CA1313116C - Pneumatic radial tire for heavy-duty vehicles - Google Patents
Pneumatic radial tire for heavy-duty vehiclesInfo
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- CA1313116C CA1313116C CA000564421A CA564421A CA1313116C CA 1313116 C CA1313116 C CA 1313116C CA 000564421 A CA000564421 A CA 000564421A CA 564421 A CA564421 A CA 564421A CA 1313116 C CA1313116 C CA 1313116C
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- tread
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- sipe
- pneumatic radial
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Abstract
TITLE OF THE INVENTION
"PNEUMATIC RADIAL TIRE FOR HEAVY-DUTY VEHICLES"
ABSTRACT OF THE DISCLOSURE
A pneumatic radial tire for heavy-duty vehicles comprising a tread divided into at least two ribs by at least one groove extending substantially in the circumferential direction of the tire, and a plurality of sipes formed in lateral end portions of the tread and in end portions of the ribs, each of the sipes having a length of 1 to 3 mm on a tread surface of the tread, when the tire is new, and spacing between the sipes being 1 to 4 mm.
"PNEUMATIC RADIAL TIRE FOR HEAVY-DUTY VEHICLES"
ABSTRACT OF THE DISCLOSURE
A pneumatic radial tire for heavy-duty vehicles comprising a tread divided into at least two ribs by at least one groove extending substantially in the circumferential direction of the tire, and a plurality of sipes formed in lateral end portions of the tread and in end portions of the ribs, each of the sipes having a length of 1 to 3 mm on a tread surface of the tread, when the tire is new, and spacing between the sipes being 1 to 4 mm.
Description
~313116 FIELD OF THE INVENTION
The present invention relates in general to pneumatic radial tires used on heavy-duty vehicles, and in particular to an improvement in uneven wear proof of heavy-duty radial tires on trucks, buses and the like.
DESCRIPTION OF THE PRIOR ART
To prevent uneven wear from occurring in the tread of a pneumatic radial tire for heavy-duty vehicles, a plurality of sipes ~extremely narrow grooves) have so far been provided in the end portions of ribs or blocks in the tread.
While these sipes have been fairly satisfactory in improvement in uneven wearl there is a drawback that tear failure tends to occur in the sipe ends.
A generally known pneumatic radial tire for heavy-duty vehicles, which is designed for improving uneven wear occurring in the tread, is such as shown in Fig. 14. The conventional pneumatic radial tire for heavy-duty vehicles 1 has a tread 2 which is circumferentially divided into ribs 5 by grooves 3 each extending zigzag in the circumferential direction of the tire. In the end portions Sa of the ribs 5 and opposite end portions 2a of the tread 2 are circumferentially provided a plurality of sipes 6 each having a width of .3 to 1.0 mm. The sipe 6 is open at one end 6a thereof to the groove 3 or a buttress portion 2b between the tread 2 and a sidewall portion, and terminates in the other end 6b thereof. Since the rigidities of the end portions 5a of the ribs S and the end portions 2a of the tread 2 are reduced by the sipes 6 and the end portions are thus readily deformed, the occurrence of un~ven wear in the end portions is satisfactorily prevented. However, if the heavy-duty tire with these sipes 6 formed in the tread 2 runs at high speeds or on rough road surface, there is a disadvantage that tear failure 7 occurs from the other end 6b of the sipe 6, as shown in Fig. 14.
Accordingly, it is the object of the present invention to provide an improved pneumatic radial tire for heavy-duty vehicles in which sipes having suitable length and spacing therebetween are properly arranged in such a manner that the occurrence of uneven wear on the tread and furthermore the occurrence of tear failure in the sipe ends can be prevented.
The inventors have made various investigations and experiments with respect to the relation between the length of the sipes and the spacing between the sipes which are formed in the tread end portions and the rib end portions, and the occurrences of uneven wear on the tread and tear failure in the sipe end, and found the following facts. That is, if the spacing between the sipes formed in the tread end portions and the rib end portions becomes extremely wider, the margins of the end portions cannot be satisfactorily prevented from wearing round, because the rigidities in these end portions cannot be sufficientIy reduced. And also, self-wear cannot be satisfactorily reduced because wear resulting from the difference in radii between the tread end and central portions cannot be sufficiently reduced. As a result, it has been found that by arranging properly the spacing between the , 1313~16 sipes, the wear on the tread end portions and the rib end portions and the self-wear are reduced and thus the uneven wear proof can be enhanced.
In addition, if the length of the sipe becomes extremely longer, the rigidity of the end portion in which the sipes are provided is sufficiently reduced, but strain in the sipe end becomes larger. For this reason, the tear failure tends to occur from the sipe end. As a result, it has been found that the occurrence of tear failure in the sipe end can be prevented by making the length of the sipe less than a predetermined length. In addition, it has been found that with respect to the length of the sipe there is difference in the effect of prevention of the occurrence of tear failure, between at the time tire is new and at the time the height of the rib is decreased by the wear on the tread. Furthermore, it has been found that in the tire with circumferentially extending ribs on the tread the occurrence of the uneven wear is greatly reduced by providing the sipes in both the tread end portion and the rib end portion.
The inventors has further made various investigations and experiments with respect to the length of the sipe, the spacing between the sipes, the arrangement of the sipe, etc., and reached the present invention.
SUMMARY OF THE INVENTION
The foregoing objects are accomplished in accordance with the present invention by providing a pneumatic radial tire for heavy-duty vehicles comprising a tread divided into at least two ribs by at least one groove extending 1313~ ~
substantially in the circumferential direction of the tire, and a plurality of sipes formed in lateral end portions of the tread and in end portions of the ribs, each of the sipes having a length of 1 to 3 mm on a tread surface of the tread, when the tire is new, and spacing between the sipes being 1 to 4 mm.
The foregoing objects are also accomplished in accordance with the present invention by providing a pneumatic radial tire for heavy-duty vehicles comprising a tread divided into at least two ribs by at least one groove extending substantially in the circumferential direction of the tire, and a plurality of sipes formed in end portions of the ribs, each of the sipes having a length of 1 to 3 mm on a tread surface of the tread, when the tire is new, and spacing between the sipes being 1 to 4 mm.
Each of the sipes may be grooved in such a manner that the length remains essentially constant from the beginning to the end of wear on the tread. Each of the sipes may have a trapezoid section. The sipe of a trapezoid section may have, at the position which is half of a groove depth of the groove, a length which is 1 to 1.7 times greater than the length of 1 to 3 mm on the tread surface. The sipes may comprise sipes of same length and same spacing or different sipes of different lengths and different spacings.
Since in the pneumatic radial tire for heavy-duty vehicles according to the present invention a plurality of sipes wherein the length is 1 to 3 mm and the spacing therebetween is 1 to 4 mm are provided in the rib end portions or tread end portions, the rigidities in the rib end portions or tread end portions become smaller, and thus sidewise force applied to the tire and dragging resulting from the difference in radii between the tread end and central portions are greatly alleviated. As a result, the early occurrence of uneven wear on each end portion are greatly reduced, maximum tire life and tire durability are enhanced and the occurrence of tear failure in the sipe end are greatly reduced. In addition, because the sipe length is determined so as to remain essentially constant or within a predetermined range from the beginning to the end of tread wear, the aforementioned effect of the present invention continues from the beginning to the end of tread wear. That is, the uneven wear on the tread is greatly reduced and furthermore the 5 occurrence of tear failure in the sipe end is greatly reduced.
BRIEF DESCRIPTION OF THE DRAWINGS
The drawbacks of a conventional pneumatic radial tire for heavy-duty vehicles and the features and advantages of a pneùmatic radial tire for heavy-duty vehicles according to the present invention will be more clearly understood from the following description taken in conjunction with the accompanying drawings in which:
Figure 1 is a schematic plan view, partly broken away and partly in planform, showing a first embodiment of the pneumatic radial tire for heavy-duty vehicles according to the present invention wherein a plurality of sipes are formed in the end portion of the tread and the end portions of the ribs;
Figure 2 is an enlarged cross sectional view 13~3116 substantially taken along line II-II in Figure 1, showing the sipe has an axial length which remains essentially constant from the beginning to the end of tread wear;
Figure 3 is a schematic plan view, partly broken away and partly in planform, showning a second embodiment of the pneumatic radial tire for heavy-duty vehicles according to the present invention;
Figure 4 is an enlarged cross sectional view, partly broken away, showing a sipe that is formed adjacent a wide groove in accordance with a third embodiment of the present invention;
Figure 5 is a view similar to Figure 4 showing a sipe that is formed in the tread end portion in accordance with the third embodiment of the present invention;
Figure 6 is a schematic plan view, partly broken away and partly in planform, showing a comparative example 1 with the sipe spacing of more than 4 mm;
Figure 7 is a schematic plan view, partly broken away and partly in planform, showing a conventional tire which is used as a comparative example 2 in uneven wear and tear failure tests:
Figure 8 is a schematic plan view, partly broken away and partly in planform, showing a conventional tire with no sipes on the tread which is used as a comparative example 3 in uneven wear and tear failure tests;
Figure 9 is an enlarged cross sectional view showing a condition at which uneven wear occurred;
Figure 10 is a diagram graphically representing the 1313~l16 relation ~etween the occurrence of uneven wear and the sipe spacing;
Figure 11 is a diagram graphically representing the relation between the rate of the occurrence of tear ~ailuxe in the sipe end and the length of the sipe;
Figure 12 is a cross sectional view, partly broken away, showing at the half position of the groove depth at which the pneumatic radial tire for heavy-duty vehicles according to the present invention is buffed;
Figure 13 is a diagram graphically representing the rate of the occurrence of the tear failure in the sipe end;
and Fiqure 14 is a schematic plan view, partly broken away and partly in planform, showing a conventional pneumatic radial tire for heavy-duty vehicles DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now in detail to the drawings and initially to Figs. 1 and 2, there is shown a preferred embodiment of a pneumatic radial tire for heavy-duty vehicles which is constructed in accordance with the present invention.
Reference numeral 11 generally designates the pneumatic radial tire for heavy-duty vehicles according to the invention. The tire size is 10.00 R 20. The pneumatic radial tire for heavy-duty vehicles 11 has a tread 13 extending between a pair of shoulders 12 (only one shoulder is shown), which tread 13 is formed with four wide grooves 15 each extending zigzag in the circumferential direction of the tire (only two grooves are shown in Figs. 1 and 2). The tread 13 is divided by the . :
:
.
four wide grooves lS and has five tread ribs 16. A plurality of sipes 17 are formed in the circumferential direction of the tire in the end portions 16a of the ribs 16 and also in the end portions 13a of the tread 13. Each sipe 17 has a width W
of .5 mm and an axial length L of 3 mm. The spacing D of the tire circumferential direction between the sipes 17 is 2.2 mm.
As is shown in Fig. 2, the sipe 17 is grooved in such a manner that a length La of the sipe 17 at the beginning of tread wear is substantially equal to a length Lb of the sipe 17 at the end of tread wear. That is, as shown in Fig. 2, thè sipe 17 has a sipe end 17a thereof parallel to a groove wall 15a of the wide groove 15, or a sipe end 17b thereof parallel to a buttress surface 13b between the tread 13 and the sidewall of the tread. The reason why the length L of the sipe 17 is kept essentially constant from the beginning to the end of the wear on the tread 13 is for avoiding that the sipe length L changes as the wear on the tread 13 increases, the effect of the improvement of uneven wear becomes zero, and the tear failure of the sipe ends 17a and 17b tends to occur. The portions of the tire which have not been described are substantially identical to those of a normal pneumatic radial tire for heavy-duty vehicles, a belt of cord 18 is laid directly under the tread 13, a carcass 19 is laid under the belt 18, and the detailed descriptions will hereinafter be omitted.
Next, the operation of the pneumatic radial tire for heavy-duty vehicles according to the present invention will hereinafter be described in detail.
Since in the pneumatic radial tire of the present - 13~3~16 invention a plurality of sipes 17 are formed in the end portions 16a of the ribs 16 and the end portions 13a of the tread 13 and since the axial length L of the sipe 17 is 3 mm and the circumferential spacing D between the sipes 17 is 2 mm, the end portions 16a of the ribs 16 and the end portions 13a of the tread 13 have small rigidities and thus are resilient. For this reason, these end portions 13a and 16a are easily deformed when they meet the road surface, and therefore sidewise force applied to the tire is reduced and dragging resulting from the difference in the radii between the tread central portion and the tread end portion is alleviated, so that the relative movement to the ground surface is decreased. And, the occurrence of so-called uneven wear, which causes only the these end portions of the ribs and tread to unevenly wear at the beginning of the wear on the tread, is greatly reduced. Also, strains in the sipe ends 17a and 17b of the sipe 17 become small, so that the occurrence of the tear failure of the sipe ends 17a and 17b is greatly reduced.
In addition, since the sipes 17 each having the sipe length L which remains essentially constant from the beginning to the end of the wear on the tread 13 are formed in the end portions 13a of the tread 13 and the end portions 16a of the ribs 16, the aforementioned occurrences of uneven wear and the tear failure in the sipe ends 17a and 17b are also greatly reduced from the beginning to the end of the wear on the tread 13. For this reason, maximum tread wear life greatly increases and thus tire durability performance is greatly promoted.
Fig. 3 schematically illustrates a second embodiment of the pneumatic radial tire for heavy-duty vehicles according to the present invention, The pneumatic radial tire for heavy-duty vehicles is generally denoted by reference numeral 21. The second embodiment of Fig. 3 is characterized in that the circumferential spacing D between sipes 17 is 3.5 mm on both the end portions 13a of the tread 13 and the end portions 16a of the ribs 16. The second embodiment is substantially identical to the first embodiment of Fig. 1 except the aforesaid spacing D between the sipes 17, and therefore the description will hereinafter be omitted by designating like reference numerals.
Figs. 4 and 5 show a third embodiment of the pneumatic radial tire for heavy-duty vehicles 23 which is constructed in accordance with the present invention. The portions of this embodiment substantially identical to those of the first embodiment are indicated by like reference numerals.
In the third embodiment, the arrangement of the sipe 17 and the circumferential spacing D (2.2 mm) are substantially identical to those of the first embodiment shown in Fig. 1. The sipe 17 has a length Lo of 3 mm on the outer surface 13c of the tread 13, when the tire is new, and a length L1 of 5.1 mm at the position H/2 which is half of the depth H15 of the adjacent groove 15, and thus has a trapezoid section, as shown in Figs. 4 and 5.
As previously indicated, such a tire can greatly 13131~6 reduce the occurrence of the tear failure in the sipe ends 17a and 17b of the sipe 17, when the tire is new. Although, when the groove depth was reduced to its half due to the wear on the tread, the length Ll (5.1 mm) of the sipe 17 becomes longer than the length Lo (3 mm) when the tire is new, the movement and fatigue of the rib 16 is small because the rib rigidity becomes larger. For this reason, the lenqth L1 of the sipe is longer than the surface length Lo (3 mm), but there is no occurrence of the tear failure in the sipe ends 17a and 17b of the sipe 17. On the other hand, since the length Ll of the sipe 17 becomes longer, the rigidities in the rib end portion 16a and the tread end portion 13a are reduced.
Consequently, the occurrence of the uneven wear is more effectively prevented.
Next, the effect of the present invention will hereinafter be explained in conjunction with five different kinds of test tires (test tires A, B, C, D and E).
The test tires were built, shaped and cured in a conventional tire mold, and each have a tire size 10.00 R 20.
Each test tire with five ribs on the tread is of the rib type, the width W of the sipe is .5 mm, and the length L of the sipe is 3 mm. The spacing D (mm) between the sipes is shown in the following Table 1.
Table 1 Kind of A s C D E
test tire . _ First Second Compara- Compara- Compara-embodi- embodi- tive tive tive ment of ment of example 1 example 2 example 3 Fig. 1 Fig. 3 of Fig. 6 of Fig. 7 of Fig. 8 Spacing D
between sipes in2.2 3.5 4.3 10.6 no sipes tread end portion Spacing D
between sipes in2.2 3.5 4.3 21.0 no sipes rib end portion _ The test tire A is substantially identical to the aforementioned first embodiment shown in Figs. 1 and 2. The test tire B is substantially identical to the aforementioned second embodiment shown in Fig. 3. The test tires C, D and E
are comparative examples 1, 2 and 3 shown in Figs. 6, 7 and 8, respectively, and the respective spacing D between the sipes is shown in Table 1. The comparative example 2 is a conventional tire, and the comparative example 3 is a tire with no sipes on the tread.
The test tires were used as the front tires of a test truck with loading 9 tons and the test truck was driven on a normal test course under the same condition, and the occurrence conditions of uneven wear on the tread and tear 1~1311~
failure in the sipe end were compared.
As shown in Fig. 9, the uneven wear occurs in the latexal end portion of the tread 13 and causes a long, narrow depression 19 extending in the circumferential direction of the tire. The width W19 and depth D19 of the depression 19 were measured as an amount of uneven wear and compared. The amounts of uneven wears occurring on the end portions of the outer and inner treads of the right front tire and left front tire of the test truck, were measured. The test values for the test tire E were normalized to a value of lO0 for comparison purposes. The test values for the test tires A, B, C and D were compared to the test values of the test tire E
and reported relative to the normalized values of 100 for the test tire E as shown in Tables 2 and 3. The occurrence conditions of the tear failures in the sipe ends were checked by visual inspection, after the test truck has been driven on the test course.
13131~6 Table 2 Xind of A B C D E
test tire -First Second Compara- Compara- Compara-embodi- embodi- tive tive tive ment of ment of example 1 example 2 example 3 Fig. 1 Fig. 3 of Fig. 6 of Fig. 7 of Fig. 8 _ Depression width W g in oute~
tread end45 54 61 66 100 portion of right front tire Depression width W g in inne~
tread end84 90 97 100 100 portion of right front tire Depression width W g in oute~
tread end23 30 42 64 100 portion of left front tire 20- _ Depression width W g in inne~
tread end 0 0 67 97 100 portion of left front tire 131311~
Table 3 Kind of A B C D E
test tire First Second Compara- Compara- Compara-embodi- embodi- tive tive tive ment of ment of example 1 example 2 example 3 Fig. 1 Fig. 3 of Fig. 6 of Fig. 7 of Fig. 8 Depression depth D g in oute~
tread end52 58 63 70 100 portion of right front tire _ Depression depth D g in inne~
tread end 8 17 55 72 100 portion of right front tire -Depression depth D 9 in oute~
tread end10 12 21 79 100 portion of left front tire Depression depth D 9 in inne~
tread end 0 5 40 60 100 portion of left front tire 13131~
~ 17 -From the test results shown in Tables 2 and 3, it can be readily understood that the amounts of uneven wears of the tires of the first and second embodiments are extremely small as compared with those of the tires o~ the comparative examples 1, 2 and 3. Consequently, maximum tire life is greatly increased. In addition, there was no occurrence of the tear failure in the sipe end.
The occurrence condition of the uneven wear on the end portion 16a of the rib 16 was visually checked, and the test result is as follows: The test tire A is substantially equal to the test tire B. The test tire B is better than the test tire C. The test tire C is better than the test tire D.
The test tire D is substantially equal to the test tire D.
Namely, the test tires A and B (according to the first and second embodiments) have been greatly increased in uneven wear proof as compared with the test tires C, D and E (that is, comparative examples 1, 2 and 3).
The aforementioned spacing D between the sipes is preferable to be not more than 4 mm for the following reasons.
The relation between the spacing D between the sipes and the occurrence condition of the uneven wear is graphically represented in Fig. 10. The occurrence condition of the uneven wear was checked by using the depression widths Wlg in the outer tread end portions of the right and left front tires which are shown in the aforementioned test results shown in Table 2. As can be seen from Fig. 10, the spacing D between the sipes is preferable to be not more than g mm, because the occurrence of the uneven wear is greatly increased if the sipe -`- 131311~
spacing D exceeds 4 mm.
The aforementioned length L of the sipe is preferable to be not more than 3 mm for the following reasons.
Six different kinds of test tires were prepared which each have sipe spacing D = 3.5 mm (which is equal to the spacing of the aforementioned test tire B (second embodiment)) and which have sipe lengths (L) 2 mm, 3 mm, 4 mm, 5 mm, 6 mm and 7 mm, respectively. Also, six different kinds of test tires were prepared which each have sipe spacing D = 4.3 mm (which is equal to the spacing of the aforementioned test tire C (comparative example l)) and which have sipe lengths (L) 2 mm, 3 mm, 4 mm, 5 mm, 6 mm and 7 mm, respectively.
These twelve different kinds of test tires were used on the front wheels of the aforesaid test truck, and it was driven on the aforesaid test course. The rate of the occurrence of the tear failure in the sipe ends of the test tires was checked. It is noted that the rate of the occurrence of the tear failure is a ratio (%) of the number of sipes, in which the tear failure occurred, to the total number of sipes formed in the tread end portions and rib end portions. The test values for the test tire with the sipe length L 7 mm were normalized to a value of lO0 for comparison purposes, and the test results are shown in Fig. ll.
As can be readily understood from the test results shown in Fig. 11, the rate of the occurrence of the tear failure rapidly increases if the sipe length L exceeds 3 mm.
Consequently, it is desirable that the length L of the sipe be not more than 3 mm.
... ~ .. .
From the foregoing test results, it has been found that it is preferable that the length L of the sipes, which are formed in the tread end portions and the rib end portions, be not more than 3mm and the spacing D between the sipes be not more than 4 mm The aforesaid length Ll of the sipe at the position which is half of the groove depth of a new tire, may be 1 to 1.7 times greater than the length Lo of the sipe when the tire is new, for the following reasons.
A first group of six different kinds of test tires were prepared which each have sipe spacing D = 3.5 mm (which is equal to the spacing of the aforementioned test tire B (the second embodiment shown in Fig. 3)) and which have sipe lengths (L~ 2 mm, 3 mm, 4 mm, 5 mm, 6 mm and 7 mm, respectively, on the tread surfaces, when the tires are new.
Also, a second group of six different kinds of test tires were prepared which each have sipe spacing D = 3.5 mm (which is equal to the spacing of the aforementioned test tire B (the second embodiment shown in Fig. 3)) and in which, as shown in Fig. 12, an outer tread portion 25 of each test tire is so buffed that these test tires substantially correspond to a tire in which the groove depth became half of its original depth due to the wear on the tread.
These twelve different kinds of test tires were used on the front wheels of the aforesaid test truck, and it was driven on the aforesaid test course. The rate of the occurrence of the tear failure in the sipe ends of the test tires was checked. It is noted that the rate of the - 1313~1~
occurrence of the tear failure is a ratio (%) of the number of sipes, in which the tear failure occurred, to the total number of sipes formed in the tread end portions and rib end portions. The test values for the test tire with the sipe length L 7 mm were normalized to a value of 100 for comparison purposes, and the test results are shown in Fig. 13.
As can be seen from the test results shown in Fig.
13, the rate of the occurrence of the tear failure rapidly increases in the first group of test tires, if the sipe length L exceeds 3 mm. On the other hand, in the second group of test tires, the rate of the occurrence of the tear failure rapidly increases, if the sipe length L exceeds 5.1 mm.
Consequently, even if the sipe length is increased up to 5.1 mm in the case of the tire in which the groove depth became lS half of its original depth due to the wear on the tread, the tear failure can be prevented from occurring in the sipe ends.
While the aforementioned embodiments have been described and illustrated in conjunction with the sipes each extending in the axial direction of the tire, it is noted that the sipes each may also extend in the circumferential direction perpendicular to the axial direction.
Also, the sipes of same length and spacing have been described and illustrated in each of the aforementioned embodiments, but it is noted that different sipes of different lengths and spacings may be also used if they are within the range defined by the present invention.
While in the aforementioned embodiments the sipes have been provided in both the tread end portions and the rib ......
`-` 1313~16 end portions, it is noted that they may be also provided in either of the tread end portions and the rib end portions or only in the rib end portions.
Furthermore, while the present invention has been described and illustrated with a tire of the rib type, it is noted that the tire may also be of the block type or of rib-lug type.
From the foregoing description, it will be seen that there is provided in accordance with the present invention an improved pneumatic radial tire for heavy-duty vehicles in which sipes having suitable length and spacing therebetween are properly arranged in such a manner that the occurrence of uneven wear on the tread and furthermore the occurrence of tear failure in the sipe end can be prevented.
The present invention relates in general to pneumatic radial tires used on heavy-duty vehicles, and in particular to an improvement in uneven wear proof of heavy-duty radial tires on trucks, buses and the like.
DESCRIPTION OF THE PRIOR ART
To prevent uneven wear from occurring in the tread of a pneumatic radial tire for heavy-duty vehicles, a plurality of sipes ~extremely narrow grooves) have so far been provided in the end portions of ribs or blocks in the tread.
While these sipes have been fairly satisfactory in improvement in uneven wearl there is a drawback that tear failure tends to occur in the sipe ends.
A generally known pneumatic radial tire for heavy-duty vehicles, which is designed for improving uneven wear occurring in the tread, is such as shown in Fig. 14. The conventional pneumatic radial tire for heavy-duty vehicles 1 has a tread 2 which is circumferentially divided into ribs 5 by grooves 3 each extending zigzag in the circumferential direction of the tire. In the end portions Sa of the ribs 5 and opposite end portions 2a of the tread 2 are circumferentially provided a plurality of sipes 6 each having a width of .3 to 1.0 mm. The sipe 6 is open at one end 6a thereof to the groove 3 or a buttress portion 2b between the tread 2 and a sidewall portion, and terminates in the other end 6b thereof. Since the rigidities of the end portions 5a of the ribs S and the end portions 2a of the tread 2 are reduced by the sipes 6 and the end portions are thus readily deformed, the occurrence of un~ven wear in the end portions is satisfactorily prevented. However, if the heavy-duty tire with these sipes 6 formed in the tread 2 runs at high speeds or on rough road surface, there is a disadvantage that tear failure 7 occurs from the other end 6b of the sipe 6, as shown in Fig. 14.
Accordingly, it is the object of the present invention to provide an improved pneumatic radial tire for heavy-duty vehicles in which sipes having suitable length and spacing therebetween are properly arranged in such a manner that the occurrence of uneven wear on the tread and furthermore the occurrence of tear failure in the sipe ends can be prevented.
The inventors have made various investigations and experiments with respect to the relation between the length of the sipes and the spacing between the sipes which are formed in the tread end portions and the rib end portions, and the occurrences of uneven wear on the tread and tear failure in the sipe end, and found the following facts. That is, if the spacing between the sipes formed in the tread end portions and the rib end portions becomes extremely wider, the margins of the end portions cannot be satisfactorily prevented from wearing round, because the rigidities in these end portions cannot be sufficientIy reduced. And also, self-wear cannot be satisfactorily reduced because wear resulting from the difference in radii between the tread end and central portions cannot be sufficiently reduced. As a result, it has been found that by arranging properly the spacing between the , 1313~16 sipes, the wear on the tread end portions and the rib end portions and the self-wear are reduced and thus the uneven wear proof can be enhanced.
In addition, if the length of the sipe becomes extremely longer, the rigidity of the end portion in which the sipes are provided is sufficiently reduced, but strain in the sipe end becomes larger. For this reason, the tear failure tends to occur from the sipe end. As a result, it has been found that the occurrence of tear failure in the sipe end can be prevented by making the length of the sipe less than a predetermined length. In addition, it has been found that with respect to the length of the sipe there is difference in the effect of prevention of the occurrence of tear failure, between at the time tire is new and at the time the height of the rib is decreased by the wear on the tread. Furthermore, it has been found that in the tire with circumferentially extending ribs on the tread the occurrence of the uneven wear is greatly reduced by providing the sipes in both the tread end portion and the rib end portion.
The inventors has further made various investigations and experiments with respect to the length of the sipe, the spacing between the sipes, the arrangement of the sipe, etc., and reached the present invention.
SUMMARY OF THE INVENTION
The foregoing objects are accomplished in accordance with the present invention by providing a pneumatic radial tire for heavy-duty vehicles comprising a tread divided into at least two ribs by at least one groove extending 1313~ ~
substantially in the circumferential direction of the tire, and a plurality of sipes formed in lateral end portions of the tread and in end portions of the ribs, each of the sipes having a length of 1 to 3 mm on a tread surface of the tread, when the tire is new, and spacing between the sipes being 1 to 4 mm.
The foregoing objects are also accomplished in accordance with the present invention by providing a pneumatic radial tire for heavy-duty vehicles comprising a tread divided into at least two ribs by at least one groove extending substantially in the circumferential direction of the tire, and a plurality of sipes formed in end portions of the ribs, each of the sipes having a length of 1 to 3 mm on a tread surface of the tread, when the tire is new, and spacing between the sipes being 1 to 4 mm.
Each of the sipes may be grooved in such a manner that the length remains essentially constant from the beginning to the end of wear on the tread. Each of the sipes may have a trapezoid section. The sipe of a trapezoid section may have, at the position which is half of a groove depth of the groove, a length which is 1 to 1.7 times greater than the length of 1 to 3 mm on the tread surface. The sipes may comprise sipes of same length and same spacing or different sipes of different lengths and different spacings.
Since in the pneumatic radial tire for heavy-duty vehicles according to the present invention a plurality of sipes wherein the length is 1 to 3 mm and the spacing therebetween is 1 to 4 mm are provided in the rib end portions or tread end portions, the rigidities in the rib end portions or tread end portions become smaller, and thus sidewise force applied to the tire and dragging resulting from the difference in radii between the tread end and central portions are greatly alleviated. As a result, the early occurrence of uneven wear on each end portion are greatly reduced, maximum tire life and tire durability are enhanced and the occurrence of tear failure in the sipe end are greatly reduced. In addition, because the sipe length is determined so as to remain essentially constant or within a predetermined range from the beginning to the end of tread wear, the aforementioned effect of the present invention continues from the beginning to the end of tread wear. That is, the uneven wear on the tread is greatly reduced and furthermore the 5 occurrence of tear failure in the sipe end is greatly reduced.
BRIEF DESCRIPTION OF THE DRAWINGS
The drawbacks of a conventional pneumatic radial tire for heavy-duty vehicles and the features and advantages of a pneùmatic radial tire for heavy-duty vehicles according to the present invention will be more clearly understood from the following description taken in conjunction with the accompanying drawings in which:
Figure 1 is a schematic plan view, partly broken away and partly in planform, showing a first embodiment of the pneumatic radial tire for heavy-duty vehicles according to the present invention wherein a plurality of sipes are formed in the end portion of the tread and the end portions of the ribs;
Figure 2 is an enlarged cross sectional view 13~3116 substantially taken along line II-II in Figure 1, showing the sipe has an axial length which remains essentially constant from the beginning to the end of tread wear;
Figure 3 is a schematic plan view, partly broken away and partly in planform, showning a second embodiment of the pneumatic radial tire for heavy-duty vehicles according to the present invention;
Figure 4 is an enlarged cross sectional view, partly broken away, showing a sipe that is formed adjacent a wide groove in accordance with a third embodiment of the present invention;
Figure 5 is a view similar to Figure 4 showing a sipe that is formed in the tread end portion in accordance with the third embodiment of the present invention;
Figure 6 is a schematic plan view, partly broken away and partly in planform, showing a comparative example 1 with the sipe spacing of more than 4 mm;
Figure 7 is a schematic plan view, partly broken away and partly in planform, showing a conventional tire which is used as a comparative example 2 in uneven wear and tear failure tests:
Figure 8 is a schematic plan view, partly broken away and partly in planform, showing a conventional tire with no sipes on the tread which is used as a comparative example 3 in uneven wear and tear failure tests;
Figure 9 is an enlarged cross sectional view showing a condition at which uneven wear occurred;
Figure 10 is a diagram graphically representing the 1313~l16 relation ~etween the occurrence of uneven wear and the sipe spacing;
Figure 11 is a diagram graphically representing the relation between the rate of the occurrence of tear ~ailuxe in the sipe end and the length of the sipe;
Figure 12 is a cross sectional view, partly broken away, showing at the half position of the groove depth at which the pneumatic radial tire for heavy-duty vehicles according to the present invention is buffed;
Figure 13 is a diagram graphically representing the rate of the occurrence of the tear failure in the sipe end;
and Fiqure 14 is a schematic plan view, partly broken away and partly in planform, showing a conventional pneumatic radial tire for heavy-duty vehicles DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now in detail to the drawings and initially to Figs. 1 and 2, there is shown a preferred embodiment of a pneumatic radial tire for heavy-duty vehicles which is constructed in accordance with the present invention.
Reference numeral 11 generally designates the pneumatic radial tire for heavy-duty vehicles according to the invention. The tire size is 10.00 R 20. The pneumatic radial tire for heavy-duty vehicles 11 has a tread 13 extending between a pair of shoulders 12 (only one shoulder is shown), which tread 13 is formed with four wide grooves 15 each extending zigzag in the circumferential direction of the tire (only two grooves are shown in Figs. 1 and 2). The tread 13 is divided by the . :
:
.
four wide grooves lS and has five tread ribs 16. A plurality of sipes 17 are formed in the circumferential direction of the tire in the end portions 16a of the ribs 16 and also in the end portions 13a of the tread 13. Each sipe 17 has a width W
of .5 mm and an axial length L of 3 mm. The spacing D of the tire circumferential direction between the sipes 17 is 2.2 mm.
As is shown in Fig. 2, the sipe 17 is grooved in such a manner that a length La of the sipe 17 at the beginning of tread wear is substantially equal to a length Lb of the sipe 17 at the end of tread wear. That is, as shown in Fig. 2, thè sipe 17 has a sipe end 17a thereof parallel to a groove wall 15a of the wide groove 15, or a sipe end 17b thereof parallel to a buttress surface 13b between the tread 13 and the sidewall of the tread. The reason why the length L of the sipe 17 is kept essentially constant from the beginning to the end of the wear on the tread 13 is for avoiding that the sipe length L changes as the wear on the tread 13 increases, the effect of the improvement of uneven wear becomes zero, and the tear failure of the sipe ends 17a and 17b tends to occur. The portions of the tire which have not been described are substantially identical to those of a normal pneumatic radial tire for heavy-duty vehicles, a belt of cord 18 is laid directly under the tread 13, a carcass 19 is laid under the belt 18, and the detailed descriptions will hereinafter be omitted.
Next, the operation of the pneumatic radial tire for heavy-duty vehicles according to the present invention will hereinafter be described in detail.
Since in the pneumatic radial tire of the present - 13~3~16 invention a plurality of sipes 17 are formed in the end portions 16a of the ribs 16 and the end portions 13a of the tread 13 and since the axial length L of the sipe 17 is 3 mm and the circumferential spacing D between the sipes 17 is 2 mm, the end portions 16a of the ribs 16 and the end portions 13a of the tread 13 have small rigidities and thus are resilient. For this reason, these end portions 13a and 16a are easily deformed when they meet the road surface, and therefore sidewise force applied to the tire is reduced and dragging resulting from the difference in the radii between the tread central portion and the tread end portion is alleviated, so that the relative movement to the ground surface is decreased. And, the occurrence of so-called uneven wear, which causes only the these end portions of the ribs and tread to unevenly wear at the beginning of the wear on the tread, is greatly reduced. Also, strains in the sipe ends 17a and 17b of the sipe 17 become small, so that the occurrence of the tear failure of the sipe ends 17a and 17b is greatly reduced.
In addition, since the sipes 17 each having the sipe length L which remains essentially constant from the beginning to the end of the wear on the tread 13 are formed in the end portions 13a of the tread 13 and the end portions 16a of the ribs 16, the aforementioned occurrences of uneven wear and the tear failure in the sipe ends 17a and 17b are also greatly reduced from the beginning to the end of the wear on the tread 13. For this reason, maximum tread wear life greatly increases and thus tire durability performance is greatly promoted.
Fig. 3 schematically illustrates a second embodiment of the pneumatic radial tire for heavy-duty vehicles according to the present invention, The pneumatic radial tire for heavy-duty vehicles is generally denoted by reference numeral 21. The second embodiment of Fig. 3 is characterized in that the circumferential spacing D between sipes 17 is 3.5 mm on both the end portions 13a of the tread 13 and the end portions 16a of the ribs 16. The second embodiment is substantially identical to the first embodiment of Fig. 1 except the aforesaid spacing D between the sipes 17, and therefore the description will hereinafter be omitted by designating like reference numerals.
Figs. 4 and 5 show a third embodiment of the pneumatic radial tire for heavy-duty vehicles 23 which is constructed in accordance with the present invention. The portions of this embodiment substantially identical to those of the first embodiment are indicated by like reference numerals.
In the third embodiment, the arrangement of the sipe 17 and the circumferential spacing D (2.2 mm) are substantially identical to those of the first embodiment shown in Fig. 1. The sipe 17 has a length Lo of 3 mm on the outer surface 13c of the tread 13, when the tire is new, and a length L1 of 5.1 mm at the position H/2 which is half of the depth H15 of the adjacent groove 15, and thus has a trapezoid section, as shown in Figs. 4 and 5.
As previously indicated, such a tire can greatly 13131~6 reduce the occurrence of the tear failure in the sipe ends 17a and 17b of the sipe 17, when the tire is new. Although, when the groove depth was reduced to its half due to the wear on the tread, the length Ll (5.1 mm) of the sipe 17 becomes longer than the length Lo (3 mm) when the tire is new, the movement and fatigue of the rib 16 is small because the rib rigidity becomes larger. For this reason, the lenqth L1 of the sipe is longer than the surface length Lo (3 mm), but there is no occurrence of the tear failure in the sipe ends 17a and 17b of the sipe 17. On the other hand, since the length Ll of the sipe 17 becomes longer, the rigidities in the rib end portion 16a and the tread end portion 13a are reduced.
Consequently, the occurrence of the uneven wear is more effectively prevented.
Next, the effect of the present invention will hereinafter be explained in conjunction with five different kinds of test tires (test tires A, B, C, D and E).
The test tires were built, shaped and cured in a conventional tire mold, and each have a tire size 10.00 R 20.
Each test tire with five ribs on the tread is of the rib type, the width W of the sipe is .5 mm, and the length L of the sipe is 3 mm. The spacing D (mm) between the sipes is shown in the following Table 1.
Table 1 Kind of A s C D E
test tire . _ First Second Compara- Compara- Compara-embodi- embodi- tive tive tive ment of ment of example 1 example 2 example 3 Fig. 1 Fig. 3 of Fig. 6 of Fig. 7 of Fig. 8 Spacing D
between sipes in2.2 3.5 4.3 10.6 no sipes tread end portion Spacing D
between sipes in2.2 3.5 4.3 21.0 no sipes rib end portion _ The test tire A is substantially identical to the aforementioned first embodiment shown in Figs. 1 and 2. The test tire B is substantially identical to the aforementioned second embodiment shown in Fig. 3. The test tires C, D and E
are comparative examples 1, 2 and 3 shown in Figs. 6, 7 and 8, respectively, and the respective spacing D between the sipes is shown in Table 1. The comparative example 2 is a conventional tire, and the comparative example 3 is a tire with no sipes on the tread.
The test tires were used as the front tires of a test truck with loading 9 tons and the test truck was driven on a normal test course under the same condition, and the occurrence conditions of uneven wear on the tread and tear 1~1311~
failure in the sipe end were compared.
As shown in Fig. 9, the uneven wear occurs in the latexal end portion of the tread 13 and causes a long, narrow depression 19 extending in the circumferential direction of the tire. The width W19 and depth D19 of the depression 19 were measured as an amount of uneven wear and compared. The amounts of uneven wears occurring on the end portions of the outer and inner treads of the right front tire and left front tire of the test truck, were measured. The test values for the test tire E were normalized to a value of lO0 for comparison purposes. The test values for the test tires A, B, C and D were compared to the test values of the test tire E
and reported relative to the normalized values of 100 for the test tire E as shown in Tables 2 and 3. The occurrence conditions of the tear failures in the sipe ends were checked by visual inspection, after the test truck has been driven on the test course.
13131~6 Table 2 Xind of A B C D E
test tire -First Second Compara- Compara- Compara-embodi- embodi- tive tive tive ment of ment of example 1 example 2 example 3 Fig. 1 Fig. 3 of Fig. 6 of Fig. 7 of Fig. 8 _ Depression width W g in oute~
tread end45 54 61 66 100 portion of right front tire Depression width W g in inne~
tread end84 90 97 100 100 portion of right front tire Depression width W g in oute~
tread end23 30 42 64 100 portion of left front tire 20- _ Depression width W g in inne~
tread end 0 0 67 97 100 portion of left front tire 131311~
Table 3 Kind of A B C D E
test tire First Second Compara- Compara- Compara-embodi- embodi- tive tive tive ment of ment of example 1 example 2 example 3 Fig. 1 Fig. 3 of Fig. 6 of Fig. 7 of Fig. 8 Depression depth D g in oute~
tread end52 58 63 70 100 portion of right front tire _ Depression depth D g in inne~
tread end 8 17 55 72 100 portion of right front tire -Depression depth D 9 in oute~
tread end10 12 21 79 100 portion of left front tire Depression depth D 9 in inne~
tread end 0 5 40 60 100 portion of left front tire 13131~
~ 17 -From the test results shown in Tables 2 and 3, it can be readily understood that the amounts of uneven wears of the tires of the first and second embodiments are extremely small as compared with those of the tires o~ the comparative examples 1, 2 and 3. Consequently, maximum tire life is greatly increased. In addition, there was no occurrence of the tear failure in the sipe end.
The occurrence condition of the uneven wear on the end portion 16a of the rib 16 was visually checked, and the test result is as follows: The test tire A is substantially equal to the test tire B. The test tire B is better than the test tire C. The test tire C is better than the test tire D.
The test tire D is substantially equal to the test tire D.
Namely, the test tires A and B (according to the first and second embodiments) have been greatly increased in uneven wear proof as compared with the test tires C, D and E (that is, comparative examples 1, 2 and 3).
The aforementioned spacing D between the sipes is preferable to be not more than 4 mm for the following reasons.
The relation between the spacing D between the sipes and the occurrence condition of the uneven wear is graphically represented in Fig. 10. The occurrence condition of the uneven wear was checked by using the depression widths Wlg in the outer tread end portions of the right and left front tires which are shown in the aforementioned test results shown in Table 2. As can be seen from Fig. 10, the spacing D between the sipes is preferable to be not more than g mm, because the occurrence of the uneven wear is greatly increased if the sipe -`- 131311~
spacing D exceeds 4 mm.
The aforementioned length L of the sipe is preferable to be not more than 3 mm for the following reasons.
Six different kinds of test tires were prepared which each have sipe spacing D = 3.5 mm (which is equal to the spacing of the aforementioned test tire B (second embodiment)) and which have sipe lengths (L) 2 mm, 3 mm, 4 mm, 5 mm, 6 mm and 7 mm, respectively. Also, six different kinds of test tires were prepared which each have sipe spacing D = 4.3 mm (which is equal to the spacing of the aforementioned test tire C (comparative example l)) and which have sipe lengths (L) 2 mm, 3 mm, 4 mm, 5 mm, 6 mm and 7 mm, respectively.
These twelve different kinds of test tires were used on the front wheels of the aforesaid test truck, and it was driven on the aforesaid test course. The rate of the occurrence of the tear failure in the sipe ends of the test tires was checked. It is noted that the rate of the occurrence of the tear failure is a ratio (%) of the number of sipes, in which the tear failure occurred, to the total number of sipes formed in the tread end portions and rib end portions. The test values for the test tire with the sipe length L 7 mm were normalized to a value of lO0 for comparison purposes, and the test results are shown in Fig. ll.
As can be readily understood from the test results shown in Fig. 11, the rate of the occurrence of the tear failure rapidly increases if the sipe length L exceeds 3 mm.
Consequently, it is desirable that the length L of the sipe be not more than 3 mm.
... ~ .. .
From the foregoing test results, it has been found that it is preferable that the length L of the sipes, which are formed in the tread end portions and the rib end portions, be not more than 3mm and the spacing D between the sipes be not more than 4 mm The aforesaid length Ll of the sipe at the position which is half of the groove depth of a new tire, may be 1 to 1.7 times greater than the length Lo of the sipe when the tire is new, for the following reasons.
A first group of six different kinds of test tires were prepared which each have sipe spacing D = 3.5 mm (which is equal to the spacing of the aforementioned test tire B (the second embodiment shown in Fig. 3)) and which have sipe lengths (L~ 2 mm, 3 mm, 4 mm, 5 mm, 6 mm and 7 mm, respectively, on the tread surfaces, when the tires are new.
Also, a second group of six different kinds of test tires were prepared which each have sipe spacing D = 3.5 mm (which is equal to the spacing of the aforementioned test tire B (the second embodiment shown in Fig. 3)) and in which, as shown in Fig. 12, an outer tread portion 25 of each test tire is so buffed that these test tires substantially correspond to a tire in which the groove depth became half of its original depth due to the wear on the tread.
These twelve different kinds of test tires were used on the front wheels of the aforesaid test truck, and it was driven on the aforesaid test course. The rate of the occurrence of the tear failure in the sipe ends of the test tires was checked. It is noted that the rate of the - 1313~1~
occurrence of the tear failure is a ratio (%) of the number of sipes, in which the tear failure occurred, to the total number of sipes formed in the tread end portions and rib end portions. The test values for the test tire with the sipe length L 7 mm were normalized to a value of 100 for comparison purposes, and the test results are shown in Fig. 13.
As can be seen from the test results shown in Fig.
13, the rate of the occurrence of the tear failure rapidly increases in the first group of test tires, if the sipe length L exceeds 3 mm. On the other hand, in the second group of test tires, the rate of the occurrence of the tear failure rapidly increases, if the sipe length L exceeds 5.1 mm.
Consequently, even if the sipe length is increased up to 5.1 mm in the case of the tire in which the groove depth became lS half of its original depth due to the wear on the tread, the tear failure can be prevented from occurring in the sipe ends.
While the aforementioned embodiments have been described and illustrated in conjunction with the sipes each extending in the axial direction of the tire, it is noted that the sipes each may also extend in the circumferential direction perpendicular to the axial direction.
Also, the sipes of same length and spacing have been described and illustrated in each of the aforementioned embodiments, but it is noted that different sipes of different lengths and spacings may be also used if they are within the range defined by the present invention.
While in the aforementioned embodiments the sipes have been provided in both the tread end portions and the rib ......
`-` 1313~16 end portions, it is noted that they may be also provided in either of the tread end portions and the rib end portions or only in the rib end portions.
Furthermore, while the present invention has been described and illustrated with a tire of the rib type, it is noted that the tire may also be of the block type or of rib-lug type.
From the foregoing description, it will be seen that there is provided in accordance with the present invention an improved pneumatic radial tire for heavy-duty vehicles in which sipes having suitable length and spacing therebetween are properly arranged in such a manner that the occurrence of uneven wear on the tread and furthermore the occurrence of tear failure in the sipe end can be prevented.
Claims (12)
1. A pneumatic radial tire for heavy-duty vehicles comprising a tread divided into at least two ribs by at least one groove extending substantially in the circumferential direction of the tire, and a plurality of sipes formed in lateral end portions of said tread and in end portions of said ribs, each of said sipes having a length of 1 to 3 mm on a tread surface of said tread, when the tire is new, and spacing between said sipes being 1 to 4 mm.
2. A pneumatic radial tire as set forth in claim 1, in which each of said sipes is grooved in such a manner that the length remains essentially constant from the beginning to the end of wear on said tread.
3. A pneumatic radial tire as set forth in claim 1, in which each of said sipes has a trapezoid section.
4. A pneumatic radial tire as set forth in claim 3, in which said sipe of a trapezoid section has, at the position which is half of a groove depth of said groove, a length which is 1 to 1.7 times greater than said length of 1 to 3 mm on said tread surface.
5. A pneumatic radial tire as set forth in claim 1, in which said plurality of sipes comprise sipes of same length and same spacing.
6. A pneumatic radial tire as set forth in claim 1, in which said plurality of sipes comprise different sipes of different lengths and different spacings.
7. A pneumatic radial tire for heavy-duty vehicles comprising a tread divided into at least two ribs by at least one groove extending substantially in the circumferential direction of the tire, and a plurality of sipes formed in end portions of said ribs, each of said sipes having a length of 1 to 3 mm on a tread surface of said tread, when the tire is new, and spacing between said sipes being 1 to 4 mm.
8. A pneumatic radial tire as set forth in claim 7, in which each of said sipes is grooved in such a manner that the length remains essentially constant from the beginning to the end of wear on said tread.
9. A pneumatic radial tire as set forth in claim 7, in which each of said sipes has a trapezoid section.
10. A pneumatic radial tire as set forth in claim 9, in which said sipe of a trapezoid section has, at the position which is half of a groove depth of said groove, a length which is 1 to 1.7 times greater than said length of 1 to 3 mm on said tread surface.
11. A pneumatic radial tire as set forth in claim 7, in which said plurality of sipes comprise sipes of same length and same spacing.
12. A pneumatic radial tire as set forth in claim 7, in which said plurality of sipes comprise different sipes of different lengths and different spacings.
Applications Claiming Priority (8)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP116,630/1987 | 1987-05-12 | ||
| JP11663087 | 1987-05-12 | ||
| JP11662987 | 1987-05-12 | ||
| JP116,629/1987 | 1987-05-12 | ||
| JP212,574/1987 | 1987-08-25 | ||
| JP62212573A JPS6452508A (en) | 1987-05-12 | 1987-08-25 | Pneumatic radial tire for heavy load |
| JP62212574A JPS6452509A (en) | 1987-05-12 | 1987-08-25 | Pneumatic radial tire for heavy load |
| JP212,573/1987 | 1987-08-25 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1313116C true CA1313116C (en) | 1993-01-26 |
Family
ID=27470362
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000564421A Expired - Fee Related CA1313116C (en) | 1987-05-12 | 1988-04-18 | Pneumatic radial tire for heavy-duty vehicles |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1313116C (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7481257B2 (en) * | 2004-01-09 | 2009-01-27 | The Yokahama Rubber Co., Ltd. | Pneumatic tire and tire mold |
| US7878228B2 (en) * | 2005-12-29 | 2011-02-01 | Sumitomo Rubber Industries, Ltd. | Heavy-duty tire with tread having closed sipes and edge sipes in ribs |
| US7980281B2 (en) | 2006-10-02 | 2011-07-19 | Toyo Tire & Rubber Co., Ltd. | Pneumatic tire with tread having protruding stripe in groove bottom and tire mold for making the tire |
| WO2015200249A1 (en) * | 2014-06-25 | 2015-12-30 | Compagnie Generale Des Etablissements Michelin | Tire having microsipes along lateral edges |
| US20210094357A1 (en) * | 2018-05-24 | 2021-04-01 | Victor Abarotin | Heavy truck tire tread and heavy truck tire with inclined and angled shoulder sipe |
| US11535062B2 (en) * | 2018-05-02 | 2022-12-27 | Sumitomo Rubber Industries, Ltd. | Tyre |
-
1988
- 1988-04-18 CA CA000564421A patent/CA1313116C/en not_active Expired - Fee Related
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7481257B2 (en) * | 2004-01-09 | 2009-01-27 | The Yokahama Rubber Co., Ltd. | Pneumatic tire and tire mold |
| US7878228B2 (en) * | 2005-12-29 | 2011-02-01 | Sumitomo Rubber Industries, Ltd. | Heavy-duty tire with tread having closed sipes and edge sipes in ribs |
| US7980281B2 (en) | 2006-10-02 | 2011-07-19 | Toyo Tire & Rubber Co., Ltd. | Pneumatic tire with tread having protruding stripe in groove bottom and tire mold for making the tire |
| WO2015200249A1 (en) * | 2014-06-25 | 2015-12-30 | Compagnie Generale Des Etablissements Michelin | Tire having microsipes along lateral edges |
| US11535062B2 (en) * | 2018-05-02 | 2022-12-27 | Sumitomo Rubber Industries, Ltd. | Tyre |
| US20210094357A1 (en) * | 2018-05-24 | 2021-04-01 | Victor Abarotin | Heavy truck tire tread and heavy truck tire with inclined and angled shoulder sipe |
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| Date | Code | Title | Description |
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| MKLA | Lapsed |