Pneumatic tire
A pneumatic tire has a tread having adjacent rib-shaped land portions ( 4 ) with circumferential grooves ( 3 ) therebetween. Annular elongate projection portions ( 5, 5 ) project toward each other from adjacent rib-shaped land portions ( 4 ). The elongate projection portions ( 5, 5 ) confronting each other are disposed with a spacing therebetween such that their mutually confronting tip surfaces ( 5 s, 5 s ) make contact with each other due to elastic deformation of the rib-shaped land portions ( 4, 4 ) at the time of grounding of the tire. An inside groove space ( 6 ) is formed on a radially inner side of the confronting elongate projection portions ( 5, 5 ) and an outside groove space ( 7 ) is formed on a radially outer side of the elongate projection portions ( 5, 5 ). The tip surfaces ( 5 s ) of the elongate projection portions ( 5 ) are formed with a plurality of communication recesses ( 9 ) providing communication between the inside and outside groove spaces ( 6, 7 ). The communication recesses ( 9 ) are formed at intervals in a tread circumferential direction. It is thus possible to enhance rigidity of the rib-shaped land portions over the whole tread at the time of grounding of the tire, thereby to suppress elastic deformation of the rib-shaped land portions and to reduce rolling resistance, while securing a draining property attributable to the circumferential grooves.
1. A pneumatic tire formed with a plurality of rib-shaped land portions separated by circumferential grooves extending in a tread circumferential direction, comprising:
elongate projection portions projecting toward each other from the rib-shaped land portions adjacent to each other with one of the circumferential grooves therebetween, the elongate projection portions being formed in an annular shape extending in the tread circumferential direction;
the elongate projection portions confronting each other are disposed with a spacing therebetween such that mutually confronting tip surfaces of the elongate projection portions make contact with each other through elastic deformation of the rib-shaped land portions at a time of grounding of the tire;
the circumferential groove has formed therein with an inside groove space on a radially inner side of the confronting elongate projection portions, and with an outside groove space on a radially outer side of the confronting elongate projection portions;
the confronting elongate projection portions have confronting tip surfaces thereof formed with a plurality of communication recesses providing communication between the outside groove space and the inside groove space, the communication recesses being formed at intervals in the tread circumferential direction;
the elongate projection portions projecting from the rib-shaped land portions are formed to extend to the tip surfaces, respectively, in a form of a conical surface extending radially inward from tread surfaces on the rib-shaped land portions; and
the elongate projection portions in the circumferential grooves on outermost areas in a tread width direction have a smaller inclination angle of the conical surface than an inclination angle of the conical surface of the elongate projection portions in the circumferential grooves in a central area in the tread width direction; the inclination angles being inclined with respect to the tread surfaces.
2. The pneumatic tire according to claim 1 , wherein the communication recesses are formed rectilinearly while being oriented in the radial direction, respectively.
3. The pneumatic tire according to claim 1 , wherein the mutually confronting tip surfaces of the confronting elongate projection portions are formed with the communication recesses in a mutually opposed manner.
4. The pneumatic tire according to claim 1 , wherein the circumferential groove located in a central area with respect to the tread width direction has a greater number of the communication recesses formed in the elongate projection portions than the circumferential grooves provided in outermost areas with respect to the tread width direction.
5. A pneumatic tire formed with a plurality of rib-shaped land portions separated by circumferential grooves extending in a tread circumferential direction, comprising:
elongate projection portions project toward each other from the rib-shaped land portions adjacent to each other with one of the circumferential grooves therebetween, the elongate projection portions being formed in an annular shape extending in the tread circumferential direction;
the elongate projection portions confronting each other are disposed with a spacing therebetween such that mutually confronting tip surfaces of the elongate projection portions make contact with each other through elastic deformation of the rib-shaped land portions at a time of grounding of the tire;
the circumferential groove has formed therein with an inside groove space on a radially inner side of the confronting elongate projection portions, and with an outside groove space on a radially outer side of the confronting elongate projection portions;
the confronting elongate projection portions have confronting tip surfaces thereof formed with a plurality of communication recesses providing communication between the outside groove space and the inside groove space, the communication recesses being formed at intervals in the tread circumferential direction; and
each of the communication recesses is formed rectilinearly while being oriented in a direction inclined relative to a radial direction, in such a manner that each communication recess has an inside opening communicating with the inside groove space and an outside opening communicating with the outside groove space, the outside opening being located at a position displaced relative to the inside opening in a tire rotational direction at a time of forward travel of a vehicle.