Pneumatic tire

Abstract

A pneumatic tire is provided that exhibits significantly reduced rolling resistance and excellent durability at high speeds. Each pair of sides of the pneumatic tire has a sidewall and an overlap. When the loss tangent of the sidewall is tanδsw and the loss tangent of the overlap is tanδc, (tanδsw+tanδc)≦0.3 and |tanδsw-tanδc|≦0.07, tanδsw and tanδc are measured under conditions of 70℃, 10Hz frequency, 5% initial strain, and 1% dynamic strain rate. The tire cross-section width is Wt (mm), the outer diameter is Dt (mm), and the volume of space occupied by the tire is a virtual volume V (mm²) when the pneumatic tire is mounted on a standard rim and the internal pressure is set to 250 kPa. 3 When ), equations (1) and (2) are satisfied: 1700≦(Dt) 2 ×π / 4) / Wt≦2827.4····(Equation 1); [(V+1.5×10 7 ) / Wt]≦2.88×10 5 ...(Equation 2).

Description

Technical Field

[0001] This invention relates to pneumatic tires. Background Technology

[0002] In recent years, due to increasing concerns about environmental issues and from the perspective of economic efficiency, the demand for fuel efficiency of motor vehicles has been increasing, and there is also a strong demand for improving the fuel efficiency of pneumatic tires (hereinafter referred to as "tires") installed in motor vehicles.

[0003] Tire fuel efficiency can be evaluated by rolling resistance, and it is known that the lower the rolling resistance, the better the tire's fuel efficiency.

[0004] Therefore, it has been proposed in the past to reduce rolling resistance by designing the formulation of the rubber composition constituting the tire tread (for example, Patent Documents 1-4).

[0005] [Existing Technical Documents]

[0006] [Patent Literature]

[0007] [Patent Document 1] JP2018-178034A

[0008] [Patent Document 2] JP2019-089911A

[0009] [Patent Document 3] WO2018 / 186367A

[0010] [Patent Document 4] JP2019-206643A Summary of the Invention

[0011] [Problem Solved by the Invention]

[0012] However, while tires manufactured using the aforementioned conventional technologies can reduce rolling resistance during normal low-speed driving, this is insufficient to reduce rolling resistance at high speeds, and further reductions are not expected. Furthermore, these tires cannot be considered to possess adequate durability.

[0013] Therefore, the object of the present invention is to provide a pneumatic tire that has sufficiently reduced rolling resistance at high speeds and excellent durability.

[0014] [Problem-solving methods]

[0015] After conducting in-depth research on the solutions to the above problems, the inventors discovered that the above problems can be solved by the invention described below, thereby completing the present invention.

[0016] The present invention is:

[0017] A pneumatic tire, each of its two sides having a sidewall and an overlap, wherein the pneumatic tire satisfies the following equations: (tanδsw + tanδc) ≦ 0.3 and |tanδsw - tanδc| ≦ 0.07.

[0018] In the formula, tanδsw is the loss tangent of the sidewall, and tanδc is the loss tangent of the overlap. Both tanδsw and tanδc are measured under the conditions of 70℃, 10Hz frequency, 5% initial strain, and 1% dynamic strain rate; and

[0019] When a tire is mounted on a standard rim and has an internal pressure of 250 kPa, the tire's cross-sectional width is Wt (mm), its outer diameter is Dt (mm), and the volume of space occupied by the tire is a virtual volume V (mm²). 3 When the tire satisfies the following equations (1) and (2):

[0020] 1700≦(Dt 2 (×π / 4) / Wt≦2827.4····(Equation 1);

[0021] [(V+1.5×10 7 ) / Wt]≦2.88×10 5 ...(Equation 2).

[0022] [The effects of the invention]

[0023] According to the present invention, a pneumatic tire with sufficiently reduced rolling resistance at high speeds and excellent durability can be provided. Attached Figure Description

[0024] Figure 1 This is a partial cross-sectional view of a pneumatic tire according to an embodiment of the present invention. Detailed Implementation

[0025] [1] Features of the tire of the present invention

[0026] 1. Overview

[0027] Figure 1 This is a partial cross-sectional view of the tire according to the present invention. Figure 1 In this diagram, 1 is the tire, 2 is the sidewall, 3 is the overlap, 4 is the bead core, 5 is the carcass ply, 6 is the bead triangle, and 7 is the inner liner. For example... Figure 1 As shown, the tire according to the invention has a sidewall 2 and an overlap portion 3 on each pair of sides, the overlap portion 3 being disposed in the area where the bead portion contacts the rim flange. It has the following characteristics.

[0028] First, the tire according to the present invention is characterized in that: when tanδsw is the loss tangent of the sidewall and tanδc is the loss tangent of the overlap, (tanδsw+tanδc)≦0.3 and |tanδsw-tanδc|≦0.07, and both tanδsw and tanδc are measured under the conditions of 70°C, 10Hz frequency, 5% initial strain and 1% dynamic strain rate.

[0029] Furthermore, the tire according to the present invention is characterized in that: when the tire is mounted on a standard rim and the internal pressure is 250 kPa, the tire cross-sectional width is Wt (mm), the outer diameter is Dt (mm), and the volume of space occupied by the tire is a virtual volume V (mm²). 3 When the tire satisfies the following equations (1) and (2):

[0030] 1700≦(Dt 2 (×π / 4) / Wt≦2827.4····(Equation 1);

[0031] [(V+1.5×10 7 ) / Wt]≦2.88×10 5 ...(Equation 2).

[0032] By incorporating the above features, a tire with significantly reduced rolling resistance at high speeds and excellent durability can be provided.

[0033] In the above description, "standard rim" refers to the rim defined for each tire within the specification system on which the tire is based. For example, in the case of JATMA (Japan Automobile Tire Association), it is the standard rim of the applicable size described in the "JATMA YEAR BOOK"; in the case of ETRTO (European Tire and Rim Technical Organization), it is the "Measuring Rim" described in the "Standards Manual"; and in the case of TRA (The Tire and Rim Association, Inc.), it is the "Design Rim" described in the "YEARBOOK". Where the tire is not specified in the specification, it refers to a rim that can be assembled and maintain internal pressure; that is, a rim that does not leak air between the rim and the tire, has the smallest rim diameter, and then the narrowest rim width.

[0034] Furthermore, the tire outer diameter Dt is the outer diameter of the tire when it is mounted on a standard rim, with an internal pressure of 250 kPa, and under no-load conditions. The tire section width Wt (mm) is the tire section width when it is mounted on a standard rim, with an internal pressure of 250 kPa, and under no-load conditions, and is calculated by excluding the distance of patterns, text, etc., on the tire sidewall from the straight-line distance between the sides, including all patterns, text, etc. on the tire sidewall (the total width of the tire).

[0035] In addition, the virtual volume V (mm) of the tire 3 Specifically, the tire's outer diameter Dt (mm), section height (distance from the bottom of the bead to the outermost surface of the tread; half the difference between the tire's outer diameter and the rim's nominal diameter) Ht (mm), and section width Wt (mm) can be calculated using the following formula, based on the tire's condition of being mounted on a standard rim with an internal pressure of 250 kPa and no load applied:

[0036] V = [(Dt / 2)] 2 -{(Dt / 2)-Ht} 2 ]×π×Wt.

[0037] 2. The mechanism of effect presentation in tires according to the present invention

[0038] The mechanism by which the tires of the present invention exhibit their effect, namely, the mechanism by which they effectively suppress rolling resistance at high speeds and achieve excellent durability, is hypothesized as follows.

[0039] (1) Tire shape

[0040] As described above, in this invention, the tire's cross-sectional width Wt (mm) and outer diameter Dt (mm) are set to satisfy 1700 ≤ Dt ≤ 1700. 2 ×π / 4) / Wt≦2827.4(Equation 1).

[0041] Increase the area of ​​the tire when viewed laterally by relative to the tire's cross-sectional width Wt ([(Dt / 2)]). 2 ×π)=(Dt 2×π / 4)]), and satisfying the numerical range specified in (Equation 1), it is considered that the deformation repetition per unit time is reduced, resulting in an increase in the time for heat exchange, thereby improving the heat dissipation of the side, and since the friction between the tread and the road surface can be reduced, low rolling resistance can be achieved. In (Equation 1), it is further preferred to be 1718 or more, further preferred to be 1733 or more, further preferred to be 1737 or more, further preferred to be 1740 or more, further preferred to be 1753 or more, further preferred to be 1758 or more, further preferred to be 1760 or more, further preferred to be 1763 or more, further preferred to be 1801 or more, further preferred to be 1811 or more, further preferred to be 1816 or more, further preferred to be 1818 or more, further preferred to be 1860 or more, further preferred to be 1865 or more, further preferred to be 1963.4 or more, further preferred to be 2004 or more, further preferred to be 2018 or more, further preferred to be 2027 or more, further preferred to be 2030 or more, further preferred to be 2033 or more, further preferred to be 2113 or more.

[0042] However, when viewed laterally, this type of tire has a large surface area; that is, the larger the outer diameter Dt, the greater the centrifugal force at high speeds. Therefore, there is a risk that the tire radius will increase and the sidewalls will be stretched and thinned when rolling. Then, if an impact is applied to the thinned sidewalls, the tire may be damaged. In addition, as the outer diameter increases due to centrifugal force, the amount of sidewall deformation also increases, thus there is a risk that rolling resistance at high speeds may not be sufficiently reduced.

[0043] Therefore, in this invention, the virtual volume V (mm) of the tire 3 The cross-sectional width Wt (mm) should, as far as possible, satisfy [(V+1.5×10 7 ) / Wt]≦2.88×10 5 (Equation 2).

[0044] Using this method, it can be argued that by reducing the tire's virtual volume V according to the reduction of the tire's cross-sectional width Wt, and by reducing the tire's actual volume, the increase in outer diameter caused by the increase in centrifugal force can be suppressed, and the sidewall damage resistance can be improved when subjected to side impacts. Furthermore, it is believed that the amount of sidewall deformation can be suppressed.

[0045] [(V+1.5×10 7 The value of ) / Wt] is further preferably 2.85×10 5 The following is a further preferred value: 2.84 × 10⁻⁶ 5 The following is a further preferred value: 2.78 × 10⁻⁶ 5 The following is a further preferred value: 2.60 × 10 5The following is a further preferred value: 2.56 × 10⁻⁶ 5 The following is a further preferred value: 2.54 × 10⁻⁶ 5 The following is a further preferred value: 2.50 × 10 5 The following is a further preferred value: 2.48 × 10⁻⁶ 5 The following is a further preferred value: 2.42 × 10⁻⁶ 5 The following is a further preferred value: 2.26 × 10⁻⁶ 5 The following is a further preferred value: 2.24 × 10⁻⁶ 5 The following is a further preferred value: 2.21 × 10⁻⁶ 5 The following is a further preferred value of 2.19 × 10⁻⁶. 5 The following is a further preferred value: 2.18 × 10⁻⁶ 5 The following is a further preferred value: 2.16 × 10⁻⁶ 5 the following.

[0046] At this point, [(V+2.0×10] is more preferable. 7 ) / Wt]≦2.88(Equation 3), further optimized [(V+2.5×10 7 ) / Wt]≦2.88×10 5 (Equation 4)

[0047] The above [(V+2.0×10 7 The value of ) / Wt] is further preferably 2.83×10 5 The following is a further preferred value: 2.81 × 10⁻⁶ 5 The following is a further preferred value: 2.79 × 10⁻⁶ 5 The following is a further preferred value: 2.77 × 10⁻⁶ 5 The following is a further preferred value: 2.76 × 10⁻⁶ 5 The following is a further preferred value: 2.64 × 10⁻⁶ 5 The following is a further preferred value: 2.47 × 10⁻⁶ 5 The following is a further preferred value: 2.46 × 10⁻⁶ 5 The following is a further preferred value: 2.45 × 10⁻⁶ 5 The following is a further preferred value: 2.44 × 10⁻⁶ 5 The following is a further preferred value: 2.43 × 10⁻⁶ 5 the following.

[0048] In addition, [(V+2.5×10 7 The value of ) / Wt] is further preferably 2.85×10 5 The following is a further preferred value: 2.76 × 10⁻⁶ 5 The following is a further preferred value: 2.75 × 10⁻⁶ 5 The following is a further preferred value: 2.72 × 10⁻⁶ 5The following is a further preferred value: 2.71 × 10⁻⁶ 5 The following is a further preferred value: 2.70 × 10⁻⁶ 5 The following is a further preferred value: 2.69 × 10⁻⁶ 5 The following is a further preferred value: 2.68 × 10⁻⁶ 5 the following.

[0049] (2) Physical properties of rubber on sidewalls and overlaps

[0050] In this invention, sidewalls and overlaps are formed such that they satisfy (tanδsw+tanδc)≦0.3 and |tanδsw-tanδc|≦0.07, where tanδsw is the loss tangent of the sidewall and tanδc is the loss tangent of the overlap. Both tanδsw and tanδc are measured under the conditions of 70°C, 10Hz frequency, 5% initial strain, and 1% dynamic strain rate.

[0051] By setting (tanδsw + tanδc) ≤ 0.3 in this way, it is believed that the heat generated throughout the entire side portion can be reduced, and the elongation caused by air expansion can be suppressed. Furthermore, by setting |tanδsw - tanδc| ≤ 0.07, it is believed that only the temperature of one of the sidewalls and the overlap increases, thereby suppressing uneven elongation of the side portion. It should be noted that (tanδsw + tanδc) is more preferably 0.27 or less, more preferably 0.23 or less, more preferably less than 0.17, more preferably 0.16 or less, and more preferably 0.14 or less. Moreover, |tanδsw - tanδc| is more preferably 0.07 or less, more preferably 0.03 or less, more preferably 0.02 or less, and more preferably 0.00.

[0052] These effects are believed to further improve durability and low rolling resistance, while simultaneously achieving low rolling performance and excellent durability at high speeds.

[0053] For example, the aforementioned tanδ values ​​can be measured using a viscoelasticity measuring device (such as the "Eplexor" manufactured by GABO Corporation, a registered trademark) and rubber cut from the sidewall and overlap of a tire.

[0054] [2] A more preferred embodiment of the tire according to the present invention

[0055] The tire according to the present invention can achieve better results by taking the following embodiments.

[0056] 1. The relationship between E*sw (MPa) and E*c (MPa)

[0057] In the tire according to the present invention, it is preferable that (E*cE*sw) ≤ 8.0, where the complex elastic modulus of the sidewall is E*sw (MPa) and the complex elastic modulus of the overlap portion is E*c (MPa), and both E*sw and E*c are measured under conditions of 70°C, 10Hz frequency, 5% initial strain, and 1% dynamic strain rate. Furthermore, (E*cE*sw) is more preferably 5.5 or less, more preferably 5.3 or less, more preferably 5.0 or less, and more preferably 2.8 or less.

[0058] In this way, by not increasing the rigidity difference between the sidewall and the overlap beyond what is necessary, uneven deformation of the side can be suppressed, and low rolling performance and durability at high speeds can be further improved.

[0059] Following the same method as the determination of tanδ described above, each E* can be determined using a viscoelasticity measuring device (e.g., "Eplexor (registered trademark)" manufactured by GABO).

[0060] 2. Aspect ratio

[0061] The tire according to the invention is preferably a tire with an aspect ratio of 40% or more, thereby suppressing the thinning of the sidewalls due to elongation by increasing the sidewall height and sidewall area. As a result, the reduction in tread and sidewall rigidity is suppressed, and uneven deformation of the tire can be suppressed. Consequently, the total heat generation of the tire can be significantly reduced, rolling resistance at high speeds can be further reduced, and tire durability can be further improved.

[0062] Using the section height Ht (mm) and section width Wt (mm) of a tire with an internal pressure of 250 kPa, the above aspect ratio (%) can be obtained by the following formula.

[0063] (Ht / Wt)×100(%)

[0064] The flatness ratio is more preferably 45% or more, further preferably 47.5% or more, further preferably 48% or more, further preferably 49% or more, further preferably 50% or more, further preferably 52.5% or more, further preferably 53% or more, further preferably 55% or more, further preferably 58% or more, and further preferably 59% or more. There is no particular upper limit, but for example, it is 100% or less.

[0065] 3. Butadiene rubber content

[0066] If the area of ​​the side portion is increased, the heat generated by the side portion may become greater than the heat released. Therefore, in this invention, it is considered that the sidewalls and overlapping portions constituting the side portion preferably contain butadiene rubber, which has excellent low heat generation properties, as the rubber component, and its content has been studied.

[0067] As a result, it was found that when 10≦|Bsw-Bc|≦40 (Equation 5) is satisfied (where the content in the sidewall is Bsw (parts by mass) and the content in the overlap is Bc (parts by mass)), the uneven deformation of the side can be fully suppressed by suppressing the heat generated in the side, and the low rolling performance and durability at high speed can be further improved.

[0068] 4. The relationship between tanδsw, tanδc, V, and Wt

[0069] As mentioned above, increasing the area of ​​the side portion may result in more heat being generated than heat being released from it. To prevent this, the tanδ of the side portion needs to be reduced as the area increases to control the heat generation.

[0070] Therefore, after studying the relationship between V / Wt (as an indicator related to the area of ​​the annular (doughnut-shaped) side) and tanδ of the entire side (as an indicator related to heat generation) (i.e., (tanδsw + tanδc)), it was found that if (tanδsw + tanδc) × V / Wt ≤ 50000 (Equation 6), heat generation can be appropriately controlled, rolling resistance at high speeds can be further reduced, and tire durability can be further improved. (tanδsw + tanδc) × V / Wt is more preferably 48789 or less, and even more preferably 47637 or less.

[0071] Then, more preferably (tanδsw+tanδc)×V / Wt≤45000 (Equation 7), even more preferably 44488 or less, even more preferably 43294 or less, even more preferably 38705 or less, even more preferably 36362 or less, even more preferably 35863 or less, even more preferably 33450 or less, even more preferably 30500 or less, even more preferably 27053 or less, even more preferably 25335 or less, even more preferably 25085 or less, even more preferably 23329 or less, even more preferably 22975 or less, even more preferably 20914 or less.

[0072] 5. Tire shape

[0073] In the tire according to the present invention, when the tire is mounted on a standard rim and the internal pressure is 250 kPa, the specific outer diameter Dt (mm) is preferably, for example, 515 mm or more, more preferably 558 mm or more, even more preferably 585 mm or more, even more preferably 649 mm or more, even more preferably 658 mm or more, even more preferably 663 mm or more, even more preferably 664 mm or more, even more preferably 665 mm or more, even more preferably 672 mm or more, and most preferably 673 mm or more.

[0074] On the other hand, it is preferably less than 843 mm, more preferably less than 733 mm, even more preferably less than 725 mm, even more preferably less than 718 mm, even more preferably less than 717 mm, even more preferably less than 716 mm, even more preferably less than 714 mm, even more preferably less than 710 mm, even more preferably less than 707 mm, even more preferably less than 692 mm, even more preferably less than 690 mm, even more preferably less than 685 mm, even more preferably less than 684 mm, even more preferably less than 680 mm, even more preferably less than 679 mm, even more preferably less than 674 mm.

[0075] The specific cross-sectional width Wt (mm) is preferably 115 mm or more, more preferably 130 mm or more, even more preferably 150 mm or more, even more preferably 170 mm or more, even more preferably 175 mm or more, even more preferably 176 mm or more, even more preferably 177 mm or more, even more preferably 178 mm or more, even more preferably 181 mm or more, even more preferably 182 mm or more, even more preferably 185 mm or more, and most preferably 193 mm or more.

[0076] On the other hand, it is preferably less than 305mm, more preferably less than 245mm, even more preferably less than 233mm, even more preferably less than 231mm, even more preferably less than 229mm, even more preferably less than 225mm, even more preferably less than 210mm, even more preferably less than 205mm, even more preferably less than 201mm, even more preferably less than 200mm, even more preferably less than 200mm, even more preferably less than 199mm.

[0077] The specific cross-sectional height Ht (mm) is preferably 37mm or more, more preferably 69mm or more, even more preferably 70mm or more, even more preferably 78mm or more, even more preferably 79mm or more, even more preferably 80mm or more, even more preferably 87mm or more, even more preferably 88mm or more, even more preferably 90mm or more, even more preferably 95mm or more, even more preferably 96mm or more, even more preferably 98mm or more, even more preferably 99mm or more.

[0078] On the other hand, it is preferably less than 180 mm, more preferably less than 116 mm, even more preferably less than 113 mm, even more preferably less than 112 mm, even more preferably less than 105 mm, even more preferably less than 101 mm, and even more preferably less than 101 mm.

[0079] The specific virtual volume V is preferably 13,000,000 mm². 3 The above, more preferably 23,136,067 mm 3 The above are further preferred to be 23, 206, and 160 mm. 3 The above is further preferred to be 23,377,471 mm. 3 The above is further preferred to be 28,575,587 mm. 3 The above is further preferred to be 28,813,525 mm. 3 The above is further preferred to be 29,000,000 mm. 3 The above is further preferred to be 29,087,378 mm. 3 The above is further preferred to be 29,823,416 mm. 3 The above is further preferred to be 30, 327, 983 mm. 3 The above is further preferred to be 34,466,507 mm. 3 The above is further preferred to be 36,000,000 mm. 3 The above is further preferred to be 36,015,050 mm. 3 The above are further preferred, with 36, 140, and 254 mm being the most suitable. 3 The above is further preferred to be 36,203,610 mm. 3 The above are further preferred to be 36, 260, and 445 mm. 3 The above is further preferred to be 37,040,131 mm. 3 above.

[0080] On the other hand, it is preferably less than 66,000,000 mm. 3 More preferably, it is 51,283,296 mm.3 Hereinafter, less than 44,000,000 mm is preferred. 3 More preferably 43,478,150mm 3 Hereinafter, 42,045,141 mm is further preferred. 3 Hereinafter, 40, 755, 756 mm is further preferred. 3 Hereinafter, a further preferred value is less than 38,800,000 mm. 3 .

[0081] Furthermore, in this invention, considering the stability of ride comfort during driving, (Dt-2×Ht) is preferably 450 (mm) or more, more preferably 457 (mm) or more, even more preferably 458 (mm) or more, even more preferably 470 (mm) or more, even more preferably 480 (mm) or more, even more preferably 482 (mm) or more, and even more preferably 483 (mm) or more.

[0082] On the other hand, considering the deformation of the tread, it is preferably less than 560 (mm), more preferably less than 559 (mm), even more preferably less than 558 (mm), even more preferably less than 534 (mm), even more preferably less than 533 (mm), even more preferably less than 530 (mm), even more preferably less than 510 (mm), even more preferably less than 508 (mm), and even more preferably less than 507 (mm).

[0083] Furthermore, in this invention, the thickness S (mm) of the sidewall in the tire width direction at the maximum width of the tire is preferably 2.0 mm or less. By reducing the sidewall thickness S in this way, a further improvement in heat dissipation can be expected, and it is considered that rolling resistance and durability are improved. More preferably, it is 1.9 mm or less, even more preferably 1.8 mm or less, even more preferably 1.7 mm or less, and even more preferably 1.6 mm or less.

[0084] [3] Specific embodiments of the present invention

[0085] The present invention will now be described in detail based on its implementation methods.

[0086] 1. Tire shape

[0087] In this embodiment, when the tire is mounted on a standard rim with an internal pressure of 250 kPa, the tire's cross-sectional width is Wt (mm), its outer diameter is Dt (mm), and the volume of space occupied by the tire is a virtual volume V (mm²). 3 When the tire satisfies the following equations (1) and (2):

[0088] 1700≦(Dt 2(×π / 4) / Wt≦2827.4····(Equation 1);

[0089] [(V+1.5×10 7 ) / Wt]≦2.88×10 5 ...(Equation 2).

[0090] By configuring the tire shape (Wt, Dt, V) in this way, a pneumatic tire with sufficiently reduced rolling resistance at high speeds and excellent durability can be provided.

[0091] 2. Rubber composition

[0092] Unless otherwise specified, the following compound materials can be used in the sidewalls and overlaps that constitute the side portions in this embodiment. The amount of each compound can be appropriately adjusted according to the desired physical properties of the rubber composition used for the sidewalls and the rubber composition used for the overlaps.

[0093] (1) Compound materials

[0094] (a) Rubber composition

[0095] In this embodiment, rubber (polymers) commonly used in tire manufacturing can be used as the rubber component, such as butadiene rubber (BR), styrene-butadiene rubber (SBR), isoprene rubber, and nitrile rubber (NBR). Among these, butadiene rubber (BR) and isoprene rubber are preferred.

[0096] (a-1)BR

[0097] Of 100 parts by weight of the rubber component, the content of BR is preferably 40 parts by weight or more, more preferably 50 parts by weight or more, and even more preferably 55 parts by weight or more. On the other hand, this content is preferably 80 parts by weight or less, more preferably 75 parts by weight or less, and even more preferably 70 parts by weight or less.

[0098] As described above, the difference between the BR content (parts by mass) in the sidewall rubber composition and the BR content (parts by mass) in the overlap rubber composition is preferably 10 parts by mass or more and 40 parts by mass or less.

[0099] The weight-average molecular weight of BR is, for example, greater than 100,000 and less than 2 million. The vinyl bonding content of BR is, for example, greater than 1% by mass and less than 30% by mass. The cis content of BR is, for example, greater than 1% by mass and less than 98% by mass. The trans content of BR is, for example, greater than 1% by mass and less than 60% by mass. The cis content can be determined by infrared absorption spectroscopy.

[0100] There are no particular limitations on BR; BR with high cis content (cis content above 90%), BR with low cis content, and BR containing syndiotactic polybutadiene crystals can be used. BR can be unmodified or modified. As a modified BR, for example, BR modified with a compound (modifier) ​​represented by the following formula can be used.

[0101] [Chemical Formula 1]

[0102]

[0103] In the formula, R 1 R 2 and R 3 Represents the same or different alkyl, alkoxy, silyloxy, acetal, carboxyl (-COOH), mercapto (-SH) groups or their derivatives. R 4 and R 5 Indicates the same or different hydrogen atoms or alkyl groups. R 4 and R 5 It can combine with nitrogen atoms to form a ring structure. n represents an integer.

[0104] As a modified BR modified by the compound (modifier) ​​represented by the above formula, examples of BRs modified by compounds whose polymerization ends (active ends) are represented by the above formula can be listed.

[0105] As R 1 R 2 and R 3 Preferably, it is an alkoxy group (preferably an alkoxy group having 1 to 8 carbon atoms, more preferably an alkoxy group having 1 to 4 carbon atoms). As R 4 and R 5 Preferably, it is an alkyl group (preferably an alkyl group having 1 to 3 carbon atoms). n is preferably 1 to 5, more preferably 2 to 4, and even more preferably 3. Furthermore, in R... 4 and R 5 When combined with a nitrogen atom to form a ring structure, a 4- to 8-membered ring is preferred. Alkoxy groups also include cycloalkoxy groups (e.g., cyclohexyloxy) and aryloxy groups (e.g., phenoxy, benzyloxy).

[0106] Specific examples of the aforementioned modifiers include: 2-dimethylaminoethyltrimethoxysilane, 3-dimethylaminopropyltrimethoxysilane, 2-dimethylaminoethyltriethoxysilane, 3-dimethylaminopropyltriethoxysilane, 2-diethylaminoethyltrimethoxysilane, 3-diethylaminopropyltrimethoxysilane, 2-diethylaminoethyltriethoxysilane, and 3-diethylaminopropyltriethoxysilane. These can be used alone or in combination of two or more.

[0107] In addition, modified BRs can also be used as modified BRs by modifying them with the following compounds (modifiers). Examples of modifiers include: polyglycidyl ethers of polyols, such as ethylene glycol diglycidyl ether, glycerol triglycidyl ether, trimethylolethane triglycidyl ether, and trimethylolpropane triglycidyl ether; polyglycidyl ethers of aromatic compounds having two or more phenolic groups, such as diglycidylated bisphenol A; polyepoxides, such as 1,4-diglycidylbenzene, 1,3,5-triglycidylbenzene, and polyepoxide liquid polybutadiene; and tertiary amines containing epoxy groups, such as 4,4'-diglycidyl-diphenylmethylamine, 4,4'-diglycidyl-diphenylmethylamine, etc. Benzylmethylamine; diglycidylamino compounds, such as diglycidylaniline, N,N'-diglycidyl-4-glycidyloxyaniline, diglycidyl-o-toluidine, tetraglycidyl-m-phenylenediamine, tetraglycidylaminodiphenylmethane, tetraglycidyl-p-phenylenediamine, diglycidylaminomethylcyclohexane, tetraglycidyl-1,3-diaminomethylcyclohexane; amino-containing acyl chlorides, such as bis-(1-methylpropyl)carbamate chloride, 4-morpholinocarbamate chloride, 1-pyrrolidinecarbamate chloride, N,N-dimethylcarbamide acid Chloride), N,N-diethylcarbamoyl chloride; silane compounds containing epoxy groups, such as 1,3-bis-(glycidoxypropyl)-tetramethyldisiloxane, (3-glycidoxypropyl)-pentamethyldisiloxane; silane compounds containing thioether groups, such as (trimethylsilyl)[3-(trimethoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(triethoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(tripropoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(tributoxysilyl)propyl]sulfide, (trimethylsilyl)[3-(methyldimethoxysilyl)propyl] Sulfides, (trimethylsilyl)[3-(methyldiethoxysilyl)propyl] sulfide, (trimethylsilyl)[3-(methyldipropoxysilyl)propyl] sulfide and (trimethylsilyl)[3-(methyldibutoxysilyl)propyl] sulfide; N-substituted aziridine compounds, such as ethyleneimine, acrylimine; alkoxysilanes, such as methyltriethoxysilane, N,N-bis(trimethylsilyl)-3-aminopropyltrimethoxysilane, N,N-bis(trimethylsilyl)-3-aminopropyltriethoxysilane, N,N-bis(trimethylsilyl)aminoethyltrimethoxysilane, N,N-bis(trimethylsilyl)aminoethyltriethoxysilane;(Thio)benzophenone compounds having an amino group and / or a substituted amino group, such as 4-N,N-dimethylaminobenzophenone, 4-N,N-di-tert-butylaminobenzophenone, 4-N,N-diphenylaminobenzophenone, 4,4'-bis(dimethylamino)benzophenone, 4,4'-bis(diethylamino)benzophenone, 4,4'-bis(diphenylamino)benzophenone and N,N,N',N'-bis-(tetraethylamino)benzophenone; Benzaldehyde compounds, such as 4-N,N-dimethylaminobenzaldehyde, 4-N,N-diphenylaminobenzaldehyde, and 4-N,N-divinylaminobenzaldehyde; N-substituted pyrrolidones, such as N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, N-phenyl-2-pyrrolidone, N-tert-butyl-2-pyrrolidone, and N-methyl-5-methyl-2-pyrrolidone; N-substituted piperidinones, such as N-methyl-2-piperidinone and N-vinyl-2-piperidinone. N-Phenylaceton; N-substituted lactams, such as N-methyl-ε-caprolactam, N-phenyl-ε-caprolactam, N-methyl-ω-laurolactam, N-vinyl-ω-laurolactam, N-methyl-β-propiolactam and N-phenyl-β-propiolactam; and N,N-bis-(2,3-epoxypropoxy)-aniline, 4,4-methylene-bis-(N,N-glycidylaniline), tri-(2,3-epoxypropyl)-1,3,5-trimethylaniline The following compounds are used: 2,4,6-triones, N,N-diethylacetamide, N-methylmaleimide, N,N-diethylurea, 1,3-dimethylethylidene urea, 1,3-divinylethylidene urea, 1,3-diethyl-2-imidazolinone, 1-methyl-3-ethyl-2-imidazolinone, 4-N,N-dimethylaminoacetophenone, 4-N,N-diethylaminoacetophenone, 1,3-bis(diphenylamino)-2-propanone, and 1,7-bis(methylethylamino)-4-heptanone. Modification using these compounds (modifiers) can be carried out by known methods. These modified BRs can be used alone or in combination of two or more.

[0108] As a business partner (BR), products from companies such as Ube Industries, Ltd., JSR Corporation, Asahi Kasei Corporation, and Zeon Corporation can be used.

[0109] (a-2) Isoprene-based rubbers

[0110] Of 100 parts by weight of the rubber composition, the content (total content) of isoprene-based rubber is preferably 25 parts by weight or more, more preferably 30 parts by weight or more, and even more preferably 35 parts by weight or more. On the other hand, it is preferably 55 parts by weight or less, more preferably 50 parts by weight or less, and even more preferably 45 parts by weight or less.

[0111] Examples of isoprene-based rubbers include natural rubber (NR), isoprene rubber (IR), modified NR, modified NR, and modified IR. Among these, NR is preferred from the perspective of superior strength.

[0112] For example, NRs commonly used in the tire industry, such as SIR20, RSS#3, and TSR20, can be used. IRs are not particularly limited; for example, IR 2200, manufactured by Zeon Corporation of Japan, commonly used in the tire industry, can be used. Modified NRs include deproteinized natural rubber (DPNR) and high-purity natural rubber (UPNR). Modified NRs include epoxidized natural rubber (ENR), hydrogenated natural rubber (HNR), and grafted natural rubber. Modified IRs include epoxidized isoprene rubber, hydrogenated isoprene rubber, and grafted isoprene rubber. These can be used alone or in combination of two or more.

[0113] (a-3)SBR

[0114] The rubber component may contain SBR as needed. In this case, the SBR content in 100 parts by weight of the rubber component is, for example, more than 1 part by weight and less than 100 parts by weight. More preferably, it is more than 5 parts by weight, even more preferably more than 15 parts by weight, and particularly preferably more than 25 parts by weight. On the other hand, it is preferably less than 65 parts by weight, more preferably less than 55 parts by weight, even more preferably less than 45 parts by weight, and particularly preferably less than 35 parts by weight.

[0115] The weight-average molecular weight of the SBR is, for example, greater than 100,000 and less than 2 million. The styrene content of the SBR is preferably greater than 5% by mass and less than 50% by mass, more preferably greater than 10% by mass and less than 40% by mass, and even more preferably greater than 20% by mass and less than 35% by mass. The vinyl bond content (1,2-bonded butadiene unit content) of the SBR is, for example, greater than 5% by mass and less than 70% by mass. Structural identification of the SBR (determination of styrene content and vinyl bond content) can be performed using, for example, a JNM-ECA series device manufactured by Nippon Egis Corporation.

[0116] There are no particular limitations on SBR. For example, emulsion polymerized styrene-butadiene rubber (E-SBR) and solution polymerized styrene-butadiene rubber (S-SBR) can be used. SBR can be unmodified SBR or modified SBR, and these can be used alone or in combination of two or more types.

[0117] The modified SBR can be any SBR having functional groups that interact with fillers (such as silica). Examples include: terminal-modified SBRs (terminal-modified SBRs having the aforementioned functional groups at their ends), wherein at least one end of the SBR is modified with a compound (modifier) ​​having the aforementioned functional groups; main-chain modified SBRs having the aforementioned functional groups on the main chain; main-chain terminal-modified SBRs having the aforementioned functional groups on both the main chain and at the ends (e.g., main-chain terminal-modified SBRs having the aforementioned functional groups on the main chain and at least one end modified with the aforementioned modifier); and terminal-modified SBRs modified (coupled) with a polyfunctional compound having two or more epoxy groups in the molecule and to which epoxy groups or hydroxyl groups are introduced.

[0118] As an SBR, for example, SBR manufactured and sold by companies such as Sumitomo Chemical Co., Ltd., JSR Corporation, Asahi Kasei Corporation, and Zeon Corporation can be used. SBR can be used alone or in combination of two or more types.

[0119] (a-4) Other rubber components

[0120] In addition, as other rubber components, the rubber composition may contain rubber (polymers) commonly used in tire manufacturing, such as nitrile rubber (NBR).

[0121] (b) Compounds other than rubber components

[0122] (b-1) Packing

[0123] In this embodiment, the rubber composition preferably contains a reinforcing agent (such as carbon black or silica) as a filler. Examples of fillers besides carbon black and silica include graphite, calcium carbonate, talc, bauxite, clay, aluminum hydroxide, and mica. When using silica, it is preferable to use it in conjunction with a silane coupling agent.

[0124] (i) Carbon black

[0125] The carbon black content, relative to 100 parts by weight of rubber, is preferably 10 parts by weight or more and 100 parts by weight or less, more preferably 30 parts by weight or more and 90 parts by weight or less, and even more preferably 35 parts by weight or more and 80 parts by weight or less. As a result, the tire's resistance to crack growth, durability, and resistance to UV degradation can be improved.

[0126] The nitrogen adsorption specific surface area (N2SA) of carbon black is, for example, greater than 30 m². 2 / g and less than 250m 2 / g. The dibutyl phthalate (DBP) absorption of carbon black is, for example, greater than 50 ml / 100g and less than 250 ml / 100g. The nitrogen adsorption specific surface area of ​​carbon black was determined according to ASTM D4820-93, and the DBP absorption was determined according to ASTM D2414-93.

[0127] Carbon black is not specifically limited, but examples include furnace black (furnace black), such as SAF, ISAF, HAF, MAF, FEF, SRF, GPF, APF, FF, CF, SCF and ECF; acetylene black; thermal black (thermal cracking black), such as FT and MT; and channel black (channel black), such as EPC, MPC and CC.

[0128] Commercially available products include those from companies such as Asahi Carbon Co., Ltd., Cabot Corporation, Tokai Carbon Co., Ltd., Mitsubishi Chemical Co., Ltd., Lion Corporation, Shin-Nippon Ka Carbon Co., Ltd., and Columbia Carbon Co., Ltd. These can be used individually or in combination of two or more.

[0129] (ii) Silicon dioxide

[0130] The rubber composition may contain silica as needed. From the perspective of obtaining good durability, the BET specific surface area of ​​silica is preferably greater than 140 m². 2 / g, more preferably greater than 160m 2 / g. On the other hand, from the perspective of obtaining good rolling resistance at high speeds, it is preferably less than 250m. 2 / g, more preferably less than 220m 2 / g. Furthermore, from the perspective of obtaining good durability, the silica content relative to 100 parts by weight of rubber composition is preferably greater than 35 parts by weight, more preferably greater than 40 parts by weight, and even more preferably greater than 45 parts by weight. On the other hand, from the perspective of obtaining good rolling resistance at high speeds, it is preferably less than 70 parts by weight, more preferably less than 65 parts by weight, and even more preferably less than 60 parts by weight. The above-mentioned BET specific surface area is the N2SA value determined by the BET method according to ASTM D3037-93.

[0131] Examples of silica include dry silica (anhydrous silica) and wet silica (hydrated silica). Wet silica is preferred because it has a large number of silanol groups.

[0132] Products made from companies such as Degussa, Rhodia, Tosoh Silica Co., Ltd., Solvay Japan Co., Ltd., and Tokuyama Co., Ltd. can be used as silica.

[0133] (iii) Silane coupling agent

[0134] When using silica as a filler, as mentioned above, it is preferable to use a silane coupling agent together with the silica. There are no particular limitations on the silane coupling agent. Examples of silane coupling agents include:

[0135] Sulfide-based silane coupling agents, such as bis(3-triethoxysilylpropyl)tetrasulfide, bis(2-triethoxysilylethyl)tetrasulfide, bis(4-triethoxysilylbutyl)tetrasulfide, bis(3-trimethoxysilylpropyl)tetrasulfide, bis(2-trimethoxysilylethyl)tetrasulfide, bis(2-triethoxysilylethyl)trisulfide, and bis(4-trimethoxysilylbutyl)trisulfide. Bis(3-triethoxysilylpropyl) disulfide, bis(2-triethoxysilylethyl) disulfide, bis(4-triethoxysilylbutyl) disulfide, bis(3-trimethoxysilylpropyl) disulfide, bis(2-trimethoxysilylethyl) disulfide, bis(4-trimethoxysilylbutyl) disulfide, 3-trimethoxysilylpropyl-N,N-dimethylthiocarbamoyltetrasulfide Silane coupling agents, including 2-triethoxysilyl-1-ethyl-N,N-dimethylthiocarbamoyl tetrasulfide and 3-triethoxysilyl-propyl methacrylate monosulfide; mercapto-based silane coupling agents, such as 3-mercaptopropyltrimethoxysilane, 2-mercaptoethyltriethoxysilane, Momentive's NXT and NXT-Z; vinyl-based silane coupling agents, such as vinyltriethoxysilane and vinyltrimethoxysilane; amino-based silane coupling agents. Coupling agents, such as 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane; epoxypropoxysilane coupling agents, such as γ-epoxypropoxypropyltriethoxysilane and γ-epoxypropoxypropyltrimethoxysilane; nitrosilane coupling agents, such as 3-nitropropyltrimethoxysilane and 3-nitropropyltriethoxysilane; and chlorinated silane coupling agents, such as 3-chloropropyltrimethoxysilane and 3-chloropropyltriethoxysilane. These can be used alone or in combination of two or more.

[0136] Products from companies such as Degussa, Momentive, Shin-Etsu Silicones, Tokyo Chemical Industries, Azmax, and Toray Corning can be used as silane coupling agents.

[0137] The content of silane coupling agent relative to 100 parts by weight of silicon dioxide is, for example, greater than 3 parts by weight and less than 25 parts by weight.

[0138] (iv) Other packing materials

[0139] In addition to carbon black and silica, the rubber composition may also contain fillers commonly used in the tire industry, such as graphite, calcium carbonate, talc, bauxite, clay, aluminum hydroxide, and mica. These contents, for example, are greater than 0.1 parts by weight and less than 200 parts by weight relative to 100 parts by weight of the rubber component.

[0140] (b-2) Softener

[0141] The rubber composition may contain oil (including extender oil), liquid rubber, etc., as a softener. The total content of these components relative to 100 parts by weight of the rubber component is preferably greater than 5 parts by weight, more preferably greater than 10 parts by weight, and even more preferably greater than 12 parts by weight. On the other hand, it is preferably less than 30 parts by weight, more preferably less than 20 parts by weight, and even more preferably less than 17 parts by weight. The oil content also includes the amount of oil contained in the rubber (oil-extended rubber).

[0142] Examples of oils include mineral oils (commonly referred to as processing oils), vegetable oils, or mixtures thereof. Mineral oils (processing oils) can include, for example, alkane-based processing oils, aromatic processing oils, cycloalkane-based processing oils, etc. Examples of vegetable oils include castor oil, cottonseed oil, linseed oil, rapeseed oil, soybean oil, palm oil, coconut oil, peanut oil, rosin, pine oil, pine tar, tall oil, corn oil, rice bran oil, safflower oil, sesame oil, olive oil, sunflower oil, palm kernel oil, camellia oil, jojoba oil, macadamia oil, and tung oil. These can be used alone or in combination of two or more.

[0143] Examples of processing oils (mineral oils) include products from Idemitsu Kosan Co., Ltd., Sankyo Oil & Chemical Co., Ltd., Nippon Energy Co., Ltd., Olisoy Co., Ltd., H&R Co., Ltd., Toyokuni Oil Co., Ltd., Showa Shell Oil Co., Ltd., Fuji Kosan Co., Ltd., etc.

[0144] Liquid rubbers, as examples of plasticizers, are polymers that are liquid at room temperature (25°C) and have monomers similar to those in solid rubber as constituent elements. Examples of liquid rubbers include farnesene-based polymers, liquid diene-based polymers, and their hydrides.

[0145] Farnese polymers are polymers obtained by polymerizing farneses and have farnese-based structural units. Farneses include isomers such as α-farnese ((3E,7E)-3,7,11-trimethyl-1,3,6,10-dodecathetene) and β-farnese (7,11-dimethyl-3-methylene-1,6,10-dodecathetene).

[0146] Farnese polymers can be homopolymers of farnese (farnese homopolymers) or copolymers of farnese and vinyl monomers (farnese-vinyl monomer copolymers).

[0147] Examples of liquid diene polymers include liquid styrene-butadiene copolymer (liquid SBR), liquid butadiene polymer (liquid BR), liquid isoprene polymer (liquid IR), and liquid styrene-isoprene copolymer (liquid SIR).

[0148] The weight-average molecular weight (Mw) of polystyrene-based liquid diene polymers, determined by gel permeation chromatography (GPC), is, for example, greater than 1.0 × 10⁻⁶. 3 And less than 2.0 × 10 5 In this specification, the Mw of the liquid diene polymer is a polystyrene conversion value determined by gel permeation chromatography (GPC).

[0149] As a liquid rubber, products from companies such as Kuraray Corporation and CrayValley can be used.

[0150] (b-3) Resin composition

[0151] The rubber composition preferably contains a resin component as needed. The resin component may be solid or liquid at room temperature, and specific examples of resin components include styrene-based resins, benzofuran-based resins, terpene-based resins, C5 resins, C9 resins, C5C9 resins, and acrylic resins. Two or more resin components may be used in combination. The content of the resin component relative to 100 parts by weight of the rubber composition is preferably greater than 2 parts by weight and less than 45 parts by weight, more preferably less than 30 parts by weight.

[0152] Styrene-based resins are polymers that use styrene-based monomers as constituent monomers, and examples include polymers obtained by polymerizing styrene-based monomers as the main component (50% by mass or more). Specifically, they include homopolymers obtained by polymerizing styrene-based monomers (styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-methoxystyrene, p-tert-butylstyrene, p-phenylstyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, etc.) separately, copolymers obtained by copolymerizing two or more styrene-based monomers, and copolymers obtained by copolymerizing styrene-based monomers with other monomers that can be copolymerized with the styrene-based monomers.

[0153] Examples of other monomers mentioned above include: acrylonitriles, such as acrylonitrile and methacrylonitrile; unsaturated carboxylic acids, such as acrylic acid and methacrylic acid; unsaturated carboxylic acid esters, such as methyl acrylate and methyl methacrylate; dienes (such as chloroprene, butadiene, and isoprene), alkenes (such as 1-butene and 1-pentene); α,β-unsaturated carboxylic acids and their anhydrides, such as maleic anhydride.

[0154] As a benzofuran-based resin, benzofuran-indene resin is preferred. Benzofuran-indene resin is a resin containing benzofuran and indene as monomeric components constituting the resin backbone (main chain). Examples of monomeric components in the backbone other than benzofuran and indene include styrene, α-methylstyrene, methylindene, and vinyltoluene.

[0155] The content of benzofuran-indene resin relative to 100 parts by weight is, for example, greater than 1.0 parts by weight and less than 50.0 parts by weight.

[0156] The hydroxyl value (OH value) of benzofuran-indene resin is, for example, greater than 15 mg KOH / g and less than 150 mg KOH / g. The OH value is the amount of potassium hydroxide required to neutralize the acetic acid bound to the hydroxyl group when 1 g of resin is acetylated, and is expressed in milligrams. It is determined by potentiometric titration (JIS K 0070:1992).

[0157] The softening point of benzofuran-indene resin is, for example, greater than 30°C and less than 160°C. The softening point is the temperature at which the ball falls when the softening point specified in JIS K 6220-1:2001 is determined using a ring-and-ball softening point tester.

[0158] Examples of terpene-based resins include polyterpenes, terpene phenols, and aromatic modified terpene resins. Polyterpenes are resins obtained by polymerizing terpene compounds and their hydrides. Terpene compounds are those with the structure (C5H8). n Hydrocarbons or their oxygen-containing derivatives that are composed of compounds classified as monoterpenes (C6H2O) 10 H 16 ), sesquiterpenes (C 15 H 24 ), diterpenes (C 20 H 32 Compounds with terpenes as their basic skeleton include α-pinene, β-pinene, dipentene, limonene, myrcene, allocirrhene, ocimene, α-phellandrene, α-terpinene, γ-terpinene, isopinolene, 1,8-cineol, 1,4-cineol, α-terpineol, β-terpineol, and γ-terpineol.

[0159] Examples of polyterpenes include: terpene resins, such as α-pinene resin, β-pinene resin, limonene resin, dipentene resin, and β-pinene / limonene resin made from the above-mentioned terpene compounds; and hydrogenated terpene resins obtained by hydrogenating the terpene resin. Examples of terpene phenols include: resins obtained by copolymerizing the above-mentioned terpene compounds and phenolic compounds, and resins obtained by hydrogenating the above-mentioned resins. Specifically, resins obtained by condensing the above-mentioned terpene compounds, phenolic compounds, and formalin can be cited. Examples of phenolic compounds include phenol, bisphenol A, cresol, and xylenol. Examples of aromatic-modified terpene resins include resins obtained by modifying terpene resins with aromatic compounds, and resins obtained by hydrogenating the above-mentioned resins. Aromatic compounds are not specifically limited to any compound having an aromatic ring. Examples include: phenolic compounds, such as phenol, alkylphenol, alkoxyphenol, and phenol containing an unsaturated hydrocarbon group; naphthol compounds, such as naphthol, alkylnaphthol, alkoxynaphthol, and naphthol containing an unsaturated hydrocarbon group; styrene derivatives, such as styrene, alkylstyrene, alkoxystyrene, and styrene containing an unsaturated hydrocarbon group; benzofuran; and indene.

[0160] C5 resin refers to resin obtained by polymerizing C5 fractions. Examples of C5 fractions include petroleum fractions having 4 to 5 carbon atoms, such as cyclopentadiene, pentene, pentadiene, and isoprene. Dicyclopentadiene resin (DCPD resin) is preferably used as a C5-based petroleum resin.

[0161] C9 resin refers to a resin obtained by polymerizing a C9 fraction, which can be hydrogenated or modified. Examples of C9 fractions include petroleum fractions having 8 to 10 carbon atoms, such as vinyltoluene, alkylstyrene, indene, and methylindene. Specifically, benzofuran-indene resins, benzofuran resins, indene resins, and aromatic vinyl resins are preferred. As aromatic vinyl resins, homopolymers of α-methylstyrene or styrene, or copolymers of α-methylstyrene and styrene, are preferred for economic reasons, ease of processing, and excellent exothermic properties; copolymers of α-methylstyrene and styrene are more preferred. For example, those purchased from Kraton, Eastman Chemical, etc., can be used as aromatic vinyl resins.

[0162] C5C9 resin refers to a resin obtained by copolymerizing the aforementioned C5 fraction and C9 fraction, and can be hydrogenated or modified. Examples of C5 and C9 fractions include the aforementioned petroleum fractions. For example, those purchased from Tosoh Corporation, LUHUA Corporation, etc., can be used as C5C9 resins.

[0163] There are no particular limitations on acrylic resins, but solvent-free acrylic resins can be used, for example.

[0164] Examples of solvent-free acrylic resins include (meth)acrylic resins (polymers) synthesized via high-temperature continuous polymerization (high-temperature continuous bulk polymerization: methods described in US4414370B, JP 84-6207A, JP 93-58805B, JP 89-313522A, US 5010166B, and the Toa Synthetic Research Yearbook TREND2000 No. 3, pp. 42-45). In this invention, (meth)acrylic acid refers to methacrylic acid and acrylic acid.

[0165] Examples of monomeric components constituting the above-mentioned acrylic resins include: (meth)acrylic acid, and (meth)acrylic acid derivatives such as (meth)acrylates (alkyl esters, aryl esters, aralkyl esters, etc.), (meth)acrylamide, and (meth)acrylamide derivatives.

[0166] In addition, as a monomer component constituting the above-mentioned acrylic resin, aromatic vinyl compounds (such as styrene, α-methylstyrene, vinyltoluene, vinylnaphthalene, divinylbenzene, trivinylbenzene, divinylnaphthalene) can be used together with (meth)acrylic acid or (meth)acrylic acid derivatives.

[0167] The aforementioned acrylic resin may be a resin composed solely of (meth)acrylic acid components, or a resin that also contains components other than (meth)acrylic acid components. Furthermore, the aforementioned acrylic resin may contain hydroxyl, carboxyl, or silanol groups, etc.

[0168] As a resin component, products from companies such as Maruzen Petrochemical Co., Ltd., Sumitomo Bakelite Co., Ltd., Yasuhara Chemical Co., Ltd., Tosoh Co., Ltd., Rutgers Chemicals, BASF, Arizona Chemical, Nippon Paint Co., Ltd., Nippon Shokubai Co., Ltd., JX Energy Co., Ltd., Arakawa Chemical Industry Co., Ltd., and Taoka Chemical Industry Co., Ltd. can be used.

[0169] (b-4) Anti-aging agents

[0170] The rubber composition preferably contains an antioxidant. The antioxidant content, for example, is greater than 1 part by weight and less than 10 parts by weight per 100 parts by weight of the rubber component.

[0171] Examples of antioxidants include: naphthylamine-based antioxidants, such as phenyl-α-naphthylamine; diphenylamine-based antioxidants, such as octyl diphenylamine and 4,4'-bis(α,α'-dimethylbenzyl)diphenylamine; p-phenylenediamine-based antioxidants, such as N-isopropyl-N'-phenyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine, and N,N'-di-2-naphthyl-p-phenylenediamine; quinoline-based antioxidants, such as polymers of 2,2,4-trimethyl-1,2-dihydroquinoline; monophenol-based antioxidants, such as 2,6-di-tert-butyl-4-methylphenol and styreneated phenol; and bisphenol, triphenol, and polyphenol-based antioxidants, such as tetra-[methylene-3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionate]methane. These can be used alone or in combination of two or more.

[0172] As an anti-aging agent, products from companies such as Seiko Chemical Co., Ltd., Sumitomo Chemical Co., Ltd., Ouchi Shinsei Chemical Co., Ltd., and Flexsys Co., Ltd. can be used.

[0173] (b-5) Stearic acid

[0174] The rubber composition may contain stearic acid. The stearic acid content, for example, is greater than 0.5 parts by weight and less than 10.0 parts by weight per 100 parts by weight of the rubber component. Conventionally known stearic acids, such as those produced by Nippon Yu Corporation, NOF Corporation, Kao Corporation, Fujifilm, and Koh Geny Pharmaceutical Co., Ltd., and Chiba Fatty Acid Co., Ltd., can be used as the stearic acid.

[0175] (b-6) Zinc oxide

[0176] The rubber composition may contain zinc oxide. The zinc oxide content, for example, is greater than 0.5 parts by weight and less than 10 parts by weight per 100 parts by weight of the rubber component. As zinc oxide, conventionally known zinc oxides can be used, such as those produced by Mitsui Metal Mining Co., Ltd., Toho Zinc Co., Ltd., Hakusui Tech Co., Ltd., Seido Chemical Industry Co., Ltd., and Sakai Chemical Industry Co., Ltd.

[0177] (b-7) Wax

[0178] The rubber composition preferably contains wax. The wax content is, for example, 0.5 to 20 parts by weight, preferably 1.0 to 15 parts by weight, and more preferably 1.5 to 10.0 parts by weight, relative to 100 parts by weight of the rubber component.

[0179] Waxes are not specifically limited, and examples include: petroleum-based waxes, such as paraffin wax and microcrystalline wax; natural waxes, such as plant waxes and animal waxes; and synthetic waxes, such as polymers of ethylene or propylene. These can be used alone or in combination of two or more.

[0180] As a wax, products from companies such as Ouchi Shinshin Chemical Industry Co., Ltd., Nippon Seiwa Co., Ltd., and Seiko Chemical Co., Ltd. can be used.

[0181] (b-8) Crosslinking agents and vulcanization accelerators

[0182] The rubber composition preferably contains a crosslinking agent, such as sulfur. The content of the crosslinking agent is, for example, greater than 0.1 parts by weight and less than 10.0 parts by weight per 100 parts by weight of the rubber component.

[0183] Examples of sulfur include powdered sulfur, precipitated sulfur, colloidal sulfur, insoluble sulfur, highly dispersed sulfur, and soluble sulfur, which are commonly used in the rubber industry. These can be used alone or in combination of two or more.

[0184] For example, products from companies such as Tsurumi Chemical Industry Co., Ltd., Karuizawa Sulfur Co., Ltd., Shikoku Chemical Industry Co., Ltd., Flexsys Co., Ltd., Nippon Inkyu Co., Ltd., and Hosoi Chemical Industry Co., Ltd. can be used as sulfur.

[0185] Examples of crosslinking agents other than sulfur include: sulfur-containing vulcanizing agents, such as Tackirol V200 manufactured by Taoka Chemical Industry Co., Ltd., DURALINK HTS (sodium 1,6-hexamethylene dithiosulfate dihydrate) manufactured by Flexsys, and KA91889 (1,6-bis(N,N'-dibenzylthiocarbamoyl dithiohexane: hybrid crosslinking agent) manufactured by Lanxess; and organic peroxides, such as dicumyl peroxide.

[0186] The rubber composition preferably contains a vulcanization accelerator. The content of the vulcanization accelerator is, for example, greater than 0.3 parts by weight and less than 10.0 parts by weight per 100 parts by weight of the rubber component.

[0187] Examples of vulcanization accelerators include: thiazole-based vulcanization accelerators, such as 2-mercaptobenzothiazole, di-2-benzothiazole disulfide, and N-cyclohexyl-2-benzothiazole sulfenamide; thiuram-based vulcanization accelerators, such as tetramethylthiuram disulfide (TMTD), tetrabenzylthiuram disulfide (TBzTD), and tetra(2-ethylhexyl)thiuram disulfide (TOT-N); sulfenamide-based vulcanization accelerators, such as N-cyclohexyl-2-benzothiazole sulfenamide, N-tert-butyl-2-benzothiazole sulfenamide, N-oxoethylene-2-benzothiazole sulfenamide, N-oxoethylene-2-benzothiazole sulfenamide, and N,N'-diisopropyl-2-benzothiazole sulfenamide; and guanidine-based vulcanization accelerators, such as diphenylguanidine, di-o-tolylguanidine, and o-tolyl biguanide. These can be used individually or in combination of two or more.

[0188] (b-9) Other

[0189] In addition to the components mentioned above, the rubber composition may also contain additives commonly used in the tire industry, such as metal salts of fatty acids, metal salts of carboxylic acids, and organic peroxides. The content of these additives relative to 100 parts by weight of the rubber composition is, for example, greater than 0.1 parts by weight and less than 200 parts by weight.

[0190] 2. Manufacturing of a rubber composition for forming the side portion

[0191] The rubber composition is manufactured by a conventional method, for example by a manufacturing method comprising the steps of: a basic mixing step of mixing the rubber components with a filler (such as carbon black), and a final mixing step of mixing the mixture obtained in the basic mixing step with a crosslinking agent.

[0192] Mixing can be carried out using well-known (closed) mixing machines such as Banbury mixers, kneaders, or open mills.

[0193] The mixing temperature in the basic mixing process is, for example, greater than 50°C and less than 200°C, and the mixing time is, for example, greater than 30 seconds and less than 30 minutes. In addition to the above-mentioned components, commonly used compounding agents in the rubber industry, such as softeners (e.g., oils), stearic acid, zinc oxide, antioxidants, waxes, and vulcanization accelerators, may be added and mixed as needed in the basic mixing step.

[0194] In the final mixing step, the compound obtained in the basic mixing step is mixed with a crosslinking agent. The mixing temperature in the final mixing step is, for example, above room temperature and below 80°C, and the mixing time is, for example, above 1 minute and below 15 minutes. In addition to the above components, vulcanization accelerators, zinc oxide, etc., may be added and mixed in the final mixing step as needed.

[0195] 3. Tire manufacturing

[0196] The tires of the present invention are manufactured using uncured rubber compositions obtained through a final compounding step by conventional methods. That is, the uncured rubber compositions are extruded into the respective shapes of the sidewalls and overlaps, and then formed together with other tire components on a tire forming machine using conventional methods to manufacture uncured tires.

[0197] Specifically, on a forming drum, the inner liner (which ensures tire airtightness), the tire carcass (which bears the load, impact, and inflation pressure on the tire), and the belt (which firmly tightens the tire carcass to increase tread rigidity) are wound, and the two ends of the tire carcass are fixed to the side edges. A bead portion (which secures the tire to the rim) is then configured and shaped into a toroidal shape. The tread is then bonded to the center of the outer periphery, and the sides (sidewalls and overlaps) (which protect the tire carcass and resist bending) are bonded to the radially outer side to manufacture an uncured tire.

[0198] In this embodiment, the belt is preferably provided as an inclined belt layer that extends at an angle of 15° to 30° relative to the tire circumference. As a result, tire durability is ensured while tread rigidity is adequately maintained. Furthermore, since it can be constrained in the circumferential direction, it becomes easier to suppress the growth of the outer diameter.

[0199] The manufactured uncured tires are then heated and pressurized in a vulcanizing machine to obtain a tire. The vulcanization step can be carried out using known vulcanization methods. The vulcanization temperature is, for example, greater than 120°C and less than 200°C, and the vulcanization time is, for example, greater than 5 minutes and less than 15 minutes.

[0200] At this point, the tire is shaped to satisfy the above (Equation 1) and (Equation 2) when the tire is mounted on a standard rim and the internal pressure is set to 250 kPa.

[0201] Specific tires that can satisfy the above (Equation 1) and (Equation 2) include tires with size markings such as 145 / 60R18, 145 / 60R19, 155 / 55R18, 155 / 55R19, 155 / 70R17, 155 / 70R19, 165 / 55R20, 165 / 55R21, 165 / 60R19, 165 / 65R19, 165 / 70R18, 175 / 55R19, 175 / 55R20, 175 / 55R22, 175 / 60R18, 185 / 55R19, 185 / 60R20, 195 / 50R20, and 195 / 55R20.

[0202] In this embodiment, a tire that can satisfy (Equation 1) and (Equation 2) is preferably applied to a pneumatic tire for passenger cars, and satisfying the above equations can more advantageously contribute to solving the problem of the present invention, namely, providing a pneumatic tire with sufficiently reduced rolling resistance and excellent durability at high speeds.

[0203] [Example]

[0204] The present invention will now be described in more detail with reference to embodiments.

[0205] [Experiment 1]

[0206] In this experiment, a tire with a size of 175 was made and evaluated.

[0207] 1. Manufacturing of a rubber composition for forming the sides

[0208] First, a rubber composition for forming the sides is manufactured.

[0209] (1) Compound materials

[0210] First, prepare the following compounding materials.

[0211] (a) Rubber composition

[0212] (a-1)NR:TSR20

[0213] (a-2)BR-1: UBEPOL-BR150B, manufactured by Ube Industries, Ltd.

[0214] (cis content: 97% by mass)

[0215] (a-3)BR-2: Nipol-BR1250H, manufactured by Zeon Corporation of Japan.

[0216] (Tin-terminated modified BR, cis content: 40% by mass)

[0217] (a-4)BR-3: UBEPOL VCR617, manufactured by Ube Industries, Ltd.

[0218] (cis content: 98% by mass)

[0219] (b) Compounds other than rubber components

[0220] (b-1) Carbon Black-1: Show Black N550, manufactured by Cabot Corporation, Japan.

[0221] (DOP oil absorption: 115ml / 100g)

[0222] (b-2) Carbon Black-2: Show Black N330T, manufactured by Cabot Corporation, Japan.

[0223] (DOP oil absorption: 104ml / 100g)

[0224] (b-3) Oil: Process X-140, manufactured by Nippon Energy Corporation.

[0225] (b-4) Stearic acid: Stearic acid "Tsubaki", manufactured by Nippon Oil Co., Ltd.

[0226] (b-5) Zinc oxide: Zinc oxide No. 1, manufactured by Mitsui Metals & Minerals Co., Ltd.

[0227] (b-6) Wax: Sannok wax, manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.

[0228] (b-7) Antioxidant-1: Nocrac 6C, manufactured by Ouchi Shinsei Chemical Co., Ltd.

[0229] (N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine)

[0230] (b-8) Antioxidant-2: Antage RD (2,2,4-trimethyl-1,2-dihydroquinoline), manufactured by Kawaguchi Chemical Co., Ltd.

[0231] (b-9) Crosslinking agents and vulcanization accelerators

[0232] Sulfur: Powdered sulfur, manufactured by Tsurumi Chemical Industry Co., Ltd.

[0233] Vulcanization accelerator: Nocceler NS, manufactured by Ouchi Shinsei Chemical Co., Ltd.

[0234] (N-tert-butyl-2-benzothiazolylsulfonamide)

[0235] Vulcanization Accelerator-2: Nocceler D(DPG)(1,3-diphenylguanidine), manufactured by Ouchi Shinsei Chemical Co., Ltd.

[0236] (2) Manufacturing of rubber composition for forming the side portion

[0237] Following the formulations shown in Table 1 (Rubber Composition for Sidewalls) and Table 2 (Rubber Composition for Overlaps), the materials, excluding sulfur and vulcanization accelerators, were mixed for 5 minutes at 150°C using a Banbury internal mixer to obtain the compound. Each compound is expressed in parts by weight.

[0238] Next, sulfur and vulcanization accelerator are added to the obtained mixture, and the mixture is kneaded at 80°C for 5 minutes using an open mill to obtain various rubber compositions for forming the sides (rubber composition for sidewalls and rubber composition for overlap).

[0239] [Table 1]

[0240] formula A B C D E NR 40 40 40 40 40 BR-1 60 60 60 BR-2 30 30 BR-3 30 30 Carbon Black-1 60 75 65 45 40 Oil 15 25 15 15 10 stearic acid 3 3 3 3 3 Zinc oxide 4.5 4.5 4.5 4.5 4.5 wax 2 2 2 2 2 Anti-aging agent-1 4.5 4.5 4.5 4.5 4.5 Anti-aging agent-2 2 2 2 2 2 sulfur 1.9 1.9 1.9 1.9 1.9 vulcanization accelerator 0.9 1.4 1.2 1.2 1.4 E* 3.2 6.5 6.7 4.0 4.5 tanδ 0.20 0.19 0.15 0.08 0.06

[0241] [Table 2]

[0242]

[0243]

[0244] 2. Tire manufacturing

[0245] Using the obtained rubber compositions, sidewalls and overlaps with predetermined shapes were formed, and these were bonded together with other tire components in the combinations shown in Tables 3 and 4 to form uncured tires. Then, they were pressurized and vulcanized at 170°C for 10 minutes to manufacture test tires of size 175 (Examples 1-1 to 1-5 and Comparative Examples 1-1 to 1-7).

[0246] 3. Parameter Calculation

[0247] Then, for each test tire, the sidewall thickness S (mm), outer diameter Dt (mm), cross-sectional width Wt (mm), cross-sectional height Ht (mm), and aspect ratio (%) were obtained, and the virtual volume V (mm²) was calculated. 3 The results are shown in Tables 3 and 4.

[0248] Simultaneously, viscoelasticity testing rubber specimens (20 mm long × 4 mm wide × 2 mm thick, with the tire circumference as the long side) were cut from each rubber layer of the sidewall and overlap of each test tire. Then, for each rubber specimen, tanδ (tanδsw, tanδc) and E* (E*sw, E*c) were measured using an Eplexor series rubber sampler manufactured by GABO at 70°C, 10 Hz, 5% initial strain, and 1% dynamic strain. The thickness direction of the sample was radial to the tire. The results are shown in Tables 1 and 2, and Tables 3 and 4.

[0249] Then, calculate tanδsw + tanδc, |tanδsw - tanδc|, (E*cE*sw), |Bsw - Bc|, (Dt - 2×Ht), (Dt) 2 ×π / 4) / Wt、(V+1.5×10 7 ) / Wt、(V+2.0×10 7 ) / Wt、(V+2.5×10 7 The results are shown in Tables 3 and 4.

[0250] 4. Performance evaluation test

[0251] (1) Evaluation of rolling resistance at high speed

[0252] All test tires were installed on all wheels of the vehicle (a Japanese-made FF car with a 2000cc engine), inflated with air to a pressure of 250 kPa, and then driven at 100 km / h on a dry test track. After completing 10 km laps, the accelerator was released, and the distance from when the accelerator was turned off until the vehicle came to a stop was measured as the rolling resistance at high speed.

[0253] Next, the results from Comparative Examples 1-7 were set to 100, and the results were exponentialized based on the following formula to relatively evaluate rolling resistance at high speeds. The larger the value, the longer the distance from when the accelerator is turned off until the vehicle stops, the smaller the rolling resistance in a steady state, and the better the fuel efficiency.

[0254] Rolling resistance = [(Results of the test tire) / (Results of Comparative Examples 1-7)] × 100

[0255] (2) Evaluation of durability performance

[0256] After installing all test tires on all wheels of the vehicle (a Japanese-made FF car with a 2000cc engine) and inflating them to an internal pressure of 250 kPa, the vehicle was driven under overload conditions on a dry test track for 10 laps at 50 km / h, followed by a drive at 80 km / h up an uneven surface. Afterward, the vehicle was driven around the track again at 50 km / h, and the speed was gradually increased to determine the speed at the point when the driver experienced an abnormality.

[0257] Next, the results from Comparative Examples 1-7 were set to 100, and the durability performance was relatively evaluated by exponentiation based on the following formula. The larger the value, the better the durability performance.

[0258] Durability = [(Results of the test tires) / (Results of Comparative Examples 1-7)] × 100

[0259] (3) Comprehensive evaluation

[0260] The evaluation results of (1) and (2) above are added together to obtain a comprehensive evaluation.

[0261] (4) Evaluation Results

[0262] The evaluation results are shown in Tables 3 and 4.

[0263] [Table 3]

[0264]

[0265] [Table 4]

[0266]

[0267] [Experiment 2]

[0268] In this experiment, a tire of size 195 was made and evaluated.

[0269] After manufacturing the test tires of Examples 2-1 to 2-5 and Comparative Examples 2-1 to 2-7 shown in Tables 5 and 6 in the same manner as in Experiment 1, the parameters were calculated by executing the same procedure. Then, performance evaluation tests were conducted and evaluated in the same manner. In this experiment, the results of Comparative Examples 2-7 were set to 100 for evaluation. The evaluation results are shown in Tables 5 and 6.

[0270] [Table 5]

[0271]

[0272] [Table 6]

[0273]

[0274] [Experiment 3]

[0275] In this experiment, a 225-sized tire was made and evaluated.

[0276] After manufacturing the test tires of Examples 3-1 to 3-5 and Comparative Examples 3-1 to 3-7 shown in Tables 7 and 8 in the same manner as in Experiment 1, the parameters were calculated by performing the same procedure. Then, performance evaluation tests were conducted and evaluated in the same manner. In this experiment, the results of Comparative Examples 3-7 were set to 100 for evaluation. The evaluation results are shown in Tables 7 and 8.

[0277] [Table 7]

[0278]

[0279] [Table 8]

[0280]

[0281] [Summary of Experiments 1-3]

[0282] Based on the results of experiments 1-3 (Tables 3-8), for tires of any size (175, 195, 225), it is demonstrated that when the above (Equation 1) and (Equation 2) are satisfied, and further (tanδsw+tanδc)≦0.3 and |tanδsw-tanδc|≦0.07, a pneumatic tire with reduced rolling resistance and excellent durability at high speeds can be provided.

[0283] Then, it is demonstrated that by satisfying the requirements specified in claim 2 and thereafter, a tire with further improved rolling resistance and durability at high speeds can be provided.

[0284] On the other hand, its proof is:

[0285] If any of the following conditions are not met: (Equation 1), (Equation 2), (tanδsw+tanδc)≦0.3, and |tanδsw-tanδc|≦0.07, it is impossible to fully achieve the reduction of rolling resistance and excellent durability at high speeds.

[0286] [Experiment 4]

[0287] Next, three types of tires (Examples 4-1 to 4-3) with no significant difference in the relationship between virtual volume V and cross-sectional width Wt were manufactured using the same formula, and evaluated in the same manner, with the results in Example 4-3 set as 100. Here, in addition to the evaluation of rolling resistance and chipping resistance at high speeds, ride comfort was also evaluated.

[0288] Specifically, test tires were installed on all wheels of a vehicle (a Japanese-made FF car with a 2000cc engine), inflated to a pressure of 250 kPa, and then driven on a dry test track. Drivers used a five-sensory test to assess ride comfort while the vehicle traveled 10 km at 100 km / h. Based on the combined evaluations of 20 drivers, the evaluations were indexed using the following formula, where the total score from Examples 4-3 was set to 100, and ride comfort was evaluated relatively. A higher value indicates better ride comfort.

[0289] Ride comfort = [(Total evaluation score of the test tires) / (Total evaluation score of Examples 4-3)] × 100

[0290] Then, as in Experiments 1-3, the evaluation results are summed to obtain a comprehensive evaluation. Table 9 shows the results of each evaluation.

[0291] [Table 9]

[0292]

[0293] Table 9 shows that when the difference in the relationship between virtual volume V and cross-sectional width Wt is not significant, as the cross-sectional width Wt decreases from less than 205 mm to less than 200 mm, and as the flatness increases, the rolling resistance, resistance to falling debris, and ride comfort at high speeds are all improved.

[0294] Although the present invention has been described above based on embodiments, the present invention is not limited to the above embodiments. Various modifications can be made to the above embodiments within the same and equivalent scope as the present invention.

[0295] The present invention (1) is:

[0296] A pneumatic tire, each of its two sides having a sidewall and an overlap, wherein...

[0297] A pneumatic tire satisfies the following equations: (tanδsw + tanδc) ≦ 0.3 and |tanδsw - tanδc| ≦ 0.07.

[0298] In the formula, tanδsw is the loss tangent of the sidewall, and tanδc is the loss tangent of the overlap. Both tanδsw and tanδc are measured under the conditions of 70℃, 10Hz frequency, 5% initial strain, and 1% dynamic strain rate; and

[0299] When a tire is mounted on a standard rim and has an internal pressure of 250 kPa, the tire's cross-sectional width is Wt (mm), its outer diameter is Dt (mm), and the volume of space occupied by the tire is a virtual volume V (mm²). 3 When the tire satisfies the following equations (1) and (2):

[0300] 1700≦(Dt 2 ×π / 4) / Wt≦2827.4····(Equation 1)

[0301] [(V+1.5×10 7 ) / Wt]≦2.88×10 5 ...(Equation 2).

[0302] The present invention (2) is a pneumatic tire according to the present invention (1), wherein the pneumatic tire satisfies the following formula: (E*cE*sw)≦8.0,

[0303] In the formula, the complex elastic modulus of the sidewall is E*sw (MPa), and the complex elastic modulus of the lap joint is E*c (MPa). Both E*sw and E*c are measured under the conditions of 70℃, 10Hz frequency, 5% initial strain, and 1% dynamic strain rate.

[0304] The present invention (3) is an inflatable tire according to the present invention (1) or (2), wherein the following (Formula 3) is satisfied.

[0305] [(V+2.0×10 7 ) / Wt]≦2.88×10 5 ...(Equation 3)

[0306] The present invention (4) is a pneumatic tire according to the present invention (3), wherein the following (Formula 4) is satisfied.

[0307] [(V+2.5×10 7 ) / Wt]≦2.88×10 5 ...(Equation 4)

[0308] The present invention (5) is an inflatable tire according to any combination of (1) to (4) of the present invention, wherein when the tire is mounted on a standard rim and the internal pressure is 250 kPa, the tire outer diameter is Dt (mm) and the tire cross section height is Ht (mm), (Dt-2×Ht) is 470 (mm) or more.

[0309] The present invention (6) is an inflatable tire according to any combination of (1) to (5) of the present invention, wherein the aspect ratio of the tire is 40% or more.

[0310] The present invention (7) is a pneumatic tire according to the present invention (6), wherein the aspect ratio of the tire is 45% or more.

[0311] The present invention (8) is a pneumatic tire according to the present invention (7), wherein the aspect ratio of the tire is 47.5% or more.

[0312] The present invention (9) is a pneumatic tire according to the present invention (8), wherein the aspect ratio of the tire is 50% or more.

[0313] The present invention (10) is a pneumatic tire according to any combination of (1) to (9) of the present invention, wherein,

[0314] The sidewalls and overlaps each contain butadiene rubber as a rubber component, and

[0315] When the butadiene rubber content in the sidewall is Bsw (parts by mass) and the butadiene rubber content in the overlap is Bc (parts by mass), the following (Equation 5) is satisfied:

[0316] 10≦|Bsw-Bc|≦40·····(Equation 5).

[0317] The present invention (11) is a pneumatic tire according to any combination of (1) to (10) of the present invention, wherein the following (Equation 6) is satisfied:

[0318] (tanδsw+tanδc)×V / Wt≦50000···(Equation 6)

[0319] The present invention (12) is a pneumatic tire according to the present invention (11), wherein the following (Equation 7) is satisfied:

[0320] (tanδsw+tanδc)×V / Wt≦45000···(Equation 7).

[0321] The present invention (13) is an inflatable tire according to any combination of (1) to (12) of the present invention, wherein Dt is less than 685 (mm) and Dt (mm) is the outer diameter of the tire when the tire is mounted on a standard rim and the internal pressure is 250 kPa.

[0322] The present invention (14) is an inflatable tire according to any combination of (1) to (13) of the present invention, wherein the cross-sectional width Wt (mm) is less than 205mm.

[0323] The present invention (15) is an inflatable tire according to the present invention (14), wherein the cross-sectional width Wt (mm) is less than 200mm.

[0324] The present invention (16) is an inflatable tire according to any combination of (1) to (15) of the present invention, wherein the thickness S (mm) of the sidewall in the tire width direction at the maximum tire width is 2.0 mm or less.

[0325] The present invention (17) is an inflatable tire according to the present invention (16), wherein the thickness S (mm) of the sidewall in the tire width direction is 1.7 mm or less.

[0326] The present invention (18) is an inflatable tire according to any combination of (1) to (17) of the present invention, wherein (tanδsw+tanδc)<0.17.

[0327] The present invention (19) is an inflatable tire according to any combination of (1) to (18) of the present invention, wherein the tire is an inflatable tire for passenger cars.

Claims

1. A pneumatic tire, each of a pair of sides of the pneumatic tire having a sidewall and an overlap, wherein, The pneumatic tire satisfies the following formula: (tanδsw+tanδc)≦0.3 and |tanδsw-tanδc|≦0.07, In the formula, tanδsw is the loss tangent of the sidewall, and tanδc is the loss tangent of the overlap. Both tanδsw and tanδc are measured under the conditions of 70℃, 10Hz frequency, 5% initial strain, and 1% dynamic strain rate; and When a tire is mounted on a standard rim with an internal pressure of 250 kPa, and the tire's cross-sectional width is Wt, its outer diameter is Dt, and the volume of the space occupied by the tire is a virtual volume V, the tire satisfies the following equations 1 and 4: 1700≦(Dt 2 (×π / 4) / Wt≦2827.4····Equation 1; [(V+2.5×10 7 ) / Wt]≦2.75×10 5 ...Formula 4; The virtual volume V is calculated based on the tire's outer diameter Dt, cross-sectional height Ht, and cross-sectional width Wt, under the condition that the tire is mounted on a standard rim, with an internal pressure of 250 kPa and no load applied, using the following formula: V=[(Dt / 2) 2 -{(Dt / 2)-Ht} 2 ]×π×Wt; The units for the cross-sectional width Wt, outer diameter Dt, and cross-sectional height Ht are mm, and the unit for the virtual volume V is mm. 3 .

2. The pneumatic tire according to claim 1, wherein, The pneumatic tire satisfies the following formula: (E*cE*sw)≦8.0, In the formula, the complex elastic modulus of the sidewall is E*sw, and the complex elastic modulus of the lap joint is E*c. Both E*sw and E*c are measured under the conditions of 70℃, 10Hz frequency, 5% initial strain, and 1% dynamic strain rate. The units are both MPa.

3. The pneumatic tire according to claim 1, wherein, When the tire is mounted on a standard rim and the internal pressure is 250 kPa, with an outer diameter of Dt and a section height of Ht, (Dt-2×Ht) is 470 mm or more.

4. The pneumatic tire according to any one of claims 1 to 3, wherein, The aspect ratio of the pneumatic tire is 40% or more.

5. The pneumatic tire according to claim 4, wherein, The aspect ratio of the pneumatic tire is 45% or higher.

6. The pneumatic tire according to claim 5, wherein, The aspect ratio of the pneumatic tire is 47.5% or higher.

7. The pneumatic tire according to claim 6, wherein, The aspect ratio of the pneumatic tire is 50% or more.

8. The pneumatic tire according to any one of claims 1 to 3, wherein, The sidewalls and overlaps each contain butadiene rubber as a rubber component, and When the butadiene rubber content in the sidewall is Bsw and the butadiene rubber content in the overlap is Bc, the pneumatic tire satisfies the following formula 5: 10≦|Bsw-Bc|≦40·····Equation 5; Both Bsw and Bc are in parts by mass.

9. The pneumatic tire according to any one of claims 1 to 3, wherein, The pneumatic tire satisfies the following equation 6: (tanδsw+tanδc)×V / Wt≦50000···Equation 6.

10. The pneumatic tire according to claim 9, wherein, The pneumatic tire satisfies the following equation 7: (tanδsw+tanδc)×V / Wt≦45000···Equation 7.

11. The pneumatic tire according to any one of claims 1 to 3, wherein, Dt is less than 685mm. Dt is the outer diameter of the tire when it is mounted on a standard rim and the internal pressure is 250kPa.

12. The pneumatic tire according to any one of claims 1 to 3, wherein, The cross-sectional width Wt is less than 205mm.

13. The pneumatic tire according to claim 12, wherein, The cross-sectional width Wt is less than 200mm.

14. The pneumatic tire according to any one of claims 1 to 3, wherein, The thickness S of the sidewall in the tire width direction at the maximum tire width is less than 2.0 mm.

15. The pneumatic tire according to claim 14, wherein, The thickness S of the sidewall in the tire width direction is less than 1.7mm.

16. The pneumatic tire according to any one of claims 1 to 3, wherein, The pneumatic tire satisfies (tanδsw+tanδc)<0.

17.

17. The pneumatic tire according to any one of claims 1 to 3, wherein, The tire is a pneumatic tire for passenger cars.

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