pneumatic tires
The tire design addresses air resistance and wet performance challenges by optimizing airflow and drainage through specific profile features, achieving both low fuel consumption and improved wet performance.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- SUMITOMO RUBBER INDUSTRIES LTD
- Filing Date
- 2024-12-26
- Publication Date
- 2026-07-08
AI Technical Summary
Existing pneumatic tires face challenges in achieving both low fuel consumption and wet performance, with improvements needed in air resistance and wet performance, respectively.
A pneumatic tire design with a specific profile defined by a contact surface, sidewall surface inclinations, and circumferential grooves that optimize airflow and drainage, including angles and distances to reduce air resistance and enhance wet performance.
The tire achieves both low fuel consumption and improved wet performance by smoothing airflow and enhancing drainage, resulting in reduced air resistance and increased handling stability.
Smart Images
Figure 2026114785000001_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to pneumatic tires.
Background Art
[0002] Conventionally, various pneumatic tires having specific profiles have been proposed. For example, Patent Document 1 below proposes a pneumatic tire capable of achieving both noise performance and low fuel consumption performance by including a profile in which the distance from the maximum width position of the tire to the outer end position has a single radius of curvature.
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] However, in addition to the rolling resistance that the pneumatic tire of Patent Document 1 has improved, the resistance related to low fuel consumption performance includes air resistance during driving. Further improvement has been expected for the air resistance during driving even in the pneumatic tire of Patent Document 1. In addition, there has also been a desire for improvement in wet performance, although the profile that improves rolling resistance tends to reduce wet performance.
[0005] The present invention has been devised in view of the above actual situation, and the main object thereof is to provide a pneumatic tire capable of achieving both low fuel consumption performance and wet performance.
Means for Solving the Problems
[0006] The present invention relates to a pneumatic tire having a profile defined on the outer surface of the tire meridian cross section in a normal state, which is an unloaded state in which the tire is mounted on a normal rim and adjusted to a normal internal pressure, wherein the profile includes a contact surface of a tread portion extending from a first contact end to a second contact end, and a first side outer surface of a sidewall portion extending radially inward from the first contact end, wherein the first side outer surface has a first position defined at a distance of 15% of the tire cross section height radially inward from the tire equator of the contact surface, and the tread portion includes a first shoulder circumferential groove extending furthest towards the first contact end in the tire circumferential direction between the tire equator and the first contact end, a first shoulder land portion separated by the first shoulder circumferential groove and the first contact end, and adjacent to the first shoulder land portion across the first shoulder circumferential groove The tire is a pneumatic tire having a first middle land portion, wherein the contact surface of the first shoulder land portion has a first imaginary line, which is a tangent to the midpoint of the tire axial direction of the first shoulder land portion, inclined inward in the tire radial direction toward the outward direction of the tire axial direction, and the first imaginary line has a first angle of 74 to 80° with respect to the tire radial direction, and the first side outer surface has a second imaginary line, which is a tangent to the first position, inclined in the same direction as the first imaginary line with respect to the tire radial direction, and the second imaginary line has a second angle of 36 to 40° with respect to the tire radial direction, and the first middle land portion includes a first middle outer end on the outside in the tire axial direction and a first middle inner end on the inside in the tire axial direction, and the first middle outer end is located radially inward from the imaginary contact surface connecting the contact surface of the first shoulder land portion and the first middle inner end. [Effects of the Invention]
[0007] The pneumatic tire of the present invention, by having the above-described configuration, can achieve both low fuel consumption and wet performance. [Brief explanation of the drawing]
[0008] [Figure 1] This is a cross-sectional view showing one embodiment of the profile of the pneumatic tire of the present invention. [Figure 2]This is an enlarged view of section A in Figure 1. [Figure 3] This is an enlarged cross-sectional view of the 1st Middle Track and Field Section. [Figure 4] This is a schematic diagram of a mold for forming pneumatic tires. [Modes for carrying out the invention]
[0009] Figure 1 is a meridian cross-sectional view of the pneumatic tire 1 of this embodiment, showing the profile 2 in its normal state. Here, "normal state" refers to the unloaded state in which the pneumatic tire 1 is mounted on a normal rim R and adjusted to the normal internal pressure. Unless otherwise specified, the dimensions of each part of the pneumatic tire 1 are values measured in this normal state.
[0010] "Regular Rim R" refers to the rim specified for each tire by a standard system that includes the standard on which the pneumatic tire 1 is based. For example, it is a "Standard Rim" for JATMA, a "Design Rim" for TRA, and a "Measuring Rim" for ETRTO. If there is no standard system that includes the standard on which the pneumatic tire 1 is based, "Regular Rim R" refers to the rim with the smallest rim diameter and the smallest rim width among rims that can be mounted on and do not cause air leaks.
[0011] "Regular internal pressure" refers to the air pressure specified for each tire by each standard, if there is a standard system on which the pneumatic tire 1 is based. For example, it is the "maximum air pressure" for JATMA, the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" for TRA, and the "INFLATION PRESSURE" for ETRTO. If there is no standard system on which the pneumatic tire 1 is based, "regular internal pressure" refers to the air pressure specified for each tire by the manufacturer, etc.
[0012] As shown in Figure 1, the pneumatic tire 1 is suitably used, for example, as a passenger car tire. The pneumatic tire 1 of this embodiment has a profile 2 defined by the outer surface in the tire meridian cross-section in a normal state. The profile 2 of this embodiment includes the contact surface 3a of the tread portion 3 extending from the first contact end Te1 to the second contact end Te2.
[0013] The contact surface 3a has, for example, a tire equator C which is the midpoint in the tire axial direction between the first contact end Te1 and the second contact end Te2, and a contact width TW which is the distance in the tire axial direction between the first contact end Te1 and the second contact end Te2. Here, "first contact end Te1" and "second contact end Te2" are the outermost contact points in the tire axial direction when a pneumatic tire 1 in a normal state is loaded with 70% of the normal load and makes contact with a plane at a camber angle of 0°.
[0014] "Regular load" refers to the load specified for each tire by each standard, if there is a standard system on which the pneumatic tire 1 is based. For example, it is the "maximum load capacity" for JATMA, the maximum value listed in the table "TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES" for TRA, and the "LOAD CAPACITY" for ETRTO. If there is no standard system on which the pneumatic tire 1 is based, "Regular load" refers to the maximum load applicable when using the pneumatic tire 1, as specified by the manufacturer for each tire.
[0015] The tread portion 3 of this embodiment has a plurality of circumferential grooves 4 extending in the circumferential direction of the tire, and a plurality of land portions 5 separated by the plurality of circumferential grooves 4. The plurality of circumferential grooves 4 may, for example, extend linearly in the circumferential direction of the tire, or they may extend in a zigzag pattern, or a mixture of linear and zigzag grooves may be present. Such a tread portion 3 helps to achieve both rigidity and drainage of the land portion 5.
[0016] The circumferential grooves 4 of this embodiment include a first shoulder circumferential groove 4A that extends furthest towards the first contact end Te1 between the tire equator C and the first contact end Te1, and a second shoulder circumferential groove 4B that extends furthest towards the second contact end Te2 between the tire equator C and the second contact end Te2. The circumferential grooves 4 also include, for example, a first crown circumferential groove 4C that extends furthest towards the tire circumferential groove 4A between the tire equator C and the first shoulder circumferential groove 4A, and a second crown circumferential groove 4D that extends furthest towards the tire circumferential groove 4B between the tire equator C and the second shoulder circumferential groove 4B. Such circumferential grooves 4 have excellent drainage properties and help improve the wet performance of the pneumatic tire 1. Note that the circumferential grooves 4 are not limited to four, but may be three, five or more, for example.
[0017] In this embodiment, the land portion 5 includes a first shoulder land portion 5A, which is divided by a first shoulder circumferential groove 4A and a first ground contact end Te1, and a second shoulder land portion 5B, which is divided by a second shoulder circumferential groove 4B and a second ground contact end Te2. Preferably, the land portion 5 includes a first middle land portion 5C, which is divided by a first shoulder circumferential groove 4A and a first crown circumferential groove 4C, and a second middle land portion 5D, which is divided by a second shoulder circumferential groove 4B and a second crown circumferential groove 4D. In this embodiment, the first middle land portion 5C is adjacent to the first shoulder land portion 5A, with the first shoulder circumferential groove 4A in between.
[0018] The land portion 5 includes, for example, a crown land portion 5E divided by a first crown circumferential groove 4C and a second crown circumferential groove 4D. Such a land portion 5 has excellent rigidity and helps to improve the handling stability of the pneumatic tire 1.
[0019] The contact surface 3a should preferably have a first virtual line L1, which is a tangent to the first shoulder land portion 5A at an intermediate position Pm in the tire axial direction, inclined outward in the tire axial direction and inward in the tire radial direction. Such a contact surface 3a helps to smooth the airflow from the tread portion 3 to the sidewall portion 6, which will be described later, during driving, thereby suppressing air separation.
[0020] Here, the intermediate position Pm of the first shoulder land part 5A is a position that is separated by a distance W1 / 2, which is half of the maximum width W1 in the tire axial direction, from the first grounding end Te1 inward in the tire axial direction.
[0021] FIG. 2 is an enlarged view of part A in FIG. 1. As shown in FIG. 2, the first virtual line L1 of the present embodiment is inclined at a first angle θ1 with respect to the tire radial direction. The first angle θ1 is preferably 74° or more. By having the first angle θ1 of 74° or more, excessive deformation during grounding can be suppressed, and the rolling resistance can be reduced. From such a perspective, the first angle θ1 is more preferably 76° or more, and still more preferably 77° or more.
[0022] The first angle θ1 is preferably 80° or less. By having the first angle θ1 of 80° or less, the flow of air during traveling from the tread part 3 to the sidewall part 6 described later becomes smooth, peeling of air is suppressed, and the air resistance during traveling can be reduced. From such a perspective, the first angle θ1 is more preferably 78° or less, and still more preferably 77° or less.
[0023] From these facts, the first angle θ1 is preferably 74 to 80°, more preferably 76 to 78°, and still more preferably 77°. Note that the combination of the upper limit value and the lower limit value of these numerical ranges can be arbitrarily selected.
[0024] As shown in FIG. 1, the profile 2 of the present embodiment includes a first side outer surface 6a of the sidewall part 6 that extends inward in the tire radial direction from the first grounding end Te1, and a second side outer surface 6b of the sidewall part 6 that extends inward in the tire radial direction from the second grounding end Te2.
[0025] In this embodiment, a first position P1 is defined on the first side outer surface 6a, located radially inward from the tire equator C of the contact surface 3a at a distance D1 of 15% of the tire cross-sectional height SH. It is desirable that the second virtual line L2, which is tangent to the first position P1, is inclined in the same direction as the first virtual line L1 with respect to the tire radial direction. Such a first side outer surface 6a helps to smooth the airflow from the tread portion 3 to the sidewall portion 6 during driving, thereby suppressing air separation.
[0026] As shown in Figure 2, the second dashed line L2 in this embodiment is inclined at a second angle θ2 with respect to the tire radial direction. The second angle θ2 is preferably 36° or more. When the second angle θ2 is 36° or more, the airflow from the tread portion 3 to the sidewall portion 6 during driving becomes smoother, suppressing air separation and reducing air resistance during driving. From this viewpoint, the second angle θ2 is more preferably 37° or more, and even more preferably 38° or more.
[0027] The second angle θ2 is preferably 40° or less. By having the second angle θ2 be 40° or less, air separation on the outer side of the sidewall portion 6 in the tire radial direction can be suppressed, thereby reducing air resistance during driving. From this viewpoint, the second angle θ2 is more preferably 39° or less, and even more preferably 38° or less.
[0028] Based on these considerations, the second angle θ2 is preferably 36 to 40°, more preferably 37 to 39°, and even more preferably 38°. The combination of the upper and lower limits within these numerical ranges can be arbitrarily selected.
[0029] Figure 3 is an enlarged cross-sectional view of the first middle land portion 5C. As shown in Figure 3, the first middle land portion 5C of this embodiment includes a first middle outer end 5o that is on the outside in the tire axial direction and a first middle inner end 5i that is on the inside in the tire axial direction. The first middle outer end 5o of this embodiment is located radially inward from the virtual contact surface L3 that connects the contact surface 3a of the first shoulder land portion 5A and the first middle inner end 5i.
[0030] This first middle section 5C reduces air resistance during driving by smoothly directing air that has been swept around by the vehicle's influence into the first shoulder circumferential groove 4A, and improves the drainage performance of the first shoulder circumferential groove 4A when driving on wet surfaces. Therefore, the pneumatic tire 1 having the profile 2 of this embodiment can achieve both low fuel consumption and wet performance.
[0031] In a more preferred embodiment, the contact surface 3a of the first middle land portion 5C includes an arc portion 5r that passes through the outer end 5o of the first middle portion and is in contact with the virtual contact surface L3. Such a first middle land portion 5C can make the flow of air that has been swept around by the vehicle's influence during driving smoother into the first shoulder circumferential groove 4A, thereby reducing air resistance during driving.
[0032] The arc portion 5r preferably has a single radius of curvature. Such a first middle land portion 5C can mitigate the impact when in contact with the road surface and improve the noise performance of the pneumatic tire 1.
[0033] In the tire meridian cross-section, the maximum protrusion amount ts of the arc portion 5r from the imaginary straight line L4 connecting both ends of the arc portion 5r is preferably 0.08 mm or more. A maximum protrusion amount ts of 0.08 mm or more for the arc portion 5r suppresses excessive deformation during contact with the ground and reduces rolling resistance. From this viewpoint, the maximum protrusion amount ts of the arc portion 5r is more preferably 0.10 mm or more.
[0034] The maximum protrusion amount ts of the arc portion 5r is preferably 0.18 mm or less. Having a maximum protrusion amount ts of 0.18 mm or less of the arc portion 5r allows for smoother airflow to the first shoulder circumferential groove 4A during travel. From this viewpoint, the maximum protrusion amount ts of the arc portion 5r is more preferably 0.15 mm or less.
[0035] Based on these considerations, the maximum protrusion amount ts of the arc portion 5r is preferably 0.08 to 0.18 mm, and more preferably 0.10 to 0.15 mm. The combination of the upper and lower limits within these numerical ranges can be arbitrarily selected.
[0036] The first shoulder circumferential groove 4A preferably has a virtual groove wall L5 that extends the groove wall 4i on the side of the first middle land portion 5C to the virtual contact surface L3, a groove wall 4o on the side of the first shoulder land portion 5A, and a groove bottom 4g on the inner side in the tire radial direction. In this embodiment, the first shoulder circumferential groove 4A has a virtual cross-sectional area S1 enclosed by the virtual groove wall L5, the groove wall 4o, the groove bottom 4g, and the virtual contact surface L3 in the tire meridian cross-section.
[0037] The first middle land portion 5C of this embodiment has a virtual area S2 enclosed by a virtual contact surface L3, an arc portion 5r, and a virtual groove wall L5 in the tire meridian cross-section. The virtual area S2 is preferably 0.5% or more of the virtual cross-sectional area S1. Having a virtual area S2 of 0.5% or more of the virtual cross-sectional area S1 allows for smooth airflow to the first shoulder circumferential groove 4A during driving. From this viewpoint, the virtual area S2 is more preferably 1.0% or more of the virtual cross-sectional area S1.
[0038] The virtual area S2 is preferably 5.0% or less of the virtual cross-sectional area S1. By having a virtual area S2 of 5.0% or less of the virtual cross-sectional area S1, excessive deformation upon contact with the ground can be suppressed and rolling resistance can be reduced. From this viewpoint, the virtual area S2 is more preferably 4.0% or less of the virtual cross-sectional area S1.
[0039] Based on these considerations, the virtual area S2 is preferably 0.5% to 5.0% of the virtual cross-sectional area S1, and more preferably 1.0% to 4.0%. The combination of the upper and lower limits within these numerical ranges can be arbitrarily selected.
[0040] As shown in Figure 1, the radial distance t between the first contact point Te1 and the tire equator C is preferably 2% or more of the contact width TW. When the distance t is 2% or more of the contact width TW, the airflow from the tread portion 3 to the sidewall portion 6 during driving becomes smoother, suppressing air separation and reducing air resistance during driving. From this viewpoint, the distance t between the first contact point Te1 and the tire equator C is more preferably 3% or more of the contact width TW.
[0041] The distance t between the first contact point Te1 and the tire equator C is preferably 6% or less of the contact width TW. Having a distance D2 of 6% or less of the contact width TW suppresses excessive deformation during contact and reduces rolling resistance. From this viewpoint, the distance t between the first contact point Te1 and the tire equator C is more preferably 5% or less of the contact width TW.
[0042] Based on these considerations, the distance t between the first contact end Te1 and the tire equator C is preferably 2% to 6% of the contact width TW, and more preferably 3% to 5%. The combination of the upper and lower limits within these numerical ranges can be arbitrarily selected.
[0043] As shown in Figures 1 and 3, it is desirable that the virtual cross-sectional area S1, virtual area S2, distance t, and contact width TW satisfy the following equation 1.
number
[0044] Such a tread section 3 maintains good rolling resistance while reducing air resistance and also has excellent drainage properties, thus enabling a high level of balance between the fuel efficiency and wet performance of the pneumatic tire 1.
[0045] The virtual contact surface L3 includes, for example, a first virtual point Pf which is the intersection with the virtual groove wall L5, and a first contact point Pc which is the point of contact with the arc portion 5r.
[0046] The distance Dv1 between the first virtual point Pf and the first contact point Pc in the tire axial direction is preferably 50% or more of the width W2 in the tire axial direction at the contact surface 3a of the first middle land area 5C. Having the distance Dv1 between the first virtual point Pf and the first contact point Pc be 50% or more of the width W2 of the first middle land area 5C allows for smoother airflow into the first shoulder circumferential groove 4A during driving. From this viewpoint, the distance Dv1 between the first virtual point Pf and the first contact point Pc is more preferably 55% or more of the width W2 of the first middle land area 5C.
[0047] The distance Dv1 between the first virtual point Pf and the first contact point Pc in the tire axial direction is preferably 80% or less of the width W2 in the tire axial direction at the contact surface 3a of the first middle land area 5C. By having the distance Dv1 between the first virtual point Pf and the first contact point Pc be 80% or less of the width W2 of the first middle land area 5C, excessive deformation during contact can be suppressed and rolling resistance can be reduced. From this viewpoint, the distance Dv1 between the first virtual point Pf and the first contact point Pc is more preferably 75% or less of the width W2 of the first middle land area 5C.
[0048] Based on these considerations, the tire axial distance Dv1 between the first virtual point Pf and the first contact point Pc is preferably 50% to 80% of the tire axial width W2 at the contact surface 3a of the first middle land portion 5C, and more preferably 55% to 75%. The combination of the upper and lower limits within these numerical ranges can be arbitrarily selected.
[0049] The radial distance Dv2 between the first virtual point Pf and the first middle outer end 5o is preferably 5% or more of the maximum depth Dm of the first shoulder circumferential groove 4A from the virtual contact surface L3 to the groove bottom 4g. Having the distance Dv2 between the first virtual point Pf and the first middle outer end 5o be 5% or more of the maximum depth Dm of the first shoulder circumferential groove 4A allows for smoother airflow into the first shoulder circumferential groove 4A during driving. From this perspective, the distance Dv2 between the first virtual point Pf and the first middle outer end 5o is more preferably 10% or more of the maximum depth Dm of the first shoulder circumferential groove 4A.
[0050] The radial distance Dv2 between the first virtual point Pf and the first middle outer end 5o is preferably 25% or less of the maximum depth Dm of the first shoulder circumferential groove 4A from the virtual contact surface L3 to the groove bottom 4g. By keeping the distance Dv2 between the first virtual point Pf and the first middle outer end 5o at 25% or less of the maximum depth Dm of the first shoulder circumferential groove 4A, excessive deformation during contact can be suppressed and rolling resistance can be reduced. From this viewpoint, the distance Dv2 between the first virtual point Pf and the first middle outer end 5o is more preferably 20% or less of the maximum depth Dm of the first shoulder circumferential groove 4A.
[0051] Based on these considerations, the tire radial distance Dv2 between the first virtual point Pf and the first middle outer end 5o is preferably 5% to 25% of the maximum depth Dm from the virtual contact surface L3 to the groove bottom 4g of the first shoulder circumferential groove 4A, and more preferably 10% to 20%. The combination of the upper and lower limits within these numerical ranges can be arbitrarily selected.
[0052] As shown in Figure 1, the maximum width W1 of the first shoulder land portion 5A in the tire axial direction is preferably 20% or more of the contact width TW. By having a maximum width W1 of the first shoulder land portion 5A of 20% or more of the contact width TW, air that has been swept around by the vehicle's influence during driving can be smoothly directed into the first shoulder circumferential groove 4A, thereby reducing air resistance during driving. Furthermore, by positioning the first shoulder circumferential groove 4A at a location with high ground pressure, it also helps to increase the driving speed at which hydroplaning occurs. From this viewpoint, the maximum width W1 of the first shoulder land portion 5A is more preferably 22% or more of the contact width TW.
[0053] The maximum width W1 of the first shoulder land portion 5A in the tire axial direction is preferably 30% or less of the contact width TW. By having the maximum width W1 of the first shoulder land portion 5A be 30% or less of the contact width TW, it is possible to suppress the rigidity of the first shoulder land portion 5A from becoming excessively high, thereby improving the handling stability performance of the pneumatic tire 1 and also helping to improve the drainage performance on the outer side in the tire axial direction. From this viewpoint, the maximum width W1 of the first shoulder land portion 5A is more preferably 28% or less of the contact width TW.
[0054] Based on these considerations, the maximum width W1 in the tire axial direction of the first shoulder land portion 5A is preferably 20% to 30% of the contact width TW, and more preferably 22% to 28%. The combination of the upper and lower limits within these numerical ranges can be arbitrarily selected.
[0055] The pneumatic tire 1 of this embodiment does not have a rim guard on the sidewall portion 6. Since such a pneumatic tire 1 does not have a rim guard, which has a significant impact on air resistance, it can reduce air resistance during driving.
[0056] A normal rim R has, for example, a first rim end R1 which is the end on the first grounding end Te1 side, a second rim end R2 which is the end on the second grounding end Te2 side, and a maximum width RW which is the distance in the rim width direction between the first rim end R1 and the second rim end R2.
[0057] The pneumatic tire 1 should preferably have a tire section width SW that is 6 mm or more larger than the maximum width RW in the rim width direction of the regular rim R. Such a pneumatic tire 1 can prevent the regular rim R from contacting curbs, etc., even without a rim guard, and can achieve both durability and fuel efficiency. Here, the tire section width SW is the maximum width in profile 2 and does not include localized protrusions or rim guards.
[0058] Profile 2 of this embodiment includes a first bead outer surface 7a of the bead portion 7 located on the inside of the first side outer surface 6a in the tire radial direction, and a second bead outer surface 7b of the bead portion 7 located on the inside of the second side outer surface 6b in the tire radial direction.
[0059] The radial distance d between the first rim edge R1 and the first bead outer surface 7a is preferably 3 mm or less. Such a first bead outer surface 7a suppresses the generation of turbulence between the first rim edge R1 and the first bead outer surface 7a, and by maintaining the kinetic energy of the air, it is possible to reduce air resistance during driving.
[0060] It is desirable that the first side outer surface 6a has a second position P2 located at a distance D2 of 25% of the tire cross-sectional height SH, inward from the tire equator C in the tire radial direction, and a third position P3 located at a distance D3 of 19 mm inward from the tire equator C in the tire radial direction. In this embodiment, the first side outer surface 6a has a fourth position P4 located inward in the tire radial direction from the virtual intersection Pv of the first virtual line L1 and the second virtual line L2.
[0061] As shown in Figure 2, it is desirable that the tire radial distance D4 between the first position P1 and the second position P2 is equal to the tire radial distance D4 between the first position P1 and the fourth position P4. In this case, the first position P1 is an intermediate position in the tire radial direction between the second position P2 and the fourth position P4. Such a first position P1 is suitable as a representative point of the outer region of the first side outer surface 6a in the tire radial direction.
[0062] Figure 4 is a schematic diagram of a mold M for forming a pneumatic tire 1. As shown in Figures 1 to 4, the mold M of this embodiment includes a tread mold M1 for forming the tread portion 3 and a side mold M2 for forming the sidewall portion 6. The pneumatic tire 1 has, for example, a mold divider line ML between the tread mold M1 and the side mold M2.
[0063] As shown in Figure 2, the mold splitting line ML preferably includes a stepped portion 8 having a height h of 0.4 mm or less. Such a stepped portion 8 can suppress the occurrence of cracks originating from the mold splitting line ML and improve the durability of the pneumatic tire 1.
[0064] Furthermore, by keeping the height h of the stepped portion 8 to 0.4 mm or less, the increase in air resistance during driving can be suppressed, improving the fuel efficiency of the pneumatic tire 1. Here, the height h of the stepped portion 8 is the maximum height of the step portion 8 protruding from the first side outer surfaces 6a on both sides in the tire radial direction in a direction perpendicular to the first side outer surfaces 6a.
[0065] The stepped portion 8 of the mold division line ML is preferably located between the second position P2 and the third position P3. By positioning the stepped portion 8 further outward in the tire radial direction than the second position P2, the decrease in airflow velocity near the maximum width position of the first side outer surface 6a can be suppressed, thereby reducing air resistance during driving.
[0066] By positioning the stepped portion 8 inward in the tire radial direction compared to the third position P3, the reduction in airflow velocity near the buttress on the outer side of the first side outer surface 6a in the tire radial direction can be suppressed, thereby reducing air resistance during driving.
[0067] As shown in Figure 1, the pneumatic tire 1 of this embodiment has a specified orientation for mounting on the vehicle in the tire axial direction. The first contact end Te1 of this embodiment is located on the outside of the vehicle when mounted on the vehicle. The second contact end Te2 is preferably located on the inside of the vehicle when mounted on the vehicle. Such a pneumatic tire 1 can define the profile 2 on the outside of the vehicle, which has a large impact on air resistance, as a shape that reduces air resistance, thereby improving fuel efficiency.
[0068] Profile 2 may be formed symmetrically in the tire axial direction, for example, with respect to the tire equator C. In this case, the contact surface 3a of the second shoulder land portion 5B, the contact surface 3a of the second middle land portion 5D, the second side outer surface 6b, and the second bead outer surface 7b are symmetrical to the contact surface 3a of the first shoulder land portion 5A, the contact surface 3a of the first middle land portion 5C, the first side outer surface 6a, and the first bead outer surface 7a, respectively. Such a pneumatic tire 1 can reduce air resistance when driving inside the vehicle, and can further improve fuel efficiency.
[0069] Although particularly preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the embodiments described above and can be implemented in various modified forms.
[0070] [Note] The present invention is as follows:
[0071] [Invention 1] It is a pneumatic tire, The tire has a profile defined by the outer surface in the meridional cross-section of a tire in a normal state, which is a tire mounted on a normal rim and adjusted to the normal internal pressure in an unloaded state. The profile includes a contact surface of the tread portion extending from a first contact end to a second contact end, and a first side outer surface of the sidewall portion extending inward in the tire radial direction from the first contact end. On the outer surface of the first side, a first position is defined at a distance of 15% of the tire cross-sectional height, located radially inward from the tire equator of the contact surface. The tread portion has a first shoulder circumferential groove that extends furthest towards the first contact end in the tire circumferential direction between the tire equator and the first contact end, a first shoulder land portion separated by the first shoulder circumferential groove and the first contact end, and a first middle land portion adjacent to the first shoulder land portion with the first shoulder circumferential groove in between. The aforementioned contact surface has a first imaginary line, which is a tangent at the midpoint of the tire axial direction of the first shoulder land portion, that is inclined outward in the tire axial direction and inward in the tire radial direction. The first dashed line has a first angle of 74-80° with respect to the tire radial direction, The first outer side surface is such that the second imaginary line, which is tangent at the first position, is inclined in the same direction as the first imaginary line with respect to the tire radial direction. The second dashed line has a second angle of 36-40° with respect to the tire radial direction. The first middle land portion includes a first middle outer end on the outer side in the tire axial direction and a first middle inner end on the inner side in the tire axial direction. The outer end of the first middle is located inward in the tire radial direction from the virtual contact surface connecting the contact surface of the first shoulder land portion and the inner end of the first middle, Pneumatic tires.
[0072] [Invention 2] The contact surface has a contact width TW which is the distance in the tire axial direction between the first contact end and the second contact end. The pneumatic tire according to the present invention 1, wherein the distance t in the tire radial direction between the first contact end and the tire equator is 2% to 6% of the contact width TW.
[0073] [Invention 3] The pneumatic tire according to the present invention, wherein the contact surface of the first middle land portion includes an arc portion that passes through the outer end of the first middle portion and is in contact with the virtual contact surface.
[0074] [4th Invention] The first shoulder circumferential groove has a virtual cross-sectional area S1 enclosed in the tire meridian cross-section by a virtual groove wall extending from the groove wall on the first middle land portion side to the virtual contact surface, the groove wall on the first shoulder land portion side, the groove bottom on the inner side in the tire radial direction, and the virtual contact surface. The first middle land portion has a virtual area S2 enclosed by the virtual contact surface, the circular arc portion, and the virtual groove wall in the tire meridian cross-section. The pneumatic tire according to the present invention, wherein the virtual cross-sectional area S1, the virtual area S2, the distance t, and the contact width TW satisfy the following formula 1.
number
[0075] [5th Invention] The virtual contact surface is defined as having a first virtual point which is the intersection with the virtual groove wall and a first contact point which is the contact point with the arc portion. The pneumatic tire according to the present invention, wherein the distance in the tire axial direction between the first virtual point and the first contact point is 50% to 80% of the width in the tire axial direction of the first middle land portion.
[0076] [Invention 6] The pneumatic tire according to the present invention, wherein the radial distance between the first virtual point and the first middle outer end of the tire is 5% to 25% of the maximum depth of the first shoulder circumferential groove from the virtual contact surface to the bottom of the groove.
[0077] [7th Invention] A pneumatic tire according to any one of invention 1 to 6, having a tire cross-sectional width that is 6 mm or more greater than the maximum width in the rim width direction of the standard rim.
[0078] [8th Invention] The profile includes the first bead outer surface of the bead portion located radially inward of the first side outer surface of the tire, The pneumatic tire according to any one of inventions 1 to 7, wherein the distance in the tire radial direction between the first rim end, which is the end of the regular rim on the first contact end side, and the outer surface of the first bead is 3 mm or less.
[0079] [Invention 9] The mold has a split line between the tread mold for forming the tread portion and the side mold for forming the sidewall portion. The aforementioned mold cut line includes a stepped portion having a height of 0.4 mm or less, as described in any one of invention 1 to 8.
[0080] [Invention 10] The orientation in which it is installed on the vehicle is specified. The first contact end is located on the outside of the vehicle when mounted on the vehicle, as described in any one of invention 1 to 9. [Explanation of Symbols]
[0081] 1. Pneumatic tire 3. Tread section 3a Ground plane 4A First shoulder circumferential groove 5A 1st Shoulder Track and Field Club 5C 1st Middle Track and Field Club 5i 1st Middle Inner End 5o First middle outer end 6a First side outer surface
Claims
1. It is a pneumatic tire, The tire has a profile defined by the outer surface in the meridional cross-section of a tire in a normal state, which is a tire mounted on a normal rim and adjusted to the normal internal pressure in an unloaded state. The profile includes a contact surface of the tread portion extending from a first contact end to a second contact end, and a first side outer surface of the sidewall portion extending inward in the tire radial direction from the first contact end. On the outer surface of the first side, a first position is defined at a distance of 15% of the tire cross-sectional height, located radially inward from the tire equator of the contact surface. The tread portion has a first shoulder circumferential groove that extends furthest towards the first contact end in the tire circumferential direction between the tire equator and the first contact end, a first shoulder land portion separated by the first shoulder circumferential groove and the first contact end, and a first middle land portion adjacent to the first shoulder land portion with the first shoulder circumferential groove in between. The aforementioned contact surface has a first imaginary line, which is a tangent at the midpoint of the tire axial direction of the first shoulder land portion, that is inclined outward in the tire axial direction and inward in the tire radial direction. The first dashed line has a first angle of 74 to 80° with respect to the tire radial direction, The first side outer surface is such that the second imaginary line, which is tangent at the first position, is inclined in the same direction as the first imaginary line with respect to the tire radial direction. The second dashed line has a second angle of 36 to 40° with respect to the tire radius direction. The first middle land portion includes a first middle outer end on the outer side in the tire axial direction and a first middle inner end on the inner side in the tire axial direction, The outer end of the first middle is located inward in the tire radial direction from the virtual contact surface connecting the contact surface of the first shoulder land portion and the inner end of the first middle, Pneumatic tires.
2. The contact surface has a contact width TW which is the distance in the tire axial direction between the first contact end and the second contact end. The pneumatic tire according to claim 1, wherein the distance t in the tire radial direction between the first contact end and the tire equator is 2% to 6% of the contact width TW.
3. The pneumatic tire according to claim 2, wherein the contact surface of the first middle land portion includes an arc portion that passes through the outer end of the first middle portion and is in contact with the virtual contact surface.
4. The first shoulder circumferential groove has a virtual cross-sectional area S1 enclosed in the tire meridional cross-section by a virtual groove wall extending from the groove wall on the first middle land portion side to the virtual contact surface, the groove wall on the first shoulder land portion side, the groove bottom on the inner side in the tire radial direction, and the virtual contact surface. The first middle land portion has a virtual area S2 enclosed by the virtual contact surface, the circular arc portion, and the virtual groove wall in the tire meridian cross-section. The pneumatic tire according to claim 3, wherein the virtual cross-sectional area S1, the virtual area S2, the distance t, and the contact width TW satisfy the following formula 1. [Math 1]
5. The virtual contact surface is defined as having a first virtual point which is the intersection with the virtual groove wall and a first contact point which is the contact point with the arc portion. The pneumatic tire according to claim 4, wherein the distance in the tire axial direction between the first virtual point and the first contact point is 50% to 80% of the width in the tire axial direction of the first middle land portion.
6. The pneumatic tire according to claim 5, wherein the radial distance between the first virtual point and the first middle outer end of the tire is 5% to 25% of the maximum depth of the first shoulder circumferential groove from the virtual contact surface to the bottom of the groove.
7. A pneumatic tire according to any one of claims 1 to 6, having a tire cross-sectional width that is 6 mm or more greater than the maximum width in the rim width direction of the standard rim.
8. The profile includes the first bead outer surface of the bead portion located on the inner side of the first side outer surface in the radial direction of the tire, The pneumatic tire according to any one of claims 1 to 6, wherein the distance in the tire radial direction between the first rim end, which is the end of the regular rim on the first contact end side, and the outer surface of the first bead is 3 mm or less.
9. The mold has a split line between the tread mold for forming the tread portion and the side mold for forming the sidewall portion. The pneumatic tire according to any one of claims 1 to 6, wherein the mold cut line includes a stepped portion having a height of 0.4 mm or less.
10. The orientation in which it is installed on the vehicle is specified. The first ground contact end is located on the outside of the vehicle when mounted on the vehicle, as described in any one of claims 1 to 6.