JP2016141317A - Pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of improving steering stability during straight traveling and cornering traveling, while achieving the steering stability during straight traveling and that during cornering traveling with an appropriate balance.SOLUTION: In a pneumatic tire, both of radial direction inner ends 35b, 36b of inner/outer side reinforcement layers 35, 36 are both located more on an inner side in the radial direction from radial direction outer ends 22a of a filler 22, so that a sidewall portion 14 is reinforced in a wide range to increase rigidity and both of straight advance steering stability and turning steering stability are improved. Moreover, since the radial direction outer end 35a of the inner side reinforcement layer 35 is located more on an outer side in the radial direction from the radial direction outer end 36a of the outer side reinforcement layer 36, the straight advance steering stability is further improved. As a result, a driver can travel comfortably even on an ordinary road where a ratio of straight traveling is larger than that of cornering traveling.SELECTED DRAWING: Figure 1

Description

    The present invention relates to a pneumatic tire in which a side reinforcing layer in which a reinforcing cord is embedded is disposed in a sidewall portion.

    As conventional pneumatic tires, for example, those described in Patent Document 1 below are known.

JP 2010-202122 A

  This includes a pair of bead portions each having a bead core embedded therein, a pair of sidewall portions extending radially outward from these bead portions, and a tread portion connecting the radially outer ends of these sidewall portions. In addition, a side reinforcing layer in which reinforcing cords made of a plurality of organic fibers are embedded is disposed only in a sidewall portion that is outside the vehicle when mounted on the vehicle. As described above, the side reinforcement layer is not arranged on the vehicle inner side, but only on the side wall portion on the outer side of the vehicle, so that the rigidity of the side wall portion on the outer side of the vehicle, which is important at the time of cornering driving, is increased, and the cornering driving is performed. The handling stability at the time is improved.

    Here, when actually traveling on a general road, the ratio of straight traveling is larger than the ratio of cornering traveling, but the one described in Patent Document 1 improves only the steering stability during cornering traveling, No improvement measures have been taken with respect to steering stability during straight running. For this reason, when trying to travel on a general road, there has been a problem that performance, in particular, steering stability during straight traveling is insufficient.

  An object of the present invention is to provide a pneumatic tire capable of improving the steering stability during straight traveling and cornering while satisfying an appropriate balance.

    Such a purpose is that a pair of bead portions each embedded with a bead core, a pair of sidewall portions extending radially outward from these bead portions, and a tread portion connecting the radially outer ends of these sidewall portions. A pneumatic tire that is applied to both front and rear wheels of a vehicle, wherein a side reinforcing layer in which a reinforcing cord made of a plurality of organic fibers is embedded is disposed in the sidewall portion. While the reinforcing layers are arranged on both sidewalls, the radially outer end of the inner side reinforcing layer, which is the inner side when mounted on the vehicle, is radially outward from the radially outer end of the outer side reinforcing layer, which is the outer side of the mounting. The inner and outer side reinforcing layers are positioned at the inner ends in the radial direction from the outer ends in the radial direction of the filler in which the inner ends in the radial direction are in close contact with the bead core. The pneumatic tire is positioned radially inside, it can be achieved.

  In this invention, the side reinforcing layers are arranged on both side wall portions, and the radial inner ends of the inner side reinforcing layer and the outer side reinforcing layer, which are the inner mounting side and the outer side reinforcing layer when mounting on the vehicle, are used as the radius of the filler. Since both the sidewalls between the radially outer end of the filler and the radially outer end of the side reinforcing layer are reinforced by the side reinforcing layer, since they are positioned radially inward from the outer end of the direction. As a result, the rigidity becomes high, and the steering stability during straight traveling is considerably improved, and the steering stability during cornering is sufficiently improved. In addition, in the present invention, since the radially outer end of the inner side reinforcing layer is positioned radially outward from the radially outer end of the outer side reinforcing layer, the steering stability during straight traveling is further improved. In addition, the steering stability during straight running is sufficient. Here, as described above, the reason why the steering stability during the straight traveling is further improved is that the pneumatic tire is usually attached to the vehicle with a negative camber attached, and therefore the tread portion on the inner side of the pneumatic tire is mainly used during the straight traveling. This is because the rigidity of the sidewall portion on the inner side, which is the main grounding side, can be increased by reinforcing the inner side reinforcing layer in a wide range. For this reason, it is possible to improve the steering stability during straight travel and cornering while maintaining an appropriate balance, and it is possible to travel comfortably on ordinary roads where the straight travel ratio is greater than the cornering travel ratio. I will be able to.

  Moreover, if comprised as described in Claim 2, the steering stability at the time of straight running can fully be improved. Furthermore, if it comprises as described in Claim 3, the crack generation | occurrence | production in the radial direction outer end of an inner side and an outer side side reinforcement layer can be suppressed effectively, and tire durability improves. According to the fourth aspect of the present invention, the pneumatic tire having the inner and outer side reinforcing layers can be easily manufactured, and the durability of the tire can be improved. Furthermore, if it comprises as described in Claim 5, the tire noise at the time of driving | running | working can be reduced easily. Moreover, if comprised as described in Claim 6, the steering stability at the time of straight running can be improved effectively. Furthermore, if it comprises as described in Claim 7, the steering stability at the time of cornering driving | running | working can further be improved. Moreover, if comprised as described in Claim 8, the steering stability at the time of cornering driving | running | working can be improved, suppressing the fall of uneven wear resistance.

1 is a cross-sectional view in the width direction of a pneumatic tire showing Embodiment 1 of the present invention. FIG.

Embodiment 1 of the present invention will be described below with reference to the drawings.
1 and 2, reference numeral 11 denotes a pneumatic tire having a flatness ratio of 40% or more to be mounted on a vehicle such as a passenger car. The pneumatic tire 11 has a pair of bead portions 13. A pair of bead cores 12 is embedded. Reference numeral 14 denotes a pair of sidewall portions that extend radially outward from the bead portion 13, and these sidewall portions 14 are curved in a convex shape toward the outer side in the tire width direction. The pneumatic tire 11 includes a substantially cylindrical tread portion 15 that connects the outer ends in the radial direction of the sidewall portions 14.

  The pneumatic tire 11 includes a carcass layer 18 that reinforces the sidewall portion 14 and the tread portion 15. The carcass layer 18 is disposed between a pair of bead cores 12 and extends in a toroidal shape, and the main body Continuing on both side ends of the portion 18a, it is composed of a folded portion 18b which is turned around the bead core 12 from the inner side in the axial direction toward the outer side in the axial direction. The carcass layer 18 is composed of at least one carcass ply 19 here, and this carcass ply 19 is 70 to 90 degrees with respect to the tire equator plane S (a plane passing through the tire equator and perpendicular to the tire rotation axis). A plurality of non-stretchable parallel belt cords, for example, steel cords, which cross at the cord angles of each other, ie, extend substantially in the radial direction (meridian direction), are coated with a coating rubber.

  22 is a filler having a pair of annular shapes extending radially outward while the radially inner end is in close contact with the bead core 12, and these fillers 22 are made of high-hardness (high rigidity) rubber and are sidewalls in the vicinity of the bead portion 13. The deformation of the portion 14 is suppressed. These fillers 22 are disposed in close contact with the main body 18a and the folded portion 18b. Reference numeral 23 denotes a belt layer disposed radially outward of the carcass layer 18 (main body portion 18a) in the tread portion 15. The belt layer 23 includes at least two (here, two) belt plies 24 in the radial direction. It is configured by stacking.

  Each belt ply 24 is constituted by coating a plurality of non-stretchable parallel belt cords made of, for example, steel or aromatic polyamide with a coating rubber. The belt cords constituting the belt plies 24 are inclined at an angle of 10 to 50 degrees with respect to the tire equatorial plane S, and the inclination directions of at least two belt plies 24 are opposite to each other. Reference numeral 25 denotes a top tread disposed radially outward of the carcass layer 18 and the belt layer 23 in the tread portion 15, and a plurality of main grooves 26 extending in the circumferential direction on the outer surface of the top tread 25 and the main grooves A plurality of lateral grooves 27 intersecting with 26 are formed. Reference numeral 28 denotes a side tread disposed on both outer sides in the axial direction of the carcass layer 18 (main body portion 18a).

  Reference numeral 31 denotes side reinforcing layers respectively disposed on both side wall portions 14, and these side reinforcing layers 31 are composed of at least one, here, one side reinforcing ply 32. The side reinforcing layer 31 (side reinforcing ply 32) is formed by covering a plurality of reinforcing cords parallel to each other with a coating rubber. As a result, the inside of the side reinforcing layer 31 (side reinforcing ply 32) is formed. A plurality of reinforcing cords are embedded in the. Here, these reinforcing cords are made of organic fiber cords such as polyester such as polyethylene terephthalate, nylon, rayon, and aromatic polyamide, and are inclined in the same direction at an angle of 20 to 45 degrees with respect to the tire circumferential direction. As a result, the cut ends of these reinforcing cords are exposed at the radially outer end and the radially inner end of the side reinforcing layer 31 (side reinforcing ply 32). If steel having high compression rigidity is used as the reinforcing cord, the rolling resistance of the pneumatic tire 11 deteriorates and cannot be used.

  And in this embodiment, when these pneumatic tires 11 are mounted on the vehicle, the radially outer end 35a of the inner side reinforcing layer 35 that is the mounting inner side (vehicle inner side) is the outer side that is the mounting outer side (vehicle outer side). While the radially outer end 36 a of the side reinforcing layer 36 is positioned radially outward, the radially inner end 35 b of the inner side reinforcing layer 35 and the radially inner end 36 b of the outer side reinforcing layer 36 are both of the filler 22. It is located radially inward from the radially outer end 22a. In this way, the side reinforcing layers 31 are arranged on both side wall portions 14, while the radially inner end 35b of the inner side reinforcing layer 35 and the radially inner end 36b of the outer side reinforcing layer 36 are both in the radial direction of the filler 22. If the outer end 22a is positioned radially inward (the inner and outer side reinforcing layers 35 and 36 are radially overlapped with the radially inner ends of the filler 22 in the tire axial direction), the filler The sidewall 14 between the radially outer end 22a of 22 and the radially outer end of the side reinforcing layer 31 is reinforced by the inner and outer side reinforcing layers 35 and 36 in any part, and the rigidity is increased. As a result, the steering stability (straight-ahead maneuverability) during straight traveling is considerably improved, and the steering stability (turning maneuverability) during cornering traveling is sufficiently improved.

  In addition, as described above, the radially outer end 35a of the inner side reinforcing layer 35 that is the inner side of the mounting is positioned radially outward from the radial outer end 36a of the outer side reinforcing layer 36 that is the outer side of the mounting. Since the height position of the end 35a is increased (the distance from the tire rotation axis is increased), the steering stability during straight traveling is further improved, and the steering stability during straight traveling is also sufficient. Here, the reason why the steering stability is further improved when traveling straight as described above is that the pneumatic tire 11 is usually attached to the vehicle while being provided with a negative camber. This is because the rigidity of the side wall 14 on the inner side of the mounting, which is the main grounding side, can be increased by reinforcing the inner side reinforcing layer 35 in a wider range. For this reason, it is possible to improve the steering stability during straight travel and cornering while maintaining an appropriate balance, and it is possible to travel comfortably on ordinary roads where the straight travel ratio is greater than the cornering travel ratio. I will be able to. In the present invention, the inner and outer side reinforcing layers 35 and 36 described above may be composed of two or more side reinforcing plies. In this case, any one of the inner side reinforcing layers is formed. The outer ends in the radial direction of the side reinforcing plies may be positioned radially outward from the outer ends in the radial direction of all the side reinforcing plies constituting the outer side reinforcing layer. When the inner and outer side reinforcing layers 35 and 36 are composed of two or more side reinforcing plies as described above, the inclination direction of the reinforcing cords in the side reinforcing plies that are in close contact with each other is reversed. That's fine.

  In this embodiment, the pneumatic tire 11 as described above is applied to both the front and rear wheels of a vehicle such as a passenger car, and as a result, the above-described effects can be obtained with all the wheels. The effect is powerful. Here, the mounting inner side means a side closer to the center in the width direction of the vehicle than the tire equator plane S when the pneumatic tire 11 is mounted on the vehicle, and the vehicle outer side means a tire equator when mounted on the vehicle. The side farther from the center in the width direction of the vehicle than the surface S is said. The radial distance L between the radially outer end 35a of the inner side reinforcing layer 35 and the radially outer end 36a of the outer side reinforcing layer 36 is within a range of 0.01 to 0.15 times the tire cross-section height H. It is preferable to do. The reason for this is that, as will be understood from Test Example 1 to be described later, if the value of L / H is less than 0.01, the effect of improving the steering stability during straight running is not sufficient, while the L / H If the value exceeds 0.15, cracks will occur at either the radially outer end 35a of the inner side reinforcing layer 35 or the radially outer end 36a of the outer side reinforcing layer 36, resulting in a slight decrease in tire durability. This is because, within the above-mentioned range, it is possible to appropriately improve steering stability during straight traveling while maintaining tire durability.

  Here, the tire cross-sectional height H is the outermost position in the tire radial direction from the bead base line B when a pneumatic tire is assembled to a standard rim, 80% of the normal internal pressure is filled, and no load is applied. The radial distance to. Further, the bead base line B is parallel to the tire rotation axis through the intersection (the rim diameter position of the standard rim) of the beat base contour and the axial outer contour of the bead portion in the tire width direction cross section (the meridian cross section). A straight line. Furthermore, the above-mentioned normal internal pressure is the air pressure corresponding to the maximum load (maximum load capacity) in the applicable size / ply rating described in the following standard, and the standard rim is described in the following standard. Standard rim (or "DESIGN RIM", "Recommended Rim") at the applicable size. The standards are determined by industrial standards effective in the region where tires are produced or used. For example, “The Tire and Rim Association Inc. Year Book” in the United States and “The European Tire and Rim Technical Organization's Standards Manual ”corresponds to“ JATMA Year Book of Japan Automobile Tire Association ”in Japan.

  Further, both the radially outer end 35a of the inner side reinforcing layer 35 and the radially outer end 36a of the outer side reinforcing layer 36 are 0.45 to 0.60 times the tire cross-sectional height H from the bead base line B to the radially outer side. It is preferable that the positions are separated from each other. The reason for this is E / H or F obtained by dividing the radial distances E and F from the bead base line B to the radial outer ends 35a and 36a by the tire cross-section height H, as will be understood from Test Example 2 described later. If any of the values of / H is less than 0.45 or exceeds 0.60, the cut ends of the reinforcing cords exposed at the radially outer ends 35a and 36a are subjected to a large strain during traveling and are liable to crack. Although tire durability will fall a little, if it exists in the above-mentioned range, the above cracks can be suppressed effectively and tire durability can be improved. When the value of the radial distance L exceeds 0.15 times the tire cross-section height H, either the radial outer end 35a of the inner side reinforcing layer 35 or the radial outer end 36a of the outer side reinforcing layer 36 is selected. Is outside the range of 0.45 to 0.60 times the tire cross-section height H, and cracks are likely to occur as described above.

  Further, both the inner and outer side reinforcing layers 35 and 36 are closely arranged on the inner side in the width direction of the main body portion 18a of the carcass layer 18, or the entire inner side and outer side reinforcing layers 35 and 36 are arranged on the outer side in the width direction of the main body portion 18a of the carcass layer 18. Closely arranged (radially inner part is located between the main body part 18a and the filler 22), and the radially outer part is closely arranged on the outer side in the width direction of the main body part 18a of the carcass layer 18, while the radially inner side Is disposed in close contact with the inner side in the width direction of the folded portion 18b of the carcass layer 18 (positioned between the filler 22 and the folded portion 18b of the carcass layer 18), and the outer portion in the radial direction is the main body portion of the carcass layer 18 The inner side in the radial direction can be closely arranged on the outer side in the width direction of the folded portion 18b of the carcass layer 18 while being arranged in close contact with the outer side in the width direction of 18a. Steering stability during driving On, and it is possible to further improve the steering stability during straight running.

  Here, in this embodiment, both the inner and outer side reinforcing layers 35 and 36 are arranged on the outer side in the width direction of the main body portion 18a of the carcass layer 18 while directly adhering without interposing any members ( The inner part in the radial direction is located between the main body part 18a and the filler 22. However, in this way, the belt-like inner and outer side reinforcing layers are supplied to the outer side of the cylindrical carcass layer in the manufacturing stage. Since the inner and outer side reinforcing layers can be formed simply by winding the tire, the pneumatic tire 11 having the inner and outer side reinforcing layers 35 and 36 can be easily manufactured, and deformation during running is suppressed. The durability of can be improved.

  Further, in this embodiment, in addition to the radially outer end 35a of the inner side reinforcing layer 35 being positioned radially outward from the radially outer end 36a of the outer side reinforcing layer 36 as described above, the carcass layer 18 (If a plurality of carcass plies are used, the innermost carcass ply is used. In this embodiment, the carcass ply 19 is used, and thus the carcass ply 19 is used.) When the length along the carcass layer 18 from the tire equatorial plane S to the radially inner end of the bead core 12 is the carcass peripheral length P, the carcass peripheral length Po on the outer side is the carcass peripheral length on the inner side. It is larger than Pi. When both are combined in this way, the transmission timing to the rim of the vibration applied to the pneumatic tire 11 due to the unevenness of the road surface during traveling will be different between the inner side and the outer side of the mounting, Since the rigidity of the sidewall portion 14 is different, the natural frequency is different between the mounting inner side and the mounting outer side, and the resonance is lowered. As a result, road noise transmitted to the occupant's ear through tire vibration through the rim and the vehicle body is reduced, and tire noise during traveling can be easily reduced.

  In general, the ground contact length of the tread portion 15 is shortened by the negative camber on the outer side of the wearing. However, as described above, the carcass peripheral length Po on the outer side of the wearing is made larger than the carcass peripheral length Pi on the inner side of the wearing. In this case, the contact length on the outside of the wearing is increased, and the steering stability during cornering is improved. The carcass peripheral length P described above is obtained by cutting the pneumatic tire in the tire width direction and then crossing the carcass layer (innermost carcass ply) and the tire equatorial plane S on the cross section in the width direction. The distance to the point where the carcass layer and a straight line passing through the radially inner end of the bead core and parallel to the tire rotation axis intersect can be determined by measuring along the carcass layer.

  In this embodiment, as described above, the radius from the bead base line B to the maximum tire width position W is set so that the carcass peripheral length Po on the outer side of the mounting is larger than the carcass peripheral length Pi on the inner side of the mounting. The directional distance is increased from the inner side to the outer side, and the tire half width from the tire equatorial plane S to the maximum tire width position W is increased from the inner side to the inner side. In the present invention, Po> Pi may be set by only one of the above-described configurations, that is, only the former or only the latter. Here, the tire maximum width position is parallel to the tire equatorial plane S in a cross section in the width direction of the tire when a pneumatic tire is mounted on a standard rim and filled with a normal internal pressure to be in an unloaded state. The position where the drawn tangent line touches the outer contour of the sidewall excluding patterns, characters and rim guards.

  The carcass peripheral length Po on the outer side of the mounting is preferably in the range of 1.010 to 1.030 times the carcass peripheral length Pi on the inner side of the mounting. The reason for this is that, as will be understood from Test Example 3 to be described later, when the Po / Pi value is less than 1.010 or more than 1.030, the steering stability during straight running is slightly reduced. If it does so, the steering stability at the time of straight running can be improved effectively, and the balance between straight running maneuverability and turning maneuverability can be easily made appropriate. The reason why the steering stability slightly decreases when the Po / Pi value exceeds 1.030 is that the tread portion 15 on the outer side of the mounting projects outward in the radial direction, and the tread portion 15 on the outer side of the mounting mainly contacts the ground. Because it becomes like this.

  Furthermore, in this embodiment, the negative rate of the tread portion 15 on the inner side of the mounting is set larger than the negative rate of the tread portion 15 on the outer side of the mounting. In this way, since the land area in the tread portion 15 on the outer side of the mounting increases, the ground contact area during cornering traveling increases, and thereby, the steering stability during cornering traveling easily improves. Here, the negative rate is a numerical value expressed as a percentage of the total area of the openings of the grooves (main groove 26, lateral groove 27) located within the unit area when the unit area of the tread portion 15 is 100%. The smaller the figure, the wider the land area.

  When the total area of the openings of the grooves (main grooves 26, lateral grooves 27) formed in the tread portion 15 is M, the total area N of the openings of the grooves formed in the outer tread portion 15 is The total area Q of the openings of the grooves formed in the tread portion 15 on the inner side of the mounting is preferably in the range of 0.71 to 0.61 times the M, while the range is 0.29 to 0.39 times the M. The reason for this is that, as will be understood from Test Example 4 to be described later, when the N / M value exceeds 0.39 on the outer side of the wearing (the Q / M value is 0.61 or lower on the inner side of the wearing), the steering during cornering traveling is performed. If the N / M value is less than 0.29 on the outer side (Q / M value is 0.71 or more on the inner side), the ground contact area on the outer tread portion 15 is not sufficient. The steering stability when running straight ahead is slightly reduced, but if it is within the above-mentioned range, the steering stability during cornering running and straight running is improved, so that straight running stability and turning maneuverability are improved. This is because the balance can be easily made appropriate.

    Next, Test Example 1 will be described. In this test, the conventional tire in which the side reinforcing layer is disposed only on the outer side of the mounting, the comparative tires 1 and 2 having L / H values of 0.004 and 0.008, and the L / H values of 0.010 and 0.013, respectively. Test tires 1, 2, and 3 having 0.145 and comparative tires 3 and 4 having L / H values of 0.160 and 0.170, respectively, were prepared. Here, the size of each tire described above was 215 / 65R16, and the tire was mounted on a rim having a size of 6.5J-16. In addition, the outer and inner radial ends of the outer side reinforcing layer in each tire are separated from the bead base line by 0.586 times and 0.258 times the tire cross-section height H, and the inner side reinforcement in each tire (excluding conventional tires). The inner radial end of the layer is separated from the bead baseline by 0.256 times the tire cross-section height H. Further, the radially outer end of the inner side reinforcing layer in the test tire 2 is separated from the bead base line by 0.599 times the tire cross-section height H. However, the inner side reinforcing layer in other tires excluding the conventional tire and the test tire 2 is used. The height position of the outer radial direction of the test tire 2 is different from the radial outer end of the test tire 2 by the above-described difference.

  A plurality of reinforcing cords made of polyethylene terephthalate inclined at 40 degrees with respect to the circumferential direction are embedded in the outer and inner side reinforcing layers of each tire. In addition, the outer radial ends of the fillers located on the outer and inner sides of each tire are separated from the bead baseline by 0.375 times and 0.379 times the tire cross-section height H. As a result, the outer and inner sides of each tire are separated. The inner end in the radial direction of the reinforcing layer (the inner side reinforcing layer does not exist only in the conventional tire) is located radially inward from the outer end in the radial direction of the filler. Further, in each tire except the conventional tire, the radial distance from the bead base line B to the tire maximum width position W is increased from the inner side to the outer side of the mounting, and from the tire equatorial plane S to the maximum tire width position W. By making the tire half width larger from the inner side to the inner side of the mounting, the carcass peripheral length Po on the outer side of the mounting is set to 1.018 times (Po / Pi = 1.018) of the carcass peripheral length Pi on the inner side of the mounting. In the conventional tire, the Po / Pi value is 1. Furthermore, when the total area of the groove openings formed in the tread portion of each tire excluding the conventional tire is M, the total areas N and Q of the groove openings formed in the outer tread portion and the inner tread portion are defined as above. 0.34 and 0.66 times M. In the conventional tire, the values of N / M and Q / M were both 0.50.

  Next, after assembling each of these tires on the rim, each tire was filled with an internal pressure (gauge pressure) of 250 kPa, and mounted on all front and rear wheels of a 2300cc class domestic passenger car. In the test course consisting of a round circuit that includes a round and a gently-curved handling evaluation road, etc., run at a speed range from low speed to around 100km / h. Steering stability (straight running stability) and cornering during straight running The driving stability (swinging maneuverability) during driving was evaluated by a skilled test driver bar on a 10-point scale. In addition, while pressing the standard load (the maximum load in the applicable size and ply rating described in the above standard) on each of the tires, it is pressed against the drum and continuously running on the drum at 60 km / h, Alternatively, the mileage when a failure occurred at the radially outer end of the inner side reinforcing layer was measured, and the tire durability was determined with the mileage of the test tire 2 as an index of 100. The results are shown in Table 1 below. As understood from Table 1, when the value of L / H is less than 0.01, the effect of improving the steering stability during straight running is not sufficient, When the value of L / H exceeds 0.15, the tire durability is slightly lowered.

    Next, Test Example 2 will be described. In this test, the test tire 2 described above and the comparison tires 5 and 6 having the same specifications as the test tire 2 except that the E / H values are 0.650 and 0.620, respectively, and the E / H values are respectively Test tires 4 and 5 having the same specifications as the test tire 2 except for 0.600 and 0.450, and comparative tires having the same specifications as the test tire 2 except that the values of F / H are 0.430 and 0.400, respectively. 7 and 8 were prepared. Next, each tire described above was subjected to an endurance test under the same conditions as the above-described endurance test, and the durability of the tire was determined with the distance traveled at the time of failure as the distance traveled by the test tire 2 as an index of 100. The results are shown in Table 2 below. As understood from Table 2, when the E / H value exceeds 0.60 or the F / H value is less than 0.45, the tire durability is slightly reduced. ing.

    Next, Test Example 3 will be described. In this test, except for the test tire 2 described above and the Po / Pi values of 1.000 and 1.005, the comparison tires 9 and 10 having the same specifications as the test tire 2 and the Po / Pi value of 1.010, Test tires 6 and 7 having the same specifications as the test tire 2 except 1.030, and comparative tires 11 and 12 having the same specifications as the test tire 2 except that Po / Pi values are 1.035 and 1.040 Got ready. Next, a traveling test was performed on each of the tires described above under the same conditions as the traveling test described above, and straight running stability was obtained. The results are shown in Table 3 below. As understood from Table 3, when the Po / Pi value is less than 1.010 and exceeds 1.030, the steering stability during straight running is not sufficient.

    Next, Test Example 4 will be described. In this test, the test tire 2 was the same as the test tire 2 except that the N / M value was 0.45 (Q / M value was 0.55) and 0.41 (Q / M value was 0.59), respectively. Except for the comparative tires 13 and 14, which are the original, and the N / M value is 0.39 (Q / M value is 0.71) and 0.29 (Q / M value is 0.81), the same specifications as the test tire 2 are used. A comparative tire having the same specifications as test tire 2 except that some test tires 8 and 9 have an N / M value of 0.27 (Q / M value is 0.73) and 0.23 (Q / M value is 0.77). 15 and 16 were prepared.

  Next, a traveling test was performed on each of the tires described above under the same conditions as the traveling test described above to determine the turning stability during cornering traveling and the steering stability during straight traveling. The results are shown in Table 4 below. As understood from Table 4, when the value of N / M exceeds 0.39 on the outside of the wearing (the value of Q / M is 0.61 or less on the inside of the wearing), On the other hand, if the N / M value is less than 0.29 on the outer side (Q / M value is 0.71 or higher on the inner side), The ground contact area at the tread portion is reduced and the steering stability during straight running is slightly reduced.

  The present invention can be applied to the industrial field of pneumatic tires in which a side reinforcing layer in which a reinforcing cord is embedded is disposed in a sidewall portion.

11 ... Pneumatic tire 12 ... Bead core
13 ... Bead part 14 ... Side wall part
15 ... Tread 18 ... Carcass layer
18a ... Body part 18b ... Folding part
22… Filler 22a… Radial outer edge
31… Side reinforcement layer 35… Inner side reinforcement layer
35a ... Radial outer end 35b ... Radial inner end
36 ... Outer side reinforcement layer 36a ... Radial outer end
36b ... Radial inner edge

Claims (8)

    A pair of bead portions each having a bead core embedded therein, a pair of sidewall portions extending radially outward from these bead portions, and a tread portion connecting the radially outer ends of these sidewall portions. In a pneumatic tire applied to both front and rear wheels of a vehicle, a side reinforcing layer in which reinforcing cords made of a plurality of organic fibers are embedded is disposed in the wall portion. The outer side radial layer outer end of the inner side reinforcing layer which is the inner side when mounted on the vehicle is positioned on the outer side in the radial direction from the outer radial direction end of the outer side reinforcing layer which is the outer side of the mounting. Both the radially inner ends of the outer side reinforcing layers are located radially inward from the radially outer ends of the fillers whose radially inner ends are in close contact with the bead core. Pneumatic tire, characterized in that it was.     The air according to claim 1, wherein a radial distance L between a radially outer end of the inner side reinforcing layer and a radially outer end of the outer side reinforcing layer is set in a range of 0.05 to 0.15 times a tire cross-sectional height H. Enter tire.     3. The pneumatic tire according to claim 1, wherein the radially outer ends of the inner and outer side reinforcing layers are both positioned radially outward from the bead base line B by 0.45 to 0.60 times the tire cross-section height H. 4. .     2. The inner and outer side reinforcing layers are both disposed in close contact with the outer side of a carcass layer main body including a toroidal main body disposed between a pair of bead cores and a folded portion folded around the bead core. The pneumatic tire as described in any one of -3.     The length along the carcass layer from the tire equatorial plane S to the radially inner end of the bead core of the carcass layer composed of a toroidal body portion disposed between the pair of bead cores and a folded portion folded back around the bead core. The pneumatic tire according to any one of claims 1 to 3, wherein a carcass peripheral length Po on the outer side of the mounting is greater than a carcass peripheral length Pi on the inner side of the mounting, where is a carcass peripheral length P. .     The pneumatic tire according to claim 5, wherein the carcass peripheral length Po on the outer side of the mounting is within a range of 1.010 to 1.030 times the carcass peripheral length Pi on the inner side of the mounting.     The pneumatic tire according to any one of claims 1 to 6, wherein a negative rate of the tread portion on the inner side of the mounting is greater than a negative rate of the tread portion on the outer side of the mounting.     Assuming that the total area of the groove openings formed in the tread portion is M, the total area N of the groove openings formed in the outer tread portion of the mounting is in the range of 0.29 to 0.39 times M. On the other hand, the pneumatic tire according to claim 7, wherein the total area Q of the opening portions of the grooves formed in the tread portion on the inner side of the mounting is within a range of 0.71 to 0.61 times the M.

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