A pneumatic tyre (100) comprising a carcass structure and a tread disposed in a radially outer position with respect to the carcass structure. The tread has an inner tread and a plurality of spaced lugs (101) outwardly projecting from the inner tread. The spaced lugs extend in a transverse direction from a central portion towards shoulder portions of the tread and a portion of said inner tread comprised between a first and a second lug, circumferentially consecutive, has at least a first axially- inner surface (102a) and a second axially- outer surface (102b). The second axially- outer surface is disposed at least partially at a different radial height with respect to the first axially- inner surface. The second axially- outer surface is positioned in accordance with different radial heights in such a way as to have a minimum radial height towards the second lug and a maximum radial height towards the first lug.