Heavy duty pneumatic tire

Patent metadata

Field	Value
Publication number	US-9987885-B2
Application number	US-201515328440-A
Country	US
Kind code	B2
Filing date	Jul 23, 2015
Priority date	Jul 23, 2014
Publication date	Jun 5, 2018
Grant date	Jun 5, 2018

Abstract

A pneumatic tire with improved heat build-up resistance in a land portion in a tread center region. The pneumatic tire is provided with a tread pattern that includes a plurality of center lug grooves ( 14 ) disposed at intervals in a tire circumferential direction that cross a tire equator line; a plurality of shoulder lug grooves ( 12 A, 12 B) disposed in intervals between the plurality of center lug grooves in the tire circumferential direction extending outward in the tire width direction, an inner end in the tire width direction being disposed outward of an end of the center lug groove in the tire width direction; a pair of circumferential primary grooves ( 11 A, 11 B) extending around an entire circumference of the pneumatic tire in a wave-like shape with the ends of the center lug grooves and the inner ends of the plurality of shoulder lug grooves in the tire width direction alternately connecting to the pair of circumferential primary grooves ( 11 A, 11 B); and
a circumferential secondary groove ( 10 ) disposed on the tire equator line around the entire circumference of the pneumatic tire that intersects the center lug grooves.

A straight line that joins an intersection portion between the center lug groove and the circumferential secondary groove and the end of the center lug groove has an inclination angle with respect to the tire circumferential direction ranging from 55° to 75°.

First claim

The invention claimed is:

1. A heavy duty pneumatic tire comprising:
a tread portion that is provided with a tread pattern,
the tread pattern comprising:
a plurality of center lug grooves disposed at intervals in a tire circumferential direction that cross a tire equator line, the plurality of center lug grooves each comprising
a first end located in a half-tread region on a first side in a tire width direction of the tire equator line, and
a second end located in a half-tread region on a second side opposite the first side in the tire width direction;
a plurality of shoulder lug grooves disposed in each space between the plurality of center lug grooves in the tire circumferential direction in both of the half-tread regions,
each of the plurality of shoulder lug grooves extending outward in the tire width direction and comprising
an outer end in the tire width direction that opens to a ground contact edge on one side of respective opposite sides in the tire width direction, and
an inner end in the tire width direction located outward in the tire width direction of a position in the tire width direction of the respective first end or the second end;
a pair of circumferential primary grooves with a groove width less than that of the plurality of shoulder lug grooves, each of the pair of circumferential primary grooves being disposed in the respective half-tread regions and extending around an entire circumference of the pneumatic tire while alternately connecting to either one of the first end and the second end, and the inner end of each of the plurality of shoulder lug grooves in the tire width direction to form a wave-like shape;
a plurality of center blocks formed in a row in the tire circumferential direction and defined by the plurality of center lug grooves and the pair of circumferential primary grooves; and
a circumferential secondary groove disposed on the tire equator line around the entire circumference of the pneumatic tire that intersects the plurality of center lug grooves; wherein
a straight line that joins the first end and a first intersection portion where the center lug groove intersects a groove wall of the circumferential secondary groove on the first side has an inclination angle with respect to the tire circumferential direction ranging from 55° to 75°;
a straight line that joins the second end and a second intersection portion where the center lug groove intersects a groove wall of the circumferential secondary groove on the second side has an inclination angle with respect to the tire circumferential direction ranging from 55° to 75°;
a ratio of a groove width of the circumferential secondary groove to a maximum groove width of the center lug grooves ranges from 1.0 to 8.5; and
a relationship 0.05≤W1/A≤1.0 is satisfied, where A is a lateral variation of the wave-like shape of each of the pair of circumferential primary grooves and W1 is a groove width of the circumferential secondary groove.

2. The heavy duty pneumatic tire according to claim 1 , wherein a groove width W1 of the circumferential secondary groove ranges from 7 mm to 60 mm.

3. The heavy duty pneumatic tire according to claim 1 , wherein a relationship W1/W2 ranges from 1.0 to 8.5, where W1 is a groove width of the circumferential secondary groove and W2 is a groove width of the center lug grooves.

4. The heavy duty pneumatic tire according to claim 1 , further comprising a raised bottom portion in each of the pair of circumferential primary grooves which is a portion where groove depth becomes shallower partially.

5. The heavy duty pneumatic tire according to claim 4 , wherein a relationship D1/T<0.05 is satisfied, where D1 is a groove depth of the raised bottom portion and T is a tread width of the tread portion in the tire width direction.

6. The heavy duty pneumatic tire according to claim 1 , wherein a relationship 0.2≤D2/D3≤1.0 is satisfied, where D2 is a maximum depth of the circumferential secondary groove and D3 is a maximum depth of the center lug grooves.

7. The heavy duty pneumatic tire according to claim 1 , wherein a ratio R of a groove area to a ground contact region of the tread portion when the pneumatic tire is inflated with air to a standard air pressure (700 kPa) and loaded with a standard load (617.81 kN) is such that R≤0.35.

8. A heavy duty pneumatic tire comprising:
a tread portion that is provided with a tread pattern,
the tread pattern comprising:
a plurality of center lug grooves disposed at intervals in a tire circumferential direction that cross a tire equator line, the plurality of center lug grooves each comprising
a first end located in a half-tread region on a first side in a tire width direction of the tire equator line, and
a second end located in a half-tread region on a second side opposite the first side in the tire width direction;
a plurality of shoulder lug grooves disposed in each space between the plurality of center lug grooves in the tire circumferential direction in both of the half-tread regions,
each of the plurality of shoulder lug grooves extending outward in the tire width direction and comprising
an outer end in the tire width direction that opens to a ground contact edge on one side of respective opposite sides in the tire width direction, and
an inner end in the tire width direction located outward in the tire width direction of a position in the tire width direction of the respective first end or the second end;
a pair of circumferential primary grooves with a groove width less than that of the plurality of shoulder lug grooves, each of the pair of circumferential primary grooves being disposed in the respective half-tread regions and extending around an entire circumference of the pneumatic tire while alternately connecting to either one of the first end and the second end, and the inner end of each of the plurality of shoulder lug grooves in the tire width direction to form a wave-like shape;
a plurality of center blocks formed in a row in the tire circumferential direction and defined by the plurality of center lug grooves and the pair of circumferential primary grooves; and
a circumferential secondary groove disposed on the tire equator line around the entire circumference of the pneumatic tire that intersects the plurality of center lug grooves; wherein
a straight line that joins the first end and a first intersection portion where the center lug groove intersects a groove wall of the circumferential secondary groove on the first side has an inclination angle with respect to the tire circumferential direction ranging from 55° to 75°;
a straight line that joins the second end and a second intersection portion where the center lug groove intersects a groove wall of the circumferential secondary groove on the second side has an inclination angle with respect to the tire circumferential direction ranging from 55° to 75°;
a ratio of a groove width of the circumferential secondary groove to a maximum groove width of the center lug grooves ranges from 1.0 to 8.5; and
a relationship 0.30≤W3/T<W4/T≤0.60 is satisfied, where W3 is an interval in the tire width direction between opposite ends of each of the center lug grooves, W4 is an interval in the tire width direction between the inner end in the tire width direction of each of the shoulder lug grooves disposed in one of the half-tread regions and the inner end in the tire width direction of each of the shoulder lug grooves disposed in the other half-tread region, and T is a tread width of the tread portion in the tire width direction.

9. The heavy duty pneumatic tire according to claim 1 , wherein a rubber of an outermost portion of the tread portion in a tire radial direction has a ratio (tan δ) of loss modulus to sto

Assignees

• Yokohama Rubber Co Ltd

Inventors

• Tauchi Risa
• KAKUTA Shoei
• Hamanaka Hideki
• Yamaguchi Yukihito
• Sato Toshiyuki

Classifications

• B60C11/0309

  further characterised by the groove cross-section · CPC title

• B60C2011/0348

  Narrow grooves, i.e. having a width of less than 4 mm · CPC title

• B60C2011/0351

  Shallow grooves, i.e. having a depth of less than 50% of other grooves · CPC title

• B60C2200/065

  for construction vehicles · CPC title

• B60C11/13 Primary

  characterised by the groove cross-section, e.g. for buttressing or preventing stone-trapping · CPC title