Pneumatic tire

Patent metadata

Field	Value
Publication number	US-9802443-B2
Application number	US-201313963175-A
Country	US
Kind code	B2
Filing date	Aug 9, 2013
Priority date	Mar 19, 2013
Publication date	Oct 31, 2017
Grant date	Oct 31, 2017

Abstract

A pneumatic tire comprises a tread portion provided with a pair of crown main grooves and a pair shoulder main grooves to divide middle portions and shoulder portions, the tread portion having a contact surface covered with a cap rubber layer with a loss tangent of from 0.03 to 0.18, the middle portions provided with only middle lug grooves with groove widths within 2 mm, each middle lug groove extending from one end connected either the crown or shoulder main groove to the other end terminating within the middle portion, the middle lug grooves having an angle of from 40 to 55 degrees with respect to a tire circumferential direction, and each shoulder portion provided with first shoulder lateral grooves having axially inner ends connected to the shoulder main groove, wherein first shoulder lateral grooves consist of grooves having groove widths within 2 mm.

First claim

The invention claimed is:

1. A pneumatic tire comprising:
a tread portion having a tire equator and axially outer tread edges, the tread portion being provided with:
a pair of circumferentially and continuously extending crown main grooves disposed axially both sides of the tire equator;
a pair of circumferentially and continuously extending shoulder main grooves disposed axially outside of the crown main grooves;
a pair of middle portions each of which is between the crown main groove and the shoulder main groove; and
a pair of shoulder portions each of which is disposed axially outward of each shoulder main groove,
the tread portion having a contact surface being covered with a cap rubber layer which is made of rubber having a loss tangent in a range of from 0.03 to 0.18,
the middle portions being provided with only a plurality of middle lug grooves having groove widths in a range of not more than 2 mm, each middle lug groove extending from one end connected to either the crown main groove or the shoulder main groove to the other end terminating within the middle portion,
the middle lug grooves having an angle in a range of from 40 to 55 degrees with respect to a circumferential direction of the tire, the middle lug grooves comprising first middle lug grooves having said one end connected to the crown main groove with the first middle lug grooves comprising an axially inner groove portion having a constant groove width W 9 and an axially outer groove portion having a constant groove width W 10 that is smaller than the groove width W 9 , wherein a ratio W 10 /W 9 of the groove width W 10 to the groove width W 9 is in a range of from 0.50 to 0.70, and wherein the axially inner groove portion extends at an angle larger than that of the axially outer groove portion with respect to the circumferential direction of the tire, and
each shoulder portion being provided with a plurality of first shoulder lateral grooves having axially inner ends connected to the shoulder main groove, having axially outer ends terminating within the shoulder portion without reaching the tread edge, and having groove widths in a range of not more than 2 mm.

2. The tire according to claim 1 , wherein the tread portion has a land ratio Sa/Sb in a range of from 0.65 to 0.75, wherein “Sa” is a net footprint area of the contact surface of the tread portion, and “Sb” is a gross footprint area including both the contact surface and whole grooves of the tread portion.

3. The tire according to claim 1 , wherein a total groove width of crown main grooves and shoulder grooves is in a range of from 0.15 to 0.30 times with respect to the tread width.

4. The tire according to claim 1 , wherein an axial maximum length of middle lug grooves is in a range of from 0.15 to 0.85 times with respect to a maximum axial length of the middle portion.

5. The tire according to claim 1 , wherein
the middle lug grooves include a second middle lug groove having said one end being connected to the shoulder main groove, and
a total length (L 1 +L 2 ) of an axial length L 1 of one said of said first middle lug grooves and an axial length L 2 of one of said second middle lug grooves is in a range of from 0.4 to 1.2 times with respect to a maximum axial length of the middle portion.

6. The tire according to claim 5 , wherein the first middle lug groove and the second middle lug groove are inclined in a direction opposite to each other.

7. The tire according to claim 5 , wherein
said middle lug grooves include a plurality of said second middle lug grooves spaced in the circumferential direction of the tire with second pitches, and
the second pitches are in a range of from 0.5 to 2.0 times with respect to the maximum axial length of the middle portion.

8. The tire according to claim 1 , wherein
said middle lug grooves include a plurality of said first middle lug grooves spaced in the circumferential direction of the tire with first pitches, and
the first pitches are in a range of from 0.5 to 2.0 times with respect to the maximum axial length of the middle portion.

9. The tire according to claim 1 , wherein the middle lug grooves have a groove depth D 3 reaching a base layer disposed radially inward of the cap rubber layer.

10. The tire according to claim 1 , wherein the axially inner groove portion of the first middle lug groove has a length shorter than that of the axially outer groove portion of the first middle lug groove.

11. The tire according to claim 1 , wherein the middle lug grooves include a second middle lug groove having said one end being connected to the shoulder main groove, the axially outer groove portion of the first middle lug groove is arranged so as to overlap with the second middle lug groove in the circumferential direction of the tire, and the axially inner groove portion of the first middle lug groove is arranged not to overlap with the second middle lug groove in the circumferential direction of the tire.

12. The tire according to claim 11 , wherein the axially outer groove portion of the first middle lug groove is arranged so as to overlap with the second middle lug groove in the axial direction of the tire, and the axially inner groove portion of the first middle lug groove is arranged not to overlap with the second middle lug groove in the axial direction of the tire.

13. The tire according to claim 1 , wherein the middle lug grooves include a second middle lug groove having said one end being connected to the shoulder main groove, the axially outer groove portion of the first middle lug groove is arranged so as to overlap with the second middle lug groove in the axial direction of the tire, and the axially inner groove portion of the first middle lug groove is arranged not to overlap with the second middle lug groove in the axial direction of the tire.

Assignees

• Sumitomo Rubber Ind

Inventors

• Horiguchi Takuya

Classifications

• B60C11/04

  in which the raised area of the pattern consists only of continuous circumferential ribs, e.g. zig-zag (B60C11/12, B60C11/13 take precedence) · CPC title

• B60C11/005

  with cap and base layers · CPC title

• B60C2011/0025

  Modulus or tan delta · CPC title

• B60C11/033 Primary

  by the void or net-to-gross ratios of the patterns · CPC title

• B60C11/12

  characterised by the use of narrow slits or incisions, e.g. sipes · CPC title