JP2006176077A - Bias tire for mini-car class automobile - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance overturn resistance performance of a vehicle without causing increase of kinds of tire. <P>SOLUTION: The bias tire is provided with: a carcass 6 comprising at least two sheets of carcass plies 6A, 6B in which a carcass cord is arranged at an angle θ1 of 40-55°; and a reinforcement layer 7 comprising at least one sheet of reinforcement ply 7A in which a reinforcement cord is arranged at an angle θ2 in a range of angle θ1±5° with an inclination reverse to the cord of the outermost carcass ply 6B. In the tread part 2, a land part area ratio La of a tread half part 2R on one side with a tire equator C as a center is made larger than a land area ratio Lb of a tread half part 2L on the other side, and the difference (La-Lb) is made to 10-30%. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a bias tire for a minicar-class automobile that is mounted on a minicar-class automobile such as a four-wheeled vehicle with a motor, for example, and can improve the fall resistance performance of the vehicle.

  In recent years, as shown in FIG. 7, small and light minicar class automobiles having a low total displacement such as a four-wheeled vehicle with a prime mover are being used due to advantages such as a small parking space and a comfortable ride like a scooter. This type of vehicle has a narrow wheel range compared to the vehicle height, and therefore has a smaller overturn limit lateral acceleration than that of a normal four-wheel vehicle. There is a fear.

  Therefore, conventionally, different types of tires having different sizes and internal structures are employed for the front and rear wheels, and the vehicle is generally provided with understeer characteristics.

  However, in such a case, it is difficult to replace the position of the tire due to uneven wear, and there is a problem that the tire life is shortened or the running performance is deteriorated due to the progress of uneven wear. In addition, the increase in the types of tires is disadvantageous for tire maintenance and cost.

  Patent Document 1 proposes a radial tire for a light vehicle in which a predetermined organic fiber cord having low elasticity is used for the belt cord and the cornering power is lowered to improve the fall-resistant performance. However, when a tire with this structure is used in a minicar-class car that has a smaller fall limit lateral acceleration than that of a light car, the cornering power is still large, and it is difficult to demonstrate satisfactory anti-falling performance. is there.

JP-A-62-39305

  The present invention adopts a bias structure with a larger cord angle than the conventional one, and increases the type of tire based on making the land area ratio of the tread pattern greatly different on one side and the other side of the tire equator. An object of the present invention is to provide a bias tire for a minicar-class automobile that can improve the overturning resistance performance of the vehicle without incurring.

In order to achieve the above object, the invention of claim 1 of the present application includes a carcass that extends from a tread portion to a bead core of a bead portion through a sidewall portion, and a reinforcement disposed inward of the tread portion and radially outward of the carcass. With layers,
The carcass is composed of at least two carcass plies in which carcass cords are arranged at an angle θ1 of 40 to 55 ° with respect to the tire circumferential direction.
The reinforcing layer includes at least one reinforcing ply in which the reinforcing cord is arranged at an angle θ2 having an inclination opposite to the carcass cord of the outermost carcass ply and in the range of the angle θ1 ± 5 °.
The tread portion has a tread half portion on one side centered on the tire equator, and the land area ratio La of the tread pattern is larger than the land portion area ratio Lb of the tread pattern on the other tread half portion. With the high ground contact surface tread half and the other side tread half as the low ground contact tread half,
A difference (La−Lb) between the land area ratio La of the high ground contact surface tread half and the land area ratio Lb of the low contact surface tread half is 10 to 30%.

In the invention of claim 2, the high ground contact surface tread half portion and the low ground contact surface tread half portion include a longitudinal main groove having a groove width Wg of 3.0 mm or more continuous in the tire circumferential direction, and the low contact surface. The number nb of vertical main grooves in the half portion of the ground tread is made larger than the number na of vertical main grooves in the half portion of the high ground surface tread, and the total sum of the widths Wg of the vertical main grooves in the half portion of the low ground surface tread. Is characterized by being 15-30% of the tread half width Tw. In the invention of claim 3, the low ground contact surface tread half portion is provided with a longitudinal main groove continuous in the tire circumferential direction and a transverse groove in a direction intersecting with the longitudinal main groove, so that at least the blocks are arranged in parallel in the tire circumferential direction. In addition to including one block row, the block is characterized in that the block length L1 in the tire circumferential direction is 1.5 to 3.0 times the block width W1 in the tire axial direction.
According to a fourth aspect of the present invention, the low ground contact surface tread half portion includes siping extending at an angle of 0 to 20 ° with respect to the tire circumferential direction.
In the invention of claim 5, the tread portion is characterized in that a loss tangent tan δ of a tread rubber portion forming a tread surface is set to 0.13 to 0.25.
The invention according to claim 6 is characterized in that the high contact surface tread half portion is arranged on the front wheel of the vehicle and toward the vehicle inner side.
The invention according to claim 7 is characterized in that the high-contact surface tread half portion is arranged on the rear wheel of the vehicle and toward the outside of the vehicle.

  In the present specification, the “tread half width Tw” means a tread surface in the tire axial direction of a tread that can be grounded in a normal load applied state in which a normal internal pressure and a normal load are applied to a tire assembled with a normal rim. It means 1/2 of the width (tread width). The “regular rim” is a rim determined for each tire in the standard system including the standard on which the tire is based, for example, a standard rim for JATMA, “Design Rim” for TRA, or ETRTO means "Measuring Rim". The “regular internal pressure” is the air pressure specified by the tire for each tire. The maximum air pressure in the case of JATMA, the maximum value described in the table “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” in the case of TRA, If it is ETRTO, it means "INFLATION PRESSURE". The “regular load” is the load specified by the standard for each tire. The maximum load capacity shown in the table “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” is the maximum load capacity for JATMA and TRA for TRA. In the case of ETRTO, it means a load obtained by multiplying "LOAD CAPACITY" by 0.88.

  The “land area ratio of the tread pattern” refers to the ratio of the land area SL (actual ground contact area) that is actually grounded to the total area S0 of the tread pattern. (Ratio SL / S0).

  By adopting a bias structure in which the carcass cord angle θ1 is in the range of 40 to 55 ° and the cord angle θ2 of the reinforcing layer is in the range of the angle θ1 ± 5 °, the necessary tire strength is ensured. It is possible to set the lateral rigidity in a balanced and low manner.

  Also, the tread half on one side centered on the tire equator is a high contact surface tread half with a large land area ratio La, and the tread half on the other side is a low ground contact surface with a small land area ratio Lb. In addition to the tread half, the land area ratio difference (La-Lb) is set to 10-30%.

  Therefore, as a front wheel, tires are mounted with the low ground contact surface tread with low pattern rigidity facing the outside of the vehicle, and in combination with the bias structure described above, the maximum value of cornering force generated during turning (hereinafter referred to as CFmax). Value) can be greatly reduced. That is, it is possible to suppress the force of the tire to bend itself and improve the anti-falling performance. Further, in the tire, as a rear wheel, a half portion of the high ground contact surface tread having high pattern rigidity can be mounted toward the outside of the vehicle. At this time, although the CFmax value of the rear wheel is low, it is relatively larger than that of the front wheel, and a large difference can be secured. In other words, since the lateral grip performance of the rear wheel can be set larger than the lateral grip performance of the front wheel, a strong understeer characteristic can be imparted. These synergistic effects make it possible to provide excellent anti-falling performance in a minicar-class automobile having a very small overturning limit lateral acceleration.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a meridional sectional view of a bias tire for a minicar-class automobile according to the present invention. As shown in FIG. 7, the minicar-class automobile is a single-seater minicar defined by the Road Traffic Law having a total displacement of 50 cc (or rated output 0.6 kW) or less, or a low displacement and small size equivalent to this. It means a lightweight one-seater or two-seater four-wheel vehicle.

  As shown in FIG. 1, a bias tire 1 for a minicar-class automobile (hereinafter referred to as a tire 1) according to this embodiment includes a carcass 6 having a bias structure that extends from a tread portion 2 through a sidewall portion 3 to a bead core 5 of a bead portion 4. And a reinforcing layer 7 disposed inward of the tread portion 2 and radially outward of the carcass 6.

  The carcass 6 includes at least two carcass plies 6A and 6B in this example, in which carcass cords are arranged at an angle θ1 (shown in FIG. 2) of 40 to 55 ° with respect to the tire circumferential direction. Each of the carcass plies 6A and 6B is superposed by alternately changing the inclination direction with respect to the tire circumferential direction so that the carcass cords cross each other between the plies. As the carcass cord, a low modulus organic fiber cord such as nylon, polyester, or rayon is adopted.

  Note that the angle θ1 of the conventional bias structure is about 35 to 40 °. In the present invention, by setting the angle θ1 higher than the conventional angle, the tire lateral rigidity is greatly reduced and the CFmax value is kept sufficiently low. Is possible. If the angle θ1 is less than 40 °, the tire lateral stiffness is too high. If the angle θ1 exceeds 55 °, the angle θ1 is too low to ensure the required running performance. Therefore, it is preferable that the angle θ1 has an upper limit value of 50 ° or less and a lower limit value of 45 ° or more.

  The carcass 6 has folded portions 6b that are folded from the inner side to the outer side in the tire axial direction around the bead core 5 on both sides of the main body portion 6a straddling the bead cores 5 and 5, and the main body portion 6a and the folded portion. A bead apex rubber 8 for bead reinforcement extending radially outward from the bead core 5 is disposed between the bead core 6b and the bead core 6b. In this example, the radial height h1 of the bead apex rubber 8 from the bead base line BL is set as low as 0.8 to 2.0 times the rim flange height hf, while the bead apex rubber 8 is a rubber. The hardness (durometer A hardness) is in the range of 70 to 95 °, which is harder than before, and the required bead rigidity is ensured while keeping the tire lateral rigidity low. The folded portion 6b extends radially outward beyond the bead apex rubber 8, and its radial height h2 is 2 to 5 times the rim flange height hf.

  The reinforcing layer 7 is formed of at least one reinforcing ply 7A, in this example, one reinforcing ply 7A in which reinforcing cords are arranged at an angle θ2 in the range of the angle θ1 ± 5 °. The reinforcing ply 7A is placed with the inclination direction opposite to that of the carcass cord of the outermost carcass ply 6B. When there are a plurality of reinforcing plies 7A, the inclinations of the reinforcing plies 7A are alternately changed.

  The reinforcing layer 7 is provided to reinforce the tread portion and protect the carcass 6. When the angle θ2 exceeds the angle range (θ1 ± 5 °), the reinforcing layer 7 is strong between the carcass cord. Since the truss structure is formed, the tire rigidity is significantly increased. Accordingly, it is preferable that the angle θ1 be as close as possible within the above range. As the reinforcing cord, a low modulus organic fiber cord such as nylon, polyester, rayon or the like is adopted, but the same cord as the carcass cord can also be suitably adopted.

  Further, in order to protect the carcass, the reinforcing layer 7 needs to have a width BW that is at least 1.0 times the tread half width Tw. In order to stabilize the ground pressure of the tread surface 2S, the tread width 2 × It is preferably 0.95 to 1.05 times Tw (twice the tread half width Tw). If the reinforcing layer 7 is radially outward from the folded portion 6b of the carcass 6, it can be extended to the inside of the sidewall portion 3 such as in the vicinity of the tire maximum width position M as required.

  A tread rubber G having a tread rubber portion G1 forming the tread surface 2S is disposed outside the reinforcing layer 7. In this example, the tread rubber G is illustrated as having a single layer structure consisting of only the tread rubber portion G1, but a two-layer structure in which a base rubber portion is formed radially inward of the tread rubber portion G1. You can also. In any case, a rubber having a relatively small hysteresis loss and a loss tangent tan δ in the range of 0.13 to 0.25 is used for the tread rubber portion G1, contrary to the conventional tire. Such a rubber has a low road surface friction coefficient such as a reduced hysteresis friction, can reduce the grip performance itself, and is effective in reducing the CFmax value. If the loss tangent tan δ is less than 0.13, the grip performance is excessively impaired. Therefore, the running performance tends to be impaired, for example, a side slip when turning during normal running or a brake lock when braking. Therefore, it is more preferable that the lower limit value of the loss tangent tan δ is 0.15 or more and the upper limit value is 0.20 or less. The loss tangent tan δ is a value measured using a viscoelastic spectrometer under conditions of a temperature of 70 ° C., a frequency of 10 Hz, and a dynamic strain of ± 2%.

  Next, in the tire 1 of the present embodiment, as shown in FIG. 3, the tread half portion 2 </ b> R on the one side (right side in the drawing) centered on the tire equator C of the tread portion 2 is the tread pattern. The tread half portion 10 of the tread pattern in which the land portion area ratio La is larger than the land portion area ratio Lb of the tread pattern 2L of the tread half portion 2L on the other side (left side in the figure), and the tread on the other side The half portion 2L is a low ground contact surface tread half portion 11. In addition, the difference (La−Lb) between the land area ratios La and Lb is set to 10 to 30%.

  In this example, the longitudinal main grooves 13 and 14 extending continuously in the tire circumferential direction are provided in the tread half portions 10 and 11, and the number nb of the longitudinal main grooves 14 in the low ground contact surface tread half portion 11 is set to be high. It is larger (nb> na) than the number na of vertical main grooves 13 in the ground tread half portion 10. The vertical main grooves 13 and 14 are drainage grooves having a groove width Wg of 3.0 mm or more, and the groove depth is 50% or more of the gauge thickness of the tread rubber G. The upper limit of the groove width Wg is not particularly limited, but is preferably 10 mm or less. The upper limit of the groove depth is not more than the maximum groove depth specified by the tire standard such as JATMA.

  In this example, the low ground contact surface tread half portion 11 is provided with first to third longitudinal main grooves 14a to 14c in order from the tire equator C side, and between the longitudinal main grooves 14a and 14b and the longitudinal main groove 14b. , 14c, and between the vertical main groove 14c and the tread end Te, a plurality of horizontal grooves 16 are arranged to divide each of them into a plurality of blocks 15. Accordingly, at least one block row 15R (three in this example) in which the blocks 15 are arranged in parallel in the tire circumferential direction is formed in the low ground contact surface tread half portion 11.

  On the other hand, the high ground contact surface tread half 10 is provided with one vertical main groove 13, and a plurality of blocks 17 are divided between the vertical main groove 13 and the tread end Te into a plurality of blocks 17. A lateral groove 18 is arranged. Accordingly, in the present example in which the blocks 17 are arranged in parallel in the tire circumferential direction, one block row 17R is formed in the high ground contact surface tread half portion 10. In this example, a rib continuous in the tire circumferential direction is formed between the longitudinal main grooves 14a and 13.

  Here, the pattern rigidity of the tread pattern generally increases as the land area ratio increases. Therefore, a difference is made in the land area ratios La and Lb of the tread half portions 10 and 11 on one side and the other side of the tire equator C, and the low ground contact surface tread half portion 11 having low pattern rigidity is directed to the outside of the vehicle as a front wheel. By mounting the tire 1 in combination with the bias structure described above, the maximum value of the cornering force generated during turning (hereinafter referred to as the CFmax value) can be greatly reduced. That is, the force of the tire to bend itself can be kept low, and the anti-tip performance can be improved.

  In the tire 1, a high ground contact surface tread half portion 10 having high pattern rigidity is mounted as a rear wheel toward the outside of the vehicle. At this time, although the CFmax value of the rear wheel is low, it is relatively larger than that of the front wheel, and a large difference can be secured. In other words, since the lateral grip performance of the rear wheel can be set larger than the lateral grip performance of the front wheel, a strong understeer characteristic can be imparted. Therefore, it is possible to exhibit excellent anti-tip performance, particularly in minicar-class automobiles, due to the synergistic effect of having a strong understeer characteristic and a small CFmax value itself.

  If the land area ratio difference (La-Lb) is less than 10%, the effect of suppressing the vehicle overturning cannot be sufficiently exerted, and if it exceeds 30%, the wear difference between the tread half portions 10 and 11 is large during normal driving. It tends to cause uneven wear. The land area ratio L0 of the entire tread surface is preferably in the range of 65 to 75% as in the conventional tire.

  The vertical main grooves 13 and 14 have a greater influence on the pattern lateral rigidity than the horizontal grooves 16 and 18. Accordingly, as the means for reducing the land area ratio Lb, since the number nb of the longitudinal main grooves 14 is increased, the CFmax value can be more effectively reduced. Further, since the difference in CFmax value between the front and rear wheels is relatively large, the understeer characteristic can be further enhanced, which is more advantageous for the anti-falling performance.

  The number nb of the vertical main grooves 14 formed is 5 or less, preferably 2 to 3. In particular, in order to prevent the vehicle from falling, the low ground contact surface tread half portion 11 is provided with at least one longitudinal main groove 14 in a shoulder region Ys that is a 50% width region of the tread half width Tw from the tread end Te. In the high ground contact surface tread half 10, it is preferable not to provide the vertical main groove 13 in the shoulder region Ys. Further, from the viewpoint of the wear life and the effect of suppressing the vehicle toppling, it is preferable that the total sum of the groove widths Wg of the longitudinal main grooves 14 is in the range of 15 to 30% of the tread half width Tw. For the same reason, it is also preferable that the width (in the case of a rib, the rib width) Wb of the block row 15R in the low ground contact surface tread half portion 11 is in the range of 20 to 30% of the tread half width Tw. The block rows 15R (or ribs) may have the same width Wb, but it is preferable to sequentially reduce the width Wb from the tire equator C to the tread end Te in order to reduce the CFmax value. As the width Wb, when the block row 15R (or rib) has a zigzag shape, an average value of the maximum width and the minimum width is adopted.

  On the other hand, in the high ground contact surface tread half portion 10, the width Wa of the block row 17R (or rib) is preferably 1.5 times or more, more preferably 2.0 times or more of the width Wb.

  Next, in the low ground contact surface tread half portion 11, it is preferable that the block 15 has a vertically long shape for the purpose of reducing the pattern lateral rigidity while ensuring the pattern longitudinal rigidity. In particular, the ratio L1 / W1 between the block length L1 in the tire circumferential direction and the block width W1 in the tire axial direction is set to 1.5 to 3.0 from the viewpoint of reducing the CFmax value during turning and the balance of force during braking and driving. Furthermore, it is preferable to set it as 2.0-2.5. In the block 17 of the high ground contact surface tread half 10, the block length L2 is preferably 1.0 to 2.5 times the block length L1.

  Also, in this example, in order to further reduce the CFmax value, as shown in an enlarged view in FIG. 4, the block 15 has siping extending at an angle α of 0 to 20 °, preferably 0 to 10 ° with respect to the tire circumferential direction. 20 is formed.

  Particularly in this example, in the block rows 15R and 15R adjacent to each other in the tire axial direction, the sum Σα / Ls of the ratio between the tire circumferential direction length Ls of each siping 20 and the angle α in the block row 15R outside the tire axial direction. Is a preferable case in which the total sum in the block row 15R on the inner side in the tire axial direction is equal to or less than the sum Σα / Ls. At this time, it is desirable that the sum Σα / Ls of the outermost block row 15R in the tire axial direction is smaller than the sum Σα / Ls on the innermost side in the tire axial direction. In this example, in the outermost block row 15R in the tire axial direction, the number of formed sipings 20 having the smallest angle α (α = 0 ° in this example) is made larger than the number of formed sipings 20 in the inner block row 15R. Thus, the sum Σα / Ls is made small.

  The length Ls of the siping 20 is 40% or less of the block length L1 of the block 15 in this example, and 2 to 4 sipings 20 are spaced within one block 15 in the tire circumferential direction. Is preferred. Further, two to four sipings 20 are arranged in one block 15 in the tire axial direction.

FIG. 5 shows another embodiment of the tread pattern. In FIG.
Two (nb = 2) vertical main grooves 14 are formed in the low ground plane tread half portion 11, and one (na = 2) vertical main grooves 13 are formed in the high ground plane tread half portion 10. ing. The block length L2 of the block 17 of the high ground plane tread half 10 is 2.0 times the block length L1 of the block 15 of the low ground plane tread 11 and is between the longitudinal main grooves 13 and 14. In addition, a block row 22R composed of blocks 22 having the same size (the same width and the same length) as the block 17 is formed.

  As mentioned above, although especially preferable embodiment of this invention was explained in full detail, this invention is not limited to embodiment of illustration, It can deform | transform and implement in a various aspect.

  A tire having a tire size of 110 / 100-8 having the internal structure shown in FIG. 1 was made on the basis of the specifications shown in Table 1, and the anti-tip performance of each sample tire was evaluated. In both examples and comparative examples, the carcass has two plies and uses 1400 dtex / 2 (nylon) or 940 dtex / 2 (nylon) for the carcass cord. The reinforcing layer has one ply and the reinforcing cord uses 940 dtex / 2 (nylon). In the embodiment, the high ground contact surface tread half portion 10 is attached to the vehicle inner side as a front wheel, and the high contact surface tread half portion 10 is attached to the vehicle outer side as a rear wheel.

(1) Fall resistance performance:
Attach a sample tire to a four-wheeled vehicle with a prime mover (with a passenger compartment and a wheel distance of 50 cm or less) with a rim (2.15-8) and internal pressure (front wheel 100 kPa, rear wheel 250 kPa) to determine the J-turn road The overturning limit speed when traveling at a high speed and turning by 180 ° was measured.

  It can be confirmed that the tires of the examples can improve the anti-tip performance.

It is sectional drawing which shows one Example of the bias tire for minicar grade cars of this invention. It is an expanded view which shows notionally the code arrangement of a carcass and a reinforcing layer. It is an expanded view which shows a tread pattern. It is an enlarged view which shows the block of the low ground-contact surface tread half part. It is an expanded view which shows the other Example of a tread pattern. 3 is a development view showing a tread pattern of a tire used in a comparative example of Table 1. FIG. It is a perspective view which illustrates a minicar class automobile.

Explanation of symbols

2 Tread portion 2L, 2R Tread half portion 3 Side wall portion 4 Bead portion 5 Bead core 6 Carcass 6A, 6B Carcass ply 7 Reinforcement layer 7A Reinforcement ply 10 High ground surface tread half portion 11 Low ground surface tread half portion 13, 14 Vertical main Groove 15 Block 15R Block row 16 Horizontal groove 20 Siping G1 Tread rubber part

Claims (7)

A carcass extending from the tread portion through the sidewall portion to the bead core of the bead portion, and a reinforcing layer disposed inside the tread portion and radially outside the carcass,
The carcass is composed of at least two carcass plies in which carcass cords are arranged at an angle θ1 of 40 to 55 ° with respect to the tire circumferential direction.
The reinforcing layer includes at least one reinforcing ply in which the reinforcing cord is arranged at an angle θ2 having an inclination opposite to the carcass cord of the outermost carcass ply and in the range of the angle θ1 ± 5 °.
The tread portion has a tread half portion on one side centered on the tire equator, and the land area ratio La of the tread pattern is larger than the land portion area ratio Lb of the tread pattern on the other tread half portion. With the high ground contact surface tread half and the other side tread half as the low ground contact tread half,
Minicar class, characterized in that a difference (La-Lb) between the land area ratio La of the high contact surface tread half and the land area ratio Lb of the low contact surface tread half is 10 to 30%. Automotive bias tires.   The high ground contact surface tread half portion and the low ground contact surface tread half portion have longitudinal main grooves having a groove width Wg of 3.0 mm or more continuous in the tire circumferential direction, and the longitudinal main grooves in the low ground contact surface tread half portions. Is larger than the number nb of the vertical main grooves in the half portion of the high ground plane tread, and the sum of the groove widths Wg of the vertical main grooves in the half portion of the low ground plane tread is 15 to 30 of the tread half width Tw. The bias tire for a minicar-class automobile according to claim 1, characterized in that it is%.   The low ground contact surface tread half portion includes at least one block row in which the blocks are arranged in parallel in the tire circumferential direction by providing a longitudinal main groove that is continuous in the tire circumferential direction and a lateral groove that intersects the longitudinal main groove. The block according to claim 1 or 2, wherein the block has a block length L1 in the tire circumferential direction that is 1.5 to 3.0 times the block width W1 in the tire axial direction. tire.   The bias tire for a minicar class vehicle according to any one of claims 1 to 3, wherein the low ground contact surface tread half portion includes siping extending at an angle of 0 to 20 ° with respect to a tire circumferential direction.   The bias tire for a minicar class vehicle according to any one of claims 1 to 4, wherein the tread portion has a loss tangent tan δ of a tread rubber portion forming a tread surface of 0.13 to 0.25.   The bias tire for a minicar-class automobile according to any one of claims 1 to 5, wherein the high ground contact surface tread half portion is arranged on a front wheel of the vehicle and toward an inner side of the vehicle.   The bias tire for a minicar-class automobile according to any one of claims 1 to 5, wherein the high-contact-surface tread half portion is arranged on a rear wheel of the vehicle and toward an outer side of the vehicle.

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