CA2054426A1 - Tread for a pneumatic tire having high density siping zones located in the shoulder regions - Google Patents
Tread for a pneumatic tire having high density siping zones located in the shoulder regionsInfo
- Publication number
- CA2054426A1 CA2054426A1 CA002054426A CA2054426A CA2054426A1 CA 2054426 A1 CA2054426 A1 CA 2054426A1 CA 002054426 A CA002054426 A CA 002054426A CA 2054426 A CA2054426 A CA 2054426A CA 2054426 A1 CA2054426 A1 CA 2054426A1
- Authority
- CA
- Canada
- Prior art keywords
- high density
- zone
- tread
- siping
- edge
- 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.)
- Abandoned
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
- B60C11/03—Tread patterns
- B60C11/04—Tread patterns in which the raised area of the pattern consists only of continuous circumferential ribs, e.g. zig-zag
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
- B60C11/01—Shape of the shoulders between tread and sidewall, e.g. rounded, stepped or cantilevered
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
- B60C11/03—Tread patterns
- B60C11/0306—Patterns comprising block rows or discontinuous ribs
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
- B60C11/03—Tread patterns
- B60C11/12—Tread patterns characterised by the use of narrow slits or incisions, e.g. sipes
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
- B60C11/03—Tread patterns
- B60C2011/0337—Tread patterns characterised by particular design features of the pattern
- B60C2011/0339—Grooves
- B60C2011/0381—Blind or isolated grooves
- B60C2011/0383—Blind or isolated grooves at the centre of the tread
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
- B60C11/03—Tread patterns
- B60C11/12—Tread patterns characterised by the use of narrow slits or incisions, e.g. sipes
- B60C11/1204—Tread patterns characterised by the use of narrow slits or incisions, e.g. sipes with special shape of the sipe
- B60C2011/1213—Tread patterns characterised by the use of narrow slits or incisions, e.g. sipes with special shape of the sipe sinusoidal or zigzag at the tread surface
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
- B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
- B60C11/03—Tread patterns
- B60C11/12—Tread patterns characterised by the use of narrow slits or incisions, e.g. sipes
- B60C11/1236—Tread patterns characterised by the use of narrow slits or incisions, e.g. sipes with special arrangements in the tread pattern
- B60C2011/1254—Tread patterns characterised by the use of narrow slits or incisions, e.g. sipes with special arrangements in the tread pattern with closed sipe, i.e. not extending to a groove
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Tires In General (AREA)
Abstract
Abstract of the Disclosure A TREAD FOR A PNEUMATIC TIRE HAVING HIGH DENSITY
SIPING ZONES LOCATED IN THE SHOULDER REGIONS
The present invention relates to a tread for a pneumatic tire featuring a pair of shoulder regions each of which contain a high density siping zone. Each high density siping zone is (a) circumferentially extending about the ground contacting portion of the should regions; and features (b) an inside edge and an outside edge with a total width between the inside edge and outside edge ranging from about 1.4% to about 4.5%
of the overall tread width; (c) the outside edge of each high density siping zone being located from the nearest tread edge by a distance ranging from about 0.9% to about 6.5% of the overall tread width; (d) about 50% to about 80% of the surface area in each high density siping zone being ground contacting with the remaining percent of area being siping; (e) no more than 50% of the siping arranged in the circumferential direction; and (f) at least 75% of all sipes within the high density siping zone is arranged so that their end portions are laterally aligned with or overlap in the circumferential direction with an end portion of another sipe within the high density siping zone. When the tread width of the pneumatic tire is, for example, eight inches (203.2 mm), the total width between the inside edge and outside edge ranges from about 3 to 9 mm and the outside edge of each high density siping zone is located from the nearest tread edge by a distance ranging from about 2 mm to 13 mm. The high density siping zones reduce the tendency for shoulder edge chamfer wear by creating a weakened zone without the tendency for tearing of tread rubber associated with decoupling grooves.
SIPING ZONES LOCATED IN THE SHOULDER REGIONS
The present invention relates to a tread for a pneumatic tire featuring a pair of shoulder regions each of which contain a high density siping zone. Each high density siping zone is (a) circumferentially extending about the ground contacting portion of the should regions; and features (b) an inside edge and an outside edge with a total width between the inside edge and outside edge ranging from about 1.4% to about 4.5%
of the overall tread width; (c) the outside edge of each high density siping zone being located from the nearest tread edge by a distance ranging from about 0.9% to about 6.5% of the overall tread width; (d) about 50% to about 80% of the surface area in each high density siping zone being ground contacting with the remaining percent of area being siping; (e) no more than 50% of the siping arranged in the circumferential direction; and (f) at least 75% of all sipes within the high density siping zone is arranged so that their end portions are laterally aligned with or overlap in the circumferential direction with an end portion of another sipe within the high density siping zone. When the tread width of the pneumatic tire is, for example, eight inches (203.2 mm), the total width between the inside edge and outside edge ranges from about 3 to 9 mm and the outside edge of each high density siping zone is located from the nearest tread edge by a distance ranging from about 2 mm to 13 mm. The high density siping zones reduce the tendency for shoulder edge chamfer wear by creating a weakened zone without the tendency for tearing of tread rubber associated with decoupling grooves.
Description
2 ~ $
A TREAD FOR A PNEUMATIC TIRE HAVING HIGH DENSITY
.. . .
SIPING ZONES LOCATED IN THE SHOULDER REGIONS
Background of the Invention The present invention relates to a tread for a pneumatlc tire. Pneumatic tires are a laminated mechanical device of generally toroidal shape having beads and a tread and made of rubber, chemicals, fabric and steel or other materials. When mounted on the wheel of a motor vehicle, the tire through its tread provides traction and contains the fluid that sustains the vehicle load. In particular, the tread of the present invention is particularly suited for a radial-ply tire. The term "radial-ply'l tire is intended to include a belted or circumferentially-restricted pneumatic tire in which the ply cords which extend from bead to bead are laid at cord angles between 65 and 90 with respect to the equatorial plane of the tire. The tread is provided with high density siping zones located in the shoulder region of the tread.
Shoulder wear is a common problem in many tires and especially radial tires for trucks and busses having rib and/or rib-block tread patterns. Shoulder wear is induced by lateral force and the partial wear grows and extends unevenly in the axial direction between the tread crown and shoulder regions. The partial wear growth in the axial direction is caused by the slippage produced during a straight driving of the vehicle due to a difference in radius between the tread crown and shoulder regions. One approach to deminimize the problem of shoulder wear is to form a circumferential groove on each shoulder rib or region. The groove inhibits the patial wear from growing axially inward, -2- 2~
however the region of the shoulder rib between the groove and ~he nearest tread edge is more likely to tear during use.
Summary of_the Invention The present invention rela~es to a tread for a pneumatic tire, the tread when on the tire casing comprising a pair of shoulder regions each of which contain a high density siping zone, wherein (a) each high density siping zone is circu~ferentially extending about the ground contacting portion of the shoulder regions;
(b) each high density siping zone has an inside edge and an outside edge with a total width between said inside edge and outside edge ranging from about 1.4~ to about 4.5% of the overall tread width;
(c) said outside edge of each high density siping zone is located from the nearest tread edge by a distance ranging from about 0.9~ to about 6.5% of the overall tread width~
(d) from about 50% to about 80% of the surface area in each high density siping zone is ground contacting with the remaining percent of surface area in each high density siping zone is siping;
(e) no more than 50~ of the siping within each high density siping zone is arranged in the circumferential direction; and (f) at least 75~ of all sipes within the high density siping zone are arranged so that their end portions are laterallv aligned with or overlap in the circumferential direction with an end portion of another sipe within the high densitv siping zone.
.
A TREAD FOR A PNEUMATIC TIRE HAVING HIGH DENSITY
.. . .
SIPING ZONES LOCATED IN THE SHOULDER REGIONS
Background of the Invention The present invention relates to a tread for a pneumatlc tire. Pneumatic tires are a laminated mechanical device of generally toroidal shape having beads and a tread and made of rubber, chemicals, fabric and steel or other materials. When mounted on the wheel of a motor vehicle, the tire through its tread provides traction and contains the fluid that sustains the vehicle load. In particular, the tread of the present invention is particularly suited for a radial-ply tire. The term "radial-ply'l tire is intended to include a belted or circumferentially-restricted pneumatic tire in which the ply cords which extend from bead to bead are laid at cord angles between 65 and 90 with respect to the equatorial plane of the tire. The tread is provided with high density siping zones located in the shoulder region of the tread.
Shoulder wear is a common problem in many tires and especially radial tires for trucks and busses having rib and/or rib-block tread patterns. Shoulder wear is induced by lateral force and the partial wear grows and extends unevenly in the axial direction between the tread crown and shoulder regions. The partial wear growth in the axial direction is caused by the slippage produced during a straight driving of the vehicle due to a difference in radius between the tread crown and shoulder regions. One approach to deminimize the problem of shoulder wear is to form a circumferential groove on each shoulder rib or region. The groove inhibits the patial wear from growing axially inward, -2- 2~
however the region of the shoulder rib between the groove and ~he nearest tread edge is more likely to tear during use.
Summary of_the Invention The present invention rela~es to a tread for a pneumatic tire, the tread when on the tire casing comprising a pair of shoulder regions each of which contain a high density siping zone, wherein (a) each high density siping zone is circu~ferentially extending about the ground contacting portion of the shoulder regions;
(b) each high density siping zone has an inside edge and an outside edge with a total width between said inside edge and outside edge ranging from about 1.4~ to about 4.5% of the overall tread width;
(c) said outside edge of each high density siping zone is located from the nearest tread edge by a distance ranging from about 0.9~ to about 6.5% of the overall tread width~
(d) from about 50% to about 80% of the surface area in each high density siping zone is ground contacting with the remaining percent of surface area in each high density siping zone is siping;
(e) no more than 50~ of the siping within each high density siping zone is arranged in the circumferential direction; and (f) at least 75~ of all sipes within the high density siping zone are arranged so that their end portions are laterallv aligned with or overlap in the circumferential direction with an end portion of another sipe within the high densitv siping zone.
.
3~ L~
Brief Descrip~n o the Drawings Fig. 1 is a perspective view of a tire utilizing the tread of the invention.
Fig. 2 is an enlarged plan view of a section of the tread of the tire shown in Fig. 1.
Fig. 3 is a plan view of another embodiment of the invention.
Fig. 4 is a plan view of ano~her embodiment of the invention.
Fig. 5 is a plan view of another embodiment of the present invention.
Fig. 6 is a perspective view of a tread hoop utilizing the tread of the invention.
Description of the Preferred Embodiment In accordance with the present invention, the high density siping zones, also referred to hereln as a high density zone, located in the shoulder regions substantially reduce the axial extension of local wear to the tread crown. The high density zones decrease the rigidity of the shoulder portion without the ; tendency for tearing associated with a decoupling groove.
According to the embodiment of the invention represented if Figs. 1 and 2, the tire 10 has a tread 12 incorporating the present invention. For purposes of the present invention "tread" is used herein to mean a molded rubber component which, when bonded to a tire casing includes that portion of the tire that comes into contact with the road when the tire is normallY
inflated and under normal load. Casing is intended to mean the carcass, belt structure, beads, sidewalls, and all other components of the tire excepting the tread and undertread. The casing may be new, u~vulcanized .
2 ~ 2 ~
rubber or previously vulcanized rubber to be fitted with the new tread.
While the invention may be practiced in the form of the tread on a new tire as shown in Fig. 1, it may also be practiced in the form of a tread 12 manufactured for retreading purposes as shown in Fig. 6. In a new tire application the tread 12 is attached to a tire casing which has not been vulcanized. The tire casing and the tread 12 are vulcanized together in a mold, creating a new tire. In a retreading application, the tread 12 can be "precured", that is, vulcanized prior to being bonded to the casing bein8 retreaded. Alternativelv, the tread pattern can be formed and the tread bonded to the casing in a single "mold-cure" retreading operation. For "precured" retreading purposes, the tread 12 may be ln the form of a hoop as shown in Fig. 6 or may be in the form of a Elat slab which is then wrapped around the circumference of the tire casing.
In Fig. 2, the tread 12 is characterized by a pair of shoulder regions 13 and 14. Depending on the number of circumferentially extending ribs in the tread, if any, the total width o' each shoulder region may vary from 15% to almost 50% of the total tread width.
Preferably the shoulder region ranges from about 18~ to about 40% of the to~al tread width. Each shoulder region 13 and 14 contains a high density zone 16 and 18. The tread 12 mav con~ain one or more grooves 20, ; 22, 24, and 26 which define the lateral edges of accompanying ribs 28, 30 and 32. ~or purposes herein, rib is intended to mean a circumferentially extending strip of rubber on the tread which is defined by at least one circumferential "wi~e groove" and either a second such groave or a tateral edge of the tread, the -5- 2~ $
strip of rubber being laterally undivided by full-depth narrow or wide grooves. Lug is intended to mean a laterally extending strip of rubber on the tread which is defined by at least two lateral "wide grooves" the strip of rubber being circumferentially undivided by full dep~h narrow or wide grooves.
"Groove" means an elongated void area in a tread that may extend circumferentially or laterally about the tread in a straight, curved, or zig-zag manner.
Circumferentially and laterally extending grooves sometimes have common portions and may be subclassified as "wide", "narrow", or "slot", or "sipe". The slot typically is formed by steel blades inserted into a cast or machined mold or tread ring therefor. A "slo~"
or sipe is a groove having a width in the range Erom about 0.2~ to about 0.8~ o the compensated treacl width, whereas a "narrow groove" has a width in the range from about 0.8% to 3~ of the compensated tread width and a "wide groove" has a width greater than 3%
thereof. The "groove width" is equal to tread surface area occupied by a groove or groove portion, ~he width of which is in question, divided by the length of such groove or groove portion; thus, the groove width is its average width over its length.
Each high density zone 16 and 18, has an inside edge 34 and 36 and an outside edge 38 and 40. The inside edge 34 and 36 is defined as the edge of the sipe within the high density zone that is furthest fro~
the nearest tread edge. The outside edge 38 and 40 is defined as the edge of the sipe within the high densi~v zone that is the nearest to the closest tread edge.
The total width A between the inside edge 36 and outside edge 40 of the high density zone 16 may range from about 1.4% to about 4.5~ of the overall tread width. Preferably, the tota] width A between the insîde edge and outside edge ranges from about 2~ to about 3.5~ of the overall tread width. For example, when the tread for the pneumatic tire has an overall S width of 8 inches (203.2 mm), the width of the high density zone may range from about 3 mm to about 9 mm.
Preferably, the total width A may range from about 4 mm to about 7 mm.
The outside edge 40 of a high density zone 16 is located from the nearest tread edge 42 by distance B.
The outside edge of each high density zone may be located from the nearest tread edge by a distance ranging from about 0.9~ to about 6.5~ of the overall tread width. Preferably, the distance B ranges from about 2% to about 4% of the overall tread width. When the tread for the pneumatic tire has an overall width of 8 inches (203.2 mm). The distance of B is generally from about 2 mm to about 13 mm. Preferably, the width of B is from about 4 mm to 8mm.
Each high density zone 16 and 18 is circumferentially extending about the ground contacting ~ portion of the tread. The inside edges 34 and 36 ; and/or outside edges 38 and 40 of the high density zone may be undulated, zig-zag or be straight edged.
Preferably, the inside edges are aligned in a relatively strai.gh~ edge as well as the outside edges are so aligned. Therefore, the inside edge and outside edge is preferably parallel.
The high density æone is circumferential]~
extending, however, it must be continuous as to the ; ground contacting area in the shoulder regions 13 and 14. For example, in a lug type tread pattern, the high density æone is circumferentially extending on all ground contacting areas but is obviously not ' -7~ L~J~
continuous, due to the lug type design as defined herein. If the shoulder region in which the high density zone is located is a continuously extending rib then the high density zone must be continuously e~tending about the axis of the tread. In one embodiment the tread may contain a combination o~ lugs and two or more circumferentially extending ribs.
Each high density zone 16 and 18 has from about SOZ
to about 80% of the surface of the area 43 being ground contacting with the remaining percent of the area being siping 44. The ratio of ground contacting to the total is also known as "net to gross". Preferably, the percent of ground contacting area (net) 43 ranges from about 60% to about 77%. The various percentages for the ground contacting area 43 is also known as the footprint, contact patch or area of contact. The percent of ground contact surface area is measured when the tread 12 is on a flat surface at zero speed and under normal load and pressure.
; 20 As can be appreciated by one skilled in the art, the width of the siping 46 within a given high density zone 16 will effect the "net to gross". For example, in the embodiment illustrated in Fig. 2, when the high density zone has a total width of 4 mm, and the width of each sipe is 0.76 ~m t~e net to gross will be 77~.
When the width of each si~e is 1 mm, the net to gross will be 69~. When the width of each sipe is 1.27 mm, the net to gross will be 62Z. When the width of each sipe is 1.52 mmj the net to gross will be 54%.
No more than 50Z o~ the siping 44 is arranged in a circumferential direct{on. Preferably from about 30 t~
50% of the siping 44 is arranged in a circumferential direction. As can be seen in Figs. 1 and 2, 50% of the siping 46 is in a circumferential direction whereas 50~
-8~ ~ 3.'~
of the siping 48 and 58 is not in the circumferential direction.
At least 75% of all sipes within the high density zone are arranged 50 that their end portions 51 overlap in the circumferential direction with an end portion 53 of another sipe within the high density zone. End portion of a sipe means the outermost portion of a sipe measured in the circumferential direction from the center point of a sipe. In another embodiment, later shown in Fig. 3~, at least 75% of all sipes within the high density zone are arrang~d so that their end portions are laterally aligned with an end portion of another sipe with the high density zone. Preferably, from about 80% to 100~ of all sipes within the high density zone are laterally aligned with or overlap in the circumferential direction with an end portion o~
another sipe withln the high density zone.
The siping 44 generally has a depth ranging from about 30% to 100~ of the depth of any grooves 20, 22, 24 and 26. Preferably the depth of the siping 44 ranges from about 50% to about 90~ of the depth of any grooves 20, 22, 24 and 26.
The remainin~ features of the tread depicted in Figs. 1 and 2 illustrate those features conventional to those skilled in the art including "Z" shaped sipes 52 and axial sipes 54 within rib 32.
Fig. 3 illustrates another embodiment of the present invention. In Fig. 3 the tread is characterized by a pair of shoulder regions 56 and 58.
The tread has three grooves, 60, 62 and 64 further defining two centrally located circumferentially extending ribs 66 and 68. Each high densi~y zone 7Q
and 72 has an inside ed~e 74 and 76 and an outside ed~e 78 and 80.
In Fig. 3, the end portion of a sipe 79 within high density æone 70 are laterally aligned with an end portion of another sipe 81 within the high density zone 70. This lateral alignment can be seen along line E.
S Fig. 4 illustrates yet another embodiment of the present invention. In Fig. 4 the tread 83 was characterized by a pair shoulder regions 84 and 86.
The tread 83 has three grooves 88, 90 and 92 further defining two centrally located circumferentially extending ribs 94 and 96. Each high density zone 98 and 100 has an inside edge 102 and 104 and an outside edge 106 and 108.
Fig. 5 represents another embodiment of the present invention. The tread 112 of Fig. 5 is a lug-type tread pattern characterized by at least two lateral wicle grooves 114, 116, and 118 and a plurality of ground contacting lugs 120 and 122. Each high density zone 124 and 126 has an inside edge 128 and 130 and an outside edge 132 and 134. Each high density zone 124 and 126 is continuous as to the ground contacting lugs in the shoulder regions 136, 138, 140 and 142.
~:
Brief Descrip~n o the Drawings Fig. 1 is a perspective view of a tire utilizing the tread of the invention.
Fig. 2 is an enlarged plan view of a section of the tread of the tire shown in Fig. 1.
Fig. 3 is a plan view of another embodiment of the invention.
Fig. 4 is a plan view of ano~her embodiment of the invention.
Fig. 5 is a plan view of another embodiment of the present invention.
Fig. 6 is a perspective view of a tread hoop utilizing the tread of the invention.
Description of the Preferred Embodiment In accordance with the present invention, the high density siping zones, also referred to hereln as a high density zone, located in the shoulder regions substantially reduce the axial extension of local wear to the tread crown. The high density zones decrease the rigidity of the shoulder portion without the ; tendency for tearing associated with a decoupling groove.
According to the embodiment of the invention represented if Figs. 1 and 2, the tire 10 has a tread 12 incorporating the present invention. For purposes of the present invention "tread" is used herein to mean a molded rubber component which, when bonded to a tire casing includes that portion of the tire that comes into contact with the road when the tire is normallY
inflated and under normal load. Casing is intended to mean the carcass, belt structure, beads, sidewalls, and all other components of the tire excepting the tread and undertread. The casing may be new, u~vulcanized .
2 ~ 2 ~
rubber or previously vulcanized rubber to be fitted with the new tread.
While the invention may be practiced in the form of the tread on a new tire as shown in Fig. 1, it may also be practiced in the form of a tread 12 manufactured for retreading purposes as shown in Fig. 6. In a new tire application the tread 12 is attached to a tire casing which has not been vulcanized. The tire casing and the tread 12 are vulcanized together in a mold, creating a new tire. In a retreading application, the tread 12 can be "precured", that is, vulcanized prior to being bonded to the casing bein8 retreaded. Alternativelv, the tread pattern can be formed and the tread bonded to the casing in a single "mold-cure" retreading operation. For "precured" retreading purposes, the tread 12 may be ln the form of a hoop as shown in Fig. 6 or may be in the form of a Elat slab which is then wrapped around the circumference of the tire casing.
In Fig. 2, the tread 12 is characterized by a pair of shoulder regions 13 and 14. Depending on the number of circumferentially extending ribs in the tread, if any, the total width o' each shoulder region may vary from 15% to almost 50% of the total tread width.
Preferably the shoulder region ranges from about 18~ to about 40% of the to~al tread width. Each shoulder region 13 and 14 contains a high density zone 16 and 18. The tread 12 mav con~ain one or more grooves 20, ; 22, 24, and 26 which define the lateral edges of accompanying ribs 28, 30 and 32. ~or purposes herein, rib is intended to mean a circumferentially extending strip of rubber on the tread which is defined by at least one circumferential "wi~e groove" and either a second such groave or a tateral edge of the tread, the -5- 2~ $
strip of rubber being laterally undivided by full-depth narrow or wide grooves. Lug is intended to mean a laterally extending strip of rubber on the tread which is defined by at least two lateral "wide grooves" the strip of rubber being circumferentially undivided by full dep~h narrow or wide grooves.
"Groove" means an elongated void area in a tread that may extend circumferentially or laterally about the tread in a straight, curved, or zig-zag manner.
Circumferentially and laterally extending grooves sometimes have common portions and may be subclassified as "wide", "narrow", or "slot", or "sipe". The slot typically is formed by steel blades inserted into a cast or machined mold or tread ring therefor. A "slo~"
or sipe is a groove having a width in the range Erom about 0.2~ to about 0.8~ o the compensated treacl width, whereas a "narrow groove" has a width in the range from about 0.8% to 3~ of the compensated tread width and a "wide groove" has a width greater than 3%
thereof. The "groove width" is equal to tread surface area occupied by a groove or groove portion, ~he width of which is in question, divided by the length of such groove or groove portion; thus, the groove width is its average width over its length.
Each high density zone 16 and 18, has an inside edge 34 and 36 and an outside edge 38 and 40. The inside edge 34 and 36 is defined as the edge of the sipe within the high density zone that is furthest fro~
the nearest tread edge. The outside edge 38 and 40 is defined as the edge of the sipe within the high densi~v zone that is the nearest to the closest tread edge.
The total width A between the inside edge 36 and outside edge 40 of the high density zone 16 may range from about 1.4% to about 4.5~ of the overall tread width. Preferably, the tota] width A between the insîde edge and outside edge ranges from about 2~ to about 3.5~ of the overall tread width. For example, when the tread for the pneumatic tire has an overall S width of 8 inches (203.2 mm), the width of the high density zone may range from about 3 mm to about 9 mm.
Preferably, the total width A may range from about 4 mm to about 7 mm.
The outside edge 40 of a high density zone 16 is located from the nearest tread edge 42 by distance B.
The outside edge of each high density zone may be located from the nearest tread edge by a distance ranging from about 0.9~ to about 6.5~ of the overall tread width. Preferably, the distance B ranges from about 2% to about 4% of the overall tread width. When the tread for the pneumatic tire has an overall width of 8 inches (203.2 mm). The distance of B is generally from about 2 mm to about 13 mm. Preferably, the width of B is from about 4 mm to 8mm.
Each high density zone 16 and 18 is circumferentially extending about the ground contacting ~ portion of the tread. The inside edges 34 and 36 ; and/or outside edges 38 and 40 of the high density zone may be undulated, zig-zag or be straight edged.
Preferably, the inside edges are aligned in a relatively strai.gh~ edge as well as the outside edges are so aligned. Therefore, the inside edge and outside edge is preferably parallel.
The high density æone is circumferential]~
extending, however, it must be continuous as to the ; ground contacting area in the shoulder regions 13 and 14. For example, in a lug type tread pattern, the high density æone is circumferentially extending on all ground contacting areas but is obviously not ' -7~ L~J~
continuous, due to the lug type design as defined herein. If the shoulder region in which the high density zone is located is a continuously extending rib then the high density zone must be continuously e~tending about the axis of the tread. In one embodiment the tread may contain a combination o~ lugs and two or more circumferentially extending ribs.
Each high density zone 16 and 18 has from about SOZ
to about 80% of the surface of the area 43 being ground contacting with the remaining percent of the area being siping 44. The ratio of ground contacting to the total is also known as "net to gross". Preferably, the percent of ground contacting area (net) 43 ranges from about 60% to about 77%. The various percentages for the ground contacting area 43 is also known as the footprint, contact patch or area of contact. The percent of ground contact surface area is measured when the tread 12 is on a flat surface at zero speed and under normal load and pressure.
; 20 As can be appreciated by one skilled in the art, the width of the siping 46 within a given high density zone 16 will effect the "net to gross". For example, in the embodiment illustrated in Fig. 2, when the high density zone has a total width of 4 mm, and the width of each sipe is 0.76 ~m t~e net to gross will be 77~.
When the width of each si~e is 1 mm, the net to gross will be 69~. When the width of each sipe is 1.27 mm, the net to gross will be 62Z. When the width of each sipe is 1.52 mmj the net to gross will be 54%.
No more than 50Z o~ the siping 44 is arranged in a circumferential direct{on. Preferably from about 30 t~
50% of the siping 44 is arranged in a circumferential direction. As can be seen in Figs. 1 and 2, 50% of the siping 46 is in a circumferential direction whereas 50~
-8~ ~ 3.'~
of the siping 48 and 58 is not in the circumferential direction.
At least 75% of all sipes within the high density zone are arranged 50 that their end portions 51 overlap in the circumferential direction with an end portion 53 of another sipe within the high density zone. End portion of a sipe means the outermost portion of a sipe measured in the circumferential direction from the center point of a sipe. In another embodiment, later shown in Fig. 3~, at least 75% of all sipes within the high density zone are arrang~d so that their end portions are laterally aligned with an end portion of another sipe with the high density zone. Preferably, from about 80% to 100~ of all sipes within the high density zone are laterally aligned with or overlap in the circumferential direction with an end portion o~
another sipe withln the high density zone.
The siping 44 generally has a depth ranging from about 30% to 100~ of the depth of any grooves 20, 22, 24 and 26. Preferably the depth of the siping 44 ranges from about 50% to about 90~ of the depth of any grooves 20, 22, 24 and 26.
The remainin~ features of the tread depicted in Figs. 1 and 2 illustrate those features conventional to those skilled in the art including "Z" shaped sipes 52 and axial sipes 54 within rib 32.
Fig. 3 illustrates another embodiment of the present invention. In Fig. 3 the tread is characterized by a pair of shoulder regions 56 and 58.
The tread has three grooves, 60, 62 and 64 further defining two centrally located circumferentially extending ribs 66 and 68. Each high densi~y zone 7Q
and 72 has an inside ed~e 74 and 76 and an outside ed~e 78 and 80.
In Fig. 3, the end portion of a sipe 79 within high density æone 70 are laterally aligned with an end portion of another sipe 81 within the high density zone 70. This lateral alignment can be seen along line E.
S Fig. 4 illustrates yet another embodiment of the present invention. In Fig. 4 the tread 83 was characterized by a pair shoulder regions 84 and 86.
The tread 83 has three grooves 88, 90 and 92 further defining two centrally located circumferentially extending ribs 94 and 96. Each high density zone 98 and 100 has an inside edge 102 and 104 and an outside edge 106 and 108.
Fig. 5 represents another embodiment of the present invention. The tread 112 of Fig. 5 is a lug-type tread pattern characterized by at least two lateral wicle grooves 114, 116, and 118 and a plurality of ground contacting lugs 120 and 122. Each high density zone 124 and 126 has an inside edge 128 and 130 and an outside edge 132 and 134. Each high density zone 124 and 126 is continuous as to the ground contacting lugs in the shoulder regions 136, 138, 140 and 142.
~:
Claims (14)
1. A tread for a pneumatic tire, the tire tread when on the tire casing comprising a pair of shoulder regions each of which contain a high density siping zone, wherein (a) each high density siping zone is circumferentially extending about the ground contacting portion of the shoulder region;
(b) each high density siping zone has an inside edge and an outside edge with a total width between said inside edge and outside edge ranging from about 3 to about 9 mm;
(c) said outside edge of each high density siping zone is located from the nearest tread edge by a distance ranging from about 2 mm to about 13 mm;
(d) from about 50% to about 80% of the surface area in each high density siping zone is ground contacting with the remaining percent of area being siping;
(e) no more than 50% of the siping within each high density siping zone is arranged in the circumferential direction; and (f) at least 75% of all sipes within the high density siping zone is arranged so that their end portions are laterally aligned with, or overlap in the circumferential direction with, an end portion of another sipe within the high density siping zone.
(b) each high density siping zone has an inside edge and an outside edge with a total width between said inside edge and outside edge ranging from about 3 to about 9 mm;
(c) said outside edge of each high density siping zone is located from the nearest tread edge by a distance ranging from about 2 mm to about 13 mm;
(d) from about 50% to about 80% of the surface area in each high density siping zone is ground contacting with the remaining percent of area being siping;
(e) no more than 50% of the siping within each high density siping zone is arranged in the circumferential direction; and (f) at least 75% of all sipes within the high density siping zone is arranged so that their end portions are laterally aligned with, or overlap in the circumferential direction with, an end portion of another sipe within the high density siping zone.
2. The tread according to claim 1 additional containing two or more circumferentially extending ribs.
3. The tread according to claim 1 additionally containing lugs.
4. The tread according to claim 2 wherein said tread has three circumferentially extending ribs.
5. The tread according to claim 1 wherein said total width between said inside edge and said outside edge ranges from about 2% to about 3.5% of the overall tread width.
6. The tread according to claim 1 wherein said outside edge of each high density siping zone is located from the nearest tread edge by distance ranging from about 2% to about 4% of the overall tread width.
7. The tread according to claim 1 wherein said high density siping zone has from about 60% to about 77% of the surface area being ground contacting.
8. The tread according to claim 1 where from about 30% to 50% of the siping located within the high density siping zone are arranged in the circumferential direction.
9. The tread according to claim 1 wherein from about 80% to about 100% of all sipes within the high density siping zone are arranged so that their end portions are laterally aligned with, or overlap in the circumferential direction, with an end portion of another sipe within the high density siping zone.
10. The tread according to claim 1 wherein at least 75% of all sipes within the high density siping zone are arranged so that their end portions are laterally aligned with an end portion of another sipe within the high density siping zone.
11. The tread according to claim 1 wherein at least 75% of all sipes within the high density siping zone are arranged so that their end portions overlap in the circumferential direction with an end portion of another sipe within the high density siping zone.
12. The tread according to claim 1 wherein said total width between said inside edge and said outside edge ranges from about 4 mm to 7 mm.
13. The tread according to claim 1 wherein said outside edge of each high density siping zone is located from the nearest tread edge by distance ranging from about 4 mm to about 8 mm.
14. A tread for a pneumatic tire, the tire tread when on the tire casing comprising a pair of shoulder regions each of which contain a high density siping zone, wherein (a) each high density siping zone is circumferentially extending about the ground contacting portion of the shoulder region;
(b) each high density siping zone has an inside edge and an outside edge with a total width between said inside edge and outside edge ranging from about 1.4% to about 4.5% of the overall tread width;
(c) said outside edge of each high density siping zone is located from the nearest tread edge by a distance ranging from about 0.9% to about 6.5% of the overall tread width;
(d) from about 50% to about 80% of the surface area in each high density siping zone is ground contacting with the remaining percent of area being siping;
(e) no more than 50% of the siping within each high density siping zone is arranged in the circumferential direction; and (f) at least 75% of all sipes within the high density siping zone are arranged so that their end portions are laterally aligned with or overlap in the circumferential direction with an end portion of another sipe within the high density siping zone.
(b) each high density siping zone has an inside edge and an outside edge with a total width between said inside edge and outside edge ranging from about 1.4% to about 4.5% of the overall tread width;
(c) said outside edge of each high density siping zone is located from the nearest tread edge by a distance ranging from about 0.9% to about 6.5% of the overall tread width;
(d) from about 50% to about 80% of the surface area in each high density siping zone is ground contacting with the remaining percent of area being siping;
(e) no more than 50% of the siping within each high density siping zone is arranged in the circumferential direction; and (f) at least 75% of all sipes within the high density siping zone are arranged so that their end portions are laterally aligned with or overlap in the circumferential direction with an end portion of another sipe within the high density siping zone.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US67225091A | 1991-03-20 | 1991-03-20 | |
| US672,250 | 1991-03-20 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2054426A1 true CA2054426A1 (en) | 1992-09-21 |
Family
ID=24697777
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002054426A Abandoned CA2054426A1 (en) | 1991-03-20 | 1991-10-29 | Tread for a pneumatic tire having high density siping zones located in the shoulder regions |
Country Status (2)
| Country | Link |
|---|---|
| CA (1) | CA2054426A1 (en) |
| GB (1) | GB2253816B (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19700101A1 (en) * | 1997-01-03 | 1998-07-09 | Pirelli Reifenwerke | Tread pattern for a vehicle tire |
| JP5779164B2 (en) * | 2012-10-30 | 2015-09-16 | 住友ゴム工業株式会社 | Pneumatic tire |
| JP5841558B2 (en) * | 2013-04-23 | 2016-01-13 | 住友ゴム工業株式会社 | Pneumatic tire |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1265652A (en) * | 1968-04-20 | 1972-03-01 | ||
| GB1273133A (en) * | 1968-07-09 | 1972-05-03 | Dunlop Holdings Ltd | Improvements in pneumatic tyres |
| FR2612129B1 (en) * | 1987-03-10 | 1989-09-29 | Michelin & Cie | TREAD FOR RADIAL TIRES OF WHICH THE RELATED ELEMENTS ARE INCORPORATED WITH BROKEN OR CORRUGATED LINE TRACKS IN THE SENSE OF THEIR DEPTHS |
-
1991
- 1991-10-29 CA CA002054426A patent/CA2054426A1/en not_active Abandoned
-
1992
- 1992-03-09 GB GB9205076A patent/GB2253816B/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| GB9205076D0 (en) | 1992-04-22 |
| GB2253816B (en) | 1994-10-26 |
| GB2253816A (en) | 1992-09-23 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Dead |