235 is 60% of the length along the carcass reinforcement 25 between the upper side point 233 and the bottom side point 235. According to the ETRTO Standard Manual 2020, the standard mounted rim size is 8.0 inches, and the nominal pressure is 290 kPa in the case of additional load and 250 kPa in the case of no additional load.

[0078] like Figure 3 and Figure 4As shown, each side portion 23 includes an upper side portion 231, which is defined as a portion of the side portion 23 located outside the radially outermost carcass reinforcement 25 and bounded by a virtual line passing through the upper side point 233 and a virtual line passing through the middle side point 234, and a bottom side portion 232, which is defined as a portion of the side portion 23 located outside the radially outermost carcass reinforcement 25 and bounded by a virtual line passing through the bottom side point 235 and a virtual line passing through the middle side point 234. By means of the lightweight (lightweight) bottom side portion 2321, the weight of the bottom side portion 232 on one side portion 23 is at least 15% lighter than the weight of the bottom side portion 232 on the other side portion 23, and the profile of the tire 21 is symmetrical between the two side portions 23.

[0079] Since the contour line of the tire 21 is symmetrical between the two side portions 23 , the tire 21 can be manufactured using an existing mold having a standard contour on the side portions 23 , thereby improving the cost-effectiveness of the tire 21 .

[0080] The lightweight bottom side portion 2321 may be made of foam rubber, a material having a low specific gravity such as plastic or resin, a material having a low density, or a mixture of these materials.

[0081] A similar effect can be achieved by at least partially replacing the use of the lightweight bottom side portion 2321 by adding weight to one side of the bottom side portion 232 (i.e., the bottom side portion 232 on one side), but considering energy and raw material consumption, it is preferred to reduce the weight of one side of the bottom side portion 232 with the aid of the lightweight bottom side portion 2321.

[0082] The invention is not limited to the examples described and presented and various modifications can be made without departing from its framework.

[0083] Example

[0084] In order to confirm the effects of the present invention, two types of examples to which the present invention was applied and other types of reference examples were prepared.

[0085] Example 1 is a tire as described in the first embodiment described above, considering the area defined by the virtual line VM and the virtual line VB1, and the tire is configured so that one side of the bottom side portion (i.e., the bottom side portion of one side) is 25.4% lighter than the other side of the bottom side portion (i.e., the bottom side portion of the other side). Example 2 is a tire similar to Example 1, considering an area equivalent to the area of ​​Example 1, and it is configured so that one side of the bottom side portion is 32.3% lighter than the other side of the bottom side portion. The reference example is a tire with equal weights set on both bottom side portions. Considering the area defined by the virtual line VU1 and the virtual line VM, the weight of the upper side portion of each of the examples and the reference example is equal between the two side portions. All examples and reference examples use the same tire size 235 / 45R18 and have the same internal structure using the same materials as a standard radial pneumatic tire.

[0086] Noise performance test:

[0087] Unused test tires were mounted on all four wheels of a 2,500cc rear-wheel drive hybrid vehicle. The vehicle was decelerated (coasted) from 105 kph to 50 kph with the engine off on a straight weatherproof asphalt road (straight weatherproof asphalt). The interior noise was measured using a microphone positioned at the passenger's ear near the window. The average A-weighted sound pressure level between 50 and 500 Hz was calculated from 85 kph to 75 kph.

[0088] The results are shown in Table 1. In this Table 1, the results are presented by the difference in dB(A) relative to the reference example, with lower values ​​indicating better performance.

[0089] Maneuverability test:

[0090] The cornering power of an unused test tire mounted on a standard rim and inflated to the nominal internal pressure is measured using a flat belt tire tester. When the tire is driven at a constant speed of 80 kph, a load of 460 kg is applied, the lateral force at a slip angle of ±1° is measured, and the lateral forces measured at +1° and -1° are averaged.

[0091] The results are also shown in Table 1. In this Table 1, the results are presented with an index of 100 for the reference example, and a higher number indicates better performance.

[0092] [Table 1]

[0093] Example 1 Example 2 Reference example Noise performance (dB(A)) -0.9 -1.5 - Maneuverability index 100 100 100

[0094] As can be seen from Table 1, the examples show improved noise performance while maintaining handling performance.

[0095] Reference numerals list

[0096] 1.21 Tire

[0097] 2, 22 Tire top

[0098] 3.23 Side part

[0099] 31, 231 upper side part

[0100] 32, 232 bottom side part

[0101] 33, 233 upper point

[0102] 34, 234 middle side point

[0103] 35, 235 bottom side point

[0104] 2321 Lightweight bottom and side parts

[0105] 4, 24 bead

[0106] 5.25 Carcass reinforcement

[0107] 6.26 Tire top reinforcement

[0108] 61, 261 Reinforced cord layer

[0109] 7, 27 tread

Claims

1. A tyre (1) intended to be mounted on a mounting rim (W), the tyre (1) comprising a tread (2) surrounded on both sides by side portions (3) terminating in beads (4), the beads (4) being arranged to cooperate with the mounting rim (W), the tyre (1) comprising at least one carcass reinforcement (5) extending in the tread (2) and in the side portions (3) and anchored at both ends in the beads (4), the at least one carcass reinforcement (5) being covered radially on the outside from the top by a tread reinforcement (6) consisting of a plurality of reinforcing plies (61), the tread reinforcement (6) being covered radially on the outside from the top by a tread (7) intended to come into contact with the ground during rolling, When the tire (1) is mounted on its standard mounting rim and inflated to its nominal pressure, each side portion (3) has three points: an upper point (33) defined as a point on the radially outermost carcass reinforcement (5) at which an imaginary line perpendicular to said carcass reinforcement (5) extends from the point on the contour of said tire (1) where it intersects an imaginary horizontal line extending from the axial end point of the widest reinforcing ply (61); a bottom point (35) defined as a point on the radially outermost carcass reinforcement (5) at which an imaginary line perpendicular to said carcass reinforcement (5) extends from the point on the contour of said tyre (1) intersecting a radially outermost imaginary horizontal line touching the rim flange (RF); an intermediate side point (34) defined as a point on the radially outermost carcass reinforcement (5) at which the length along the carcass reinforcement (5) from the bottom side point (35) is 60% of the length along the carcass reinforcement (5) between the upper side point (33) and the bottom side point (35), Each side portion (3) comprises: an upper lateral portion (31) defined as the portion of the lateral portion (3) situated outside the radially outermost carcass reinforcement (5) delimited by an imaginary line passing through the upper lateral point (33) and an imaginary line passing through the intermediate lateral point (34); a bottom side portion (32) defined as the portion of the side portion (3) situated outside the radially outermost carcass reinforcement (5) delimited by an imaginary line passing through the bottom side point (35) and an imaginary line passing through the intermediate side point (34), The weight of the bottom side portion (32) on one side portion (3) is at least 15% lighter than the weight of the bottom side portion (32) on the other side portion (3), The tire is characterized in that the tire (1) has a predetermined installation side, and wherein the lighter bottom side portion (32) is located inside the predetermined installation side, and wherein the weight of the upper side portion (31) without the lighter bottom side portion (32) is lighter than the weight of the upper side portion (31) provided with the lighter bottom side portion (32).

2. The tire (1) according to claim 1, wherein: The weight of the bottom side portion (32) on one side portion (3) is at most 50% lighter than the weight of the bottom side portion (32) on the other side portion (3).

3. The tire (1) according to claim 1 or claim 2, wherein: The profile of the tire (1) is asymmetrical between the two side portions (3).

4. The tire (1) according to claim 1 or claim 2, wherein: The profile of the tire (1) is symmetrical between the two side portions (3).

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