JP2006347457A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the motion performance of the tire by setting a rubber gauge within a predetermined area (so called shoulder area) from the ground contact end of a tread section asymmetrically in the right and left in a pneumatic tire having a plurality of tire air chambers. <P>SOLUTION: Since one side rubber gauge TGI is set larger than the other rubber gauge TGO for the rubber gauge of the tread section 16 in a shoulder area 36, the distribution of the ground contact pressure of the shoulder area 36 becomes asymmetric, and the lateral force F from the rubber gauge TGO side toward the rubber gauge TGI is generated in the straight running. The lateral force F is generated from the outside of the tire mounted to the vehicle toward the inside and the operation stability becomes very excellent by making the rubber gauge TGI side be the inside of the tire mounted to the vehicle, and making the rubber gauge TGO side be the outside of the tire mounted to the vehicle. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a pneumatic tire in which a plurality of tire air chambers are formed when mounted on a rim.

The conventional tire chamber that can be filled with air obtained when a general tire is mounted on a rim has been one chamber, but at least one partition wall is provided on the inner side of the tire and is independent from the rim. Tires in which a plurality of tire air chambers are formed have also been developed (see Patent Document 1).
JP 2003-39914 A

  However, the above-described conventional example only discloses that a plurality of tire air chambers are formed by providing the partition walls, and does not suggest any setting of the rubber gauge in the so-called shoulder region of the tread portion. It has not been.

  In consideration of the above facts, the present invention is a pneumatic tire having a plurality of tire air chambers, and by setting a rubber gauge within a predetermined range (so-called shoulder region) from the ground contact end of the tread portion, The purpose is to improve performance.

  In a pneumatic tire in which, for example, two partition walls are provided and three air chambers are formed when the rim is mounted, the main air chamber on the inner side in the tire width direction mainly shares the belt tension and is located on both sides in the tire width direction. The first auxiliary air chamber and the second auxiliary air chamber share the carcass tension of the sidewall portion, and the internal pressure of each air chamber can be set independently.

  For this reason, for example, by setting the internal pressure of the main air chamber to be lower than the normal internal pressure of the conventional tire and setting the internal pressure of the first sub air chamber and the second sub air chamber to be higher than the normal internal pressure of the conventional tire, It is possible to control the balance of tire stiffness, which is impossible with conventional tires, such as increasing the lateral stiffness (lateral spring) while lowering the stiffness (vertical spring).

  The three air chamber tire is a tire having such characteristics. However, as a result of further research, the left and right auxiliary air chambers (the first auxiliary air chamber and the second auxiliary air chamber) are set to different internal pressures. It has been newly verified that lateral force is generated mainly from the low pressure side to the high pressure side when going straight. This is because the tension stiffness of the left and right outer sidewalls and the left and right bulkheads is asymmetric on both sides of the tire equator, resulting in asymmetric contact pressure distribution. As a result, the lateral force (lateral force) when running straight Is considered to occur.

  In addition, when a normal tire rolls with a slip angle and a camber angle of 0, a price tear force and a consistency force are generated as uniformity components, but this time also when subtracting those contributions The existence of the generated lateral force was verified. Since this lateral force acts in the same direction as the lateral force generated when a negative camber angle is given to the tire, it will be referred to as “pseudo camber thrust” for convenience.

  Furthermore, in the case of a three-chamber internal pressure combination in which a sufficient lateral force is generated from the outside of the vehicle to the inside of the vehicle by a steering stability test conducted with tires attached to the test vehicle, the steering stability Is newly verified to be very good. This improvement in steering stability is almost the same as when the wheels are set to toe-in in terms of vehicle alignment, and the improvement in motion performance can be explained by a mechanism almost the same as that of toe-in.

  Here, it will be described what kind of tire ground contact shape is a satisfactory level that generally has no problem in motion performance. The ground contact shape with zero slip angle and camber is divided into three in the tire width direction, that is, the so-called center region and the left and right shoulder regions. Is slightly shorter than the ground contact length of the center region (generally about 10 to 20%). That is, it is considered that deterioration in tire ground contact causes a decrease in exercise performance even if the contact length of either one of the left and right shoulder regions is too short or too long.

  Accordingly, the invention of claim 1 includes a pair of left and right outer bead portions in which bead cores are embedded, a sidewall portion extending outward in the tire radial direction from the outer bead portion, a tread portion connected to the sidewall portion, The outer bead portion is provided between the pair of outer bead portions so as to be spaced apart in the tire width direction, and extends inward in the tire radial direction from a base portion on the tire inner surface side in at least one of the sidewall portion and the tread portion, One or more partitions that form a plurality of independent tire air chambers in the tire width direction between the inner bead portion provided at the inner end in the tire radial direction and the rim when the inner bead portion is attached to the rim; If the ground contact width of the tread portion is TW, the tires from the ground contact ends on both sides of the tire equatorial plane in the cross section in the tire axial direction. Measured in a direction perpendicular to the tread surface from the outermost surface of the reinforcing layer to the tread surface of the reinforcing layer located in the lower layer of the tread portion in a range of at least 20% of the contact width TW from the ground end in the range to the equator surface. The average rubber gauge is characterized in that one rubber gauge TGI is larger than the other rubber gauge TGO.

  Here, the range of 20% of the contact width TW from the contact end to the tire equatorial plane side refers to a so-called shoulder region, and the range of the shoulder region set in this way is less than 20%. This is because the asymmetry of the distribution is insufficient and the magnitude of the lateral force (pseudo camber thrust) is not so large as to improve the motion performance, which is not preferable.

  The grounding end means that a pneumatic tire is mounted on a standard rim specified in JATMA YEAR BOOK (2004 edition, Japan Automobile Tire Association Standard), and the maximum load capacity (internal pressure) in the applicable size and ply rating in JATMA YEAR BOOK. -When the maximum load capacity is loaded by filling the internal pressure of 100% of the air pressure (maximum air pressure) corresponding to the bold load in the load capacity correspondence table. When the TRA standard or ETRTO standard is applied at the place of use or manufacturing, the respective standards are followed.

  TGI> TGO, if TGI <TGO, the direction of the lateral force (pseudo camber thrust) from the side having the tread rubber of the rubber gauge TGI is the rubber gauge TGO even if the internal pressure of each tire chamber is the same. When the tread rubber side of the rubber gauge TGI is set to the vehicle mounting inner side, and the tread rubber side of the rubber gauge TGO is set to the outer side of the vehicle mounting, it is toe-out if compared to vehicle alignment. This is because the same movement performance degradation as the setting occurs, which causes a safety problem.

  In the pneumatic tire according to claim 1, since the rubber gauge TGI on the inner side of the vehicle is set larger than the rubber gauge TGO on the outer side of the vehicle for the so-called shoulder region rubber gauge of the tread portion, the rigidity in the shoulder region is left-right asymmetric. Thus, the contact pressure distribution is also asymmetric. Due to the asymmetrical contact pressure distribution, a lateral force (pseudo camber thrust) is generated from the side having the tread rubber of the rubber gauge TGO toward the side having the tread rubber of the rubber gauge TGI when traveling straight. Accordingly, by setting the side having the tread rubber of the rubber gauge TGI as the vehicle mounting inner side and the side having the tread rubber of the rubber gauge TGO as the vehicle mounting outer side, this lateral force is generated from the vehicle mounting outer side to the inner side. The properties are very good.

  According to a second aspect of the present invention, in the pneumatic tire according to the first aspect, when the average gauge of the tread rubber is MG, the rubber gauge TGO and the rubber gauge TGI are 0.1 × MG ≦ TGI−TGO ≦ 0.5. It is characterized by satisfying the relationship of × MG.

  Here, TGI-TGO ≧ 0.1 × MG is set so that if TGI-TGO <0.1 × MG, the difference in rubber gauge between the left and right shoulder regions is small, so the lateral force (pseudo camber thrust) is also This is because it becomes smaller and it is difficult to clearly improve the handling stability.

  In addition, TGI-TGO ≦ 0.5 × MG is set such that TGI-TGO> 0.5 × MG has a sufficient lateral force (pseudo camber thrust) for improving exercise performance. However, as a result of the extremely large left-right asymmetry of the contact shape and contact pressure distribution, the contact property of the tire is deteriorated and the exercise performance is likely to be deteriorated.

  In the pneumatic tire according to claim 2, since the range of the difference between the rubber gauges TGI and TGO is appropriately set, the contact pressure distribution can be appropriately asymmetrical, thereby deteriorating the contact property. In addition, a sufficient lateral force (pseudo camber thrust) for improving exercise performance can be generated from the side having the tread rubber of the rubber gauge TGO toward the side having the tread rubber of the rubber gauge TGI. By setting the side having the tread rubber as the vehicle mounting inner side and the side having the tread rubber of the rubber gauge TGO as the vehicle mounting outer side, the steering stability can be improved.

  According to a third aspect of the present invention, in the pneumatic tire according to the first or second aspect, when the average gauge of the tread rubber is MG, the rubber gauge TGO and the rubber gauge TGI are 0.5 × MG ≦ TGO <. It is characterized by satisfying the relationship of TGI ≦ 1.5 × MG.

  Here, TGO ≧ 0.5 × MG is set such that when TGO <0.5 × MG, the average value of the rubber gauge in the tire width direction of the tread portion becomes considerably thin. This is because the input when getting over the vehicle is increased, and the vibration ride comfort is deteriorated.

  The reason why TGI ≦ 1.5 × MG is that when TGI> 1.5 × MG, the average value of the rubber gauge in the tire width direction of the tread portion becomes considerably thick. This is because the absolute level of athletic performance is reduced by the decrease, and as a result, it is difficult to clearly improve the handling stability even if the rubber gauge is changed on the left and right.

  In the pneumatic tire according to claim 3, since the ranges of the rubber gauges TGI and TGO are appropriately set, the contact pressure distribution can be made moderately asymmetrical, and thereby the contact property is not deteriorated. A sufficient lateral force (pseudo camber thrust) for improving the movement performance can be generated from the tread rubber side of the rubber gauge TGO toward the tread rubber side of the rubber gauge TGI, and the tread rubber of the rubber gauge TGI. If the side having the tread rubber of the rubber gauge TGO is the vehicle mounting inner side, the steering stability can be improved.

  According to a fourth aspect of the present invention, in the pneumatic tire according to any one of the first to third aspects, the radius from the tire center to the rim base line of the outer bead portion is RO, and If the radius of the inner bead portion to the rim base line is RI, 0 <RO-RI <50 mm.

  When the relationship between the radius RO of the outer bead portion and the radius RI of the inner bead portion is RO = RI, the tall hump for preventing the inner bead portion formed on the partition wall from moving outward in the tire axial direction. It is necessary to use a rim provided with a portion, and the assembling work must be very difficult. Further, when RO-RI ≧ 50 mm, it is difficult and unrealistic to manufacture a tire using the current tire manufacturing method.

  Further, when the relationship between the radius RO of the outer bead portion and the radius RI of the inner bead portion becomes RO−RI ≧ 50 mm, the radius of the inner bead portion becomes too small with respect to the radius of the outer bead portion, and accordingly the rim As a result, the diameter of the brake that can be mounted inside the rim is reduced. This is not preferable because it may cause a decrease in vehicle motion performance.

  Therefore, it is preferable to satisfy 0 <RO-RI <50 mm because it is possible to prevent inconvenience as described above.

  According to a fifth aspect of the present invention, when the pneumatic tire according to any one of the first to fourth aspects is mounted on a vehicle, the rubber gauge TGI has a tread rubber side facing the vehicle inside, and the rubber gauge TGO. The side having the tread rubber is attached to the outside of the vehicle.

  In the pneumatic tire according to any one of claims 1 to 4, a lateral force (pseudo camber thrust) from the side having the tread rubber of the rubber gauge TGO toward the side having the tread rubber of the rubber gauge TGI when traveling straight Therefore, when the pneumatic tire is mounted on the vehicle as in the method for mounting the pneumatic tire according to claim 5, the side having the tread rubber of the rubber gauge TGI faces the inside of the vehicle, and the tread of the rubber gauge TGO. If the side having the rubber is mounted toward the outside of the vehicle, a lateral force is generated from the outside of the vehicle mounting toward the inside, and as a result, the steering stability of the vehicle can be made very good.

  As described above, according to the pneumatic tire of the present invention, the tire movement performance can be improved by setting the rubber gauge within a predetermined range (so-called shoulder region) from the ground contact end of the tread portion to be asymmetrical. , Has an excellent effect.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In FIG. 1, a pneumatic tire 10 according to this embodiment includes an outer bead portion 12, a sidewall portion 14, a tread portion 16 connected to the sidewall portion 14, a partition wall 18, an outer carcass 21, and an inner carcass. 22, and a belt layer 40 is disposed on the lower layer (inner side in the tire radial direction) of the tread portion 16 in the same manner as a general tire.

  A pair of outer bead portions 12 are provided on the left and right sides of the tire equatorial plane CL, and the bead cores 30 are embedded therein. The sidewall portions 14 are formed so as to extend outward from the pair of left and right outer bead portions 12 in the tire radial direction.

  The partition walls 18 are provided between the pair of left and right outer bead portions 12 so as to be spaced apart from the outer bead portions 12 in the tire width direction, for example, on the left and right sides of the tire equatorial plane CL. At least one is formed to extend inward in the tire radial direction from the base portion 20 on the tire inner surface side. When the pneumatic tire 10 is mounted on the rim 26 and the inner bead portion 24 provided at the inner end in the tire radial direction is brought into contact with the rim 26, the partition wall 18 is independent of the tire rim 26. Chambers (a total of three air chambers including the main air chamber 28 and the first sub air chamber 31 and the second sub air chamber 32 on both sides thereof) are formed in the tire width direction.

  The inner carcass 22 is disposed in a toroidal shape between inner bead portions 24 formed at inner ends in the tire radial direction of the pair of left and right partition walls 18, with respect to the bead core 34 disposed on the inner bead portion 24. Each end is rolled back from the inside to the outside. The inner carcass 22 may be wound around the bead core 34 from the outside to the inside.

  The outer carcass 21 is disposed so as to straddle between the outer bead portions 12, and is wound around the bead core 30 disposed in the outer bead portion 12 from the inner side to the outer side and terminates.

  As shown in the figure, the outer carcass 21 is disposed so as to cover the outer side of the inner carcass 22 in the tire radial direction, and is a lower layer of the tread portion 16 between the pair of left and right partition walls 18 (more specifically, a lower layer of the belt layer 40). ) And the inner carcass 22. Note that the arrangement of the carcass is not limited to this.

  Assuming that the ground contact width of the tread portion 16 is TW, in the cross section in the tire axial direction, in the range from the ground contact ends 16B, 16C to the tire equatorial plane CL, in the range of at least 20% of the ground contact width TW from the ground contact ends 16B, 16C. The rubber gauge TGI on the vehicle mounting inner side is the outer rubber mounting TGI of the average rubber gauge measured in the direction perpendicular to the tread treading surface 16A from the outermost surface of the belt layer 40 (reinforcing layer) positioned below the tread portion 16 to the tread treading surface 16A It is formed larger than the rubber gauge TGO. In the case where the belt layer 40 is not provided, for example, the outermost surface of the outer carcass 21 becomes a reference for rubber gauge measurement.

  Here, the grounding end 16B is a grounding end inside the vehicle mounting, and the grounding end 16C is a grounding end outside the vehicle mounting. The range of 20% of the contact width TW from the contact ends 16B, 16C to the tire equatorial plane CL side indicates a so-called shoulder region 36. The range of the shoulder region 36 is set in this way, and if it is less than 20%, the asymmetry of the contact pressure distribution is insufficient, so the magnitude of the lateral force F (pseudo camber thrust) is the exercise performance. This is because it is not so large that it is not preferable. A portion between the left and right shoulder regions 36 is a center region 38 of the tread portion 16. When the circumferential main groove is formed in the tread portion 16, a portion extending from the ground end 16B to the circumferential main groove 42 closest to the ground end 16B, and a circumferential direction closest to the ground end 16C from the ground end 16C. The portions reaching the main groove 44 may be used as shoulder regions 36, respectively.

  TGI> TGO (the rubber gauge TGI is larger than the rubber gauge TGO outside the vehicle). If TGI <TGO, the lateral force F (when the internal pressures of the tire chambers 31, 28, 32 are all the same) This is because the direction of the (pseudo camber thrust) is the direction from the inside to the outside of the vehicle, and if it is compared to the alignment of the vehicle, the same movement performance as that set to toe-out occurs, which causes a safety problem.

  When the average gauge of the tread rubber is MG, the relationship between the rubber gauge TGO and the rubber gauge TGI is as follows: 0.1 × MG ≦ TGI−TGO ≦ 0.5 × MG and 0.5 × MG ≦ TGO <TGI ≦ 1.5 × It is set so as to satisfy at least one condition of MG. Here, TGI−TGO ≧ 0.1 × MG is set such that when TGI−TGO <0.1 × MG, the difference in rubber gauge between the left and right shoulder regions 36 is small, so that the lateral force F (pseudo camber thrust) ) Is also small, and it is difficult to clearly improve the handling stability.

  In addition, TGI−TGO ≦ 0.5 × MG is set such that the TGI-TGO> 0.5 × MG has sufficient lateral force F to improve the exercise performance, but the ground contact shape As a result, the left-right asymmetry of the contact pressure distribution becomes very large, so that the contact property of the tire is deteriorated and the exercise performance is easily lowered.

  The reason TGO ≧ 0.5 × MG is that when TGO <0.5 × MG, the average value of the rubber gauge in the tire width direction of the tread portion 16 becomes considerably thin, and as a result, it gets over small protrusions on the road surface. This is because the input at the time becomes large, and the vibration ride comfort is deteriorated.

  The reason why TGI ≦ 1.5 × MG is that when TGI> 1.5 × MG, the average value of the rubber gauge in the tire width direction of the tread portion 16 becomes considerably thick. This is because the absolute level of athletic performance is reduced due to the decrease in speed, and as a result, it is difficult to clearly improve the handling stability even if the rubber gauge is changed on the left and right.

  In the case of a general tire for passenger cars, 1 mm <TGI-TGO <10 mm, TGO ≧ 6 mm, and TGI ≦ 20 mm, and more preferably 2 mm <TGI-TGO <5 mm. In the rubber gauges TGI and TGO, the tire is assembled to the rim 26 corresponding to the normal rim, and the internal pressure corresponding to the normal internal pressure is applied to each tire air chamber (the main air chamber 28, the first sub air chamber 31 and the second sub air chamber 32). It shall be filled and unloaded.

  In the pneumatic tire 10, the inner diameter of the inner bead portion 24 is smaller than the inner diameter of the outer bead portion 12. Specifically, assuming that the radius from the tire center (not shown) to the rim base line BLO of the outer bead portion 12 is RO and the radius from the tire center to the rim base line BLI of the inner bead portion 24 is RI, 0 <RO− RI <50 mm.

  When the relationship between the radius RO of the outer bead portion 12 and the radius RI of the inner bead portion 24 is RO = RI, the inner bead portion 24 formed on the partition wall 18 is prevented from moving outward in the tire axial direction. A rim provided with a tall hump part must be used, and the assembly work must be very difficult. Further, when RO-RI ≧ 50 mm, it is difficult and unrealistic to manufacture a tire using the current tire manufacturing method.

  Furthermore, when the relationship between the radius RO of the outer bead portion 12 and the radius RI of the inner bead portion 24 is RO−RI ≧ 50 mm, the radius of the inner bead portion 24 becomes too small with respect to the radius of the outer bead portion 12, Accordingly, the radius of the rim is reduced, and as a result, the diameter of the brake that can be mounted on the inner side of the rim is reduced. This is not preferable because it may cause a decrease in vehicle motion performance.

  Therefore, it is preferable to satisfy 0 <RO-RI <50 mm because it is possible to prevent inconvenience as described above.

  In the pneumatic tire 10, since the inner bead portion 24 has an inner diameter smaller than the inner diameter of the outer bead portion 12, the rim 26 for mounting the pneumatic tire 10 has the pneumatic tire 10. It is necessary to be configured so that the tire 10 can be correctly attached.

  For this reason, the rim 26 is provided with a pair of left and right outer bead seats 26A that respectively contact the inner peripheral surfaces of the pair of left and right outer bead portions 12, and a step portion 26D on the inner side in the rim axial direction of each of the outer bead sheets 26A. A pair of left and right inner bead sheets 26B which are set to have a smaller diameter than the outer bead sheet 26A and come into contact with the inner peripheral surfaces of the pair of left and right inner bead parts 24, and one of the pair of left and right inner bead sheets 26B. A drop portion 26C provided between the other and set to have a smaller diameter than the inner bead sheet 26B is provided.

  The configuration of the rim 26 will be described in more detail. The outer bead sheet 26 </ b> A is formed according to the inner diameter of the outer bead portion 12, and the inner bead sheet 26 </ b> B is formed according to the inner diameter of the inner bead portion 24. In this example, as described above, since the inner diameter of the outer bead portion 12 is larger than the inner diameter of the inner bead portion 24, the inner bead sheet 26B is set to have a smaller diameter than the outer bead sheet 26A. Has been.

  A flange 26F that prevents the outer bead portion 12 from being pushed outward in the tire width direction is formed on the outer side in the axial direction of the outer bead sheet 26A, and is formed between the inner bead sheet 26B and the outer bead sheet 26A. Is formed with a step portion 26D that functions to prevent the inner bead portion 24 from being pushed outward in the tire width direction.

  Further, at the center in the axial direction of the rim 26, a drop portion (well) 26C in which the diameter of the groove bottom is smaller than that of the inner bead sheet 26B is provided.

  Although not shown, the rim 26 has an air valve for filling the first auxiliary air chamber 31 with gas, an air valve for filling the second auxiliary air chamber 32 with gas, and the main air chamber 28. Air valves for filling the gas are provided.

  The tire / rim assembly 51 is configured by mounting the pneumatic tire 10 on the rim 26.

(Function)
In the rim 26 in the tire / rim assembly 51, the radius RO of the outer bead portion 12 is set larger than the radius RI of the inner bead portion 24, and the drop portion 26C is provided in the middle portion. When the tire 10 is mounted, the outer bead portion 12 and the inner bead portion 24 can be dropped into the drop portion 26C, and the pneumatic tire 10 is assembled to the rim 26 in the same manner as the conventional pneumatic tire assembly. Work is easy.

  Further, the tire width of the inner bead portion 24 is determined by the difference in diameter between the outer bead seat 26A to which the outer bead portion 12 is attached and the inner bead seat 26B to which the inner bead portion 24 is attached. Since the step portion 26D that prevents the movement outward in the direction is formed, the inner bead portion 24 is caught when the rim is assembled, and the tall hump portion that deteriorates workability is placed outside the inner bead portion 24 in the tire width direction. There is no need to form the rim, and rim assembly is facilitated.

  Further, as a basic function of the tire / rim assembly 51 of the present embodiment, a first auxiliary air chamber 31, a main air chamber 28, which are partitioned by a partition wall 18 between the pneumatic tire 10 and the rim 26, In addition, since the second auxiliary air chamber 32 is formed in the tire width direction, any of the puncture on the ground contact surface due to the nailing of the tread portion 16 or the puncture of the sidewall portion 14 due to curb rubbing, etc. Since the two unpunctured air chambers support the load, although the tire height is slightly reduced, the steering stability and the vibration ride are slightly deteriorated, the vehicle can continue to travel safely without problems.

  Further, in the pneumatic tire 10, the rubber gauge TGI on the inner side of the vehicle is set larger than the rubber gauge TGO on the outer side of the vehicle for the rubber gauge of the tread tread 16A in the shoulder region 36, so that the contact pressure distribution in the shoulder region 36 is asymmetric. Thus, a lateral force F is generated from the outside in the vehicle width direction to the inside when traveling straight. When such a lateral force F is generated, the steering stability becomes very good. In terms of vehicle alignment, this improvement in steering stability is almost the same as if the wheels were set to toe-in, and almost the same mechanism as toe-in (stability during high-speed straight travel was ensured, and the steering wheel (It is not staggered and a firm response is obtained), which improves exercise performance.

  If the conventional one-chamber tire (not shown) tries to improve the exercise performance, the radius of curvature of the shoulder area of the tread portion needs to be changed considerably on the left and right, but the tire has been used for a long time. In this case, a difference in wear occurs due to a difference in ground pressure between the left and right shoulder regions, and the desired lateral force F cannot be generated, or other performance such as vibration riding comfort deteriorates due to the progress of uneven wear. There is concern.

  However, in the case of a three-chamber tire such as the pneumatic tire 10 according to the present embodiment, the first auxiliary air chamber 31 does not change the internal pressure of the main air chamber 28, that is, without changing the tire basic performance. Further, by finely adjusting the internal pressure of the second auxiliary air chamber 32, it is possible to continuously generate the lateral force F from the initial stage of wear to the end stage and continue to obtain the merit of improving the exercise performance.

  In addition to the setting of the rubber gauges TGI and TGO in the present embodiment, if the internal pressure of the first auxiliary air chamber 31 inside the vehicle is set to be appropriately larger than the internal pressure of the second auxiliary air chamber 32 outside the vehicle, A lateral force from the outside to the inside of the vehicle due to the pressure is also generated, and the steering stability can be improved more effectively.

(Test example)
The conventional examples shown in Tables 1 and 2 and the tires according to Comparative Examples 1 to 4 and Examples 1 to 4 were mounted on an actual vehicle, and tests on steering stability and vibration ride comfort were performed. The tire size is 255 / 55R17, and the tire structure is as shown in FIG. The internal pressure of all three chambers was 200 kPa.

  Steering stability and vibration ride comfort were evaluated by scoring the driving feeling during actual vehicle driving by a plurality of test drivers and calculating the average value. The result shown in Table 1 is an index when the scoring average value of the conventional example is set to 100, and the larger the value, the better the result.

  According to this test example, in each comparative example, the steering stability or the vibration ride comfort is lower than the conventional example, but in each example, good results are obtained without any lower than the conventional example. ing.

1 is a cross-sectional view of a tire / rim assembly in which a pneumatic tire is mounted on a rim.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Pneumatic tire 12 Outer bead part 14 Side wall part 16 Tread part 16A Tread tread 16B Grounding end 16C Grounding end 18 Bulkhead 20 Base 21 Outer carcass 24 Inner bead part 26 Rim 28 Main air chamber (tire air chamber)
30 Bead core 31 First auxiliary air chamber (tire air chamber)
32 Second auxiliary air chamber (tire air chamber)
34 Bead Core BLI Rim Baseline BLO Rim Baseline CL Tire Equatorial Surface TGI Rubber Gauge TGO Rubber Gauge

Claims (5)

A pair of left and right outer bead parts with embedded bead cores;
Sidewall portions extending outward from the outer bead portion in the tire radial direction,
A tread portion connected to the sidewall portion;
The outer bead portion is provided between the pair of left and right outer bead portions so as to be spaced apart in the tire width direction, and extends inward in the tire radial direction from a base portion on the tire inner surface side in at least one of the sidewall portion and the tread portion. The inner bead portion provided at the inner end in the tire radial direction contacts the rim, and at least one partition wall that forms a plurality of independent tire air chambers in the tire width direction between the inner rim and the rim when the inner bead is attached to the rim. A pneumatic tire having
When the ground contact width of the tread portion is TW, in the tire axial section, in the range from the ground contact edge on both sides of the tire equator surface to the tire equator surface, in the range of at least 20% of the ground contact width TW from the ground contact edge, The average rubber gauge measured in a direction perpendicular to the tread tread surface from the outermost surface of the reinforcing layer located below the tread portion to the tread tread surface, wherein one rubber gauge TGI is larger than the other rubber gauge TGO tire. When the average gauge of the tread rubber is MG, the rubber gauge TGO and the rubber gauge TGI are
0.1 × MG ≦ TGI−TGO ≦ 0.5 × MG,
The pneumatic tire according to claim 1, wherein the relationship is satisfied. When the average gauge of the tread rubber is MG, the rubber gauge TGO and the rubber gauge TGI are:
0.5 × MG ≦ TGO <TGI ≦ 1.5 × MG,
The pneumatic tire according to claim 1, wherein the relationship is satisfied. When the radius from the tire center to the rim baseline of the outer bead portion is RO, and the radius from the tire center to the rim baseline of the inner bead portion is RI,
The pneumatic tire according to any one of claims 1 to 3, wherein 0 <RO-RI <50 mm.   When the pneumatic tire according to any one of claims 1 to 4 is mounted on a vehicle, the side having the tread rubber of the rubber gauge TGI faces the inside of the vehicle, and the side having the tread rubber of the rubber gauge TGO is disposed. A method for attaching a pneumatic tire, characterized by being attached toward the outside of the vehicle.

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