Two-wheeled vehicle tire for running on rough terrain
A two-wheeled vehicle tire for running on rough terrain, the tire comprising a tread portion. The tread portion comprises a plurality of middle blocks located between a tire equator and a tread edge. The plurality of middle blocks comprises at least one first middle block having an outer surface in a tire radial direction, and at least one second middle block having an outer surface in the tire radial direction whose area is larger than an area of the outer surface of the at least one first middle block. The outer surface in the tire radial direction of the at least one first middle block is not provided with sipes. The outer surface of the at least one second middle block is provided with at least one sipe.
1. A two-wheeled vehicle tire for running on rough terrain, comprising:
a tread portion provided with middle blocks located between a tire equator and a tread edge,
the middle blocks including
a first middle block whose radially outer surface is not provided with sipes, and
a second middle block whose radially outer surface is provided with at least one sipe,
wherein
the tread portion has a designated rotation direction,
each of the radially outer surface of the first middle block and the radially outer surface of the second middle block has an axially extending leading edge located on a leading side in the designated rotation direction and an inner longitudinal edge extending in a tire circumferential direction from an end of a tire equator side of the leading edge, and
an angle between the leading edge and the inner longitudinal edge of the first middle block is greater than an angle between the leading edge and the inner longitudinal edge of the second middle block.
2. The two-wheeled vehicle tire for running on rough terrain according to claim 1 , wherein
the angle between the leading edge and the inner longitudinal edge of the first middle block ranges from 90 to 110 degrees, and
the angle between the leading edge and the inner longitudinal edge of the second middle block ranges from 50 to 60 degrees.
3. The two-wheeled vehicle tire for running on rough terrain according to claim 1 , wherein
the inner longitudinal edge of the first middle block includes two straight edges, and
the straight edges are connected such that the inner longitudinal edge is recessed toward the centroid of figure of the radially outer surface of the first middle block.
4. The two-wheeled vehicle tire for running on rough terrain according to claim 3 , wherein an angle between the straight edges of the inner longitudinal edge of the first middle block ranges from 160 to 170 degrees.
5. The two-wheeled vehicle tire for running on rough terrain according to claim 3 , wherein
the radially outer surface of the first middle block has an outer longitudinal edge extending in the tire circumferential direction from an end on a tread edge side of the leading edge,
the outer longitudinal edge of the first middle block includes two straight edges,
the straight edges of the outer longitudinal edge are connected such that the outer longitudinal edge is recessed toward the centroid of figure of the radially outer surface of the first middle block, and
an angle between the straight edges of the outer longitudinal edge is smaller than an angle between the straight edges of the inner longitudinal edge.
6. A two-wheeled vehicle tire for running on rough terrain comprising:
a tread portion comprising middle blocks and shoulder blocks located between a tire equator and a tread edge,
the middle blocks including a first middle block having a radially outer surface and a second middle block having a radially outer surface that has an area larger than an area of the radially outer surface of the first middle block, wherein
the radially outer surface of the first middle block is not provided with sipes,
the radially outer surface of the second middle block is provided with two sipes,
each of the two sipes extends linearly over its entire length, across the radially outer surface completely in a tire axial direction so that the second middle block comprises a first portion defined between the two sipes,
the radially outer surface of the first portion has an axially outer longitudinal edge extending in a tire circumferential direction and an axially inner longitudinal edge extending in a tire circumferential direction, and extends continuously from the axially outer longitudinal edge to the axially inner longitudinal edge,
the two sipes are arranged non-parallel to each other so that the first portion has a circumferential length increasing toward the tread edge, and an actual length of the axially inner longitudinal edge is smaller than an actual length of the axially outer longitudinal edge, and
the shoulder blocks are provided with no sipes or grooves,
each of the shoulder blocks is defined such that its radially outer surface has a centroid of figure located in a shoulder region, the shoulder region being defined as extending from the tread edge toward the tire equator by a width of ⅙ of a tread development width, and
each of the middle blocks is defined such that its radially outer surface has a centroid of figure located in a middle region, the middle region defined as extending from the shoulder region toward the tire equator to a position spaced apart from the tire equator toward the tread edge by a width of ⅙ of the tread development width.
7. The two-wheeled vehicle tire for running on rough terrain according to claim 1 , wherein the actual length of the inner longitudinal edge is equal to or more than 2 mm.
8. The two-wheeled vehicle tire for running on rough terrain according to claim 6 , wherein an area of the radially outer surface of the first middle block is equal to or more than 65% of an area of the radially outer surface of the second middle block.
9. The two-wheeled vehicle tire for running on rough terrain according to claim 6 , wherein the tread portion further comprises a shoulder tie-bar that connects one of the shoulder blocks with one of the middle blocks.
10. The two-wheeled vehicle tire for running on rough terrain according to claim 6 , wherein one of the two sipes extends parallel to a tire axial direction.
11. The two-wheeled vehicle tire for running on rough terrain according to claim 6 , wherein one of the two sipes located on a leading side in a designated tire rotation direction is parallel to a tire axial direction.
12. The two-wheeled vehicle tire for running on rough terrain according to claim 6 , wherein
the second middle block comprises two second portions located on both outer sides of the first portion, and
the first portion and the second portions have different heights.
13. The two-wheeled vehicle tire for running on rough terrain according to claim 12 , wherein a maximum height of the first portion is greater than a maximum height of each of the second portions.
14. The two-wheeled vehicle tire for running on rough terrain according to claim 12 , wherein
radially outer surfaces of the second portions respectively have longitudinal straight edges each extending straight in a tire circumferential direction and both located on a tire equator side or alternatively a tread edge side, and
in a plan view of the radially outer surface of the second middle block, the radially outer surface of the first portion comprises a projection that projects outwardly in a block-width direction from respective virtual extensions of the longitudinal straight edges of the radially outer surfaces of the second portions.
15. The two-wheeled vehicle tire for running on rough terrain according to claim 14 , wherein in the plan view, an area of the protrusion is equal to or less than 50% of an entire area of the radially outer surface of the first portion.