A pneumatic motorcycle tire includes a tread portion provided in each half tread region with a unit pattern repeatedly arranged in the tire circumferential direction to form a unidirectional tread pattern. The unit pattern includes a first groove extending axially outwardly from a vicinity of the tire equator, while inclining to the opposite direction to the intended tire rotational direction; a second groove disposed on the heel-side in the tire rotational direction of the first groove and extending along the first groove; a third groove disposed on the heel-side of the second groove and extending along the second groove; a fourth groove disposed on the heel-side of the third groove and extending along the third groove; and a narrow groove extending from an axially inner end of the first groove to an axially inner end of the fourth groove, while inclining to the intended tire rotational direction.

Each central land portion row (9) has at least one first narrow groove (21) that is open to the central main groove (5) and has a length a in a tire width direction and an angle to the tire width direction, and at least one second narrow groove (23) has a length b in the tire width direction and an angle to the tire width direction. Each outer land portion row (11) located on an outer side of a different one of the outer main grooves (7) in the tire width direction has at least one third narrow groove (25) that is open to the outer main groove (7) and has a length c in the tire width direction and an angle to the tire width direction. In the tire, a<b, and <<.

A pneumatic tire includes a tread portion provided with a shoulder main groove and a crown main groove to form a middle land portion therebetween. The middle land portion is provided with a first middle lug groove including a first groove wall and a second groove wall, wherein the first groove wall includes a protrusion protruding toward the second groove wall on the side of the shoulder main groove. The protrusion includes a front wall located so as to form a sipe portion between the front wall and the second groove wall, a top wall, a first lateral wall located axially outward of the front wall and a second lateral wall located axially inward of the front wall. The front wall is configured to a triangular shape.

Disclosed herein is a tread for a tire. The tread includes at least one elongate block of rubbery material of width W and length L with L>>W. This elongate block extends in a circumferential direction (X) when the tread is mounted on the tire. The elongate block includes a contact surface intended to come into contact with the ground and a first lateral wall and a second lateral wall delimiting this contact surface. The elongate block includes a plurality of sipes opening onto the contact surface of the elongate block, with each sine extending in an oblique direction opening onto the first lateral wall and onto the second lateral wall. The sipes are distributed over the contact surface of the block in such a way that when one sipe reaches the second lateral wall another sipe starts out from the first lateral wall, at a same circumferential level (N) on the elongate block. With the sipes delimiting sub-blocks in the elongate block, at least two of these sub-blocks are configured differently in the tread.

In a pneumatic tire 10 according to the present invention, as an average block edge component Dball is defined by an average of edge components of all blocks against a tire circumferential direction, an average sipe edge component Dsall is defined by an average of edge components of all sipes against the tire circumferential direction and an average block rigidity G is defined by an average of the rigidity of all blocks, a relation of 2.20 (mm).sup.3/N?(Dball/Dsall)/G?4.00 (mm).sup.3/N is fulfilled.

A rigidity measurement device of a tread ring comprises a support jig for detachably holding a tread ring unit. The support jig has an open part for deformably exposing a measurement area, which is one portion of the tread ring, to the exterior, and a restraining part for essentially non-deformably restraining a non-measurement area, which is an area other than the measurement area of the tread ring. The restraining part inhibits deformation of the non-measurement area, whereby stress is no longer generated in the non-measurement area and the rigidity of the measurement area alone can be measured.

A pneumatic tire includes: a plurality of land portions; and in at least one land portion of the plurality of land portions, a sipe extending in the tread width direction, of which ends open at the circumferential grooves or the tread ends. The sipe has at least one bent portion extending continuously in the extending direction of the sipe from one of the end regions of the sipe to the other end region in the depth direction of the sipe. The at least one bent portion is located on the outer side in the tire radial direction in the center region than in the end regions.

The pneumatic tire includes lateral communication grooves, and circumferential grooves. In a tread portion shoulder region, the lateral communication groove is disposed between a pair of V-shaped crossing grooves adjacent in a tire circumferential direction and extends from a tread edge portion toward a tire equatorial plane. In a tread portion center region, the lateral communication groove communicates with the V-shaped crossing groove located to a projecting side of the V-shape of the pair of V-shaped crossing grooves and does not communicate with the other V-shaped crossing groove of the pair. The circumferential grooves are disposed in the tread portion shoulder region and extend in the tire circumferential direction, communicating with the V-shaped crossing grooves and the lateral communication grooves.

A tire tread is provided with a crown main groove, and outboard and inboard shoulder main grooves to divide the tread portion into an outboard crown land portion, an inboard crown land portion, an outboard shoulder land portion and an inboard shoulder land portion. The inboard shoulder land portion is provided with inboard shoulder lateral grooves connecting an inboard tread edge and the inboard shoulder main groove. The outboard shoulder land portion is provided with outboard shoulder lateral grooves extending axially inwardly from an outboard tread edge and terminating within the outboard shoulder land portion. The inboard crown land portion is provided with inboard crown lateral grooves extending from the inboard shoulder main groove and terminating within the inboard crown land portion. The outboard crown land portion is provided with outboard crown lateral grooves extending from the crown main groove and terminating within the outboard crown land portion.

A pneumatic tire includes a tread portion being provided with a plurality of inclined main grooves extending beyond a tire equator from one of a first tread edge and a second tread edge and terminating without reaching the other one of the first tread edge and the second tread edge. Each of the inclined main grooves includes an outer portion and an inner portion. The outer portion extends from the first tread edge or the second tread edge without reaching the tire equator while increasing an angle relative to an axial direction of the tire. The inner portion is connected to the outer portion and traverses the tire equator at a smaller angle relative to the axial direction of the tire than the angle of the outer portion.