Pneumatic tire

Patent metadata

Field	Value
Publication number	US-12220951-B2
Application number	US-202318474884-A
Country	US
Kind code	B2
Filing date	Sep 26, 2023
Priority date	Oct 21, 2022
Publication date	Feb 11, 2025
Grant date	Feb 11, 2025

Abstract

A pneumatic tire comprises: a tread portion having a ground contacting surface; a sidewall portions having an outer surface; a bead portions; a carcass extending between the bead portions; and an inner rubber extending between bead portions. The inner rubber comprises a first portion extending through the tread portion with a first thickness t 1 , and a second portion extending through the sidewall portion with a second thickness t 2 . The first thickness t 1 is more than the second thickness t 2 . In a meridian cross section of the tire under its normal state, when a first reference point (Pb 1 ), a second reference point (Pb 2 ), a shoulder reference point (Ps), a reference line segment (Lb), and a shoulder line segment (Ls) are defined, then a length (L 1 ) of the shoulder line segment (Ls) is 85.9% to 89.3% of a length (L 2 ) of the reference line segment (Lb).

First claim

The invention claimed is:

1. A pneumatic tire comprising:
a tread portion;
a pair of sidewall portions;
a pair of bead portions;
a carcass extending between the bead portions; and
an inner rubber extending between the bead portions, on the inside of the carcass, wherein
the inner rubber comprises a first portion extending through the tread portion with a first thickness, and a second portion extending through the sidewall portions with a second thickness;
the first thickness is more than the second thickness;
the tread portion has a ground contacting surface between a first tread edge and a second tread edge;
the sidewall portions respectively have outer surfaces extending radially inward from the first tread edge and the second tread edge, respectively;
the ground contacting surface has a tire equator at the central position in the tire axial direction between the first tread edge and the second tread edge; and
the outer surfaces have tire maximum width positions which are the outermost positions in the tire axial direction,
wherein
in a meridian cross section of the tire under a normal state in which the tire is mounted on a regular rim, inflated to a normal internal pressure, and loaded with no load, when
a first reference point is defined as an intersection of a bead base line with a straight line extending parallel to the tire radial direction through the tire equator;
a second reference point is defined as an intersection of a straight line extending parallel to the tire axial direction through the tire equator with a straight line extending parallel to the tire radial direction through the tire maximum width position;
a reference line segment is defined as a strain line extending between the first reference point and the second reference point;
a shoulder reference point is defined as an intersection of the reference line segment with the ground contacting surface or the outer surface; and
a shoulder line segment is defined as a straight line connecting between the first reference point and the shoulder reference point,
then
the length of the shoulder line segment is in a range from 85.9% to 89.3% of the length of the reference line segment.

2. The pneumatic tire according to claim 1 , wherein
an average value of the first thickness is in a range from 1.5 to 3.5 times an average value of the second thickness.

3. The pneumatic tire according to claim 1 , wherein
an average value of the first thickness is 2.0 to 4.5 mm.

4. The pneumatic tire according to claim 1 , wherein
in the meridian cross section of the tire,
the ground contacting surface is made up of a plurality of arcs having different radii of curvature, and
the plurality of arcs includes a first arc passing through the tire equator, a second arc adjacent to the first arc on the outer side in the tire axial direction, and a third arc adjacent to the second arc on the outer side in the tire axial direction.

5. The pneumatic tire according to claim 4 , wherein
a radius R 1 of curvature of the first arc is in a range from 1.85 to 2.00 times a radius R 2 of curvature of the second arc.

6. The pneumatic tire according to claim 4 , wherein
the radius R 2 of curvature of the second arc is in a range from 2.08 to 2.74 times a radius R 3 of curvature of the third arc.

7. The pneumatic tire according to claim 1 , wherein
a tread width which is the distance in the tire axial direction between the first tread edge and the second tread edge, is in a range from 74% to 84% of a maximum width which is the distance in the tire axial direction at a maximum tire width position.

8. The pneumatic tire according to claim 1 , wherein
with respect to a shape of a ground contacting surface of the pneumatic tire when the pneumatic tire under the normal state is put on a flat surface at a camber angle of 0 degrees, and is loaded with 70% of a normal load,
a tread shape index F defined as a ratio (L 3 /L 4 ) of
a length L 3 in the tire circumferential direction measured at the tire equator to
a length L 4 in the tire circumferential direction measured at a position spaced apart from the tire equator by 80% of the distance from the tire equator to the first tread edge, is in a range from 1.05 to 1.35.

9. The pneumatic tire according to claim 1 , wherein
the outer surface of at least one of the sidewall portions comprises a serration portion,
the serration portion comprises
a plurality of grooves each extending in a tire radial direction and arranged in the tire circumferential direction, and
a plurality of ridges divided by the plurality of grooves, and
each of the plurality of grooves comprises a radially outer end portion having a depth of 0.2 mm or less.

10. The pneumatic tire according to claim 9 , wherein
each of the plurality of grooves comprises a radially inner end portion, and has a depth decreasing from the radially inner end portion to the radially outer end portion.

11. The pneumatic tire according to claim 1 , wherein
the tread portion comprises a tread rubber forming a ground contacting surface, and
a loss tangent tan δ 1 of the first portion at 70 degrees C. is not less than a loss tangent tan δ 2 of the second portion at 70 degrees C., and not more than a loss tangent tan δA of the tread rubber at 30 degrees C.

12. The pneumatic tire according to claim 11 , wherein
the loss tangent tan δ 1 of the first portion is in a range from 1.0 to 2.0 times the loss tangent tan δ 2 of the second portion.

13. The pneumatic tire according to claim 11 , wherein
the loss tangent tan δ 1 of the first portion is in a range from 0.4 to 0.7 times the loss tangent tan δA of the tread rubber.

14. The pneumatic tire according to claim 1 , wherein
the carcass comprises carcass cords having a twist coefficient of 2000 to 2500.

15. The pneumatic tire according to claim 14 , wherein
the carcass has a main portion extending between the bead portions, and a turnup portion connected to the main portion and turned up around a bead core of the bead portion from the inside to the outside in the tire axial direction, and
the turnup portion has a radially outer end positioned radially outside a maximum width position of the main portion.

16. The pneumatic tire according to claim 1 , wherein
the outer surface of at least one of the sidewall portions comprises a serration portion,
the serration portion comprises
a plurality of grooves each extending in a tire radial direction and arranged in the tire circumferential direction, and
a plurality of ridges divided by the plurality of grooves, and
each of the plurality of grooves comprises a radially outer end portion having a depth of 0.2 mm or less,
the tread portion comprises a tread rubber forming the ground contacting surface,
the loss tangent tan δ 1 of the first portion at 70 degrees C. is not less than the loss tangent tan δ 2 of the second portion at 70 degrees C., and not more than the loss tangent tan δA of the tread rubber at 30 degrees C., and
the carcass comprises carcass cords having a twist coefficient of 2000 to 2500.

17. The pneumatic tire according to claim 1 , wherein
an average value of the first thickness is in a range from 1.5 to 3.5 times an average value of the second thickness;
the average value of the first thickness is in a range from 2.0 to 4.5 mm;
in the meridian cross section of the tire,
the ground contacting surface is made up of a plurality of arcs having different radii of curvature, and
the plurality of arcs includes a first arc passing through the tire equator, a sec

Assignees

• Sumitomo Rubber Ind

Inventors

• Sasaki Tatsuya
• Yano Tsukasa
• Onitsuka Rena
• Terashima Masaki
• Sueyoshi Yusuke
• Nakayama Hiroyuki
• Sueno Junya

Classifications

• B60C2011/0016

  Physical properties or dimensions · CPC title

• B60C13/001

  Decorating, marking or the like · CPC title

• B60C13/02

  Arrangement of grooves or ribs · CPC title

• B60C5/14

  with impervious liner or coating on the inner wall of the tyre · CPC title

• B60C11/01 Primary

  Shape of the shoulders between tread and sidewall, e.g. rounded, stepped or cantilevered · CPC title