A pneumatic tire comprising: a tread portion having an installing direction to a vehicle to have an outboard tread edge (To) and an inboard tread edge (Ti); the tread portion being provided with a circumferentially and continuously extending inboard shoulder main groove on a nearest side of the inboard tread edge (Ti), the inboard shoulder main groove extending in a straight shape, characterised in that the tread portion is further provided with a circumferentially and continuously extending zigzag outboard shoulder main groove on a nearest side of the outboard tread edge (To), a circumferentially and continuously extending outboard middle main groove between the outboard shoulder main groove and a tire equator, a plurality of outboard shoulder lateral grooves connecting the outboard tread edge (To) and the outboard shoulder main groove and a plurality of outboard middle lateral grooves connecting the outboard middle main groove and the outboard shoulder main groove, thereby the tread portion comprising an outboard shoulder land portion comprising a circumferentially arranged outboard shoulder blocks defined by the outboard shoulder main groove, the outboard tread edge (To) and the outboard shoulder lateral grooves and an outboard middle land portion comprising circumferentially arranged outboard middle blocks defined by the outboard shoulder main groove, the outboard middle main groove and the outboard middle lateral grooves; the outboard shoulder blocks provided with outboard shoulder lug grooves extending axially outwardly from the outboard shoulder main groove and terminating within the outboard shoulder blocks; the outboard middle blocks provided with outboard middle lug grooves extending axially inwardly from the outboard shoulder main groove and terminating within the outboard middle blocks; the outboard shoulder lateral grooves being continuous to the outboard middle lug grooves smoothly through the outboard shoulder main groove; and the outboard middle lateral grooves being continuous to the outboard shoulder lug grooves smoothly through the outboard shoulder main groove, the outboard shoulder lateral grooves are in communication with outer zigzag vertexes, which protrude axially outwardly, of the outboard shoulder main groove, and the outboard middle lateral grooves are in communication with inner zigzag vertexes, which protrude axially inwardly, of the outboard shoulder main groove. a tread portion having an installing direction to a vehicle to have an outboard tread edge (To) and an inboard tread edge (Ti); the tread portion being provided with a circumferentially and continuously extending inboard shoulder main groove on a nearest side of the inboard tread edge (Ti), the inboard shoulder main groove extending in a straight shape, characterised in that the tread portion is further provided with a circumferentially and continuously extending zigzag outboard shoulder main groove on a nearest side of the outboard tread edge (To), a circumferentially and continuously extending outboard middle main groove between the outboard shoulder main groove and a tire equator, a plurality of outboard shoulder lateral grooves connecting the outboard tread edge (To) and the outboard shoulder main groove and a plurality of outboard middle lateral grooves connecting the outboard middle main groove and the outboard shoulder main groove, thereby the tread portion comprising an outboard shoulder land portion comprising a circumferentially arranged outboard shoulder blocks defined by the outboard shoulder main groove, the outboard tread edge (To) and the outboard shoulder lateral grooves and an outboard middle land portion comprising circumferentially arranged outboard middle blocks defined by the outboard shoulder main groove, the outboard middle main groove and the outboard middle lateral grooves; the outboard shoulder blocks provided with outboard shoulder lug grooves extending axially outwardly from the outboard shoulder main groove and terminating within the outboard shoulder blocks; the outboard middle blocks provided with outboard middle lug grooves extending axially inwardly from the outboard shoulder main groove and terminating within the outboard middle blocks; the outboard shoulder lateral grooves being continuous to the outboard middle lug grooves smoothly through the outboard shoulder main groove; and the outboard middle lateral grooves being continuous to the outboard shoulder lug grooves smoothly through the outboard shoulder main groove, the outboard shoulder lateral grooves are in communication with outer zigzag vertexes, which protrude axially outwardly, of the outboard shoulder main groove, and the outboard middle lateral grooves are in communication with inner zigzag vertexes, which protrude axially inwardly, of the outboard shoulder main groove.