TREAD FOR A PNEUMATIC TIRE

Abstract

A tread for a tire includes: a first tread zone extending circumferentially, continuously, and entirely around the tire, the first tread zone being formed of a first compound; a second tread zone extending circumferentially, continuously, and entirely around the tire, the second tread zone being formed of a second compound different from the first compound; and a boundary groove axially separating the first tread zone from the second tread zone, the first tread zone, the second tread zone, and the boundary groove entirely forming the tread, the boundary groove having an axial centerline disposed an axial distance from an equatorial plane of the tire. The first tread zone has a first circumferential groove and a sidewall portion defining an intermediate circumferential rib of the first tread zone and a shoulder circumferential rib of the first tread zone.

Claims

1. A tread for a tire comprising: a first tread zone extending circumferentially, continuously, and entirely around the tire, the first tread zone being formed of a first compound; a second tread zone extending circumferentially, continuously, and entirely around the tire, the second tread zone being formed of a second compound different from the first compound; and a boundary groove axially separating the first tread zone from the second tread zone, the first tread zone, the second tread zone, and the boundary groove entirely forming the tread, the boundary groove having an axial centerline disposed an axial distance from an equatorial plane of the tire, the first tread zone having a first circumferential groove and a sidewall portion defining an intermediate circumferential rib of the first tread zone and a shoulder circumferential rib of the first tread zone.

2. The tread as set forth in claim 1 wherein the axial distance is between 10 mm and 30 mm.

3. The tread as set forth in claim 1 wherein the axial distance defines a first tread zone with an axial width less than an axial width of the second tread zone.

4. The tread as set forth in claim 1 wherein the second tread zone has no circumferential grooves extending entirely around the tire.

5. The tread as set forth in claim 1 wherein the intermediate circumferential rib includes curved grooves extending laterally from the boundary circumferential groove across an entire axial width of the intermediate circumferential rib to the first circumferential groove.

6. The tread as set forth in claim 1 wherein the intermediate circumferential rib includes curved blind sipes extending axially away from the boundary groove.

7. The tread as set forth in claim 1 wherein the shoulder circumferential rib includes curved blind sipes extending axially away from the first circumferential groove.

8. The tread as set forth in claim 1 wherein the second tread zone includes first lateral inclined and curved grooves spaced in the tire circumferential direction from each other.

9. The tread as set forth in claim 8 wherein the second tread zone includes second lateral inclined and curved grooves intersecting the first lateral inclined and curved grooves.

10. The tread as set forth in claim 9 wherein the second tread zone includes first lateral inclined and curved sipes generally parallel to the first lateral inclined and curved grooves.

11. The tread as set forth in claim 10 wherein the second tread zone includes second lateral inclined and curved sipes generally parallel to the second lateral inclined and curved grooves.

12. The tread as set forth in claim 1 wherein the second tread zone includes a circumferential sipe extending circumferentially around the entire second tread zone.

13. The tread as set forth in claim 12 wherein the circumferential sipe has an axial width between 1.0 mm and 2.0 mm.

14. The tread as set forth in claim 12 wherein the circumferential sipe has a radial depth between 5 mm and 7 mm.

15. The tread as set forth in claim 1 wherein the second tread zone includes micro-grooves for increasing traction during acceleration/braking of the tire.

16. A method for designing a tread for a tire comprising the steps of: forming a first tread zone of a first compound; extending the first tread zone circumferentially, continuously, and entirely around the tire; forming a second tread zone of a second compound different from the first compound; extending the second tread zone circumferentially, continuously, and entirely around the tire; separating the first tread zone from the second tread zone by a boundary groove; entirely forming the tread from the first tread zone, the second tread zone, and the boundary groove; offsetting the boundary groove axially from an equatorial plane of the tire by a predetermined distance; angling first curved grooves laterally across the second tread zone; angling second curved grooves laterally across the second tread zone; intersecting of the first curved grooves by the second curved grooves; angling first curved sipes generally parallel to the first curved grooves; and angling second curved sipes generally parallel to the second curved grooves.

17. The method as set forth in claim 16 wherein the second tread zone includes a circumferential sipe extending circumferentially around the entire second tread zone.

18. The method as set forth in claim 17 wherein the circumferential sipe has an axial width between 1.0 mm and 2.0 mm.

19. The method as set forth in claim 17 wherein the circumferential sipe has a radial depth between 5 mm and 7 mm.

20. The method as set forth in claim 16 wherein the second tread zone includes micro-grooves for increasing traction during acceleration/braking of the tire.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0096] FIG. 1 is a schematic view of a tread pattern of a pneumatic tire according to the present invention.

[0097] FIG. 2 is an enlarged schematic view of the tread pattern of FIG. 1.

[0098] FIG. 3 is a schematic cross-sectional view along line 3-3 in FIG. 2.

[0099] FIG. 4 is a detailed schematic perspective view of part of the tread pattern of FIGS. 1 and 2.

[0100] FIG. 5 is a detailed schematic perspective view of another part of the tread pattern of FIGS. 1 and 2.

DESCRIPTION OF EXAMPLES OF THE PRESENT INVENTION

[0101] As illustrated in FIGS. 1-3, an example tire 1 in accordance with the present invention may include a first tread zone 11 extending circumferentially, continuously, and entirely around the tire and a second tread zone 12 extending circumferentially, continuously, and entirely around the tire. In this example tire 1, the first tread zone 11 is axially adjacent the second tread zone 12 and the first and second tread zones together form a complete tread 10 for the tire. The first tread zone 11 may be formed of a first compound suitable for summer driving conditions. Such a first compound may resist deformation and provide optimal grip in dynamic handling conditions. The second tread zone 11 may be formed of a second different compound suitable for winter driving conditions. Such a second compound may enhance snow/ice/wet performance and evacuate water and slush effectively.

[0102] As seen in FIGS. 1-3, the first tread zone 11 may have an axial width less than one half the total axial width of the tread 10. The first tread zone 11 may have one circumferential groove 112. The second tread zone 12 may have no main circumferential grooves (FIGS. 1-2). The first tread zone 11 may be axially separated from the second tread zone 12 by one boundary circumferential groove 13.

[0103] The first tread zone 11 may include an intermediate circumferential rib 113 and a shoulder circumferential rib 114 defined by a sidewall 3 of the tire 1, the circumferential groove 112 of the first tread zone 11 and the boundary circumferential groove 13. An axial centerline of the boundary circumferential groove 13 may be disposed an axial distance D from the equatorial plane EP of the tire 1 giving the first tread zone 11 an axial width less than that of the second tread zone 12. The axial distance D may between 10.0 mm and 30.0 mm, or 20.0 mm.

[0104] The intermediate circumferential rib 113 may include curved grooves 1131 extending laterally from the boundary circumferential groove 13 across an entire axial width of the intermediate circumferential rib to the circumferential groove 112. The intermediate circumferential rib 113 may further include curved blind sipes 1132 extending axially away from the boundary circumferential groove 13.

[0105] The shoulder circumferential rib 114 may include curved grooves 1141 extending laterally from the circumferential groove 112 across an entire axial width of the shoulder circumferential rib to the sidewall 3. The shoulder circumferential rib 113 may further include curved blind sipes 1142 extending axially away from the circumferential groove 112.

[0106] The second tread zone 12 may include first lateral inclined and curved grooves 121 spaced in the tire circumferential direction from each other and second lateral inclined and curved grooves 122 intersecting the first lateral inclined grooves. As shown in FIG. 2, both the first lateral inclined and curved grooves 121 the second lateral inclined and curved grooves 122 may originate from the same lateral groove adjacent an opposite sidewall 3 of the tire 1. The second tread zone 12 may further include first lateral inclined and curved sipes 123 generally parallel to the first lateral inclined and curved grooves 121 and second lateral inclined and curved sipes 124 generally parallel to the second lateral inclined and curved grooves 122.

[0107] The second tread zone 12 may further include a circumferential sipe 125 extending circumferentially around the entire second tread zone. The sipe 125 may dissipate heat and thereby improve rolling resistance and fuel economy contributions from the second tread zone 12 to the overall tread 10. The circumferential sipe 125 may have an axial width between 1.0 mm and 2.0 mm, or 1.3 mm and a radial depth between 5 mm and 7 mm, or 6 mm. The second tread zone 12 may also include micro-grooves 127 for increasing traction during acceleration/braking.

[0108] As shown in FIGS. 4-5, the grooves 1131, 1141 and the sipes 1132 (not shown), 1142 of the first tread zone 11 may terminate at the grooves 13, 112 with notches 1133, 1143 that evolve during tread wear and form additional and evolving traction edges 1137, 1147 for improved traction in wet/snow conditions. The notches 1133, 1143 may widen as they project radially inward and axially inward (FIGS. 4-5). Use of the notches 1133, 1143 at termination points of the grooves 1131, 1132, 1141, 1142 as the grooves intersect with the main circumferential grooves 13, 112 may create additional voids in the tire 1 in which snow may be captured and maintained for additional generation of snow-on-snow shear force. The notches 1133, 1143 may not detract from circumferential groove volume, so there may be no negative effect on wet or hydroplaning performance (e.g., notches advantageously add additional wet void to the circumferential grooves) and may eliminate sharp block corners (90 degrees or less) for better worn/handling appearance (e.g., similar to block edge/corner chamfering (not shown)). Further, adjacent the notches 1133, 1143, L-shaped teeth 1135 may be placed at the base of the grooves 13, 112 to further reinforce the grooves and ribs 113, 114 for improved dry/wet handling. Such teeth 1135 may also enhance snow capture and thereby improve shear traction of the first tread zone 11. The L-shaped teeth 1135 may extend axially farther into the grooves 13, 112 as the teeth project radially inward (FIGS. 4-5).

[0109] The foregoing and other objects, features, and advantages of the present invention will be apparent from the above detailed descriptions of examples of the present invention, as illustrated in the accompanying drawings wherein like reference numbers represent like parts of the present invention.

[0110] Variations in the present invention are possible in light of the description of it provided herein. While certain representative embodiments and details have been shown for the purpose of illustrating the subject invention, it will be apparent to those skilled in this art that various changes and modifications can be made therein without departing from the scope of the subject invention. It is, therefore, to be understood that changes can be made in the particular embodiments described which will be within the full intended scope of the invention as defined by the following appended claims.