WO2022130657A1 - 乗用車用空気入りラジアルタイヤ - Google Patents
乗用車用空気入りラジアルタイヤ Download PDFInfo
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- WO2022130657A1 WO2022130657A1 PCT/JP2021/021088 JP2021021088W WO2022130657A1 WO 2022130657 A1 WO2022130657 A1 WO 2022130657A1 JP 2021021088 W JP2021021088 W JP 2021021088W WO 2022130657 A1 WO2022130657 A1 WO 2022130657A1
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- WIPO (PCT)
- Prior art keywords
- tire
- width
- tread
- sipe
- width direction
- Prior art date
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Images
Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C3/00—Tyres characterised by the transverse section
- B60C3/04—Tyres characterised by the transverse section characterised by the relative dimensions of the section, e.g. low profile
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
- B60C11/03—Tread patterns
- B60C11/0306—Patterns comprising block rows or discontinuous ribs
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
- B60C11/03—Tread patterns
- B60C11/032—Patterns comprising isolated recesses
- B60C11/0323—Patterns comprising isolated recesses tread comprising channels under the tread surface, e.g. for draining water
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
- B60C11/03—Tread patterns
- B60C11/12—Tread patterns characterised by the use of narrow slits or incisions, e.g. sipes
- B60C11/1236—Tread patterns characterised by the use of narrow slits or incisions, e.g. sipes with special arrangements in the tread pattern
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
- B60C11/03—Tread patterns
- B60C11/12—Tread patterns characterised by the use of narrow slits or incisions, e.g. sipes
- B60C11/1272—Width of the sipe
- B60C11/1281—Width of the sipe different within the same sipe, i.e. enlarged width portion at sipe bottom or along its length
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C3/00—Tyres characterised by the transverse section
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
- B60C11/03—Tread patterns
- B60C11/04—Tread patterns in which the raised area of the pattern consists only of continuous circumferential ribs, e.g. zig-zag
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
- B60C11/03—Tread patterns
- B60C11/12—Tread patterns characterised by the use of narrow slits or incisions, e.g. sipes
- B60C11/1204—Tread patterns characterised by the use of narrow slits or incisions, e.g. sipes with special shape of the sipe
- B60C2011/1209—Tread patterns characterised by the use of narrow slits or incisions, e.g. sipes with special shape of the sipe straight at the tread surface
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
- B60C11/03—Tread patterns
- B60C11/12—Tread patterns characterised by the use of narrow slits or incisions, e.g. sipes
- B60C2011/129—Sipe density, i.e. the distance between the sipes within the pattern
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C2200/00—Tyres specially adapted for particular applications
- B60C2200/04—Tyres specially adapted for particular applications for road vehicles, e.g. passenger cars
Definitions
- the present invention relates to a pneumatic radial tire for a passenger car.
- Patent Document 1 a technique for improving fuel efficiency and the like by increasing the width and diameter of a pneumatic radial tire for a passenger car.
- the above tires have high ring rigidity, when a vehicle equipped with the above tires travels on a snowy road surface, it causes local contact with the solidified snow, which is close to point contact. There is a problem that the vibration of the vehicle input at the time of such local contact causes a phenomenon that the vehicle body bounces and the performance on snow is deteriorated.
- an object of the present invention is to provide a pneumatic radial tire for a passenger car, which can improve fuel efficiency while suppressing deterioration of performance on snow.
- the gist structure of the present invention is as follows.
- a pneumatic radial tire for a passenger car having a carcass made of a ply of a radial arrangement code straddling a toroidal shape between a pair of bead portions.
- the cross-sectional width SW of the tire is less than 165 (mm), and the ratio SW / OD of the cross-sectional width SW of the tire and the outer diameter OD is 0.26 or less.
- the tire has a tread portion and has a tread portion. Having one or more land parts on the tread of the tread part, The land portion has a plurality of widthwise sipes extending in the tire width direction.
- the pitch length of the plurality of width direction sipes in the tire circumferential direction is 3 mm to 10 mm.
- the width direction sipe is a pneumatic radial tire for a passenger car, characterized in that the sipe bottom side has a widening portion in which the sipe width is larger than that of the tread side.
- a pneumatic radial tire for a passenger car provided with a carcass consisting of a radial arrangement code ply that straddles a toroidal shape between a pair of bead portions.
- the cross-sectional width SW of the tire is 165 (mm) or more, and the cross-sectional width SW (mm) and the outer diameter OD (mm) of the tire are related formulas. OD (mm) ⁇ 2.135 ⁇ SW (mm) +282.3
- the tire has a tread portion and has a tread portion. Having one or more land parts on the tread of the tread part, The land portion has a plurality of widthwise sipes extending in the tire width direction.
- the pitch length of the plurality of width direction sipes in the tire circumferential direction is 3 mm to 10 mm.
- the widthwise sipe is a pneumatic radial tire for a passenger car, characterized in that the sipe bottom side has a widening portion in which the sipe width is larger than that of the tread side.
- a pneumatic radial tire for a passenger car provided with a carcass consisting of a radial arrangement code ply that straddles a toroidal shape between a pair of bead portions.
- the cross-sectional width SW (mm) and the outer diameter OD (mm) of the tire are expressed in relation to each other.
- OD (mm) ⁇ -0.0187 ⁇ SW (mm) 2 + 9.15 ⁇ SW (mm) -380
- the tire has a tread portion and has a tread portion. Having one or more land parts on the tread of the tread part, The land portion has a plurality of widthwise sipes extending in the tire width direction.
- the pitch length of the plurality of width direction sipes in the tire circumferential direction is 3 mm to 10 mm.
- the width direction sipe is a pneumatic radial tire for a passenger car, characterized in that the sipe bottom side has a widening portion in which the sipe width is larger than that of the tread side.
- the "tread surface” refers to a surface covering the entire tire circumferential direction of the ground contact surface that comes into contact with the road surface when the tire is mounted on the rim, the specified internal pressure is applied, and the maximum load is applied.
- rim is an industrial standard that is effective in the area where tires are produced and used.
- JATTA Joint Automobile Tire Association
- JATMA JATMA YEAR BOOK
- ETRTO European Tire and Rim
- Standard rims in applicable sizes ETRTO STANDARDS MANUL
- YEAR BOOK of TRA The Tire and Rim Association, Inc.
- TRA's YEAR BOOK, DesignRim ie, "rim” above includes sizes that may be included in the industry standards in the future in addition to current sizes. "Sizes to be described in the future”.
- the size described as "FUTURE DEVELOPMENTS” in the 2013 edition of ETRTO can be mentioned.
- the width corresponding to the bead width of the tire can be mentioned.
- the "specified internal pressure” refers to the air pressure (maximum air pressure) corresponding to the maximum load capacity of a single wheel in the applicable size and ply rating described in the above JATMA, etc., and is of a size not described in the above industrial standard.
- the "specified internal pressure” shall mean the air pressure (maximum air pressure) corresponding to the maximum load capacity specified for each vehicle to which the tires are mounted.
- the "maximum load” means a load corresponding to the above maximum load capacity.
- the "sipe width of the widening portion” means the maximum value of the sipe width in the widening portion.
- FIG. 1 is a schematic view showing a cross-sectional width SW and an outer diameter OD of a tire.
- the pneumatic radial tire for a passenger car (hereinafter, also simply referred to as a tire) according to the first aspect of the present invention has a tire cross-sectional width SW of less than 165 (mm), and has a tire cross-sectional width SW and an outer diameter.
- the ratio SW / OD to OD is 0.26 or less, and it has a narrow width and a large diameter.
- the SW / OD is preferably 0.25 or less, and more preferably 0.24 or less.
- the above ratio is preferably satisfied when the internal pressure of the tire is 200 kPa or more, more preferably satisfied when the internal pressure is 220 kPa or more, and more preferably satisfied when the internal pressure is 280 kPa or more. Is even more preferable. This is because rolling resistance can be reduced.
- the above ratio is preferably satisfied when the internal pressure of the tire is 350 kPa or less. This is because the ride comfort can be improved.
- the cross-sectional width SW of the tire is preferably 105 mm or more, more preferably 125 mm or more, and further preferably 135 mm or more within the range satisfying the above ratio. It is preferably 145 mm or more, and particularly preferably 145 mm or more.
- the cross-sectional width SW of the tire is preferably 155 mm or less within a range satisfying the above ratio from the viewpoint of reducing air resistance.
- the outer diameter OD of the tire is preferably 500 mm or more, more preferably 550 mm or more, and further preferably 580 mm or more within the range satisfying the above ratio. ..
- the outer diameter OD of the tire is preferably 800 mm or less, more preferably 720 mm or less, and further preferably 650 mm or less within the range satisfying the above ratio. It is preferably 630 mm or less, and particularly preferably 630 mm or less. Further, from the viewpoint of reducing rolling resistance, the rim diameter is preferably 16 inches or more, more preferably 17 inches or more when the cross-sectional width SW and the outer diameter OD of the tire satisfy the above ratio. It is more preferably 18 inches or more.
- the rim diameter is preferably 22 inches or less, and more preferably 21 inches or less when the cross-sectional width SW and the outer diameter OD of the tire satisfy the above ratio. , 20 inches or less, more preferably 19 inches or less.
- the flatness of the tire is more preferably 45 to 70, more preferably 45 to 65, when the cross-sectional width SW and the outer diameter OD of the tire satisfy the above ratios.
- the specific tire size is not particularly limited, but as an example, 105 / 50R16, 115 / 50R17, 125 / 55R20, 125 / 60R18, 125 / 65R19, 135 / 45R21, 135 / 55R20, 135 / 60R17.
- the cross-sectional width SW of the tire is 165 (mm) or more, and the cross-sectional width SW (mm) and the outer diameter OD (mm) of the tire are related formulas.
- OD (mm) ⁇ 2.135 ⁇ SW (mm) +282.3 It has a narrow width and a large diameter.
- the cross-sectional width SW and the outer diameter OD of the tire preferably satisfy the above relational expression and have a ratio SW / OD of 0.26 or less, preferably 0.25 or less.
- the above relational expression and / or ratio is preferably satisfied when the internal pressure of the tire is 200 kPa or more, more preferably satisfied when the internal pressure is 220 kPa or more, and more preferably 280 kPa or more. It is more preferable that it is satisfied. This is because rolling resistance can be reduced. On the other hand, the above relational expression and / or ratio is preferably satisfied when the internal pressure of the tire is 350 kPa or less. This is because the ride comfort can be improved.
- the cross-sectional width SW of the tire is preferably 175 mm or more, and more preferably 185 mm or more within the range satisfying the above relational expression.
- the cross-sectional width SW of the tire is preferably 230 mm or less, more preferably 215 mm or less, and more preferably 205 mm or less within the range satisfying the above relational expression. It is more preferably 195 mm or less, and particularly preferably 195 mm or less.
- the outer diameter OD of the tire is preferably 630 mm or more, and more preferably 650 mm or more within the range satisfying the above relational expression.
- the outer diameter OD of the tire is preferably 800 mm or less, more preferably 750 mm or less, and more preferably 720 mm or less within the range satisfying the above relational expression. More preferred. Further, from the viewpoint of reducing rolling resistance, the rim diameter is preferably 18 inches or more, and more preferably 19 inches or more when the cross-sectional width SW and the outer diameter OD of the tire satisfy the above relational expression. .. On the other hand, from the viewpoint of reducing air resistance, the rim diameter is preferably 22 inches or less, and more preferably 21 inches or less when the cross-sectional width SW and the outer diameter OD of the tire satisfy the above relational expression. preferable.
- the flatness of the tire is preferably 45 to 70, more preferably 45 to 65.
- the specific tire size is not particularly limited, but as an example, 165 / 45R22, 165 / 55R18, 165 / 55R19, 165 / 55R20, 165 / 55R21, 165 / 60R19, 165 / 65R19, 165 / 70R18.
- the cross-sectional width SW (mm) and the outer diameter OD (mm) of the tire are the relational expressions.
- the cross-sectional width SW and the outer diameter OD of the tire preferably satisfy the above relational expression and have a ratio SW / OD of 0.26 or less, preferably 0.25 or less. It is more preferably 0.24 or less, and even more preferably 0.24 or less.
- the above relational expression and / or ratio is preferably satisfied when the internal pressure of the tire is 200 kPa or more, more preferably satisfied when the internal pressure is 220 kPa or more, and more preferably 280 kPa or more. It is more preferable that it is satisfied. This is because rolling resistance can be reduced. On the other hand, the above relational expression and / or ratio is preferably satisfied when the internal pressure of the tire is 350 kPa or less. This is because the ride comfort can be improved.
- the cross-sectional width SW of the tire is preferably 105 mm or more, more preferably 125 mm or more, and more preferably 135 mm or more within the range satisfying the above relational expression. It is more preferably 145 mm or more, and particularly preferably 145 mm or more.
- the cross-sectional width SW of the tire is preferably 230 mm or less, more preferably 215 mm or less, and more preferably 205 mm or less within the range satisfying the above relational expression. It is more preferably 195 mm or less, and particularly preferably 195 mm or less.
- the outer diameter OD of the tire is preferably 500 mm or more, more preferably 550 mm or more, and further preferably 580 mm or more within the range satisfying the above relational expression. preferable.
- the outer diameter OD of the tire is preferably 800 mm or less, more preferably 750 mm or less, and more preferably 720 mm or less within the range satisfying the above relational expression. More preferred.
- the rim diameter is preferably 16 inches or more, and more preferably 17 inches or more when the cross-sectional width SW and the outer diameter OD of the tire satisfy the above relational expression. , 18 inches or more is more preferable.
- the rim diameter is preferably 22 inches or less, and more preferably 21 inches or less when the cross-sectional width SW and the outer diameter OD of the tire satisfy the above relational expression. It is preferably 20 inches or less, and more preferably 20 inches or less. Further, the flatness of the tire is more preferably 45 to 70, more preferably 45 to 65, when the cross-sectional width SW and the outer diameter OD of the tire satisfy the above ratios.
- the specific tire size is not particularly limited, but as an example, 105 / 50R16, 115 / 50R17, 125 / 55R20, 125 / 60R18, 125 / 65R19, 135 / 45R21, 135 / 55R20, 135 / 60R17.
- It can be any of / 60R19, 185 / 60R20, 195 / 50R20, 195 / 55R20, 195 / 60R19, 205 / 50R21, 205 / 55R20, and 215 / 50R21.
- FIG. 2 is a cross-sectional view in the tire width direction showing a pneumatic radial tire for a passenger car according to an embodiment of the first to third aspects of the present invention.
- FIG. 2 shows a cross section in the width direction of the tire when the tire is incorporated in the rim, the specified internal pressure is applied, and no load is applied.
- the tire 1 includes a carcass 3 made of a ply of a radial arrangement code, which straddles a toroidal shape between a pair of bead portions 2.
- the tire 1 is provided with a belt 4 and a tread 5 composed of two belt layers 4a and 4b in order in the illustrated example on the outer side of the carcass 3 in the tire radial direction.
- the bead core 2a is embedded in each of the pair of bead portions 2.
- the cross-sectional shape and material of the bead core 2a are not particularly limited, and a configuration usually used in a pneumatic radial tire for a passenger car can be used.
- the bead core 2a may be divided into a plurality of small bead cores.
- the configuration may not have the bead core 2a.
- the tire 1 in the illustrated example has a bead filler 2b having a substantially triangular cross section on the outer side in the tire radial direction of the bead core 2a.
- the cross-sectional shape of the bead filler 2b is not limited to this example, and the material is not particularly limited. Alternatively, the weight of the tire can be reduced by a configuration that does not have the bead filler 2b.
- the tire width direction cross-sectional area S1 of the bead filler 2b is preferably 1 time or more and 4 times or less the tire width direction cross-sectional area S2 of the bead core 2a.
- the cross-sectional area S1 1 times or more the cross-sectional area S2 the rigidity of the bead portion 2 can be ensured, and by making the cross-sectional area S1 4 times or less the cross-sectional area S2, the tire can be made. This is because the weight can be reduced and the fuel efficiency can be further improved.
- the tire maximum width position (when the tire radial position where the width in the tire width direction is maximum and it is the tire radial region, the tire radial center position in that region).
- the ratio Ts / Tb of the gauge Ts of the sidewall portion and the bead width (width in the tire width direction of the bead portion 2) Tb at the center position in the tire radial direction of the bead core 2a is preferably 15% or more and 40% or less. ..
- the ratio Ts / Tb is preferably 15% or more and 40% or less.
- the gauge Ts is the total thickness of all members such as rubber, reinforcing member, and inner liner (however, even when the sound control body is arranged on the inner surface of the sidewall portion, the thickness of the sound control body is used. Does not include).
- the "sidewall portion" is the outer side in the tire width direction of the ground contact end E, and is the tire radial outer end of the bead portion from the ground contact end E (when the bead filler 2b is provided, the tire radial direction of the bead filler 2b). When it is the outer end and does not have the bead filler 2b, it means the tire radial region up to the tire radial outer end of the bead core 2a).
- the distance between the innermost end portion and the outermost outermost end portion in the tire width direction of all the small bead cores is Tb.
- the ratio Ts / Tc of the gauge Ts of the sidewall portion at the maximum width position of the tire and the diameter Tc of the carcass cord is 5 or more and 10 or less.
- the maximum tire width position is, for example, in the range of 50% to 90% of the tire cross-sectional height from the bead baseline (a virtual line passing through the bead base and parallel to the tire width direction) to the outside in the tire radial direction.
- the "bead portion” refers to a portion in the tire radial region from the rim baseline to the outermost end of the bead filler in the tire radial direction when the bead filler is provided, and the rim when the bead filler is not provided. The part in the tire radial region from the baseline to the tire radial outermost end of the bead core.
- the tire 1 may have a structure having a rim guard.
- the bead portion 2 may be further provided with additional members such as a rubber layer and a cord layer for the purpose of reinforcement and the like.
- additional members can be provided at various positions with respect to the carcass 3 and the bead filler 2b.
- the carcass 3 is composed of one carcass ply.
- the number of carcass plies is not particularly limited, and may be two or more.
- the carcass 3 has a carcass main body portion 3a that straddles the pair of bead portions 2 in a toroidal shape, and a folded-back portion 3b that is folded back from the carcass main body portion 3a around the bead core 2a.
- the carcass folded portion 3b can be wound around the bead core 2a, or can be sandwiched between a plurality of divided small bead cores.
- the end 3c of the carcass folded portion 3b is located outside the tire radial direction from the tire radial outer end of the bead filler 2b and inside the tire radial direction from the tire maximum width position.
- the end 3c of the carcass folded portion 3b may be located inside the tire radial direction from the tire radial outer end of the bead filler 2b, or may be located outside the tire radial direction from the tire maximum width position. It may be located.
- the end 3c of the carcass folded portion 3b is located inside the end of the belt 4 (for example, the end of the belt layer 4b) in the tire width direction so as to be located between the carcass main body portion 2a and the belt 4 in the tire radial direction. It can also be an envelope structure. Further, when the carcass 3 is composed of a plurality of carcass plies, the positions of the ends 3c of the carcass folded portions 3b (for example, the positions in the tire radial direction) may be the same or different between the carcass plies. ..
- the number of cords of the carcass 3 is not particularly limited, but can be, for example, in the range of 20 to 60 cords / 50 mm. In addition, various structures can be adopted for the carcass line.
- the maximum width position of the carcass can be brought closer to the bead portion 2 side or the tread 5 side.
- the maximum width position of the carcass can be provided in the range of 50% to 90% of the tire cross-sectional height on the outer side in the tire radial direction from the bead baseline.
- the above "radial arrangement" is 85 ° or more with respect to the tire circumferential direction, preferably 90 ° with respect to the tire circumferential direction.
- the tire of the present embodiment preferably has one or more inclined belt layers composed of a rubberized layer of a cord extending inclined with respect to the tire circumferential direction, and has a balance between weight reduction and suppression of distortion of the contact patch shape. It is most preferable to have two layers. From the viewpoint of weight reduction, the belt layer may be one layer, and from the viewpoint of suppressing distortion of the contact patch shape, three or more layers may be used. In the example shown in FIG. 2, of the two layers of belt layers 4a and 4b, the width of the belt layer 4b on the outer side in the tire radial direction in the tire width direction is smaller than the width in the tire width direction of the belt layer 4a on the inner side in the tire radial direction. ..
- the width of the belt layer 4b on the outer side in the tire radial direction in the tire width direction may be larger than the width in the tire width direction of the belt layer 4a on the inner side in the tire radial direction, and may be the same.
- the width in the tire width direction of the belt layer having the largest width in the tire width direction is preferably 90 to 115% of the ground contact width, and is preferably 100 to 105% of the ground contact width.
- the "ground contact width" means the distance in the tire width direction between the ground contact ends E on the ground contact surface.
- the belt cord of the belt layers 4a and 4b it is most preferable to use a metal cord, particularly a steel cord, but an organic fiber cord can also be used.
- the steel cord contains steel as a main component and can contain various trace substances such as carbon, manganese, silicon, phosphorus, sulfur, copper and chromium.
- a monofilament cord a cord in which a plurality of filaments are aligned, or a cord in which a plurality of filaments are twisted can be used as the belt cord of the belt layers 4a and 4b.
- Various twist structures can be adopted, and the cross-sectional structure, twist pitch, twist direction, and distance between adjacent filaments can also be various.
- the inclination angle of the belt cords of the belt layers 4a and 4b is preferably 10 ° or more with respect to the tire circumferential direction.
- the inclination angle of the belt cords of the belt layers 4a and 4b is set to a high angle, specifically, 20 ° or more with respect to the tire circumferential direction, preferably 35 ° or more, particularly 55 ° to more with respect to the tire circumferential direction.
- the range is preferably in the range of 85 °.
- the inclination angle is set to 20 ° or more (preferably 35 ° or more), the rigidity in the tire width direction can be increased, and the steering stability performance particularly at the time of cornering can be improved. Further, it is possible to reduce the shear deformation of the interlayer rubber and reduce the rolling resistance.
- the tire of the present embodiment is configured not to have one or more circumferential belt layers composed of cords extending substantially along the tire circumferential direction on the outer side of the belt 4 in the tire radial direction.
- the inclination angles ⁇ 1 and ⁇ 2 of the belt cords of the belt layers 4a and 4b constituting the belt 4 are 35 ° or more, it is preferable to provide a circumferential belt, and the circumferential belt is a unit of the center region C.
- the tire circumferential rigidity per width is higher than the tire circumferential rigidity per unit width of the shoulder region S.
- the tire width direction region 50% of the center in the tire width direction between the ground contact ends E is defined as the center region C.
- the tire width direction region of 25% each on both outer sides in the tire width direction from the center region is defined as the shoulder region S.
- the circumferential belt layer when the circumferential belt is provided, the circumferential belt layer preferably has high rigidity, and more specifically, it is composed of a rubberized layer of the cord extending in the circumferential direction of the tire, and the cord is Young's modulus.
- the rate is Y (GPa)
- the number of driving is n (lines / 50 mm)
- the circumferential belt layer is m layer
- the cord diameter is d (mm)
- X Y ⁇ n ⁇ m ⁇ d is defined. It is preferable that 1500 ⁇ X ⁇ 225.
- the Young's modulus means the Young's modulus with respect to the tire circumferential direction, and is obtained in accordance with JIS L1017 8.8 (2002) after being tested by JIS L1017 8.5 a) (2002).
- JIS L1017 8.8 (2002) after being tested by JIS L1017 8.5 a) (2002).
- the ground contact surface is approximately triangular, that is, the position in the tire width direction. It is easy for the shape to change the contact patch length in the circumferential direction.
- the ring rigidity of the tire is improved and deformation in the tire circumferential direction is suppressed.
- the tire width direction Deformation is also suppressed, and the ground contact shape is less likely to change. Furthermore, the improvement in ring rigidity promotes eccentric deformation and simultaneously improves rolling resistance. Further, when a highly rigid circumferential belt layer is used as described above, the inclination angle of the belt cords 4a and 4b with respect to the tire circumferential direction may be set to a high angle, specifically 35 ° or more. preferable. When a high-rigidity circumferential belt layer is used, the ground contact length may decrease depending on the tire due to the high rigidity in the tire circumferential direction.
- a belt layer with a high angle it is possible to reduce the out-of-plane bending rigidity in the tire circumferential direction, increase the elongation of the rubber in the tire circumferential direction when the tread is deformed, and suppress the decrease in the contact length. ..
- a wavy cord may be used for the circumferential belt layer in order to increase the breaking strength.
- a high elongation cord (for example, elongation at break is 4.5 to 5.5%) may be used.
- the cord of the circumferential belt layer is a monofilament cord, a cord in which a plurality of filaments are aligned, a cord in which a plurality of filaments are twisted, or a different material. It is also possible to use a hybrid cord in which the filaments of the above are twisted together.
- the number of driven belt layers in the circumferential direction can be in the range of 20 to 60/50 mm, but is not limited to this range.
- the rigidity, the material, the number of layers, the driving density and the like can be distributed in the tire width direction.
- the number of layers of the circumferential belt layer can be increased only in the shoulder portion S.
- the number of layers of the circumferential belt layer can be increased only in the center region C.
- the circumferential belt layer can be made wider or smaller in the tire width direction than the belt layers 4a and 4b.
- the width of the circumferential belt layer in the tire width direction is 90% to 110% of the width in the tire width direction of the belt layer (belt layer 4a in the illustrated example) having the widest width in the tire width direction among the belt layers 4a and 4b. Can be%.
- the circumferential belt layer is configured as a spiral layer.
- the tread rubber constituting the tread portion 5 is composed of one layer.
- the tread rubber constituting the tread portion 5 may be formed by laminating a plurality of different rubber layers in the tire radial direction.
- those having different loss tangent (tan ⁇ ), modulus, hardness, glass transition temperature, material, and the like can be used.
- the ratio of the thicknesses of the plurality of rubber layers in the tire radial direction may change in the tire width direction, and only the bottom of the main groove in the circumferential direction may be a rubber layer different from the periphery thereof.
- the tread rubber constituting the tread portion 5 may be formed of a plurality of rubber layers different in the tire width direction.
- the above-mentioned plurality of rubber layers those having different loss tangent, modulus, hardness, glass transition temperature, material, and the like can be used.
- the ratio of the widths of the plurality of rubber layers in the tire width direction may change in the tire radial direction, such as only in the vicinity of the main groove in the circumferential direction, only in the vicinity of the ground contact end, only in the shoulder land portion, and only in the center land portion. It is also possible to make only a limited part of the area a rubber layer different from the surrounding area.
- the rubber gauge of the tread rubber is preferably 5 mm or more and 8 mm or less.
- the rubber gauge in the case of the present embodiment extends from the outer surface of the tire to the outermost reinforcing member in the tire radial direction (in the illustrated example, the outermost belt layer 4b of the two belt layers 4a and 4b). It is the thickness of the tread rubber 5.
- the thickness is 8 mm or less, the weight of the tire can be reduced and the rolling resistance can be further reduced.
- the thickness is 5 mm or more, wet performance can be ensured even when wear progresses to some extent.
- a straight line passing through the point P on the tread surface on the tire equatorial plane CL and parallel to the tire width direction is defined as m1
- a straight line passing through the ground contact end E and parallel to the tire width direction is defined.
- m2 when the distance between the straight line m1 and the straight line m2 in the tire radial direction is reduced to a high LCR and the ground contact width of the tire is W, the ratio L CR / W is preferably 0.045 or less.
- the crown portion of the tire is flattened (flattened), the ground contact area is increased, the input (pressure) from the road surface is relaxed, and the tire radial direction is reached. It is possible to reduce the bending rate and improve the durability and wear resistance of the tire.
- the tire 1 of the present embodiment has an inner liner 8 on the inner surface 7 of the tire (simply also referred to as the inner surface 7 of the tire).
- the thickness of the inner liner 8 is preferably about 1.5 mm to 2.8 mm. This is because the noise inside the vehicle at 80 to 100 Hz can be effectively reduced.
- the air permeability coefficient of the rubber composition constituting the inner liner 8 is 1.0 ⁇ 10 -14 cc ⁇ cm / (cm 2 ⁇ s ⁇ cmHg) or more, 6.5 ⁇ 10 -10 cc ⁇ cm / (cm 2 ). It is preferably s ⁇ cmHg) or less.
- the inner liner 8 can be formed of a rubber layer mainly composed of butyl rubber or a film layer containing resin as a main component.
- the inner surface 7 of the tire may be provided with a sealant member for preventing air leakage during a puncture.
- FIG. 3 is a plan view showing a tread portion of a tread portion of a pneumatic radial tire for a passenger car according to an embodiment of the present invention.
- FIG. 3 is a plan view schematically showing a tread portion of a tread portion of a pneumatic radial tire for a passenger car according to an embodiment of the first to third aspects of the present invention.
- the tread surface has one or more (two in the illustrated example) circumferential main grooves 6 extending in the circumferential direction of the tire.
- the number of the circumferential main grooves 6 is preferably 1 to 4. As shown in FIG.
- each land portion can be a rib-shaped land portion that is not completely divided in the tire circumferential direction by a width direction groove extending in the tire width direction. According to such a configuration, the rigidity of the land portion can be ensured, and the tire satisfying the above-mentioned SW and OD relational expression has a groove in the width direction because drainage to the side is easy. It is also possible to ensure drainage without doing so.
- any one or more land portions may be block-shaped land portions completely divided in the tire circumferential direction by a groove in the width direction.
- the number of main grooves in the circumferential direction is two
- the tire width direction region between the ground contact ends E is divided into four equal parts and divided into two central regions C and two lateral regions S, the illustrated example.
- the two circumferential main grooves 6 are located in the central region C as described above. This is because the drainage property can be further secured.
- "extending in the tire circumferential direction” includes not only the case of extending without tilting with respect to the tire circumferential direction, but also the case of extending with an inclination angle of 5 ° or less with respect to the tire circumferential direction.
- the circumferential main groove 6 extends continuously in the circumferential direction of the tire.
- the shape of the circumferential main groove 6 is most preferably linear as shown in the illustrated example, but it can also be zigzag, curved, or the like.
- the groove width (opening width) of the circumferential main groove 6 is preferably 9 mm to 16 mm. This is because the drainage property can be further improved by setting the groove width to 9 mm or more, while the rigidity of the land portion 9 can be further secured by setting the groove width to 16 mm or less. For the same reason, the groove width of the circumferential main groove 6 is more preferably 10 mm to 15.5 mm.
- the groove depth (maximum depth) of the circumferential main groove 6 is preferably 1 to 5 mm. This is because the drainage property can be further improved by setting the groove depth to 1 mm or more, while the rigidity of the land portion 9 can be further secured by setting the groove depth to 5 mm or less. .. For the same reason, the groove depth of the circumferential main groove 6 is more preferably 2 to 4 mm.
- the negative rate of the tread of the tread portion 5 is preferably 20% or less, more preferably 18% or less, and even more preferably 15% or less. On the other hand, from the viewpoint of ensuring drainage, the negative rate of the tread of the tread portion 5 is preferably 5% or more.
- the "negative rate” means the ratio of the groove area to the area of the tread surface. When calculating the groove area, the groove area does not include the area of the sipes (the opening width in the reference state is 1 mm or less).
- the land portion 9 has a plurality of widthwise sipes 10 extending in the tire width direction.
- “Extending in the tire width direction” includes not only the case where the tire extends in the tire width direction without tilting as shown in the figure, but also the case where the tire is tilted at an inclination angle of 50 ° or less with respect to the tire width direction. ..
- the plurality of widthwise sipes 10 are arranged at equal intervals in the tire circumferential direction.
- the sipe width (opening width) of the width direction sipe 10 is not particularly limited as long as it is 1 mm or less as described above, but can be, for example, 0.3 to 0.7 mm.
- the sipe depth (maximum depth) of the width direction sipe 10 is not particularly limited, but can be made to be about the same as the depth of the circumferential main groove 6.
- the pitch length of the plurality of widthwise sipes in the tire circumferential direction is 3 mm to 10 mm, preferably 5 mm to 10 mm.
- the width direction sipes 10 may be arranged with variations in the pitch length in the tire circumferential direction (so-called pitch variation).
- both ends of the extending direction communicate with the circumferential main groove 6, while the width sipe 10 communicates with only one end of the circumferential main groove 6.
- the other end can be a so-called one-sided closed sipe that stays in the land portion 9, or both ends can be a sipe that stays in the land portion 9. If a sipe like these is used, it is possible to suppress the decrease in the rigidity of the land portion due to the formation of the sipe as much as possible.
- the width direction sipes 10 are formed in all the land portions 9a and 9b, but may have a land portion 9 in which the width direction sipes 10 are not formed. Further, in the illustrated example, the pitch length of the width direction sipes 10 formed on the land portion 9a in the tire circumferential direction is the same as the pitch length of the width direction sipes 10 formed on the land portion 9b in the tire circumferential direction. It can be long or short.
- FIG. 4 is a cross-sectional view showing an example of a width direction sipe.
- the width direction sipe 10 is composed of a flat plate portion 10a and a widening portion 10b, and has a widening portion 10b on the sipe bottom side where the sipe width is larger than that on the tread side.
- the sipe width (opening width) of the flat plate portion 10a is not particularly limited as long as it is 1 mm or less as described above, as in the case where the sipe 10 (overall) in the width direction has a flat plate shape, but is, for example, 0.3 to 0.7 mm.
- the sipe width (maximum width when measured in the same direction as the opening width) of the widened portion 10b is preferably 2 to 30 times the opening width of the flat plate portion 10a. By setting it to 2 times or more, the compressive rigidity of the land part can be further effectively reduced at the time of wear progress, while by making it 30 times or less, the rigidity of the land part at the time of wear progress becomes extremely high. It can be prevented from decreasing. More preferably, the sipe width of the first widening portion 10b is 2 to 20 times the opening width of the flat plate portion 10a.
- the length (depth) of the widened portion 10b in the tire radial direction can be 0.4 to 9 times the length (depth) of the flat plate portion 10a in the tire radial direction.
- the compressive rigidity of the land area can be effectively reduced as soon as possible when wear progresses, while by setting it to 9 times or less, the rigidity of the land area becomes extremely high. You can prevent it from dropping.
- the length (depth) of the first widening portion 10b in the tire radial direction is 0.5 to 7 times the length (depth) of the flat plate portion 10a in the tire radial direction.
- the shape of the widened portion 10b is an elliptical cross section (horizontally long), but may be various shapes such as a vertically long elliptical shape, a circular shape, and a triangular shape (a shape extending from the outside to the inside in the tire radial direction).
- the sipe width (maximum width when measured in the same direction as the opening width) of the widening portion 10b is 1.5 to 3. when the shape of the widening portion 10b is conical (triangular cross section). In the case of 5 mm and a spherical shape (circular or elliptical cross section), it is preferably 1.0 to 2.0 mm.
- Riding comfort performance can be further improved by using a flat plate-shaped sipe.
- a sipes having a non-flat cross section such as a zigzag shape can also be adopted.
- a sipe having such a shape it becomes easy to maintain the block rigidity of the entire land area, so that rolling resistance can be effectively suppressed.
- the circumferential main groove 6 is composed of a straight portion and a widening portion, and can have a widening portion on the groove bottom side in which the groove width is larger than that on the tread surface side.
- the groove width of the widened portion (maximum width when measured in the same direction as the opening width) is preferably 1.1 to 1.5 times the opening width of the straight portion.
- the length (depth) of the widened portion in the tire radial direction can be 0.4 times or more the length (depth) of the straight portion in the tire radial direction.
- the drainage property can be improved as soon as possible when the wear progresses.
- the length (depth) of the widened portion in the tire radial direction is 0.5 times or more the length (depth) of the straight portion in the tire radial direction. Since the straight portion may not be provided, the upper limit is not particularly limited.
- the shape of the widened portion is an elliptical cross section (horizontally long), but it can be various shapes such as a vertically long elliptical shape, a circle, and a triangular shape (a shape extending from the outside to the inside in the tire radial direction). ..
- the groove width of the widened portion (maximum width when measured in the same direction as the opening width) is 11 to 22 mm when the shape of the widened portion is conical (triangular cross section), and spherical (circular cross section). Or in the case of an elliptical shape), it is preferably 10 to 19 mm.
- the cross-sectional shape of the circumferential main groove 6 can also be a normal U-shape or V-shape. Then, all the circumferential main grooves 6 may have a normal U-shape or a V-shape, or all the circumferential main grooves 6 may have a shape including a straight portion and a widening portion. It can also be arranged, or these can be arranged in any combination.
- the action and effect of the pneumatic radial tire for a passenger car of the present embodiment will be described.
- the cross-sectional width SW of the tire and the outer diameter OD of the tire satisfy the above-mentioned predetermined relational expression, so that the air resistance value and the rolling resistance value are reduced. Fuel efficiency can be improved.
- such a tire may have deteriorated performance on snow due to its high ring rigidity.
- the tire of the present embodiment has a plurality of width direction sipes extending in the tire width direction on the land portion, and the width direction sipes have a widening portion on the bottom side of the sipes where the sipe width is larger than that on the tread side.
- the pitch length of the plurality of width direction sipes in the tire circumferential direction is set to 3 mm to 10 mm.
- the pitch length in the tire circumferential direction of multiple width direction sipes is less than 3 mm, it is not possible to secure a sufficient space for the widened portion to collapse, while if the pitch length in the tire circumferential direction exceeds 10 mm, the above effect Cannot be obtained sufficiently.
- a tire satisfying the predetermined relational expression of SW and OD as described above has a high edge pressure because the contact pressure is high, and the edge component in the tire width direction (tire circumferential direction) with the pitch length of 3 mm or more as described above. Even if the edge component) is reduced, sufficient traction performance on snow and cornering performance on snow can be ensured.
- the pitch length of the plurality of widthwise sipes in the tire circumferential direction is preferably 5 mm to 10 mm.
- width-direction sipes having the above-mentioned widening portion 50 to 100% (number) of all the width-direction sipes are width-direction sipes having the above-mentioned widening portion.
- one widthwise sipe having the above-mentioned widening portion is provided in the tire circumferential direction. It is preferable to arrange the tires so that they are uniformly arranged in the tire circumferential direction, such as every two tires.
- all the widthwise sipes 10 are composed of the flat plate portion 10a and the widening portion 10b as described above. Further, in order to obtain the above-mentioned effect, it is sufficient that the width-direction sipe having the above-mentioned widening portion occupying 50 to 100% of all the width-direction sipes is formed in any of the land areas. It may have a land portion such that the number of widthwise sipes having the above-mentioned widening portion is less than 50% (including 0) of the whole. Further, as an example, at least one widthwise sipe 10 including the flat plate portion 10a and the widening portion 10b as described above may be located in the ground plane.
- the above is applied to the center land portion.
- the traction performance on the snowy road surface can be improved by forming the width direction sipe having the widening portion of the shoulder, and the cornering power is increased by forming the width direction sipe having the above widening portion on the shoulder land portion. be able to.
- the inner shoulder land part when mounted on the vehicle greatly contributes to wear performance
- the outer land part when mounted on the vehicle greatly contributes to cornering performance, so that one side in the tire width direction (outside when mounted on the vehicle).
- the widthwise sipe having the widened portion is the tire circumferential length of the block (in the tire circumferential direction of the block). It is preferably located in the central region, which is the central 50% region (the region not 25% each at both ends) of the length between both ends in the tire circumferential direction. This is because it is possible to secure a sufficient space for the widened portion to be crushed and further enhance the effect of suppressing the above-mentioned deterioration of the performance on snow.
- the widthwise sipe having the above-mentioned widening portion is regarded as a one-sided closed sipe, and the widthwise sipe communicating with one circumferential main groove (or tread end) and the other circumferential main groove (or tread end) communicate with each other.
- the width direction sipes may be arranged alternately in the tire circumferential direction in a staggered manner to increase the density of the width direction sipes having the above-mentioned widening portion.
- the pitch lengths are the pitch lengths of the widthwise sipes communicating with one circumferential main groove (or tread end) and the widthwise sipes communicating with the other circumferential main groove (or tread end). Consider the pitch length.
- the widthwise sipes having the widened portion are located on one side of the block in the tire circumferential direction from the other side in the tire circumferential direction. It is also preferable that many tires are arranged.
- the stepping side has a higher effect of crushing the widened portion than the kicking side, so that the performance on snow is reduced more efficiently. This is because it can be suppressed.
- the sipe width of the widening portion of the widthwise sipes arranged on one side in the tire circumferential direction of the block is the block width. It is also preferable that the width is larger than the sipe width of the widened portion of the width sipe arranged on the other side in the tire circumferential direction.
- the stepping side has a higher effect of crushing the widened portion than the kicking side, so that the performance on snow is reduced more efficiently. This is because it can be suppressed.
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Abstract
Description
(1)一対のビード部間でトロイダル状に跨る、ラジアル配列コードのプライからなるカーカスを備えた、乗用車用空気入りラジアルタイヤであって、
前記タイヤの断面幅SWが165(mm)未満であり、前記タイヤの断面幅SWと外径ODとの比SW/ODは、0.26以下であり、
前記タイヤは、トレッド部を有し、
前記トレッド部の踏面に1つ以上の陸部を有し、
前記陸部に、タイヤ幅方向に延びる複数本の幅方向サイプを有し、
前記複数本の幅方向サイプのタイヤ周方向のピッチ長は、3mm~10mmであり、
前記幅方向サイプは、サイプ底側にサイプ幅が前記踏面側より大きくなる拡幅部を有することを特徴とする、乗用車用空気入りラジアルタイヤ。
前記タイヤの断面幅SWが165(mm)以上であり、前記タイヤの断面幅SW(mm)及び外径OD(mm)は、関係式、
OD(mm)≧2.135×SW(mm)+282.3
を満たし、
前記タイヤは、トレッド部を有し、
前記トレッド部の踏面に1つ以上の陸部を有し、
前記陸部に、タイヤ幅方向に延びる複数本の幅方向サイプを有し、
前記複数本の幅方向サイプのタイヤ周方向のピッチ長は、3mm~10mmであり、
前記幅方向サイプは、サイプ底側にサイプ幅が前記踏面側より大きくなる拡幅部を有することを特徴とする、乗用車用空気入りラジアルタイヤ。
前記タイヤの断面幅SW(mm)及び外径OD(mm)は、関係式、
OD(mm)≧-0.0187×SW(mm)2+9.15×SW(mm)-380
を満たし、
前記タイヤは、トレッド部を有し、
前記トレッド部の踏面に1つ以上の陸部を有し、
前記陸部に、タイヤ幅方向に延びる複数本の幅方向サイプを有し、
前記複数本の幅方向サイプのタイヤ周方向のピッチ長は、3mm~10mmであり、
前記幅方向サイプは、サイプ底側にサイプ幅が前記踏面側より大きくなる拡幅部を有することを特徴とする、乗用車用空気入りラジアルタイヤ。
また、「規定内圧」とは、上記JATMA等に記載されている、適用サイズ・プライレーティングにおける単輪の最大負荷能力に対応する空気圧(最高空気圧)を指し、上記産業規格に記載のないサイズの場合は、「規定内圧」は、タイヤを装着する車両毎に規定される最大負荷能力に対応する空気圧(最高空気圧)をいうものとする。さらに、「最大負荷荷重」とは、上記最大負荷能力に対応する荷重をいうものとする。
本発明の第1の態様における一実施形態の乗用車用空気入りラジアルタイヤ(以下、単にタイヤとも称する)は、タイヤの断面幅SWが165(mm)未満であり、タイヤの断面幅SWと外径ODとの比SW/ODは、0.26以下であり、狭幅・大径の形状をなしている。タイヤの断面幅SWをタイヤの外径ODに比して狭くすることにより、空気抵抗を低減することができ、且つ、タイヤの外径ODをタイヤの断面幅SWに比して大きくすることにより、タイヤの接地面付近でのトレッドゴムの変形を抑制して、転がり抵抗を低減することができ、これらにより、タイヤの燃費性を向上させることができる。上記SW/ODは、0.25以下とすることが好ましく、0.24以下とすることがより好ましい。
上記比は、タイヤの内圧が200kPa以上である場合に満たされるものであることが好ましく、220kPa以上である場合に満たされるものであることがより好ましく、280kPa以上である場合に満たされるものであることがさらに好ましい。転がり抵抗を低減することができるからである。一方で、上記比は、タイヤの内圧が350kPa以下である場合に満たされるものであることが好ましい。乗り心地性を向上させることができるからである。
ここで、タイヤの断面幅SWは、接地面積を確保する観点からは、上記比を満たす範囲において、105mm以上とすることが好ましく、125mm以上とすることがより好ましく、135mm以上とすることがさらに好ましく、145mm以上とすることが特に好ましい。一方で、タイヤの断面幅SWは、空気抵抗を低減する観点からは、上記比を満たす範囲において、155mm以下とすることが好ましい。また、タイヤの外径ODは、転がり抵抗を低減する観点からは、上記比を満たす範囲において、500mm以上とすることが好ましく、550mm以上とすることがより好ましく、580mm以上とすることがさらに好ましい。一方で、タイヤの外径ODは、空気抵抗を低減する観点からは、上記比を満たす範囲において、800mm以下とすることが好ましく、720mm以下とすることがより好ましく、650mm以下とすることがさらに好ましく、630mm以下とすることが特に好ましい。また、リム径は、転がり抵抗を低減する観点からは、タイヤの断面幅SW及び外径ODが上記比を満たすとき、16インチ以上とすることが好ましく、17インチ以上とすることがより好ましく、18インチ以上とすることがさらに好ましい。一方で、リム径は、空気抵抗を低減する観点からは、タイヤの断面幅SW及び外径ODが上記比を満たすとき、22インチ以下とすることが好ましく、21インチ以下とすることがより好ましく、20インチ以下とすることがさらに好ましく、19インチ以下とすることが特に好ましい。また、タイヤの扁平率は、タイヤの断面幅SW及び外径ODが上記比を満たすとき、45~70とすることがより好ましく、45~65とすることがより好ましい。
具体的なタイヤサイズは、特に限定されるものではないが、一例として、105/50R16、115/50R17、125/55R20、125/60R18、125/65R19、135/45R21、135/55R20、135/60R17、135/60R18、135/60R19、135/65R19、145/45R21、145/55R20、145/60R16、145/60R17、145/60R18、145/60R19、145/65R19、155/45R18、155/45R21、155/55R18、155/55R19、155/55R21、155/60R17、155/65R18、155/70R17、155/70R19のいずれかとすることができる。
OD(mm)≧2.135×SW(mm)+282.3
を満たしており、狭幅・大径の形状をなしている。
上記の関係式を満たすことにより、空気抵抗を低減することができ、且つ、転がり抵抗を低減することができ、これらにより、タイヤの燃費性を向上させることができる。
なお、第2の態様において、タイヤの断面幅SW及び外径ODは、上記の関係式を満たした上で、比SW/ODが0.26以下であることが好ましく、0.25以下であることがより好ましく、0.24以下であることがさらに好ましい。タイヤの燃費性をさらに向上させることができるからである。
上記関係式及び/又は比は、タイヤの内圧が200kPa以上である場合に満たされるものであることが好ましく、220kPa以上である場合に満たされるものであることがより好ましく、280kPa以上である場合に満たされるものであることがさらに好ましい。転がり抵抗を低減することができるからである。一方で、上記関係式及び/又は比は、タイヤの内圧が350kPa以下である場合に満たされるものであることが好ましい。乗り心地性を向上させることができるからである。
ここで、タイヤの断面幅SWは、接地面積を確保する観点からは、上記関係式を満たす範囲において、175mm以上とすることが好ましく、185mm以上とすることがより好ましい。一方で、タイヤの断面幅SWは、空気抵抗を低減する観点からは、上記関係式を満たす範囲において、230mm以下とすることが好ましく、215mm以下とすることがより好ましく、205mm以下とすることがさらに好ましく、195mm以下とすることが特に好ましい。また、タイヤの外径ODは、転がり抵抗を低減する観点からは、上記関係式を満たす範囲において、630mm以上とすることが好ましく、650mm以上とすることがより好ましい。一方で、タイヤの外径ODは、空気抵抗を低減する観点からは、上記関係式を満たす範囲において、800mm以下とすることが好ましく、750mm以下とすることがより好ましく、720mm以下とすることがさらに好ましい。また、リム径は、転がり抵抗を低減する観点からは、タイヤの断面幅SW及び外径ODが上記関係式を満たすとき、18インチ以上とすることが好ましく、19インチ以上とすることがより好ましい。一方で、リム径は、空気抵抗を低減する観点からは、タイヤの断面幅SW及び外径ODが上記関係式を満たすとき、22インチ以下とすることが好ましく、21インチ以下とすることがより好ましい。また、タイヤの断面幅SW及び外径ODが上記関係式を満たすとき、タイヤの扁平率は、45~70とすることが好ましく、45~65とすることがより好ましい。
具体的なタイヤサイズは、特に限定されるものではないが、一例として、165/45R22、165/55R18、165/55R19、165/55R20、165/55R21、165/60R19、165/65R19、165/70R18、175/45R23、175/55R19、175/55R20、175/55R22、175/60R18、185/45R22、185/50R20、185/55R19、185/55R20、185/60R19、185/60R20、195/50R20、195/55R20、195/60R19、205/50R21、205/55R20、215/50R21のいずれかとすることができる。
OD(mm)≧-0.0187×SW(mm)2+9.15×SW(mm)-380
を満たしており、狭幅・大径の形状をなしている。
上記の関係式を満たすことにより、空気抵抗を低減することができ、且つ、転がり抵抗を低減することができ、これらにより、タイヤの燃費性を向上させることができる。
なお、第3の態様において、タイヤの断面幅SW及び外径ODは、上記の関係式を満たした上で、比SW/ODが0.26以下であることが好ましく、0.25以下であることがより好ましく、0.24以下であることがさらに好ましい。タイヤの燃費性をさらに向上させることができるからである。
上記関係式及び/又は比は、タイヤの内圧が200kPa以上である場合に満たされるものであることが好ましく、220kPa以上である場合に満たされるものであることがより好ましく、280kPa以上である場合に満たされるものであることがさらに好ましい。転がり抵抗を低減することができるからである。一方で、上記関係式及び/又は比は、タイヤの内圧が350kPa以下である場合に満たされるものであることが好ましい。乗り心地性を向上させることができるからである。
ここで、タイヤの断面幅SWは、接地面積を確保する観点からは、上記関係式を満たす範囲において、105mm以上とすることが好ましく、125mm以上とすることがより好ましく、135mm以上とすることがさらに好ましく、145mm以上とすることが特に好ましい。一方で、タイヤの断面幅SWは、空気抵抗を低減する観点からは、上記関係式を満たす範囲において、230mm以下とすることが好ましく、215mm以下とすることがより好ましく、205mm以下とすることがさらに好ましく、195mm以下とすることが特に好ましい。また、タイヤの外径ODは、転がり抵抗を低減する観点からは、上記関係式を満たす範囲において、500mm以上とすることが好ましく、550mm以上とすることがより好ましく、580mm以上とすることがさらに好ましい。一方で、タイヤの外径ODは、空気抵抗を低減する観点からは、上記関係式を満たす範囲において、800mm以下とすることが好ましく、750mm以下とすることがより好ましく、720mm以下とすることがさらに好ましい。また、リム径は、転がり抵抗を低減する観点からは、タイヤの断面幅SW及び外径ODが上記関係式を満たすとき、16インチ以上とすることが好ましく、17インチ以上とすることがより好ましく、18インチ以上とすることがさらに好ましい。一方で、リム径は、空気抵抗を低減する観点からは、タイヤの断面幅SW及び外径ODが上記関係式を満たすとき、22インチ以下とすることが好ましく、21インチ以下とすることがより好ましく、20インチ以下とすることがさらに好ましい。また、タイヤの扁平率は、タイヤの断面幅SW及び外径ODが上記比を満たすとき、45~70とすることがより好ましく、45~65とすることがより好ましい。
具体的なタイヤサイズは、特に限定されるものではないが、一例として、105/50R16、115/50R17、125/55R20、125/60R18、125/65R19、135/45R21、135/55R20、135/60R17、135/60R18、135/60R19、135/65R19、145/45R21、145/55R20、145/60R16、145/60R17、145/60R18、145/60R19、145/65R19、155/45R18、155/45R21、155/55R18、155/55R19、155/55R21、155/60R17、155/65R18、155/70R17、155/70R19、165/45R22、165/55R18、165/55R19、165/55R20、165/55R21、165/60R19、165/6R19、165/70R18、175/45R23、175/55R18、175/55R19、175/55R20、175/55R22、175/60R18、185/45R22、185/50R20、185/55R19、185/55R20、185/60R19、185/60R20、195/50R20、195/55R20、195/60R19、205/50R21、205/55R20、215/50R21のいずれかとすることができる。
ここで、「ビード部」とは、ビードフィラを有する場合には、リムベースラインからビードフィラのタイヤ径方向最外側端までのタイヤ径方向領域にある部分をいい、ビードフィラを有しない場合には、リムベースラインからビードコアのタイヤ径方向最外側端までのタイヤ径方向領域にある部分をいう。
本実施形態において、ベルト層4a、4bのベルトコードとしては、金属コード、特にスチールコードを用いるのが最も好ましいが、有機繊維コードを用いることもできる。スチールコードはスチールを主成分とし、炭素、マンガン、ケイ素、リン、硫黄、銅、クロムなど種々の微量含有物を含むことができる。本実施形態において、ベルト層4a、4bのベルトコードはモノフィラメントコードや、複数のフィラメントを引き揃えたコード、複数のフィラメントを撚り合せたコードを用いることができる。撚り構造も種々のものを採用することができ、断面構造、撚りピッチ、撚り方向、隣接するフィラメント同士の距離も様々なものとすることができる。さらには異なる材質のフィラメントを撚り合せたコードを用いることもでき、断面構造としても特に限定されず、単撚り、層撚り、複撚りなど様々な撚り構造を取ることができる。
本実施形態では、ベルト層4a、4bのベルトコードの傾斜角度は、タイヤ周方向に対して10°以上とすることが好ましい。本実施形態では、ベルト層4a、4bのベルトコードの傾斜角度を高角度、具体的にはタイヤ周方向に対して20°以上、好ましくは35°以上、特にタイヤ周方向に対して55°~85°の範囲とすることが好ましい。傾斜角度を20°以上(好ましくは35°以上)とすることにより、タイヤ幅方向に対する剛性を高め、特にコーナリング時の操縦安定性能を向上させることができるからである。また、層間ゴムのせん断変形を減少させて、転がり抵抗を低減することができるからである。
なお、タイヤをリムに組み込み、規定内圧を充填し、無負荷状態とした際の、タイヤ幅方向断面において、接地端E間のタイヤ幅方向中央50%のタイヤ幅方向領域をセンター領域Cとし、該センター領域よりタイヤ幅方向両外側の25%ずつのタイヤ幅方向領域をショルダー領域Sとする。
例えば、センター領域Cにおける周方向ベルト層の層数をショルダー領域Sより多くすることにより、センター領域Cの単位幅あたりのタイヤ周方向剛性を、ショルダー領域Sの単位幅あたりのタイヤ周方向剛性より高くすることができる。ここで、ベルト層4a、4bのベルトコードがタイヤ周方向に対して35°以上で傾斜するタイヤの多くは、400Hz~2kHzの高周波域において、断面方向の1次、2次および3次等の振動モードにて、トレッド踏面が一律に大きく振動する形状となるため、大きな放射音が生じる。そこで、トレッド5のセンター領域Cのタイヤ周方向剛性を局所的に増加させると、トレッド5のセンター領域Cがタイヤ周方向に広がり難くなり、トレッド踏面のタイヤ周方向への広がりが抑制される結果、放射音を減少させることができる。
本実施形態では、タイヤ幅方向の幅が最も広いベルト層(図示例ではベルト層4a)のベルトコードのタイヤ周方向に対する傾斜角度θ1と、タイヤ幅方向の幅が最も狭いベルト層(図示例ではベルト層4b)のベルトコードのタイヤ周方向に対する傾斜角度θ2とが、35°≦θ1≦85°、10°≦θ2≦30°、及び、θ1>θ2を満たすことも好ましい。タイヤ周方向に対して35°以上で傾斜するベルトコードを有するベルト層を備えたタイヤの多くは、400Hz~2kHzの高周波域において、断面方向の1次、2次および3次等の振動モードにて、トレッド踏面が一律に大きく振動する形状となるため、大きな放射音が生じる。そこで、トレッド5のセンター領域Cのタイヤ周方向剛性を局所的に増加させると、トレッド5のセンター領域Cがタイヤ周方向に広がり難くなり、トレッド踏面のタイヤ周方向への広がりが抑制される結果、放射音を減少させることができる。
ここで、本実施形態では、周方向ベルトを設ける場合は、周方向ベルト層は高剛性であることが好ましく、より具体的にはタイヤ周方向に延びるコードのゴム引き層からなり、コードのヤング率をY(GPa)、打ち込み数をn(本/50mm)とし、周方向ベルト層をm層とし、コード径をd(mm)として、X=Y×n×m×dと定義するとき、1500≧X≧225であることが好ましい。なお、ヤング率は、タイヤ周方向に対するヤング率を意味し、JIS L1017 8.5 a) (2002)にて試験を行い、JIS L1017 8.8(2002)に準拠して求めるものである。狭幅・大径サイズの乗用車用空気入りラジアルタイヤにおいては、路面からの旋回時における入力に対しタイヤ周方向において局所的な変形を起こし、接地面は略三角形状、すなわち、タイヤ幅方向の位置によって周方向の接地長が大きく変化する形状となりやすい。これに対し、高剛性の周方向ベルト層とすることにより、タイヤのリング剛性が向上して、タイヤ周方向の変形が抑制されることとなるため、ゴムの非圧縮性により、タイヤ幅方向の変形も抑制され、接地形状が変化しにくくなる。さらには、リング剛性が向上することにより偏心変形が促進され、転がり抵抗も同時に向上する。さらに、上記のように高剛性の周方向ベルト層を用いた場合には、ベルト層4a、4bのベルトコードのタイヤ周方向に対する傾斜角度を高角度、具体的には35°以上とすることが好ましい。高剛性の周方向ベルト層を用いた場合には、タイヤ周方向の剛性が高くなることにより、タイヤによっては、接地長が減少してしまうことがある。そこで、高角度のベルト層を用いることにより、タイヤ周方向の面外曲げ剛性を低下させて、踏面変形時のゴムのタイヤ周方向の伸びを増大させ、接地長の減少を抑制することができる。また、本実施形態では、周方向ベルト層には、破断強度を高めるために波状のコードを用いてもよい。同様に破断強度を高めるために、ハイエロンゲーションコード(例えば破断時の伸びが4.5~5.5%)を用いてもよい。さらに、本実施形態では、周方向ベルト層には、種々の材質が採用可能であり、代表的な例としては、レーヨン、ナイロン、ポリエチレンナフタレート(PEN)、ポリエチレンテレフタレート(PET)、アラミド、ガラス繊維、カーボン繊維、スチール等が採用できる。軽量化の点から、有機繊維コードが特に好ましい。ここで、本実施形態では、周方向ベルトを設ける場合は、周方向ベルト層のコードは、モノフィラメントコードや、複数のフィラメントを引き揃えたコード、複数のフィラメントを撚り合せたコード、さらには異なる材質のフィラメントを撚り合せたハイブリッドコードを用いることもできる。また、本実施形態では、周方向ベルト層の打ち込み数は、20~60本/50mmの範囲とすることができるが、この範囲に限定されるのもではない。さらに、本実施形態では、タイヤ幅方向に剛性・材質・層数・打ち込み密度等の分布を持たせることもでき、例えばショルダー部Sのみにおいて、周方向ベルト層の層数を増やすこともでき、一方でセンター領域Cのみにおいて、周方向ベルト層の層数を増やすこともできる。また、本実施形態では、周方向ベルト層は、ベルト層4a、4bよりもタイヤ幅方向の幅を大きくすることも小さくすることも同じとすることもできる。例えば、周方向ベルト層のタイヤ幅方向の幅は、ベルト層4a、4bのうちタイヤ幅方向の幅が最も広いベルト層(図示例ではベルト層4a)のタイヤ幅方向の幅の90%~110%とすることができる。ここで、周方向ベルト層は、スパイラル層として構成することが製造の観点から特に有利である。
トレッドゴムのゴムゲージは、5mm以上8mm以下とすることが好ましい。本実施形態の場合のゴムゲージは、図2に示すように、タイヤ外表面からタイヤ径方向最外側の補強部材(図示例では2層のベルト層4a、4bのうち、最外側ベルト層4b)までのトレッドゴム5の厚さである。8mm以下とすることにより、タイヤを軽量化して転がり抵抗をさらに低減することができる。一方で、5mm以上とすることにより、ある程度摩耗が進展した際にもウェット性能を確保することができる。
また、本実施形態では、タイヤ幅方向断面において、タイヤ赤道面CLにおけるトレッド表面上の点Pを通りタイヤ幅方向に平行な直線をm1とし、接地端Eを通りタイヤ幅方向に平行な直線をm2として、直線m1と直線m2とのタイヤ径方向の距離を落ち高LCRとし、タイヤの接地幅をWとするとき、比LCR/Wを0.045以下とすることが好ましい。比LCR/Wを上記の範囲とすることにより、タイヤのクラウン部がフラット化(平坦化)し、接地面積が増大して、路面からの入力(圧力)を緩和して、タイヤ径方向の撓み率を低減し、タイヤの耐久性及び耐摩耗性を向上させることができる。
本実施形態では、インナーライナー8は、ブチルゴムを主体としたゴム層のほか、樹脂を主成分とするフィルム層によって形成することもできる。本実施形態では、タイヤ内面7には、パンク時の空気の漏れを防ぐためのシーラント部材を備えることもできる。
例えば、周方向主溝の本数が2本である場合、接地端E間のタイヤ幅方向領域を4等分して2つの中央領域Cと、2つの側方領域Sとに分けるとき、図示例のように2本の周方向主溝6が中央領域Cに位置することが好ましい。排水性をより確保することができるからである。
ここで、「タイヤ周方向に延びる」とは、タイヤ周方向に対して傾斜せずに延びる場合の他、タイヤ周方向に対して5°以下の傾斜角度で延びる場合も含む。また、図示のように、周方向主溝6は、タイヤ周方向に連続して延びることが好ましい。周方向主溝6の形状は、図示例のように直線状であることが最も好ましいが、ジグザグ状、湾曲状等にすることもできる。
図示例では、幅方向サイプ10は、延在方向の両端が周方向主溝6に連通しているが、一方で、幅方向サイプ10は、一方の端のみが周方向主溝6に連通し、他方の端は陸部9内に留まる、いわゆる片閉じサイプとすることができ、あるいは、両端が陸部9内に留まるサイプとすることもできる。これらのようなサイプを用いればサイプの形成による陸部の剛性の低下を極力抑制することができる。
まず、本実施形態の乗用車用空気入りラジアルタイヤでは、タイヤの断面幅SWとタイヤの外径ODとが、上記の所定の関係式を満たすため、空気抵抗値及び転がり抵抗値を低減して、燃費性を向上させることができる。しかし、上述したように、このようなタイヤは、リング剛性が高いことに起因して雪上性能が低下してしまう場合があった。これに対し、本実施形態のタイヤは、陸部に、タイヤ幅方向に延びる複数本の幅方向サイプを有し、幅方向サイプは、サイプ底側にサイプ幅が踏面側より大きくなる拡幅部を有している。これにより、陸部の圧縮剛性を低下させて路面との間で局所的な接触が生じるのを抑制しつつ、さらに摩耗進展時の排水性の低下も抑制することができる。そして、複数本の幅方向サイプのタイヤ周方向のピッチ長を3mm~10mmとしている。複数本の幅方向サイプのタイヤ周方向のピッチ長が3mm未満だと拡幅部が潰れる空間を十分に確保することができず、一方で、タイヤ周方向のピッチ長が10mm超だと上記の効果を十分に得ることができない。ここで、上記のようなSW及びODの所定の関係式を満たすタイヤは、接地圧が高いためエッジ圧が高く、上記のようにピッチ長を3mm以上としてタイヤ幅方向のエッジ成分(タイヤ周方向に対するエッジ成分)が減少しても、十分に雪上トラクション性能や雪上コーナリング性能を確保することができる。このように、高いエッジ圧、及び、路面との間の局所的な接触を抑制することのより、雪上性能の低下を抑制することができる。
以上のように、本実施形態の乗用車用空気入りラジアルタイヤによれば、雪上性能の低下を抑制しつつも、燃費性を向上することができる。
同様の理由により、複数本の幅方向サイプのタイヤ周方向のピッチ長は、好ましくは5mm~10mmである。
また、上記のような効果を得るためには、いずれかの陸部において、全ての幅方向サイプのうち50~100%を占める上記の拡幅部を有する幅方向サイプが形成されていれば良く、上記の拡幅部を有する幅方向サイプが全体の50%未満の本数(0本を含む)であるような陸部を有していても良い。また、一例としては接地面内に少なくとも1つ、上記のような平板部10aと拡幅部10bとからなる幅方向サイプ10が位置することもできる。
さらに、車両装着時の内側のショルダー陸部は、摩耗性能への寄与が大きく、車両装着時外側の陸部は、コーナリング性能への寄与が大きいため、タイヤ幅方向一方側(車両装着時外側)における上記拡幅部を有する幅方向サイプの個数密度を、タイヤ幅方向他方側(車両装着時内側)における上記拡幅部を有する幅方向サイプの個数密度より大きくすることにより、耐摩耗性とコーナリングパワーとをより高い次元で両立させることができる。
また、上記の拡幅部を有する幅方向サイプを片閉じサイプとして、一方の周方向主溝(又はトレッド端)に連通する幅方向サイプと、他方の周方向主溝(又はトレッド端)に連通する幅方向サイプとを、タイヤ周方向に交互に、千鳥状に配置して、上記の拡幅部を有する幅方向サイプの密度を高めても良い。この場合のピッチ長は、一方の周方向主溝(又はトレッド端)に連通する幅方向サイプ同士のピッチ長、及び、他方の周方向主溝(又はトレッド端)に連通する幅方向サイプ同士のピッチ長で考えるものとする。
3:カーカス、 4:ベルト、 5:トレッド部、 6:周方向主溝、
7:タイヤ内面、 8:インナーライナー、 9:陸部、 10:幅方向サイプ
Claims (7)
- 一対のビード部間でトロイダル状に跨る、ラジアル配列コードのプライからなるカーカスを備えた、乗用車用空気入りラジアルタイヤであって、
前記タイヤの断面幅SWが165(mm)未満であり、前記タイヤの断面幅SWと外径ODとの比SW/ODは、0.26以下であり、
前記タイヤは、トレッド部を有し、
前記トレッド部の踏面に1つ以上の陸部を有し、
前記陸部に、タイヤ幅方向に延びる複数本の幅方向サイプを有し、
前記複数本の幅方向サイプのタイヤ周方向のピッチ長は、3mm~10mmであり、
前記幅方向サイプは、サイプ底側にサイプ幅が前記踏面側より大きくなる拡幅部を有することを特徴とする、乗用車用空気入りラジアルタイヤ。 - 一対のビード部間でトロイダル状に跨る、ラジアル配列コードのプライからなるカーカスを備えた、乗用車用空気入りラジアルタイヤであって、
前記タイヤの断面幅SWが165(mm)以上であり、前記タイヤの断面幅SW(mm)及び外径OD(mm)は、関係式、
OD(mm)≧2.135×SW(mm)+282.3
を満たし、
前記タイヤは、トレッド部を有し、
前記トレッド部の踏面に1つ以上の陸部を有し、
前記陸部に、タイヤ幅方向に延びる複数本の幅方向サイプを有し、
前記複数本の幅方向サイプのタイヤ周方向のピッチ長は、3mm~10mmであり、
前記幅方向サイプは、サイプ底側にサイプ幅が前記踏面側より大きくなる拡幅部を有することを特徴とする、乗用車用空気入りラジアルタイヤ。 - 一対のビード部間でトロイダル状に跨る、ラジアル配列コードのプライからなるカーカスを備えた、乗用車用空気入りラジアルタイヤであって、
前記タイヤの断面幅SW(mm)及び外径OD(mm)は、関係式、
OD(mm)≧-0.0187×SW(mm)2+9.15×SW(mm)-380
を満たし、
前記タイヤは、トレッド部を有し、
前記トレッド部の踏面に1つ以上の陸部を有し、
前記陸部に、タイヤ幅方向に延びる複数本の幅方向サイプを有し、
前記複数本の幅方向サイプのタイヤ周方向のピッチ長は、3mm~10mmであり、
前記幅方向サイプは、サイプ底側にサイプ幅が前記踏面側より大きくなる拡幅部を有することを特徴とする、乗用車用空気入りラジアルタイヤ。 - 前記陸部は、タイヤ幅方向に延びる複数本の幅方向溝によりブロックに区画され、
前記拡幅部を有する前記幅方向サイプは、前記ブロックのタイヤ周方向長さの中央50%の領域である中央領域に位置する、請求項1~3のいずれか一項に記載の乗用車用空気入りラジアルタイヤ。 - 前記陸部は、タイヤ幅方向に延びる複数本の幅方向溝によりブロックに区画され、
前記拡幅部を有する前記幅方向サイプは、前記ブロックのタイヤ周方向一方側において、タイヤ周方向他方側よりも多く配置されている、請求項1~4のいずれか一項に記載の乗用車用空気入りラジアルタイヤ。 - 前記陸部は、タイヤ幅方向に延びる複数本の幅方向溝によりブロックに区画され、
前記ブロックのタイヤ周方向一方側に配置された前記幅方向サイプの前記拡幅部のサイプ幅は、前記ブロックのタイヤ周方向他方側に配置された前記幅方向サイプの前記拡幅部のサイプ幅よりも大きい、請求項1~5のいずれか一項に記載の乗用車用空気入りラジアルタイヤ。 - 前記ブロックの前記タイヤ周方向一方側は、車両装着時における前記ブロックの踏み込み側である、請求項5又は6に記載の乗用車用空気入りラジアルタイヤ。
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