JP4015280B2 - Tire and rim assembly - Google Patents

Description

【００４９】
表１のように、実施例のタイヤは、非ランフラット性の通常タイヤ（従来例２）と略同程度のタイヤ重量、転がり抵抗性能等の諸性能を維持しながら、ランフラット性能を大巾に向上しうるのが確認できた。
【００５０】
【発明の効果】
本発明のタイヤとリムの組立体は叙上の如く構成し、ランフラット時にタイヤ内腔面間で互いに接触する部分及び路面と接触する部分を集中的に強化しているため、運転者に空気抜けをタイヤ変形によって認識させうるとともに、一般リムの使用を可能とし、しかもタイヤ重量、転がり抵抗、リム着脱性等の諸性能を損ねることなく、ランフラット性能を向上できる。
【図面の簡単な説明】
【図１】本発明の一実施例のタイヤとリムの組立体の断面図である。
【図２】その内腔面上方領域及び内腔面下方領域を説明する断面図である。
【図３】式(1) 〜(2) 及び式(4) 〜(7) で用いる係数Ｋａｂを説明する線図である。
【図４】タイヤの内圧０での変形状態を示す断面図である。
【符号の説明】
１ 空気入りタイヤ
２ トレッド部
３ サイドウォール部
４ ビード部
５ ビードコア
６ カーカス
１０ リム
１０Ａ リムシート面
１０Ｂ フランジ面
２０ ゴム層
１１ ビードヒール点
１１Ｌ ヒール点半径線
Ｓ タイヤ内腔面[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an assembly of a tire and a rim having a run-flat performance that enables traveling over a certain distance even when air escape occurs in the tire.
[0002]
[Background Art and Problems to be Solved by the Invention]
There is a demand for a tire having a so-called run-flat performance that enables continuous running even when the internal pressure of the tire decreases due to puncture or the like.
[0003]
Conventionally, in this type of tire, for example, a core-like support made of an elastic body or the like is mounted inside the tire, or a hard rubber reinforcing layer is provided on the inner surface of the side wall portion, thereby puncturing the tire. The tire load acting on the tire is supported to reduce the vertical deflection, thereby suppressing the structural breakdown of the tire.
[0004]
However, in the case of using a support, the weight increases as the number of parts increases, and a special technique is required to set the support when assembling the rim. Often required. In addition, in order to reduce the vertical deflection of the tire, it is necessary to form a rubber reinforcing layer thickly in a wide area centering around the maximum width point of the tire, which is the bending point. Inevitable increase in weight and rolling resistance is impaired. Also, as the rigidity of the sidewall increases, it becomes easier to remove the rim during puncture, so a special rim is often used.
[0005]
In addition, these tires all reduce vertical deflection, so it is difficult for the driver to notice air deflation. At times, there is a risk of losing control of the car body and causing a major accident.
[0006]
In view of the circumstances described above, the present inventor, for run-flat performance, does not suppress the vertical deflection of the tire but does not destroy the tire itself during running in the flat deformation state Y at the internal pressure 0 shown in FIG. It has been found that suppression is preferable for maintaining tire performance during normal driving and preventing accidents during run-flat driving.
[0007]
And as a result of accumulating research on the mechanism of tire destruction in the deformed state Y, as shown in FIG. 4, in the deformed state Y, the side wall portion Z folds up and down and contacts at the rim flange upper end position RF. When traveling, the upper and lower folded portions Z1 and Z2 are strongly rubbed at the contact portion J, and wear and heat generation start. On the other hand, on the tire outer surface side, the tire outer surface is dragged to the road surface at a position above the contact portion J and starts to wear and generate heat.
[0008]
The rubber on the tire inner surface and the outer surface of the tire is worn or peeled off due to this wear and heat generation, so that the carcass is exposed, and the carcass or the carcass and the road surface are directly rubbed together to break the carcass cord. It turns out that it leads to fatal damage.
[0009]
And in order to suppress tire destruction based on this mechanism, it is necessary to make it difficult for the carcasses or between the carcass and the road surface to contact each other. As a simplest means, the rubber thickness under the carcass is secured to some extent. In addition, it has been found that by increasing the strength of the rubber interposed between the carcass and the road surface, it is possible to greatly improve the travel distance until the tire breaks.
[0010]
That is, the present invention is based on the principle that the rubber under the carcass at the contact portion is thickened within a predetermined range, and a high elastic rubber layer having a predetermined complex elastic modulus is provided on the tire outer surface above the contact portion. The tire and rim can be recognized by tire deformation and can be used for general rims, and can improve the run-flat performance without impairing the tire weight, rolling resistance, rim detachability, etc. The purpose is to provide an assembly.
[0011]
[Means for Solving the Problems]
To achieve the above object, the present invention provides a tire and rim assembly comprising a pneumatic tire and a rim on which a bead portion is seated.
The pneumatic tire has a carcass extending from the tread portion through the sidewall portion to the bead core of the bead portion and filled with a standard measurement internal pressure.
The tire thickness up to the closest point AT of the tire outer surface at the upper intersection point a where the heel point radius line extending in the radial direction through the bead heel point where the rim seat surface and the flange surface of the rim intersect with each other intersects the tire lumen surface on the tread portion side. The ratio of Wa to the rubber thickness wa from the upper intersection a to the closest point AC of the inner surface of the carcass, and the tire outer surface at the lower intersection b where the heel point radius line intersects the tire lumen surface on the bead side. The ratio wb / Wb between the tire thickness Wb to the nearest point BT and the rubber thickness wb from the lower intersection b to the nearest point BC on the inner surface of the carcass is 0.20 to 0.65, respectively.
The upper region LA including at least the nearest point AT on the outer surface of the tire is formed by a rubber layer having a complex elastic modulus (unit: Mpa) of 7.0 or more and 13.0 or less ,
And the upper region LA is characterized in that thickness of 1.5 to 5.0 mm.
[0012]
In order to more reliably achieve an improvement in run flat performance, the upper region LA is separated from the distance LA1 expressed by the following equation (1) on the tread portion side along the tire outer surface with the closest point AT as the center. A range between the point A1 and the point A2 leaving the distance LA2 represented by the expression (2) on the bead portion side is preferable.
0.30 · Kab ≦ LA1 ≦ 0.65 · Kab (1)
0.20 · Kab ≦ LA2 ≦ 0.30 · Kab (2)
Here, Kab is the tire lumen from the heel point radius line at the height H in the radial direction between the upper intersection a and the lower intersection b and the height intermediate point e between the upper intersection a and the lower intersection b. It calculates | requires by the following (3) Formula from the length M to a surface.
Kab = {(H ² + 4M ² ) / 4M} · SIN ⁻¹
{4H · M / (H ² + 4M ² )} (3)
[0013]
Also in order to enhance the protective effect of the rubber strength up and carcass in the upper region LA is the rubber layer, arbitrary preferred that the loss factor tanδ is the rubber from 0.035 to 0.18.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a meridional section of an assembly of a pneumatic tire 1 and a rim 10 that is mounted on a rim and filled with a measured internal pressure and filled with a measured internal pressure. The “standard measurement internal pressure” is the air pressure defined by each standard for each tire in the standard system including the standard on which the tire is based. The maximum air pressure for JATMA and the table “TIRE LOAD for TRA” The maximum value described in “LIMITS AT VARIOUS COLD INFLATION PRESSURES”, “INFLATION PRESSURE” in the case of ETRTO. In the case of passenger car tires, it is 180 KPa.
[0015]
In the drawing, a pneumatic tire 1 (hereinafter referred to as a tire 1) is a radial tire for a passenger car having a tire size of 185 / 60R14 in this example, and includes a tread portion 2 and tire radial inner sides from both ends of the tread portion 2. A pair of side wall portions 3 extending and a bead portion 4 positioned at the inner end of each side wall portion 3 are provided.
[0016]
The rim 10 is determined by a standard such as JATMA. In this example, the rim 10 is a 5 ° deep rim for a passenger car, and includes a rim seat surface 10A for receiving the bottom surface of the bead portion 4 and a flange surface for receiving the outer surface of the bead portion 4. 10B. The rim 10 has the rim width of the applicable rim by the distance between the heel point radius lines 11L and 11L extending in the radial direction through the bead heel point 11 where the rim seat surface 10A and the flange surface 10B intersect.
[0017]
In addition, a carcass 6 is bridged between the bead portions 4 and 4 in the tire 1, and a strong belt layer 7 is filled outside the carcass 6 and inside the tread portion 2, and inside the carcass 6 is filled. An inner liner 12 that holds the internal pressure hermetically is disposed.
[0018]
The carcass 6 is formed from at least one carcass ply, in this example, folded from the inner side to the outer side in the tire axial direction around the bead core 5 of the bead part 4 through the side wall part 3 from the tread part 2. Is done. This carcass ply has a carcass cord arranged at an angle of 75 to 90 degrees with respect to the tire equator C. As the carcass cord, an organic fiber cord such as nylon, rayon, or polyester can be suitably employed.
[0019]
Further, a bead apex rubber 8 rising from the bead core 5 toward the outer side in the tire radial direction is filled between the ply body 6A of the carcass 6 and the folded portions 6B on both sides of the carcass 6 to enhance the rigidity of the tire lateral groove.
[0020]
The belt layer 7 is composed of one or more belt plies 7a and 7b for passenger car tires. The belt layer 7 reinforces almost the entire width of the tread portion 2 with a tagging effect. The tire is restrained with a large flatness ratio of%. Each belt ply 7a, 7b has a belt cord arranged at an angle of 0 to 30 degrees with respect to the tire equatorial plane C, and a high elastic material such as a steel cord or an aromatic polyamide cord is used for the belt cord. It is done.
[0021]
The inner liner 12 is a rubber layer that is excellent in gas impermeability mainly composed of butyl rubber such as butyl rubber and halogenated butyl rubber, and has a substantially uniform thickness of, for example, about 0.5 to 2.0 mm. The bead cores 5 and 5 are arranged along the inner surface of the ply body 6A.
[0022]
Next, in the tire 1 of the present application, as shown in FIG. 4, in order to reinforce the contact portion J where the tire cavity surfaces S contact each other and the road surface contact portion JA on the outer surface of the tire at the time of run-flat. The road surface contact portion JA is formed of the highly elastic rubber layer 20 after the rubber thickness under the carcass 6 at the contact portion J is secured within a predetermined range.
[0023]
In this example, upper and lower protective rubber layers 13 and 14 are provided on the inner surface of the inner liner 12 in order to secure the rubber thickness under the carcass 6.
[0024]
The upper protective rubber layer 13 extends radially outward from the vicinity of the tire maximum width position 9 where the sidewall portion 3 bulges most outward in the tire axial direction when the tire is filled with the measured internal pressure. An upper surface Sa of the surface S (hereinafter referred to as a tire lumen upper surface Sa) is formed. The lower protective rubber layer 14 extends radially inward from the vicinity of the tire maximum width position 9, thereby forming a lower surface Sa of the tire lumen surface S (hereinafter referred to as a tire lumen lower surface Sb). is doing. The term “near” the tire maximum width position 9 means a region separating a distance of 10% or less of the tire cross-section height from the tire maximum width position 9 inward and outward in the radial direction.
[0025]
Further, due to the formation of the upper and lower protective rubber layers 13 and 14, in the measured internal pressure filling state, the upper intersection point a where the heel point radius line 11L intersects the tire lumen upper surface Sa and the tire lumen lower surface The rubber thicknesses wa and wb under the carcass 6 at the lower intersection b intersecting with Sb are increased.
[0026]
Specifically, the ratio wa / Wa between the tire thickness Wa from the upper intersection a to the nearest point AT of the outer surface of the tire and the rubber thickness wa from the upper intersection a to the nearest point AC of the inner surface of the carcass 6 is 0.20. The ratio of the tire thickness Wb from the lower intersection b to the nearest point BT of the outer surface of the tire at the lower intersection b and the rubber thickness wb from the lower intersection b to the nearest point BC of the inner surface of the carcass wb / Wb is increased to a range of 0.20 to 0.65.
[0027]
Here, the upper and lower intersections a and b are reference positions of the contact portion J, and at the time of run flat, rubbing occurs around the upper and lower intersections a and b. Therefore, by increasing at least the rubber thicknesses wa and wb to the above ranges, it is possible to earn a traveling distance until the carcass 6 is exposed and directly rubbed.
[0028]
The upper and lower protective rubber layers 13 and 14 are relatively thin and are separated from each other in the vicinity of the tire maximum width position 9, so that the tire weight and longitudinal rigidity are not excessively increased, and the vehicle travels normally. Various performances such as ride comfort and rolling resistance can be maintained, and at the time of puncture, the driver can recognize air loss.
[0029]
If the ratio wa / Wa and the ratio wb / Wb are each less than 0.2, the protective effect of protecting the carcass 6 from friction and heat generation is not sufficiently exhibited, and the run-flat performance cannot be improved. On the other hand, if it exceeds 0.65, the tire weight and the rolling resistance are unnecessarily increased, and various performances such as rolling resistance are impaired as compared with a normal tire (non-runflat tire). Therefore, the ratio wa / Wa and the ratio wb / Wb are preferably 0.2 to 0.45. In the bead portion 4, a rim line or the like is sometimes formed to be thick, and therefore the rubber thickness wb at the lower intersection b is preferably set to 2.0 mm or more.
[0030]
The upper and lower protective rubber layers 13 and 14 are mainly made of the rubber thicknesses wa and wb, and can be formed of the same quality as the inner liner 12 or the carcass topping rubber. However, from the viewpoint of the protective effect, it is preferable to form with a low heat-generating rubber having a loss coefficient tan δ of 0.035 or more and 0.18 or less. As a result, it is possible to suppress the deterioration of the protective rubber layers 13 and 14 themselves due to the heat generation at the contact portion J, or the inner liner 12 and the carcass 6 and the like, thereby improving the protective effect. If the loss coefficient tan δ is less than 0.035, the rubber is soft and the protective effect is not sufficiently achieved. Conversely, if it exceeds 0.18, heat is likely to be generated and thermal deterioration of the rubber cannot be suppressed. Therefore, the loss coefficient tan δ is more preferably 0.05 or more and 0.15 or less.
[0031]
Further, the upper and lower protective rubber layers 13 and 14 are preferably rubbers having excellent mechanical strength such as cut resistance and abrasion resistance. Therefore, the complex elastic modulus (unit: Mpa) is 7.0 or more and 13. Those of 0 or less can be suitably used. Since the complex elastic modulus of the inner liner 12 is usually about 3.5 Mpa and the complex elastic modulus of the carcass topping rubber is about 4.2 Mpa, the above range increases the mechanical strength and provides a high protective effect. Can be obtained. If it is less than 7.0, the rubber reinforceability is small, and if it exceeds 13.0, the strain increases and the rolling resistance is deteriorated. Here, the loss coefficient tan δ and the complex elastic modulus are values measured using a viscoelastic spectrometer manufactured by Iwamoto Seisakusho under conditions of a temperature of 70 ° C., a frequency of 10 Hz, and a dynamic strain rate of 2%.
[0032]
On the other hand, as a result of experiments by the inventors of the present application, the contact position of the contact portion J is actually a lumen surface centered on the upper intersection a due to the influence of lateral force at the time of route change, turning, etc. It was found that the upper region La and the inner surface lower region Lb centered on the lower intersection b vary.
[0033]
Therefore, in order to achieve the protective effect on the carcass 6 more reliably, as shown in FIG. 2, each of the regions La, Lb is provided in both the lumen surface upper region La and the lumen surface lower region Lb. The ratio wi / Wi between the tire thickness Wi up to the closest point IT on the outer surface of the tire at an arbitrary position i and the rubber thickness wi up to the closest point IC on the inner surface of the carcass at the position i is 0 It is preferable to be in the range of 20 to 0.65.
[0034]
Here, the lumen surface upper region La is a point a1 that leaves a distance La1 expressed by the following expression (4) on the tread portion 2 side along the tire lumen upper surface Sa with the upper intersection a as a center, and a bead It means a region between the point a2 and the part La2 that is separated from the distance La2 expressed by the equation (5) on the part side. The lower lumen surface region Lb has a point b1 on the side of the bead portion 4 and a point b1 that leaves a distance Lb1 expressed by the following expression (6) on the tread portion 2 side along the tire lumen lower surface Sb with the lower intersection b as a center. Mean a region between the point b2 and the distance Lb2 expressed by the equation (7).
[0035]
The equations (4) to (7) are as follows.
0.40 · Kab ≦ La1 ≦ 0.75 · Kab (4)
0.20 · Kab ≦ La2 ≦ 0.30 · Kab (5)
0.40 · Kab ≦ Lb1 ≦ 0.65 · Kab (6)
0.20 · Kab ≦ Lb2 ≦ 0.30 · Kab (7)
In addition, Kab in the equation is the radial height H between the upper intersection a and the lower intersection b and the heel point radius line at the height intermediate point e between the upper intersection a and the lower intersection b. This is obtained from the following equation (3) from the length M from 11L to the tire cavity surface S.
Kab = {(H ² + 4M ² ) / 4M} · SIN ⁻¹
{4H · M / (H ² + 4M ² )} (3)
[0036]
As schematically shown in FIG. 3, the Kab is defined as a single circular arc S0 passing through the tire cavity surface S between the upper and lower intersections a and b through the upper and lower intersections a and b and the middle point m. This corresponds to the distance between the upper and lower intersections a and b along the tire cavity surface S when approximated.
[0037]
Thus, in each position i of the lumen surface upper region La and the lumen surface lower region Lb, the ratio wi / Wi is set to 0.20 to 0.65 so that actual contact is made at the time of run flat. The feared portion can be protected by the upper and lower protective rubber layers 13 and 14, and the improvement of the run flat performance can be further ensured. When the distances La1, La2, Lb1, and Lb2 are smaller than 0.4 times, 0.2 times, 0.4 times, and 0.2 times of Kab, the protective effect on the carcass is reduced. If it exceeds 0.75 times, 0.30 times, 0.65 times, and 0.30 times, an unnecessary weight increase and a decrease in rolling resistance will be caused.
[0038]
In the present application, the upper and lower protective rubber layers 13 and 14 may be formed between the carcass 6 and the inner liner 12. Further, in order to secure the rubber thicknesses wa and wb, the carcass topping rubber or the inner liner 12 itself is locally thickened, and the upper and lower protective rubber layers 13, 14 may be configured.
[0039]
Next, in the tire of the present application, in order to reinforce the road surface contact portion JA in a concentrated manner, a reinforcing rubber layer 20 is formed in an upper region LA including the nearest point AT on the outer surface of the tire. The closest point AT is the reference position of the road surface contact portion JA, and at the time of run flat, rubbing occurs in the upper area LA centered on the closest point AT. Accordingly, the upper area LA corresponds to the road surface contact portion JA.
[0040]
The rubber layer 20 is made of a highly elastic rubber having a complex elastic modulus (unit: Mpa) of 7.0 or more and 13.0 or less, and is reinforced against rubbing against a road surface by increasing rubber strength and wear resistance. Increases the effect. When the complex elastic modulus is less than 7.0 MPa, the necessary reinforcing effect is not exhibited. Conversely, when the complex elastic modulus exceeds 13.0 MPa, the strain increases and the rolling resistance is excessively deteriorated.
[0041]
The rubber layer 20 preferably has low heat buildup for carcass protection, and low heat exothermic rubber having a loss coefficient tan δ of 0.035 to 0.18 can be suitably used. Thereby, deterioration of the rubber layer 20 itself due to heat generation at the road surface contact portion JA or deterioration of the tread rubber and the carcass 6 can be suppressed, and the protective effect can be improved. If the loss coefficient tan δ is less than 0.035, the rubber is soft and the protective effect is not sufficiently achieved. Conversely, if it exceeds 0.18, heat is likely to be generated and thermal deterioration of the rubber cannot be suppressed. Therefore, the loss coefficient tan δ is more preferably 0.05 or more and 0.15 or less.
[0042]
In order to obtain sufficient reinforcement and protection effects, the thickness of the rubber layer 20 is in the range of 1.5 to 5.0 mm . If it is less than 1.5 mm, the reinforcing and protective effects are poor, and if it exceeds 5.0 mm, the rolling resistance is unnecessarily reduced.
[0043]
Here, the upper area LA is centered on the nearest point AT along the tire outer surface at a point A1 leaving the distance LA1 expressed by the following equation (1) on the tread portion 2 side and on the bead portion 4 side by the equation (2). It is an area between the point A2 away from the distance LA2 to be expressed, and as a result of the inventor's experiment, it was found that rubbing mainly occurs in this area. Kab in the equation is an approximate value of the distance between the upper and lower intersections a and b along the tire cavity surface S determined by the equation (3) as described above.
0.30 · Kab ≦ LA1 ≦ 0.65 · Kab (6)
0.20 · Kab ≦ LA2 ≦ 0.30 · Kab (7)
[0044]
When the distances LA1 and LA2 are smaller than 0.3 times and 0.2 times of Kab, respectively, the reinforcement and protection effect on the carcass is reduced, and conversely, when the distance exceeds 0.65 times and 0.30 times. Unnecessary rolling resistance is reduced.
[0045]
【Example】
A tire having the structure shown in FIG. 1 was prototyped based on the specifications in Table 1, and the tire weight, rolling resistance performance, and run-flat performance of each sample tire were compared.
[0046]
In the table, Conventional Example 1 is a conventional run-flat tire in which a high-hardness rubber reinforcing layer is provided on the inner surface of the sidewall portion to reduce vertical deflection, and Conventional Example 2 is a non-run-flat normal tire. In Examples 1 to 3 and Comparative Examples 1 and 2, the upper and lower protective rubber layers are formed on the inner liner inner surface.
[0047]
・ Tire weight:
The weight per sample tire is measured, and is displayed as an index with the conventional example 2 being 100. A smaller index is better.
・ Rolling resistance performance:
Using a rolling resistance tester, each sample tire is mounted on a commercially available rim determined by the standards such as JATMA, and the rolling resistance is measured at a standard measurement internal pressure (180 kPa), speed (80 km / h), and load (415 kgf). Conventional example 2 is displayed as an index of 100. A smaller index is better.
・ Run-flat performance:
The test tire is assembled to the applicable rim and mounted on a passenger car (FR car) with an internal pressure of 0 kPa, and the test tire is run at a speed of straight travel (50 km / h) and turning (40 km / h). The comparison was made in terms of the distance traveled (km) until the tire was destroyed.
[0048]
[Table 1]

[0049]
As shown in Table 1, the tires of the examples have a wide run-flat performance while maintaining various performances such as a tire weight and rolling resistance performance that are substantially the same as those of a non-run-flat normal tire (conventional example 2). It was confirmed that it could be improved.
[0050]
【The invention's effect】
The tire and rim assembly according to the present invention is configured as described above, and the portion that contacts each other and the portion that contacts the road surface during the run-flat are intensively strengthened. The slippage can be recognized by the tire deformation, the general rim can be used, and the run-flat performance can be improved without impairing various performances such as tire weight, rolling resistance, and rim detachability.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a tire and rim assembly according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view illustrating the upper lumen surface region and the lower lumen surface region;
FIG. 3 is a diagram illustrating a coefficient Kab used in equations (1) to (2) and equations (4) to (7).
FIG. 4 is a cross-sectional view showing a deformed state of the tire when the internal pressure is zero.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Pneumatic tire 2 Tread part 3 Side wall part 4 Bead part 5 Bead core 6 Carcass 10 Rim 10A Rim seat surface 10B Flange surface 20 Rubber layer 11 Bead heel point 11L Heel point radius line S Tire lumen surface

Claims (3)

A tire and rim assembly comprising a pneumatic tire and a rim seated on its bead,
The pneumatic tire has a carcass extending from the tread portion through the sidewall portion to the bead core of the bead portion and filled with a standard measurement internal pressure.
The tire thickness up to the closest point AT of the tire outer surface at the upper intersection point a where the heel point radius line extending in the radial direction through the bead heel point where the rim seat surface and the flange surface of the rim intersect with each other intersects the tire lumen surface on the tread portion side. The ratio of Wa to the rubber thickness wa from the upper intersection a to the nearest point AC of the inner surface of the carcass, and the outer surface of the tire at the lower intersection b where the heel point radius line intersects the tire lumen surface on the bead side. The ratio wb / Wb between the tire thickness Wb to the nearest point BT and the rubber thickness wb from the lower intersection b to the nearest point BC on the inner surface of the carcass is 0.20 to 0.65, respectively.
The upper region LA including at least the nearest point AT on the outer surface of the tire is formed by a rubber layer having a complex elastic modulus (unit: Mpa) of 7.0 or more and 13.0 or less ,
And the upper region LA is tire and rim assembly of the thickness is characterized by a 1.5 to 5.0 mm. The upper region LA has a point A1 that leaves a distance LA1 expressed by the following formula (1) on the tread portion side along the tire outer surface with the closest point AT as a center, and a distance LA2 expressed by formula (2) on the bead portion side. 2. The tire / rim assembly according to claim 1, wherein the tire / rim assembly is a region between the point A2 and the point A2.
0.30 · Kab ≦ LA1 ≦ 0.65 · Kab (1)
0.20 · Kab ≦ LA2 ≦ 0.30 · Kab (2)
Here, Kab is the length from the heel point radius line to the tire lumen surface at the height H in the radial direction between the upper intersection a and the lower intersection b and the height intermediate point e between the upper intersection a and the lower intersection b. It calculates | requires from following M by the following (3) Formula.
Kab = {(H ² + 4M ² ) / 4M} · SIN ⁻¹
{4H · M / (H ² + 4M ² )} (3)   The tire and rim assembly according to claim 1 or 2, wherein the upper region LA is made of rubber having a loss coefficient tan δ of 0.035 or more and 0.18 or less.

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