The present invention relates to a pneumatic tire suitable for rough terrain, more particularly to a block type tread pattern being capable of displaying good performance in a wide variety of conditions.
A motocross tire of a pneumatic tire designed for rough terrain is usually provided with a block type tread pattern.
For example, the laid-open Japanese patent application JP-A-6-171311 discloses a motorcycle tire having a block pattern designed for muddy terrain. The laid-open Japanese patent application JP-A-5-104911 discloses a motorcycle tire having a block pattern designed for soft terrain such as sands.
In general, a block pattern in which priority is given to traction in soft terrain tends to show insufficient traction for running in hard terrain. Likewise a block pattern in which priority is given to traction in hard terrain tends to show insufficient traction for running in soft terrain. It is difficult for a block pattern tire to display good traction in both soft terrain and hard terrain. Therefore, in a motocross race for example in which a tire undergo wide variety conditions, it is difficult to shorten the lap time if failed in tire selection.
It is therefore, an object of the present invention to provide a pneumatic tire having an improved tread pattern being capable of displaying good performance such as traction under a wide variety of conditions in both soft and hard terrain.
According to the present invention, a pneumatic tire comprises
a tread portion curved so that the maximum section width of the tire lies between tread edges,
the tread portion provided with
central blocks arranged circumferentially of the tire at pitches P1,
axially outer blocks arranged circumferentially of the tire at pitches P3, and
middle blocks arranged circumferentially of the tire at pitches P2 between the central blocks and axially outer blocks, wherein
the pitches P1 are more than the pitches P2 and the central blocks, and the middle blocks are substantially aligned every two or more (number n) pitches P1,
two or more circumferential positions at which the central blocks and the middle blocks are substantially aligned are provided around the tire, and
circumferential positions of the axially outer blocks are between the middle blocks.