A pneumatic tire for vehicle wheels which includes a tread, an annular reinforcing structure, two sidewalls, two beads and having a plurality of slits in the inner and outer surfaces of the sidewalls which may come into contact with other surfaces of the tire or wheel in consequence of the deflation of the tire. The slits are prevailingly oriented in a direction perpendicular to the direction in which takes place the relative slidings between the contact surfaces. Each sidewall has a cross-section along meridian planes of such a shape that its section midline in the meridian plane has a convexity directed towards the tire inside and a flexional rigidity in the meridian plane such that the convexity does not change in direction even under normal operating inflation pressure. The flexional rigidity has a value which is smaller than that of the analogous rigidity of the remaining portions of the sidewall.