CA1044128A - Foldable pneumatic tire - Google Patents
Foldable pneumatic tireInfo
- Publication number
- CA1044128A CA1044128A CA275,136A CA275136A CA1044128A CA 1044128 A CA1044128 A CA 1044128A CA 275136 A CA275136 A CA 275136A CA 1044128 A CA1044128 A CA 1044128A
- Authority
- CA
- Canada
- Prior art keywords
- tire
- sidewalls
- tread
- groove
- folded
- 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
Links
Landscapes
- Tires In General (AREA)
- Moulds For Moulding Plastics Or The Like (AREA)
Abstract
Abstract of the Disclosure A foldable pneumatic tire comprising an annular tread, bead portions and a pair of sidewalls extending therebetween collapsible inwardly and concentrically to said tread. Each of the sidewalls is formed in an inwardly bent zone when folded with one or more circumferential grooves opening at the outer surface thereof, to effectively prevent wrinkles which would otherwise occur in the bent zone resulting ultimately in cracks in the sidewalls after they have been maintained in a folded condition for a long period of time.
Description
The present invention relates to an improved foldable pneumatic tire, and more particularly to a foldable pneumatic tire mainly used as a spare tire for vehicles su~h as automobiles.
A foldable pneumatic tire, in general, has foldable or collapsihle sidewalls and assumes the same dimension as a normal tire when inflated, but can be housed in a very small space when deflated or collapsedO Such tires are known and disclosed in U~ S. Patents No. 3,347,300 and No. 3,833,042.
.. . ..
The tire disclosed in U. Sn Patent No. 3,347,300 is molded and vulcanized in a mold having a configuration corresponding to that of the deflated or collapsed tire, so that a particularly shaped mold and particular vulcanizer ' are required. In additionl commonly known bladders cannot ! ~ -be used for vulcanization and it is consequently necessary to employ bagless vulcanization wherein a vulcanizing heat -medium should be directly in contact with the tire. Ac~ordingly, : . .
a great modification of existing equipment and installations is needed for the production of the tire. Furthermore, "
bagless vulcanization is generally prone to produce inferior products that are rejected which result in low productivity.
The tire disclosed in UO S. Patent No~ 3,833,042 is vulcanized in a mold having a configuration corresponding ~--~ to that of an extended tire in the form of a ring of a thin ; rubber plate and thereafter formed into the folded or deflated condition by a forming apparatus having rings for urging bead portions of the tire towards the center of the tread~ This tire has advantages in that existing equipment ,~ :''` ' .
4~ .
and installations can be used without any significant modifi-cation thereof for the production of the tire. Also the possibility of producing inferior tires to be rejected is reduced. However, the vulcanized tire must be greatly deformed into the configuration o~ the deflated or collapsed tire when attached to a rim. Such a large deformation causes wrinkles or creases on the surface of the inwardly bent portion of the sidewalls of the tire. These wrinkles remain permanently at the bent portion, because the foldable tire is normally stored under a folded or bent condition for a long period of time ranging from six months to two years. These wrinkles may cause cracks in the sidewalls and be very conspicuous.
An object of the invention is, therefore, to provide a foldable pneumatic tire which eliminates the above disadvan-tages in the prior art.
A further object of the invention is to provide a Il foldable pneumatic tire produced without a significant modification of existing apparatuses and having sidewalls formed with stress releasing grooves in the curved portions effectively preventing the wrinkles which would otherwise occur in the curved portions and would cause cracks in the sidewalls.
The foldable pneumatic tire according to the present ,! invention has an annular tread of a relatively thin tread rubber, a pair of sidewalls extending from both ends of ~ -said tread and bead portions. The sidewalls are collapsible inwardly and concentrically to said tread. m e tire has at least one stress releasing groove substantially circum-ferentially formed in a bent zone of each of the sidewalls located inwardly and concentrically to the tread when folded ~ ;
: ~
~ . . .
and opening at an outersurface of the sidewall.
These and other objects, features and advantages of the invention will become more apparent upon a reading of the following detailed specification and drawings, in --- -; which: -Fig. 1 is a sectional view of a prior art foldable pneumatic tire showing a folded or collapsed position in solid lines and an inflated position in phantom lines;
Fig. 2 is a sectional view of a tire molded and 10 vulcanized in a folded position in a mold according to the prior art, Fig. 3 is a sectional view of another tire molded ` and vulcanized in an extended position in a mold according ~ to another prior art;
', Fig. 4 is a sectional view of a folded portion of `~ the vulcanized tire after collapsed from the extended position `~ as shown in Fig. 3; ~
Fig. 5 is a partial sectional view of a tire molded , and vulcanized in a mold according to the present invention, .; , - . .
FigO 6 is an enlarged sectional vlew of the folded portion of the tire as shown in Fig. 5; ~ ;
Fig. 7 is an explanatory sectional view of the ., ... :.
`~ folded portion shown in Fig. 6 when the tire is folded; and ~ Figs. 8 and 9 are sectional views of typical stress `~1 releasing grooves to be formed in the tire according to the , invention, respectively~
. ~ .
A foldable pneumatic tire generally has foldable sidewalls. Xt has substantially the same dimension as in a normal pneumatic tire when in an inflated condition, but can be collapsed into a very small dimension so as to be housed ~ ~
' ,' " .
. .
~ _ 4 _ . A
., .. ,. ~ .. . .
., . ;.. .. ... .
, . " ., . ', -. ., ,, - .... . . .
. ~ , ., ~ .
in a spare housing when in an unused position or in a deflated conditionO Such tires have been known as disclosed in the above U. S. Patents No. 3,347,300 and No. 3,833,042.
These tires disclosed in the two U. S. Patents are substantially similar to each other in configuration when inflated as shown in phantom lines, and deflated and collapsed as shown in solid lines 2 in Fig. 1. The tire disclosed in UO SO Patent ~o. 3,347,300 is molded and vulcanized in a mold 11 as shown in Fig. 2, w~ose cavity corresponds substantially to that of the tire 2 when de~lated and collapsed onto the rim 3. In order to vulcanize the tire in the collapsed shape, it is required to use a correspondingly ~ ~ -particularly shaped mold and a particular vulcanizer. In i, :
addition, the vulcanization cannot be effected by the use of commonly known bladders. It is consequently required to employ bagless vulcanization wherein vulcanizing heat medium should be directly in contact with the tire. Therefore, tires according to U. S. Patent ~o. 3,347,300 require extensive modification of existing apparatus and installations.
.
Furthermore, bagless vulcanization is generally prone to produce inferior products that will be rejected.
, , On the other hand, the tire 22 disclosed in UO S. Patent ~o. 3,833,042 is vulcanized in a mold 21 as shown in Fig. 3 and immediately thereafter fcrmed by a forming apparatus into the collapsed or folded condition that is the form when deflated as shown in solid lines in Fig. 1. m~ mold 21 includes a tread portion 23, bead portions 24 and side portions 25 extending outwardly from , ,1 . , ~ , the tread portion to the bead portions and having curved portions 26 at the middle thereof. The forming apparatus ~ .
:'., ,'' ~' .' ~ - 5 -.` .A ~. ~-to be used for forming the vulcanized tire into the collapsed condition consists of rings for urging the bead portions 24 towards the center of the tread of the tire and outer rings for preventing a radial expansion of the tire. Since the forming apparatus can sufficiently achieve its forming performance without the outer rings, the PCI machine (post cure inflation machine) used for tires having polyester or nylon cords can be used without requiring any modification of the machine. Tires thus produced have advantages in that .. .
existing equipment and installations can be used in all the processes and percentages of inferior products to be rejected are very low comparable to normal tires. However, the vulcanized tire 22 in an extended position in the moLd as shown in Fig. 3 must be extensively deformed into the configuration .
of the tire when deflated or collapsed after attached to a rim, that is, when housed in a spare housing. This large deformation causes followlng disadvantages. When the molded and vulcanized tire 22 in the mold 21 as shown in Fig. 3 is attached to the rim 3 in the form of the collapsed configuration as shown in Fig. l, the curved portions 26 are bent into the shape as shown in Fig~ 4 at ~ with their insides being subjected to high compressive forces. As can be seen from Fig. 4, wrinkles or cr!eases 5 occur on the surface of the bent portion~ ~1hen the curved portions are bent only for a short period of time, these wrinkles will --disappear at the time of release of the curved portions.
Since, however, the tire of this kind is a spare tire which would be only used when a main tire cannot be used, it is normally stored in a folded or bent condition for a long period of time (si~ months to two years). Such an 6 ~
, j;: , : .~ : , :
:: , , -, :. . -- . .: ,. :: . . :
~;::, , - . . :- . .: ~
. ~ .. . . .
. .. . .
unnatural restraint may cause a rapid ageing of the tire and makes it impossible to return to the original position and the wrinkles 5 remain permanently at the folded portions 4 even if the tire i~ inflated. These wrinkles 5 may give rise to cracks in sidewalls and cause anxiety on the part of ~ the user or inflating the tire because the wrinkles are very ; conspicuous.
The inventors of the present application have investigated foldable tires of this kind in order to mitigate the disadvantages in the prior art. They have found that the provision of at least one stress releasing groove substantially circumferentially formed and opening at the outer surface in the bent zones of the sidewalls on the compression side concentric to the tread when folded or collapsed, prevents the wrinkles in the bent zones occurring in the prior art tires when folded, without requiring any significant modification of the existing equipment and ; installations for the production of the tires, thereby eliminating all the disadvantages in the prior art. -, 20 Fig. 5 illustrates à part of a foldable pneumatic ¦ tire in section molded and vulcanized according to the present invention, which may be, for example, of the type PSC78-14. As can be seen from Fig. 5, the tire according :1 - .
to the invention comprises an annular tread 23 of relatively ~, thin tread rubber, a pair of tire sidewalls 25 extending from both ends of the tread 23, and bead portions 24 and further curved portions 26 at the middle of the tire sidewalls formed with one or more stress releasing grooves 27.
:;, ;-~1 When the tire as shown in Fig. 5 is folded or collapsed, the curved portions 26 are deformed as-shown in ~; .
'. :: . ;
~ - 7 -Fig. 7. The periphery of the inner surface 29 (FigO 6) of the tire case e~pands as shown at 291 in Fig. 7 and the periphery along the neutral line P-P' remains unaltered in length. The periphery of the outer surface 28 (Fig. 6) must be shortened ~t in comparison with the length of the periphery along the neutral line P-P' where the thickness of the sidewall 25 is 2t because the neutral line extends substantially intermedlate between the inner and outer surfaces of the sidewall. On the other hand, according to the general characteristics of rubber materials, the periphery is easily deformed or elongated when subjected to a tensile force, but it is hardly deformed or contracted when subjected to a compressive force, so that if there is not provided the curved portions with grooves, the extra amount of the rubber corresponding to the ~t results in wrinkles 5 forming protrusions as shown in Fig. 4. In contrast herewith, according to the invention, the curved ~
portions 26 of the tire are formed with the stress releasing ~ -grooves 27 opening at the outer surface 28 as shown in Figs. 5 and 6, so that the width a of the grooves as shown in Fig. 6 is changed into al as shown in Fig. 7 when the tire is folded or collapsed, which narrowing of the grooves absorbs the difference ~t in the periphery to eliminate the wxinklesA
In a practical example, wherein the thickness of the tire sidewalls as shown in Fig. 5 is 2t . 6 mm, the periphery of the outer surface 28 inwardly curved when folded or collapsed contracts approximately 9.4 mm into narrower surface 28' as shown in Fig. 7. In this case, the length of the mold outer surface corresponding to the ~
~, ; - . :
, .
deformed zone Q-Q' is approximately 23 mm, because the radius of curvature of the de-formed ~one is r -.7.5 mm.
The grooves are provided within the zone of 23 mm. These grooves extend continuously and circumferentially o-f the tire sidewalls and are preferably so formed as to achieve a relation na _ ~t '. 9.~ mm between the width a and the number n of the grooves. If the number n is three as shown in the drawingsg the relation is a ~ 3.1 mm.
The depth b of the grooves must be more than one half of the width a in order to absorb the deormation oE the periphery of ~he sidewalls. The width a and depth b are so determined as to fulfil ~he relation na ~ ~t in considera-; tion of the accuracy in manufacture and the thickness of the rubber of the sidewalls. Although the stress releasing grooves are explained as circumferentially continuousgrooves in the sidewalls, they may be formed as a plurality of intermittent grooves so long as they can absorb the changes in the periphery.
The cross sectional configuration of the grooves ]nay be single semicircular as shown in Fig. 8 or rectangular as in Fig. 9 or any other forms capable of absorbing the canges in the periphery.
The tires according to the invention can be produced without a significant modification of an existing apparatus, and by providing the stress releasing grooves : ~ ' .
- in the curved portions of the sidewalls effectively prevent the wrinkles which would otherwise occur in the curved ~-.
portions resul~ing into cracks in the sidewalls in the prior -; art after have been maintained in folded or collapsed conditions for a long period o:E time, thereby enabling .
!
,, .
. ' . ~
the tires to be used as spare tires under a completely satisfactory condition.
It is understood by those skilled in the art that the foregoing description is a preferred embodiment of the :
disclosed device and that various changes and modifications may be made in the invention without departing from the ~.
spirit and scope thereof.
:~ "'' ' .
:' ' ~`' . :'"
"~ i':' :
,:', :
. ~ : : , -, .
:, ,, .i ~ : .
: ~
... . .
:,j :
,, , .
.:1 ; : -,: .
~ ~ .
. .
.i ~" ' ' ' ~, ~
~.~ , . -, , , , - . . - , - . , , .- ..... . : . .. . . .. .
.. ;,. . . . . . . . . ...
A foldable pneumatic tire, in general, has foldable or collapsihle sidewalls and assumes the same dimension as a normal tire when inflated, but can be housed in a very small space when deflated or collapsedO Such tires are known and disclosed in U~ S. Patents No. 3,347,300 and No. 3,833,042.
.. . ..
The tire disclosed in U. Sn Patent No. 3,347,300 is molded and vulcanized in a mold having a configuration corresponding to that of the deflated or collapsed tire, so that a particularly shaped mold and particular vulcanizer ' are required. In additionl commonly known bladders cannot ! ~ -be used for vulcanization and it is consequently necessary to employ bagless vulcanization wherein a vulcanizing heat -medium should be directly in contact with the tire. Ac~ordingly, : . .
a great modification of existing equipment and installations is needed for the production of the tire. Furthermore, "
bagless vulcanization is generally prone to produce inferior products that are rejected which result in low productivity.
The tire disclosed in UO S. Patent No~ 3,833,042 is vulcanized in a mold having a configuration corresponding ~--~ to that of an extended tire in the form of a ring of a thin ; rubber plate and thereafter formed into the folded or deflated condition by a forming apparatus having rings for urging bead portions of the tire towards the center of the tread~ This tire has advantages in that existing equipment ,~ :''` ' .
4~ .
and installations can be used without any significant modifi-cation thereof for the production of the tire. Also the possibility of producing inferior tires to be rejected is reduced. However, the vulcanized tire must be greatly deformed into the configuration o~ the deflated or collapsed tire when attached to a rim. Such a large deformation causes wrinkles or creases on the surface of the inwardly bent portion of the sidewalls of the tire. These wrinkles remain permanently at the bent portion, because the foldable tire is normally stored under a folded or bent condition for a long period of time ranging from six months to two years. These wrinkles may cause cracks in the sidewalls and be very conspicuous.
An object of the invention is, therefore, to provide a foldable pneumatic tire which eliminates the above disadvan-tages in the prior art.
A further object of the invention is to provide a Il foldable pneumatic tire produced without a significant modification of existing apparatuses and having sidewalls formed with stress releasing grooves in the curved portions effectively preventing the wrinkles which would otherwise occur in the curved portions and would cause cracks in the sidewalls.
The foldable pneumatic tire according to the present ,! invention has an annular tread of a relatively thin tread rubber, a pair of sidewalls extending from both ends of ~ -said tread and bead portions. The sidewalls are collapsible inwardly and concentrically to said tread. m e tire has at least one stress releasing groove substantially circum-ferentially formed in a bent zone of each of the sidewalls located inwardly and concentrically to the tread when folded ~ ;
: ~
~ . . .
and opening at an outersurface of the sidewall.
These and other objects, features and advantages of the invention will become more apparent upon a reading of the following detailed specification and drawings, in --- -; which: -Fig. 1 is a sectional view of a prior art foldable pneumatic tire showing a folded or collapsed position in solid lines and an inflated position in phantom lines;
Fig. 2 is a sectional view of a tire molded and 10 vulcanized in a folded position in a mold according to the prior art, Fig. 3 is a sectional view of another tire molded ` and vulcanized in an extended position in a mold according ~ to another prior art;
', Fig. 4 is a sectional view of a folded portion of `~ the vulcanized tire after collapsed from the extended position `~ as shown in Fig. 3; ~
Fig. 5 is a partial sectional view of a tire molded , and vulcanized in a mold according to the present invention, .; , - . .
FigO 6 is an enlarged sectional vlew of the folded portion of the tire as shown in Fig. 5; ~ ;
Fig. 7 is an explanatory sectional view of the ., ... :.
`~ folded portion shown in Fig. 6 when the tire is folded; and ~ Figs. 8 and 9 are sectional views of typical stress `~1 releasing grooves to be formed in the tire according to the , invention, respectively~
. ~ .
A foldable pneumatic tire generally has foldable sidewalls. Xt has substantially the same dimension as in a normal pneumatic tire when in an inflated condition, but can be collapsed into a very small dimension so as to be housed ~ ~
' ,' " .
. .
~ _ 4 _ . A
., .. ,. ~ .. . .
., . ;.. .. ... .
, . " ., . ', -. ., ,, - .... . . .
. ~ , ., ~ .
in a spare housing when in an unused position or in a deflated conditionO Such tires have been known as disclosed in the above U. S. Patents No. 3,347,300 and No. 3,833,042.
These tires disclosed in the two U. S. Patents are substantially similar to each other in configuration when inflated as shown in phantom lines, and deflated and collapsed as shown in solid lines 2 in Fig. 1. The tire disclosed in UO SO Patent ~o. 3,347,300 is molded and vulcanized in a mold 11 as shown in Fig. 2, w~ose cavity corresponds substantially to that of the tire 2 when de~lated and collapsed onto the rim 3. In order to vulcanize the tire in the collapsed shape, it is required to use a correspondingly ~ ~ -particularly shaped mold and a particular vulcanizer. In i, :
addition, the vulcanization cannot be effected by the use of commonly known bladders. It is consequently required to employ bagless vulcanization wherein vulcanizing heat medium should be directly in contact with the tire. Therefore, tires according to U. S. Patent ~o. 3,347,300 require extensive modification of existing apparatus and installations.
.
Furthermore, bagless vulcanization is generally prone to produce inferior products that will be rejected.
, , On the other hand, the tire 22 disclosed in UO S. Patent ~o. 3,833,042 is vulcanized in a mold 21 as shown in Fig. 3 and immediately thereafter fcrmed by a forming apparatus into the collapsed or folded condition that is the form when deflated as shown in solid lines in Fig. 1. m~ mold 21 includes a tread portion 23, bead portions 24 and side portions 25 extending outwardly from , ,1 . , ~ , the tread portion to the bead portions and having curved portions 26 at the middle thereof. The forming apparatus ~ .
:'., ,'' ~' .' ~ - 5 -.` .A ~. ~-to be used for forming the vulcanized tire into the collapsed condition consists of rings for urging the bead portions 24 towards the center of the tread of the tire and outer rings for preventing a radial expansion of the tire. Since the forming apparatus can sufficiently achieve its forming performance without the outer rings, the PCI machine (post cure inflation machine) used for tires having polyester or nylon cords can be used without requiring any modification of the machine. Tires thus produced have advantages in that .. .
existing equipment and installations can be used in all the processes and percentages of inferior products to be rejected are very low comparable to normal tires. However, the vulcanized tire 22 in an extended position in the moLd as shown in Fig. 3 must be extensively deformed into the configuration .
of the tire when deflated or collapsed after attached to a rim, that is, when housed in a spare housing. This large deformation causes followlng disadvantages. When the molded and vulcanized tire 22 in the mold 21 as shown in Fig. 3 is attached to the rim 3 in the form of the collapsed configuration as shown in Fig. l, the curved portions 26 are bent into the shape as shown in Fig~ 4 at ~ with their insides being subjected to high compressive forces. As can be seen from Fig. 4, wrinkles or cr!eases 5 occur on the surface of the bent portion~ ~1hen the curved portions are bent only for a short period of time, these wrinkles will --disappear at the time of release of the curved portions.
Since, however, the tire of this kind is a spare tire which would be only used when a main tire cannot be used, it is normally stored in a folded or bent condition for a long period of time (si~ months to two years). Such an 6 ~
, j;: , : .~ : , :
:: , , -, :. . -- . .: ,. :: . . :
~;::, , - . . :- . .: ~
. ~ .. . . .
. .. . .
unnatural restraint may cause a rapid ageing of the tire and makes it impossible to return to the original position and the wrinkles 5 remain permanently at the folded portions 4 even if the tire i~ inflated. These wrinkles 5 may give rise to cracks in sidewalls and cause anxiety on the part of ~ the user or inflating the tire because the wrinkles are very ; conspicuous.
The inventors of the present application have investigated foldable tires of this kind in order to mitigate the disadvantages in the prior art. They have found that the provision of at least one stress releasing groove substantially circumferentially formed and opening at the outer surface in the bent zones of the sidewalls on the compression side concentric to the tread when folded or collapsed, prevents the wrinkles in the bent zones occurring in the prior art tires when folded, without requiring any significant modification of the existing equipment and ; installations for the production of the tires, thereby eliminating all the disadvantages in the prior art. -, 20 Fig. 5 illustrates à part of a foldable pneumatic ¦ tire in section molded and vulcanized according to the present invention, which may be, for example, of the type PSC78-14. As can be seen from Fig. 5, the tire according :1 - .
to the invention comprises an annular tread 23 of relatively ~, thin tread rubber, a pair of tire sidewalls 25 extending from both ends of the tread 23, and bead portions 24 and further curved portions 26 at the middle of the tire sidewalls formed with one or more stress releasing grooves 27.
:;, ;-~1 When the tire as shown in Fig. 5 is folded or collapsed, the curved portions 26 are deformed as-shown in ~; .
'. :: . ;
~ - 7 -Fig. 7. The periphery of the inner surface 29 (FigO 6) of the tire case e~pands as shown at 291 in Fig. 7 and the periphery along the neutral line P-P' remains unaltered in length. The periphery of the outer surface 28 (Fig. 6) must be shortened ~t in comparison with the length of the periphery along the neutral line P-P' where the thickness of the sidewall 25 is 2t because the neutral line extends substantially intermedlate between the inner and outer surfaces of the sidewall. On the other hand, according to the general characteristics of rubber materials, the periphery is easily deformed or elongated when subjected to a tensile force, but it is hardly deformed or contracted when subjected to a compressive force, so that if there is not provided the curved portions with grooves, the extra amount of the rubber corresponding to the ~t results in wrinkles 5 forming protrusions as shown in Fig. 4. In contrast herewith, according to the invention, the curved ~
portions 26 of the tire are formed with the stress releasing ~ -grooves 27 opening at the outer surface 28 as shown in Figs. 5 and 6, so that the width a of the grooves as shown in Fig. 6 is changed into al as shown in Fig. 7 when the tire is folded or collapsed, which narrowing of the grooves absorbs the difference ~t in the periphery to eliminate the wxinklesA
In a practical example, wherein the thickness of the tire sidewalls as shown in Fig. 5 is 2t . 6 mm, the periphery of the outer surface 28 inwardly curved when folded or collapsed contracts approximately 9.4 mm into narrower surface 28' as shown in Fig. 7. In this case, the length of the mold outer surface corresponding to the ~
~, ; - . :
, .
deformed zone Q-Q' is approximately 23 mm, because the radius of curvature of the de-formed ~one is r -.7.5 mm.
The grooves are provided within the zone of 23 mm. These grooves extend continuously and circumferentially o-f the tire sidewalls and are preferably so formed as to achieve a relation na _ ~t '. 9.~ mm between the width a and the number n of the grooves. If the number n is three as shown in the drawingsg the relation is a ~ 3.1 mm.
The depth b of the grooves must be more than one half of the width a in order to absorb the deormation oE the periphery of ~he sidewalls. The width a and depth b are so determined as to fulfil ~he relation na ~ ~t in considera-; tion of the accuracy in manufacture and the thickness of the rubber of the sidewalls. Although the stress releasing grooves are explained as circumferentially continuousgrooves in the sidewalls, they may be formed as a plurality of intermittent grooves so long as they can absorb the changes in the periphery.
The cross sectional configuration of the grooves ]nay be single semicircular as shown in Fig. 8 or rectangular as in Fig. 9 or any other forms capable of absorbing the canges in the periphery.
The tires according to the invention can be produced without a significant modification of an existing apparatus, and by providing the stress releasing grooves : ~ ' .
- in the curved portions of the sidewalls effectively prevent the wrinkles which would otherwise occur in the curved ~-.
portions resul~ing into cracks in the sidewalls in the prior -; art after have been maintained in folded or collapsed conditions for a long period o:E time, thereby enabling .
!
,, .
. ' . ~
the tires to be used as spare tires under a completely satisfactory condition.
It is understood by those skilled in the art that the foregoing description is a preferred embodiment of the :
disclosed device and that various changes and modifications may be made in the invention without departing from the ~.
spirit and scope thereof.
:~ "'' ' .
:' ' ~`' . :'"
"~ i':' :
,:', :
. ~ : : , -, .
:, ,, .i ~ : .
: ~
... . .
:,j :
,, , .
.:1 ; : -,: .
~ ~ .
. .
.i ~" ' ' ' ~, ~
~.~ , . -, , , , - . . - , - . , , .- ..... . : . .. . . .. .
.. ;,. . . . . . . . . ...
Claims (3)
1. In a foldable pneumatic spare tire including an annular tread of a thin tread rubber, a pair of sidewalls extending from both ends of said tread and bead portions formed at marginal portions of said sidewalls, wherein in a deflated condition of the spare tire said annular tread having a rela-tively small overall diameter with respect to that of the annu-lar tread in an inflated condition, said sidewalls being fold-able axially inwardly toward each other into the underside of the annular tread, the improvement comprising at least one compressive stress releasing groove circumferentially formed in a bent zone of a wrinkle yielding side of each of said sidewalls when folded thereof.
2. A tire as set forth in claim 1, wherein said groove is formed so as to achieve a relation na ? .pi.t, where a is a width of said groove at its opening, n is the number of the groove and 2t is a thickness of said sidewall.
3. A tire as set forth in claim 1, wherein a depth of said groove is more than one half of a width of said groove at its opening.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1976038545U JPS564487Y2 (en) | 1976-04-01 | 1976-04-01 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1044128A true CA1044128A (en) | 1978-12-12 |
Family
ID=12528248
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA275,136A Expired CA1044128A (en) | 1976-04-01 | 1977-03-30 | Foldable pneumatic tire |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JPS564487Y2 (en) |
| CA (1) | CA1044128A (en) |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| IT1044837B (en) * | 1972-03-28 | 1980-04-21 | Pirelli | TIRE FOR VEHICLE WHEELS |
-
1976
- 1976-04-01 JP JP1976038545U patent/JPS564487Y2/ja not_active Expired
-
1977
- 1977-03-30 CA CA275,136A patent/CA1044128A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| JPS564487Y2 (en) | 1981-01-31 |
| JPS52130804U (en) | 1977-10-05 |
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