CA1314000C - Heavy duty pneumatic radial tires - Google Patents
Heavy duty pneumatic radial tiresInfo
- Publication number
- CA1314000C CA1314000C CA000564744A CA564744A CA1314000C CA 1314000 C CA1314000 C CA 1314000C CA 000564744 A CA000564744 A CA 000564744A CA 564744 A CA564744 A CA 564744A CA 1314000 C CA1314000 C CA 1314000C
- Authority
- CA
- Canada
- Prior art keywords
- sipe
- heavy duty
- pitch
- tire
- pneumatic radial
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- 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
- B60C2200/06—Tyres specially adapted for particular applications for heavy duty vehicles
Abstract
HEAVY DUTY PNEUMATIC RADIAL TIRES
Abstract of the Disclosure A heavy duty pneumatic radial tire comprises a tread divided into plural ribs by plural main grooves each extending zigzag circumferentially of the tire.
The resistance to uneven wear is improved by regulating the pitch of the open sipe crossing the tread as well as the amplitude and pitch of the main groove in connection with the sipe pitch.
Abstract of the Disclosure A heavy duty pneumatic radial tire comprises a tread divided into plural ribs by plural main grooves each extending zigzag circumferentially of the tire.
The resistance to uneven wear is improved by regulating the pitch of the open sipe crossing the tread as well as the amplitude and pitch of the main groove in connection with the sipe pitch.
Description
1 3 ~
62-125, 272 HEAVY DUTY PNEUMATIC RADIAL TIRES
This invention relates to heavy duty pneumatic radial tires for use in, for example, truck, bus and so on, and more particularly to a heavy duty pneumatic radial tire comprising a tread provided with plural ribs 05 extending circumferentially of the tire and many open sipes (hereinaEter referred to as sipe unless otherwise specified) crossing the tread.
As the heavy duty pneumatic radial tire running on good road at a high speed, there have hitherto been 10 used some tires, wherein the tread is divided inio plural ribs by main wide grooves extending zigzag circumferentially of the tire and many sipes each crossing the tread to extend between both side ends or the tread and having a thin width are arranged in the tread in the circumferential direction of the tire.
In these tiresr however, the amplitude and pitch of zigzag in the sipe and the main groove are not still optimized.
The invention will be described with reference to the accompanying drawings, wherein:
Figs. l to 3 are partial plan views of some embodiments of the conventional heavy duty pneumatic radial tire, respectively;
3~
62-125, 272 HEAVY DUTY PNEUMATIC RADIAL TIRES
This invention relates to heavy duty pneumatic radial tires for use in, for example, truck, bus and so on, and more particularly to a heavy duty pneumatic radial tire comprising a tread provided with plural ribs 05 extending circumferentially of the tire and many open sipes (hereinaEter referred to as sipe unless otherwise specified) crossing the tread.
As the heavy duty pneumatic radial tire running on good road at a high speed, there have hitherto been 10 used some tires, wherein the tread is divided inio plural ribs by main wide grooves extending zigzag circumferentially of the tire and many sipes each crossing the tread to extend between both side ends or the tread and having a thin width are arranged in the tread in the circumferential direction of the tire.
In these tiresr however, the amplitude and pitch of zigzag in the sipe and the main groove are not still optimized.
The invention will be described with reference to the accompanying drawings, wherein:
Figs. l to 3 are partial plan views of some embodiments of the conventional heavy duty pneumatic radial tire, respectively;
3~
- 2 -Fig. 4 is a graph showing a relation between pitch number of main groove in one pitch of open sipe and time of uneven wear generated in the heavy duty pneumatic radial tire according to the invention;
05 Fig. 5 is a partial plan view of a first embodiment of the heavy duty pneumatic radial tire according to the invention; and Figs. 6 and 7 are partial plan views of the other embodiments of the heavy duty pneumatic radial tire ascording to the invention, respectively.
For example, the conventional heavy duty pneumatic radial tires are shown in Figs. l to 3.
The heavy duty pneumatic radial tire l shown in Fig. l comprises a tread 2 divided into five ribs 5 by four 15 main wide grooves 3 each extending zigæag circumfer-entially of the tire. The amplitude W~ of the zigzag main groove 3 in widthwise direction of the tire is large, and the repeated pitch P3 of the zigzag main groove in circumferential direction is lon~. Numeral 6 2~ is a sipe. The sipe 6 crosses the tread 2 and extends between both side ends 2a of the tread 2 so as to have predetermined inclinin~ direction S and inclination angle ~6 of the sipe 6 with respect to the circumfer-ential direction C. Furthermore, the pitch P6 of the sipe 6 in the circumferential direction C is approxi-mately e~ual to the groove pitch P3 of the main ~ 3 ~
groove 3. The construction other than the above is the same as in the ordinary tire. However, in the heavy , duty pneumatic radial tire 1 comprising such a tread 2, rigidities of portions SA and 5B at a side end part 5a 05 of the rib 5 sandwiching the sipe 6 become ununiform, so that the wearing of the portion 5A ( shadowed region partially shown in Fig. 1) becomes faster than that of the portion 5B during the running and consequently uneven wear producing a stepped difference prematurely 10 generates at the side end part 5a of the rib 5.
The heavy duty pneumatic radial tire 8 shown in Fig. 2 is a case that the inclination angle ~6 of the sipe 6 crossing the tread 2 is made smaller than that of the heavy duty penumatic radial tire 1 shown in Fig. 1.
1~ Even in the heavy duty radial tire 8, the premature occurrence of uneven wear is caused at the side end part 5a of the rib 5 likewise the heavy duty pneumatic radial tire 1 of Fig. 1.
The heavy duty peunmat1c radial tire 9 shown in 20 Fig. 3 i5 a case that the inclination angle ~6 of the sipe 6 crossing the tread 2 is made larger than that of the heavy duty pneumatic radial tire 1 shown in Fig. 1 and is perpendicular to the circumEerential direction of the tire. Even in the heavy duty pneumatic radial 25 ~tire 9, the rigidities of convex portion 5c and concave portion 5D at the side end part Sa of the rib 5 become ~ 3 ~
ununiform and the wear.ing of the convex portion 5C iS
faster than that of the concave portion 5D likewise the case of Fig. 1, so that the uneven wear prematurely occurs.
05 It is, therefore, an object of the invention to provide a heavy duty pneumatic radial tire haviny a considerably improved resistance to uneven wear by regulating the amplitude and pitch of the main zigzag groove to the pitch oE the open sipe crossing the tread 10 provided with plural ribs to thereby make the rigidity at the side end part of the rib in the vicinity of the open sipe uniform and largely delay the time of uneven wear produced in the side end part of the rib.
According to the invention, there is the provi-sion of a heavy duty pneumatic radial tire comprising a tread divided into plural ribs by plural main grooves each extending zigzag circumferentially of the tire, characterized in that each of open sipes crossing said tread and having a thin width is arranged at a sipe 20 pitch Ps of 10~40 mm in the circumferential direction, and said main zigzag groove has an amplitude of 1~10 mm, and a ratio of said pitch Ps of said sipe to groove pitch PG of said main groove is within a range of 1.5~20.
The term "open sipe" used herein means a thin 2~ slit extending between both side ends of the tread provided with plural ribs defined by plural main qrooves ~ 3 ~
extending circumferentially of the tire, wherein both ends of the slit open to the groove wall face of the main groove or the outside wall face of the tread end without terminating in the rib.
05 The reason why the sipe pitch Ps of the sipe (open sipe) in the circumferential direction is limited to a range of 10~40 mm is due to the fact that when the sipe pitch is less than 10 mm, the rigidity of rib blocks cut by ~he sipes too lowers to advance the 10 generation tlme of uneven wear, while when it exceeds 40 mm, the rigidity of the block becomes too large and the effect by the arrangement of the sipe reduces to advance the generation time of uneven wear.
Furthermore, the reason why the amplitude of the main groove is limited to a range of 1~10 mm is due to the fact that when the amplitude is less than 1 mm, the rigidity of that portion of the rib which projects toward the main groove becomes too large, while when it exceeds 10 mm, the rigidities of rib portions near to the sipe become ununiform and the generation time of uneven wear is advanced in both cases.
Moreover, the reason why the ratio (PSips) of the sipe pitch Ps to the groove pitch PG of the main groove is limited to a range of 1.5~20 is due to the fact that when PS/PG is less than 1.5, the rigidity of a side end portion of the rib near to the sipe becomes ~ 3 ~
ununiform to advance the generation time of uneven wear as shown in Fig. 4, while when it exceeds 20, the rigidity of the side end portion of the rib too lowers to advance the generation time of uneven wear as shown o~ in Fig. 4.
In a preferred embodiment of the invention, the inclination angle ~ between the cutting direction S of the sipe and the circumferential direction C of the tire is preferable to be 55~90. When the inclination angle 10 is less than 55, the rigidity of the side end portion of the rib near to the sipe becomes ununiform to advance the generation time of uneven wear.
In another preferred embodiment of the inven-tion, the depth of the sipe is favorable to correspond 1~ to 50~38% of the depth of the main groove. When the depth of the sipe is less than 50%, the rigidity of the rib blocks cut by the sipes are not sufficiently lowered and the generation time of uneven wear is advanced.
While, when it exceeds 98%, cracks are caused in the 20 groove bottom of the main groove by the sipe.
And also, the sipe is preferable to have a width of not more than 1 mm. When the width is more than 1 mm, the movement of the rib blocks cut by the sipes becomes too large to advan¢e the generation time of 2~ uneven wear.
In Fig. 5 is shown a first embodiment of the ~ 3 ~
heavy duty pneumatic radial tire according to the invention, wherein numeral 11 is a heavy duty pneumatic radial tubeless tire having a tire size oE E13.50/80R16.
The tire 11 comprises a tread 15 divided into five ribs o5 13 by four main wide grooves 12 each extending zigzag circumferentially of the tire. The main groove 12 has a groove width Wl2 of 6.0 mm, a zigzag amplitude V12 in widthwise direction of tire of 3.0 mm and a repetitive ziyzag pitch PG in circumferential direction C of 10 9.5 mm. Numeral 16 is an open sipe (merely referred to as a sipe hereinafter). The sipe 16 crosses the tread 15 and extends between both side ends 15a of the tread 15. The sipes 16 are arranged so as to have an inclination angle ~15 between the cutting direction S
15 of the sipe 16 and the circumferential direction C of the tire of 75 and a sipe pitch Ps in the circumfer-ential direction C of the tire of 19.5 mm. Moreover, the ratio PS/PG of the sipe pitch Ps to the groove pitch P~ of the main groove 12 is 2.05. The sipe 16 opens to the groove wall face of the main groove 12 at the side end 13a of the rib 13 and the outside wall face of the tread 15 at the side end 15a of the tread 15, respec-tively. The sipe has a width of 0.7 mm and a depth of 8.0 mm corresponding to 82% of the groove depth oE the 25 main groove 12 (g.7 mm).
The construction of the tire 11 other 'chan the ~3~ ~$~
above is the same as in the ordinary pneumatic radial tire, and the details thereof are omitted.
The function of the tire 11 will be described in detail below.
05 In the heavy duty pneumatic radial tire 11 according to the invention, the amplitude V12 and pitch PG of the main groove 12 in the tread 15 are 3.0 mm and 9.5 mm, respectively, and the pitch Ps of the sipe 16 is 19.5 mm, and the ratio PS/PG of the sipe pitch Ps to the 10 groove pitch PG is 2.05, so that the rigidities of side end portions 13b of the rib 13 in the vicinity 16a of the sipe 16 become approximately equal and uniform.
Therefore, even when the tire 11 is run on good road at a high speed under a heavy loading, the wearing of these 1~ side end portions 13b in the vicinity 16a of the sipe 16 are approximately equal and consequently the occurrence of uneven wear causing premature wear in only one of the side end portions 13b near to the sipe 16 is largely suppressed to largely delay the generation time of uneven wear, whereby the resistance to uneven wear can considerably be improved. Furthermore, the sipe 16 has an inclination angle Hl6 of 75, a width of 0.7 mm and a depth of 8.0 mm corresponding to 82% of the groove depth ; of the main groove 12 (9.7 mm)~ so that the above effect 2~ o~ suppressing the occurrence of uneven wear is further increased to largely ~delay the generation time of uneven wear, whereby the resistance to uneven wear can be more improved.
The effect of -the invention will be described with reference to the following test experiment.
05 There were provided six test tires 1 to 6 (corresponding to first to third embodiments and Comparative Examples 1 to 3) having a dimension of each part of the tread as shown in the following Table 1.
The test tire 1 was the same as in the first 10 embodiment of Fig. 5. The test tires 2 and 3 were second and third embodiments as shown by 21 and 31 in Figs. 6 and 7, whose construction being the same as in the first embodiment except that the inclination angle ~16 of the sipe 16 was 60 and 90 r respectively.
1~ The test tires 4 to 6 (Comparative Examples 1 to
05 Fig. 5 is a partial plan view of a first embodiment of the heavy duty pneumatic radial tire according to the invention; and Figs. 6 and 7 are partial plan views of the other embodiments of the heavy duty pneumatic radial tire ascording to the invention, respectively.
For example, the conventional heavy duty pneumatic radial tires are shown in Figs. l to 3.
The heavy duty pneumatic radial tire l shown in Fig. l comprises a tread 2 divided into five ribs 5 by four 15 main wide grooves 3 each extending zigæag circumfer-entially of the tire. The amplitude W~ of the zigzag main groove 3 in widthwise direction of the tire is large, and the repeated pitch P3 of the zigzag main groove in circumferential direction is lon~. Numeral 6 2~ is a sipe. The sipe 6 crosses the tread 2 and extends between both side ends 2a of the tread 2 so as to have predetermined inclinin~ direction S and inclination angle ~6 of the sipe 6 with respect to the circumfer-ential direction C. Furthermore, the pitch P6 of the sipe 6 in the circumferential direction C is approxi-mately e~ual to the groove pitch P3 of the main ~ 3 ~
groove 3. The construction other than the above is the same as in the ordinary tire. However, in the heavy , duty pneumatic radial tire 1 comprising such a tread 2, rigidities of portions SA and 5B at a side end part 5a 05 of the rib 5 sandwiching the sipe 6 become ununiform, so that the wearing of the portion 5A ( shadowed region partially shown in Fig. 1) becomes faster than that of the portion 5B during the running and consequently uneven wear producing a stepped difference prematurely 10 generates at the side end part 5a of the rib 5.
The heavy duty pneumatic radial tire 8 shown in Fig. 2 is a case that the inclination angle ~6 of the sipe 6 crossing the tread 2 is made smaller than that of the heavy duty penumatic radial tire 1 shown in Fig. 1.
1~ Even in the heavy duty radial tire 8, the premature occurrence of uneven wear is caused at the side end part 5a of the rib 5 likewise the heavy duty pneumatic radial tire 1 of Fig. 1.
The heavy duty peunmat1c radial tire 9 shown in 20 Fig. 3 i5 a case that the inclination angle ~6 of the sipe 6 crossing the tread 2 is made larger than that of the heavy duty pneumatic radial tire 1 shown in Fig. 1 and is perpendicular to the circumEerential direction of the tire. Even in the heavy duty pneumatic radial 25 ~tire 9, the rigidities of convex portion 5c and concave portion 5D at the side end part Sa of the rib 5 become ~ 3 ~
ununiform and the wear.ing of the convex portion 5C iS
faster than that of the concave portion 5D likewise the case of Fig. 1, so that the uneven wear prematurely occurs.
05 It is, therefore, an object of the invention to provide a heavy duty pneumatic radial tire haviny a considerably improved resistance to uneven wear by regulating the amplitude and pitch of the main zigzag groove to the pitch oE the open sipe crossing the tread 10 provided with plural ribs to thereby make the rigidity at the side end part of the rib in the vicinity of the open sipe uniform and largely delay the time of uneven wear produced in the side end part of the rib.
According to the invention, there is the provi-sion of a heavy duty pneumatic radial tire comprising a tread divided into plural ribs by plural main grooves each extending zigzag circumferentially of the tire, characterized in that each of open sipes crossing said tread and having a thin width is arranged at a sipe 20 pitch Ps of 10~40 mm in the circumferential direction, and said main zigzag groove has an amplitude of 1~10 mm, and a ratio of said pitch Ps of said sipe to groove pitch PG of said main groove is within a range of 1.5~20.
The term "open sipe" used herein means a thin 2~ slit extending between both side ends of the tread provided with plural ribs defined by plural main qrooves ~ 3 ~
extending circumferentially of the tire, wherein both ends of the slit open to the groove wall face of the main groove or the outside wall face of the tread end without terminating in the rib.
05 The reason why the sipe pitch Ps of the sipe (open sipe) in the circumferential direction is limited to a range of 10~40 mm is due to the fact that when the sipe pitch is less than 10 mm, the rigidity of rib blocks cut by ~he sipes too lowers to advance the 10 generation tlme of uneven wear, while when it exceeds 40 mm, the rigidity of the block becomes too large and the effect by the arrangement of the sipe reduces to advance the generation time of uneven wear.
Furthermore, the reason why the amplitude of the main groove is limited to a range of 1~10 mm is due to the fact that when the amplitude is less than 1 mm, the rigidity of that portion of the rib which projects toward the main groove becomes too large, while when it exceeds 10 mm, the rigidities of rib portions near to the sipe become ununiform and the generation time of uneven wear is advanced in both cases.
Moreover, the reason why the ratio (PSips) of the sipe pitch Ps to the groove pitch PG of the main groove is limited to a range of 1.5~20 is due to the fact that when PS/PG is less than 1.5, the rigidity of a side end portion of the rib near to the sipe becomes ~ 3 ~
ununiform to advance the generation time of uneven wear as shown in Fig. 4, while when it exceeds 20, the rigidity of the side end portion of the rib too lowers to advance the generation time of uneven wear as shown o~ in Fig. 4.
In a preferred embodiment of the invention, the inclination angle ~ between the cutting direction S of the sipe and the circumferential direction C of the tire is preferable to be 55~90. When the inclination angle 10 is less than 55, the rigidity of the side end portion of the rib near to the sipe becomes ununiform to advance the generation time of uneven wear.
In another preferred embodiment of the inven-tion, the depth of the sipe is favorable to correspond 1~ to 50~38% of the depth of the main groove. When the depth of the sipe is less than 50%, the rigidity of the rib blocks cut by the sipes are not sufficiently lowered and the generation time of uneven wear is advanced.
While, when it exceeds 98%, cracks are caused in the 20 groove bottom of the main groove by the sipe.
And also, the sipe is preferable to have a width of not more than 1 mm. When the width is more than 1 mm, the movement of the rib blocks cut by the sipes becomes too large to advan¢e the generation time of 2~ uneven wear.
In Fig. 5 is shown a first embodiment of the ~ 3 ~
heavy duty pneumatic radial tire according to the invention, wherein numeral 11 is a heavy duty pneumatic radial tubeless tire having a tire size oE E13.50/80R16.
The tire 11 comprises a tread 15 divided into five ribs o5 13 by four main wide grooves 12 each extending zigzag circumferentially of the tire. The main groove 12 has a groove width Wl2 of 6.0 mm, a zigzag amplitude V12 in widthwise direction of tire of 3.0 mm and a repetitive ziyzag pitch PG in circumferential direction C of 10 9.5 mm. Numeral 16 is an open sipe (merely referred to as a sipe hereinafter). The sipe 16 crosses the tread 15 and extends between both side ends 15a of the tread 15. The sipes 16 are arranged so as to have an inclination angle ~15 between the cutting direction S
15 of the sipe 16 and the circumferential direction C of the tire of 75 and a sipe pitch Ps in the circumfer-ential direction C of the tire of 19.5 mm. Moreover, the ratio PS/PG of the sipe pitch Ps to the groove pitch P~ of the main groove 12 is 2.05. The sipe 16 opens to the groove wall face of the main groove 12 at the side end 13a of the rib 13 and the outside wall face of the tread 15 at the side end 15a of the tread 15, respec-tively. The sipe has a width of 0.7 mm and a depth of 8.0 mm corresponding to 82% of the groove depth oE the 25 main groove 12 (g.7 mm).
The construction of the tire 11 other 'chan the ~3~ ~$~
above is the same as in the ordinary pneumatic radial tire, and the details thereof are omitted.
The function of the tire 11 will be described in detail below.
05 In the heavy duty pneumatic radial tire 11 according to the invention, the amplitude V12 and pitch PG of the main groove 12 in the tread 15 are 3.0 mm and 9.5 mm, respectively, and the pitch Ps of the sipe 16 is 19.5 mm, and the ratio PS/PG of the sipe pitch Ps to the 10 groove pitch PG is 2.05, so that the rigidities of side end portions 13b of the rib 13 in the vicinity 16a of the sipe 16 become approximately equal and uniform.
Therefore, even when the tire 11 is run on good road at a high speed under a heavy loading, the wearing of these 1~ side end portions 13b in the vicinity 16a of the sipe 16 are approximately equal and consequently the occurrence of uneven wear causing premature wear in only one of the side end portions 13b near to the sipe 16 is largely suppressed to largely delay the generation time of uneven wear, whereby the resistance to uneven wear can considerably be improved. Furthermore, the sipe 16 has an inclination angle Hl6 of 75, a width of 0.7 mm and a depth of 8.0 mm corresponding to 82% of the groove depth ; of the main groove 12 (9.7 mm)~ so that the above effect 2~ o~ suppressing the occurrence of uneven wear is further increased to largely ~delay the generation time of uneven wear, whereby the resistance to uneven wear can be more improved.
The effect of -the invention will be described with reference to the following test experiment.
05 There were provided six test tires 1 to 6 (corresponding to first to third embodiments and Comparative Examples 1 to 3) having a dimension of each part of the tread as shown in the following Table 1.
The test tire 1 was the same as in the first 10 embodiment of Fig. 5. The test tires 2 and 3 were second and third embodiments as shown by 21 and 31 in Figs. 6 and 7, whose construction being the same as in the first embodiment except that the inclination angle ~16 of the sipe 16 was 60 and 90 r respectively.
1~ The test tires 4 to 6 (Comparative Examples 1 to
3) were the conventional tires as shown in Figs. 1 to 3.
In the test tires 4 to 6, the main groove had a width of 7~0 mm, an amplitude of 7.0 mm and a pitch of 28.0 mm and the inclination angle ~6 of the sipe 6 was 75, 60 and 90, respectively~ as shown in Table 1. The con-struction of these test tires 4 to 6 other than the above was the same as in the first embodiment.
Moreover, the test tires 1 to 6 were produced in the same manner.
2~
~ 3 ~
Table 1 ~est Test 5'est Test Test Test tire 1 tire 2 tire 3 tire 4 tire 5 tire 6 First Second Third Compar- Compar- Compar-embodi- embodi- ~mbodi- atlve 2xample ative ment ment ment 1 2 3 Corresponding figure Fig.5 Fig.6 Fig.7 Fig.l Fig.2 Fig.3 Width of main 6.0 6 0 6.0 7.0 7.0 7.0 groove (mm) Amplitude of main groove (mm) 3.0 3.0 3.0 7.0 7.0 7.0 _ Pitch of 9.5 9 5 9.5 28.028.0 28.0 main groove (mm) ..._ Pitch of sipe (mm)19.5 19.5 19.528.0 28.0 28.0 _ _ Inclinatlon angle 75 60 90 ... _ _ 60 90 PS/PG 2.052.05 2.05 1.0 1.0 1.0 _ _ Running distance t'll the occur- 100 100 100 80 80 80 wear (index) . . .
The test was carried out as follows. That is, each of the above test tires subjected to an internal pressure of 9.0 kg/cm2 was mounted onto a rim of 9.5 V x 16 T/L in a rear wheel of a test truck.
The test tire was run on a test course at a running speed of 80 km/hr under a loading of 4,300 kg to measure a running distance till the occurrence of uneven wear.
The test result was represented by an index on the basis that the first embodiment was 100 in Table lo 13 1 ~
The larger numerical value of the index, the better the resistance to uneven wear.
As seen from the results of Table l, the generation time of uneven wear in the first to third 05 embodiments is considerably slower than that of Comparative Examples l to 3, from which it is apparent that the effect of suppressing the occurrence of uneven wear in the tread of the heavy duty pneumatic radial tire according to the invention is large. That is, 10 according to the invention, the resistance to uneven wear is largely improved to considerably prolong the wear life of the tire.
As mentioned above, according to the invention, the rigidities of side end portions of the rib ln the 1~ vicinity of the sipe are made uniform by regulating the pitch of the open sipe arranged in the tread as well as the amplitude and pitch of the main groove to this sipe pitch, whereby the generation time of uneven wear at the side end portion of the rib can be largely suppressed to 2~ considerably improve the resistance to uneven wear and the wear life of the tire.
2~
In the test tires 4 to 6, the main groove had a width of 7~0 mm, an amplitude of 7.0 mm and a pitch of 28.0 mm and the inclination angle ~6 of the sipe 6 was 75, 60 and 90, respectively~ as shown in Table 1. The con-struction of these test tires 4 to 6 other than the above was the same as in the first embodiment.
Moreover, the test tires 1 to 6 were produced in the same manner.
2~
~ 3 ~
Table 1 ~est Test 5'est Test Test Test tire 1 tire 2 tire 3 tire 4 tire 5 tire 6 First Second Third Compar- Compar- Compar-embodi- embodi- ~mbodi- atlve 2xample ative ment ment ment 1 2 3 Corresponding figure Fig.5 Fig.6 Fig.7 Fig.l Fig.2 Fig.3 Width of main 6.0 6 0 6.0 7.0 7.0 7.0 groove (mm) Amplitude of main groove (mm) 3.0 3.0 3.0 7.0 7.0 7.0 _ Pitch of 9.5 9 5 9.5 28.028.0 28.0 main groove (mm) ..._ Pitch of sipe (mm)19.5 19.5 19.528.0 28.0 28.0 _ _ Inclinatlon angle 75 60 90 ... _ _ 60 90 PS/PG 2.052.05 2.05 1.0 1.0 1.0 _ _ Running distance t'll the occur- 100 100 100 80 80 80 wear (index) . . .
The test was carried out as follows. That is, each of the above test tires subjected to an internal pressure of 9.0 kg/cm2 was mounted onto a rim of 9.5 V x 16 T/L in a rear wheel of a test truck.
The test tire was run on a test course at a running speed of 80 km/hr under a loading of 4,300 kg to measure a running distance till the occurrence of uneven wear.
The test result was represented by an index on the basis that the first embodiment was 100 in Table lo 13 1 ~
The larger numerical value of the index, the better the resistance to uneven wear.
As seen from the results of Table l, the generation time of uneven wear in the first to third 05 embodiments is considerably slower than that of Comparative Examples l to 3, from which it is apparent that the effect of suppressing the occurrence of uneven wear in the tread of the heavy duty pneumatic radial tire according to the invention is large. That is, 10 according to the invention, the resistance to uneven wear is largely improved to considerably prolong the wear life of the tire.
As mentioned above, according to the invention, the rigidities of side end portions of the rib ln the 1~ vicinity of the sipe are made uniform by regulating the pitch of the open sipe arranged in the tread as well as the amplitude and pitch of the main groove to this sipe pitch, whereby the generation time of uneven wear at the side end portion of the rib can be largely suppressed to 2~ considerably improve the resistance to uneven wear and the wear life of the tire.
2~
Claims (4)
1. A heavy duty pneumatic radial tire comprising a tread divided into plural ribs by plural main grooves each extending zigzag circumferentially of the tire, characterized in that each of open sipes crossing said tread and having a thin width is arranged at a sipe pitch PS of 10?40 mm in the circumferential direction, and said main zigzag groove has an amplitude of 1?10 mm, and a ratio of said pitch Ps of said sipe to groove pitch PG of said main groove is within a range of 1.5?20.
2. The heavy duty pneumatic radial tire according to claim 1, wherein said sipe has an inclination angle of 55?90° with respect to the circumferential direction of the tire.
3. The heavy duty pneumatic radial tire according to claim 1, wherein said sipe has a depth corresponding to 50?98% of a depth of said main groove.
4. The heavy duty pneumatic radial tire according to claim 1,wherein said sipe has a width of not more than 1 mm.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62125272A JPS63291705A (en) | 1987-05-22 | 1987-05-22 | Pneumatic radial tire for heavy load |
| JP125,272/87 | 1987-05-22 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1314000C true CA1314000C (en) | 1993-03-02 |
Family
ID=14905972
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000564744A Expired - Fee Related CA1314000C (en) | 1987-05-22 | 1988-04-21 | Heavy duty pneumatic radial tires |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JPS63291705A (en) |
| CA (1) | CA1314000C (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5772807A (en) * | 1996-09-16 | 1998-06-30 | The Goodyear Tire & Rubber Company | Truck tire with thread of rib/groove configuration |
| JP3337415B2 (en) * | 1998-03-04 | 2002-10-21 | 住友ゴム工業株式会社 | Pneumatic tire suitable for running on ice |
| JP4793129B2 (en) * | 2006-06-23 | 2011-10-12 | 横浜ゴム株式会社 | Pneumatic tire |
| FR2965512B1 (en) * | 2010-09-30 | 2012-09-21 | Michelin Soc Tech | IMPROVED BEARING BAND FOR TIRES. |
| DE102011051387A1 (en) * | 2011-06-28 | 2013-01-03 | Continental Reifen Deutschland Gmbh | Vehicle tires |
| JP7434795B2 (en) * | 2019-10-11 | 2024-02-21 | 住友ゴム工業株式会社 | tire |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS595443A (en) * | 1982-06-30 | 1984-01-12 | Nec Home Electronics Ltd | Optical pickup |
| JPS61115703A (en) * | 1984-11-09 | 1986-06-03 | Sumitomo Rubber Ind Ltd | Radial-ply tire for truck and bus |
| JPS61175104A (en) * | 1985-01-29 | 1986-08-06 | Bridgestone Corp | Radial-ply tire for heavy duty |
-
1987
- 1987-05-22 JP JP62125272A patent/JPS63291705A/en active Pending
-
1988
- 1988-04-21 CA CA000564744A patent/CA1314000C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPS63291705A (en) | 1988-11-29 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed |