Mass asymmetric tires

Abstract

The present invention provides a tire comprising an apex surrounded by side portions terminating in a bead provided to cooperate with a mounting rim, and at least one carcass reinforcement surrounded by an apex reinforcement composed of a plurality of reinforcing plies, wherein when the tire is mounted on its standard mounting rim and inflated to its nominal pressure, each side portion has three points, namely an upper side point, a bottom side point, a middle side point, an upper side portion defined as the outer side of the radially outermost carcass reinforcement bounded by imaginary lines passing through the upper side point and the middle side point, and a bottom side portion defined as the outer side of the radially outermost carcass reinforcement bounded by imaginary lines passing through the bottom side point and the middle side point, and the weight of the bottom side portion for one side portion is at least 15% lighter than the weight of the bottom side portion for another side portion.

Description

[Technical field]

[0001] The present invention relates to tires, and in particular to tires having asymmetric mass from one side to another. [Background technology]

[0002] In recent years, the trend toward luxury vehicles and improvements in quality have led to demands for reducing various noises from the standpoint of passenger comfort and environmental considerations, particularly in the context of electrification of vehicles.

[0003] Noise from tires is known to include various components, namely, components from exterior noise and components from interior noise, which includes vibrations caused by excitation of the rolling tread portion, which are transmitted to the wheel rim, axle, suspension and body of the vehicle, and are then heard as noise inside the vehicle.

[0004] It is known that modifying the vibration characteristics of the tire is effective in improving such noise. Various solutions have been proposed to improve such noise.

[0005] JP 05-193310 A discloses a pneumatic tire having a damping coefficient ratio (Ho / Hi) where Ho is the damping coefficient of the outer sidewall (Go×tan delta o) calculated from the average thickness of the outer sidewall Go and the loss tangent tan delta o, and Hi is the damping coefficient of the inner sidewall (Gi×tan delta i) calculated from the average thickness of the inner sidewall Gi and the loss tangent tan delta i, which is set in the range of 1.2-6.5 to improve comfort performance without reducing handling performance.

[0006] Japanese Patent Laid-Open Publication No. 05-193311 discloses a pneumatic tire having an average thickness GU of each region of the sidewall extending from a position corresponding to the widest part of the tire toward the tread and a GL of the region of the sidewall extending from the same position toward the bead, which are set to be different from each other, and in order to reduce the tire mass without reducing the cut resistance of the sidewall, 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 mm. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 05-193310 [Patent Document 2] Japanese Patent Application Publication No. 05-193311 Summary of the Invention [Problem to be solved by the invention]

[0008] However, the solutions disclosed in these documents do not provide a satisfactory improvement in noise performance, and at the same time, the deterioration in handling performance is not at an acceptable level, i.e., there is a demand for further improvement in noise performance while maintaining a reasonable level for handling performance.

[0009] Thus, a need exists for a tire that offers improved noise performance while maintaining a reasonable level of handling performance.

[0010] definition

[0011] "Radial / orientation" is the direction / orientation perpendicular to the tire's axis of rotation. This direction / orientation corresponds to the thickness orientation of the tread.

[0012] "Axial / orientation" is the direction / orientation parallel to the axis of rotation of the tire.

[0013] "Circumferential direction" is the direction that is tangential to any circle about the axis of rotation. This direction is perpendicular to both the axial and radial directions.

[0014] "Tire" means any type of resilient tire, whether or not under internal pressure.

[0015] "Ply" or "reinforcing ply" means a layer of material consisting of a plurality of parallel-arranged single and / or strand wires of metal or textile wires, such as steel, polyester, or nylon, covered with a rubber composition. The direction of extension of such metal or textile wires may be different from the direction of tire rotation.

[0016] Thus, it is an object of the present invention to provide a tire which offers improvements to noise performance while maintaining a reasonable level of handling performance. [Means for solving the problem]

[0017] The invention provides a tire intended to be mounted on a mounting rim, the tire comprising an apex surrounded on both sides by lateral portions terminating in beads provided to cooperate with the mounting rim, the tire comprising at least one carcass reinforcement extending in the apex and lateral portions and secured at its two ends in the beads, the at least one carcass reinforcement bearing radially on the outside an apex reinforcement made up of a number of reinforcing plies, on which rests radially a tread intended to come into contact with the ground during rolling, the apex reinforcement bearing radially on the outside a tread intended to come into contact with the ground during rolling, each lateral portion being defined, when the tire is mounted on its standard mounting rim and inflated at its nominal pressure, as being defined as a top lateral point, defined as a point on the radially outermost carcass reinforcement at which an imaginary line perpendicular to the carcass reinforcement extending from a point on the tire's contour intersects an imaginary horizontal line extending from the axial tip of the widest reinforcing ply; and a middle side point defined as a point on the radially outermost carcass reinforcement where an imaginary line perpendicular to the carcass reinforcement extending from a point on the radially outermost carcass reinforcement intersects an imaginary horizontal line tangent to the radially outermost surface of the rim flange, and a middle side point defined as a point on the radially outermost carcass reinforcement whose length from the bottom side point along the carcass reinforcement is 60% of the length along the carcass reinforcement between the upper side point and the bottom side point, each side portion comprising an upper side portion defined as a portion of the outer side portion of the radially outermost carcass reinforcement bounded by an imaginary line passing through the upper side point and an imaginary line passing through the middle side point, and a bottom side portion defined as a portion of the outer side portion of the radially outermost carcass reinforcement bounded by an imaginary line passing through the bottom side point and an imaginary line passing through the middle side point, wherein the weight of the bottom side portion for one side portion is at least 15% lighter than the weight of the bottom side portion for another side portion.

[0018] This arrangement provides an improvement to noise performance while maintaining a reasonable level for handling performance.

[0019] Because the weight of the bottom side portion relative to one side portion is at least 15% less than the weight of the bottom side portion relative to the other side portion, the dynamic torsional stiffness of the tire 1, which is a component of the tire's dynamic stiffness that transmits vibrations from the ground, can be substantially reduced, thus improving noise performance.

[0020] If the weight difference between the two bottom side parts is less than 15%, there is a risk of insufficient improvement in noise performance due to insufficient reduction in dynamic torsional stiffness. By setting this weight difference between the two bottom side parts to at least 15%, it is possible to improve the noise performance.

[0021] Preferably, the weight of the bottom side portion relative to one side portion is at least 20% lighter than the weight of the bottom side portion relative to another side portion.

[0022] Since the bottom side portion is defined as a portion of the outer side portion of the radially outermost carcass reinforcement between a bottom side point, defined as a point on the radially outermost carcass reinforcement where an imaginary line perpendicular to the carcass reinforcement extending from a point on the tire's outline intersects with an imaginary horizontal line that touches the radially outermost part of the rim flange, and an intermediate side point, defined as a point on the radially outermost carcass reinforcement whose length from the bottom side point along the carcass reinforcement is 60% of the length along the carcass reinforcement between the upper side point and the bottom side point, it is believed that the side portion can maintain a sufficient material volume to provide a reasonable level of handling performance. Thus, it is possible to improve noise performance while maintaining a reasonable level of handling performance.

[0023] If the intermediate side point is located at a length from the bottom side point along the carcass reinforcement that is more than 60% of the length between the upper side point and the bottom side point along the carcass reinforcement, there is a risk that the side portion as a whole will not be able to maintain sufficient material volume to provide a reasonable level of handling performance. By setting this intermediate side point at a length from the bottom side point along the carcass reinforcement to be 60% of the length between the upper side point and the bottom side point along the carcass reinforcement, it is possible to improve noise performance while maintaining a reasonable level of handling performance.

[0024] In another preferred embodiment, the weight of the bottom side portion relative to one side portion is up to 50% less than the weight of the bottom side portion relative to another side portion.

[0025] If the weight of the bottom side portion for one side portion is more than 50% lighter than the weight of the bottom side portion for another side portion, there is a risk of poor handling performance or poor durability performance due to insufficient rubber volume of the bottom side portion. By setting this weight of the bottom side portion for one side portion to be at most 50% lighter than the weight of the bottom side portion for another side portion, it is possible to improve the noise performance while simultaneously maintaining a reasonable level of durability and handling performance.

[0026] The weight of the bottom side portion relative to one side portion is preferably at most 45% lighter than the weight of the bottom side portion relative to another side portion, and more preferably at most 40% lighter than the weight of the bottom side portion relative to another side portion.

[0027] In another preferred embodiment, the tire has an intended wearing side (inner-outer) and the lighter bottom side portion is positioned inboard of the intended wearing side.

[0028] This arrangement makes it possible to improve noise performance whilst maintaining a reasonable level of efficient handling performance since stiffness of the bottom side portion is more important on the outside than on the inside.

[0029] In another preferred embodiment, the weight of the upper side portion without the lighter bottom side portion is less than the weight of the upper side portion provided with the lighter bottom side portion.

[0030] This arrangement can further improve noise performance since the lighter upper side portions without the lighter bottom side portions contribute to reduced dynamic torsional stiffness.

[0031] In another preferred embodiment, the tire profile between the two side portions is asymmetric.

[0032] This arrangement makes it possible to manufacture such tires with lower raw material consumption, i.e. improving the cost-effectiveness of the tires.

[0033] In another preferred embodiment, the tire profile between the two side portions is symmetrical.

[0034] This arrangement allows for the manufacture of such tires using existing moulds having standard profiles for the sidewall portions, thus improving the cost-effectiveness of the tire.

[0035] Advantageous Effects of the Invention The above arrangement is capable of providing improvements to noise performance whilst maintaining a reasonable level of handling performance.

[0036] Other characteristics and advantages of the invention emerge from the following description, with reference to the attached drawings, which show, by way of non-limiting example, embodiments of the invention. [Brief description of the drawings]

[0037] [Figure 1] 1 is a schematic cross-sectional view of a tire according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is an enlarged schematic view showing a portion indicated as II in FIG. [Diagram 3]FIG. 2 is a schematic cross-sectional view of a tire according to a second embodiment of the present invention. [Figure 4] FIG. 4 is an enlarged schematic view showing a portion indicated as IV in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0038] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

[0039] A tire 1 according to a first embodiment of the present invention will be described with reference to Figures 1 and 2. Figure 1 is a schematic cross-sectional view of a tire according to a first embodiment of the present invention. Figure 2 is an enlarged schematic view showing a portion indicated by II in Figure 1.

[0040] The tire 1 is a tire having a dimension 235 / 45R18 intended to be mounted on a mounting rim W, having an apex 2 surrounded on both sides by lateral portions 3 terminating in beads 4 provided to cooperate with the mounting rim W. The tire 1 comprises at least one carcass reinforcement 5 extending in the apex 2 and in the lateral portions 3 and secured at both ends to the beads 4. The mounting rim W terminates on both axial sides in rim flanges RF. In this first embodiment, the tire 1 has one carcass reinforcement 5.

[0041] As shown in Figure 1, the at least one carcass reinforcement 5 is radially surmounted externally by an apex reinforcement 6 consisting of a number of reinforcing plies 61, on which is surmounted externally by a tread 7 intended to come into contact with the ground during rolling. In this first embodiment, the apex reinforcement 6 is composed of two reinforcing plies 61.

[0042] As shown in Figures 1 and 2, when the tire 1 is mounted on its standard mounting rim and inflated at its nominal pressure, each side portion 3 has three points, namely, an upper side point 33 defined as the point on the radially outermost carcass reinforcement 5 where an imaginary line VU1 perpendicular to the carcass reinforcement 5 extending from a point on the tire 1 contour intersects with an imaginary horizontal line VU2 extending from the axial tip of the widest reinforcing ply 61; a bottom side point 35 defined as the point on the radially outermost carcass reinforcement 5 where an imaginary line VB1 perpendicular to the carcass reinforcement 5 extending from a point on the tire 1 contour intersects with an imaginary horizontal line VB2 that contacts the radially outermost part of the rim flange RF; and a middle side point 34 defined as the point on the radially outermost carcass reinforcement 5 whose length from the bottom side point 35 along the carcass reinforcement 5 is 60% of the length along the carcass reinforcement 5 between the upper side point 33 and the bottom side point 35. According to the ETRTO Standards Manual 2020, the standard fitted rim size is 8.0 inches and the nominal pressure is 290kPa for extra load and 250kPa for non-extra load.

[0043] 1 and 2, each side portion 3 includes an upper side portion 31 defined as a portion of the outer side portion 3 of the radially outermost carcass reinforcement 5 bounded by an imaginary line passing through an upper side point 33 and an imaginary line passing through a middle side point 34, and a bottom side portion 32 defined as a portion of the outer side portion 3 of the radially outermost carcass reinforcement 5 bounded by an imaginary line passing through a bottom side point 35 and an imaginary line passing through the middle side point 34. The weight of the bottom side portion 32 for one side portion 3 is at least 15% less than the weight of the bottom side portion 32 for another side portion 3.

[0044] As shown in Figures 1 and 2, the profile of the tire 1 between the two side portions 3 is asymmetric so that the weight of the bottom side portion 32 for one side portion 3 is at least 15% lighter than the weight of the bottom side portion 32 for the other side portion 3. The profile of the side portion 3 with the lighter bottom side portion 32 is recessed from the profile of the side portion 3 without the lighter bottom side portion 32. The weight of the bottom side portion 32 for one side portion 3 is up to 50% lighter than the weight of the bottom side portion 32 for the other side portion 3. The weight of the upper side portion 31 without the lighter bottom side portion 32 is also lighter than the weight of the upper side portion 31 with the lighter bottom side portion 32.

[0045] 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 must be delimited by an imaginary line passing through the upper side point 33, an imaginary line passing through the midpoint 34 and the outermost carcass reinforcement 5, and the bottom side portion 32 must be delimited by an imaginary line passing through the bottom side point 35, an imaginary line passing through the midpoint 34 and the outermost carcass reinforcement 5. The imaginary lines passing through the upper side point 33, the midside point 34 and the bottom side point 35 should be equivalent for each side portion 3, e.g. the imaginary line VU1 as the imaginary line passing through the upper side point 33, the imaginary line VM perpendicular to the carcass reinforcement 5 as the imaginary line passing through the midside point 34 and the imaginary line VB1 as the imaginary line passing through the bottom side point 35.

[0046] The comparison of the weight of the bottom side portion 32 and / or the weight of the upper side portion 31 should be made by comparing the total 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 to be uniform in the circumferential direction, the comparison of their weights can be made by comparing the weights of portions extracted along an axial cross section.

[0047] 1 and 2, the tire 1 has an intended mounting side (inner-outer), in this case the outer side being the left side and the inner side being the right side, with the lighter bottom side portion 32 positioned inboard of the intended mounting side. The intended mounting side is often indicated on the face of the side portion (sidewall), for example through text such as "OUTSIDE", "INSIDE" or similar indicia (not shown).

[0048] Since the weight of the bottom side portion 32 for one side portion 3 is at least 15% less than the weight of the bottom side portion 32 for another side portion 3, the dynamic torsional stiffness of the tire 1, which is a component of the tire's dynamic stiffness that transmits vibrations from the ground, can be substantially reduced, thus improving noise performance.

[0049] If the weight difference between the two bottom side portions 32 is less than 15%, there is a risk that the improvement in noise performance is insufficient due to an insufficient reduction in dynamic torsional stiffness. By setting this weight difference between the two bottom side portions 32 to at least 15%, it is possible to improve the noise performance.

[0050] Preferably, the weight of the bottom side portion 32 for one side portion 3 is at least 20% less than the weight of the bottom side portion 32 for another side portion 3 .

[0051] The bottom side portion 32 is defined as a portion of the outer side portion 3 of the radially outermost carcass reinforcement 5 between a bottom side point 35 defined as a point on the radially outermost carcass reinforcement 5 where an imaginary line perpendicular to the carcass reinforcement 5 extending from a point on the contour of the tire 1 intersects with an imaginary horizontal line touching the radially outermost part of the rim flange RF, and an intermediate side point 34 defined as a point on the radially outermost carcass reinforcement 5 whose length from the bottom side point 35 along the carcass reinforcement 5 is 60% of the length along the carcass reinforcement 5 between the upper side point 33 and the bottom side point 35, so that the side portion 3 can maintain a sufficient material volume to provide a reasonable level of handling performance. It is therefore possible to improve noise performance while maintaining a reasonable level of handling performance.

[0052] If the intermediate side point 34 is located at a length from the bottom side point 35 along the carcass reinforcement 5 that exceeds 60% of the length between the upper side point 33 and the bottom side point 35 along the carcass reinforcement 5, there is a risk that the side portion 3 as a whole will not be able to maintain a sufficient material volume to provide a reasonable level of handling performance. By setting this intermediate side point 34 at a length from the bottom side point 35 along the carcass reinforcement 5 that is 60% of the length between the upper side point 33 and the bottom side point 35 along the carcass reinforcement 5, it is possible to improve noise performance while maintaining a reasonable level of handling performance.

[0053] The weight of the bottom side portion 32 for one side portion is up to 50% lighter than the weight of the bottom side portion 32 for another side portion, thereby improving noise performance while simultaneously maintaining reasonable levels of durability and handling performance.

[0054] If the weight of the bottom side portion 32 for one side portion is more than 50% lighter than the weight of the bottom side portion 32 for another side portion 3, there is a risk of reduced handling performance or reduced durability performance due to insufficient rubber volume in the bottom side portion 32.

[0055] The weight of the bottom side portion 32 for one side portion 3 is preferably at most 45% lighter, more preferably at most 40% lighter than the weight of the bottom side portion 32 for another side portion 3 .

[0056] Since 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 having the lighter bottom side portion 32, the upper side portion 31 without the lighter bottom side portion 32 contributes to a reduction in dynamic torsional rigidity, thereby further improving noise performance.

[0057] Because the tire 1 has an intended wearing side (inner-outer) and the lighter bottom side portion 32 is positioned on the inner side of the intended wearing side, it is possible to improve noise performance while effectively maintaining a reasonable level for handling performance since stiffness of the bottom side portion 32 is more important on the outer side than on the inner side.

[0058] Because the profile of the tire 1 between the two side portions 3 is asymmetric, it is possible to manufacture such a tire with lower raw material consumption and thus improve the cost-effectiveness of the tire 1.

[0059] When mounting the tire 1 on a mounting rim W, in order to effectively improve noise performance, it is preferable to use a mounting rim W having an inset in which the mounting disc portion of the mounting rim W is offset axially outward from the axial center of the mounting rim W, rather than a mounting rim W having a zero set (the mounting disc portion of the mounting rim W is on the same plane as the axial center of the mounting rim W) or an outset (the mounting disc portion of the mounting rim W is offset axially inward from the axial center of the mounting rim W).

[0060] When multiple carcass reinforcements 5 are provided, the upper side point 33, the middle side point 34 and the bottom side point 35 should be considered relative to the radially outermost carcass reinforcement 5, excluding the portion of the carcass reinforcement 5 after going around the bead 4.

[0061] Instead of reducing the weight on one side of the bottom side portion 32, a similar effect may be achieved by adding weight to one side of the bottom side portion 32, but reducing the weight on one side of the bottom side portion 32 is preferred due to energy and raw material consumption considerations.

[0062] In order to maintain reasonable durability performance, it may be preferable to keep a minimum thickness for the lightened bottom side portion 32 outside the carcass reinforcement 5 at least equal to 1.0 mm.

[0063] A tire 21 according to a second embodiment of the present invention will be described with reference to Figures 3 and 4. Figure 3 is a schematic cross-sectional view of a tire according to the second embodiment of the present invention. Figure 4 is an enlarged schematic view showing a portion indicated by IV in Figure 3. The configuration of this second embodiment is similar to that of the first embodiment except for the arrangement shown in Figures 3 and 4, and therefore will be described below with reference to Figures 3 and 4.

[0064] As shown in Figures 3 and 4, the tire 21 is intended to be mounted on a mounting rim W and includes an apex 22 surrounded on both sides by side portions 23 terminating in beads 24 provided to cooperate with the mounting rim W. The tire 21 includes at least one carcass reinforcement 25 extending through the apex 22 and the side portions 23 and secured at both ends to the beads 24. The mounting rim W terminates on both axial sides in rim flanges RF. In this second embodiment, the tire 21 has one carcass reinforcement 25.

[0065] As shown in Figure 3, the at least one carcass reinforcement 25 is radially borne on the outside by an apex reinforcement 26 consisting of a number of reinforcing plies 261, on which is borne on the outside by a tread 27 intended to come into contact with the ground during rolling. In this second embodiment, the apex reinforcement 26 is composed of two reinforcing plies 261.

[0066] As shown in FIGS. 3 and 4, when the tire 21 is mounted on its standard mounting rim and inflated at its nominal pressure, each side portion 23 is defined by three points: an upper side point 233 defined as a point on the radially outermost carcass reinforcement 25 where an imaginary line VU1 perpendicular to the carcass reinforcement 25 extending from a point on the tire 21 contour intersects an imaginary horizontal line VU2 extending from the axial tip of the widest reinforcing ply 261; a bottom side point 235 defined as the point on the radially outermost carcass reinforcement 25 where an imaginary line VB1 perpendicular to the carcass reinforcement 25 intersects with an imaginary horizontal line VB2 that touches the radially outermost part of the rim flange RF, and a middle side point 234 defined as the point on the radially outermost carcass reinforcement 25 whose length from the bottom side point 235 along the carcass reinforcement 25 is 60% of the length between the upper side point 233 and the bottom side point 235 along the carcass reinforcement 25. According to the ETRTO Standards Manual 2020, the standard mounted rim size is 8.0 inches and the nominal pressure is 290 kPa for extra load and 250 kPa for non-extra load.

[0067] As shown in Figures 3 and 4, each side portion 23 comprises an upper side portion 231 defined as a portion of the outer side portion 23 of the radially outermost carcass reinforcement 25 bounded by an imaginary line passing through an upper side point 233 and an imaginary line passing through a middle side point 234, and a bottom side portion 232 defined as a portion of the outer side portion 23 of the radially outermost carcass reinforcement 25 bounded by an imaginary line passing through a bottom side point 235 and an imaginary line passing through a middle side point 234. Due to the light bottom side portion 2321, the weight of the bottom side portion 232 for one side portion 23 is at least 15% less than the weight of the bottom side portion 232 for another side portion 23, and the profile of the tire 21 between the two side portions 23 is symmetrical.

[0068] Since the contour of the tire 21 between the two side portions 23 is symmetrical, it is possible to manufacture such a tire 21 using existing molds having a standard profile for the side portions 23, i.e., improving the cost-effectiveness of the tire 21.

[0069] The lightweight bottom side portion 2321 may be made of a material with a low specific gravity, a material having a low density, such as foam rubber, plastic, or resin, or a mixture thereof.

[0070] Instead of using a lightweight bottom side portion 2321, a similar effect may be achieved by adding weight to one side of the bottom side portion 232; however, due to energy and raw material consumption considerations, it is preferable to reduce the weight of one side of the bottom side portion 232 with a lightweight bottom side portion 2321.

[0071] The invention is not limited to the embodiments described and represented, but various modifications can be made thereto without departing from its framework. EXAMPLES

[0072] In order to confirm the effect of the present invention, two types of examples to which the present invention is applied and another type of reference example are prepared.

[0073] Example 1 is a tire as described in the first embodiment above, where one side of the bottom side portion is 25.4% lighter than the other side of the bottom side portion when considering the area bounded by the imaginary lines VM and VB1. Example 2 is a tire similar to Example 1, where one side of the bottom side portion is 32.3% lighter than the other side of the bottom side portion when considering the same area as Example 1. The Reference Example is a tire with equal weight for the two bottom side portions. For each Example and Reference Example, the weight of the upper side portion was equal between the two side portions when considering the area bounded by the imaginary lines VU1 and VM. The Examples and Reference Examples were all of the same tire size 235 / 45R18 and had the same internal structure as a standard pneumatic radial tire using the same materials.

[0074] Noise performance test:

[0075] Unused test tires were fitted to all four wheels of a 2500cc rear-wheel drive hybrid vehicle. The vehicle was coasted on a straight asphalt road facing into the wind at speeds of 105 km / h to 50 km / h with the engine off. Interior noise was measured using a microphone positioned at the occupant's ear closest to the window. Average A-weighted sound pressure levels from 50 to 500 Hz were calculated from speeds of 85 km / h to 75 km / h.

[0076] The results are shown in Table 1, where the results are expressed as difference in dB(A) relative to the reference, with smaller values ​​indicating better performance.

[0077] Handling performance test:

[0078] The cornering capabilities of unused test tyres mounted on standard rims and inflated to nominal internal pressure were measured using a flat belt tyre testing machine. The tyre was driven at a constant speed of 80 km / h while a load of 460 kg was applied and the lateral forces measured at slip angles of ±1° were measured and averaged at +1° and -1°.

[0079] The results are also shown in Table 1. In Table 1, the results are expressed as an index with the reference example set at 100, with a larger index indicating better performance.

[0080] [Table 1]

[0081] As can be seen from Table 1, the examples show improved noise performance while maintaining handling performance.

[0082] Reference List 1, 21 Tires 2, 22 Vertex 3, 23 Side part 31, 231 Upper side part 32, 232 Bottom side part 33, 233 Upper side point 34, 234 Mid-side point 35, 235 Bottom side point 2321 Lightweight bottom side part 4, 24 beads 5, 25 Carcass reinforcement 6, 26 Apex reinforcement 61, 261 Reinforcing ply 7, 27 Tread

Claims

1. A tire (1) intended to be mounted on a mounting rim (W), said tire (1) having an apex (2) surrounded on both sides by side portions (3) terminating in beads (4) provided to cooperate with the mounting rim (W), said tire (1) having at least one carcass reinforcement (5) extending through said apex (2) and said side portions (3) and secured at both ends in said beads (4), said at least one carcass reinforcement (5) bearing radially on the outside an apex reinforcement (6) made up of a number of reinforcing plies (61), said apex reinforcement (6) bearing radially on the outside 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 of said side portions (3) is in contact with three points, namely: an upper side point (33) defined as a point on the radially outermost carcass reinforcement (5) where an imaginary line perpendicular to the carcass reinforcement (5) extending from a point on the tire (1) contour intersects with an imaginary horizontal line extending from the axial tip of the widest reinforcing ply (61); a bottom side point (35) defined as the point on the radially outermost carcass reinforcement (5) where an imaginary line perpendicular to the carcass reinforcement (5) extending from a point on the tire (1) contour intersects with an imaginary horizontal line touching the radially outermost part of the rim flange (RF); a middle flank point defined as a point on the radially outermost carcass reinforcement (5) whose length from the bottom flank point (35) along the carcass reinforcement (5) is 60% of the length along the carcass reinforcement (5) between the upper flank point (33) and the bottom flank point (35); having The side portion (3) an upper side portion (31) defined as a portion of said side portion (3) outside said radially outermost carcass reinforcement (5) bounded by an imaginary line passing through said upper side point (33) and by an imaginary line passing through said intermediate side point (34); a bottom side portion (32) defined as a portion of the side portion (3) outside the radially outermost carcass reinforcement (5) bounded by an imaginary line passing through the bottom side point (35) and by an imaginary line passing through the intermediate side point (34); Equipped with the weight of said bottom side portion (32) relative to one side portion (3) is at least 15% less than the weight of said bottom side portion (32) relative to another side portion (3); The tire (1) has an intended wearing side (inner-outer), the lighter bottom side portion (32) is positioned inward of the intended wearing side; the weight of the upper side portion (31) without the lighter bottom side portion (32) is less than the weight of the upper side portion (31) provided with the lighter bottom side portion (32); the profile of the tire (1) between the two side sections (3) is symmetrical; A tire (1).

2. 2. Tyre (1) according to claim 1, characterized in that the weight of the bottom side portion (32) relative to one side portion (3) is at most 50% lighter than the weight of the bottom side portion (32) relative to another side portion (32).

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