A motor car tire having a tread includes a central portion situated on either side of an equatorial plane and two shoulder portions. The central portion is separated from the shoulder portions of the tread by two circumferential grooves and has at least one circumferential rib situated between a first and a second circumferential groove. The tread has a solid/void ratio of less than 0.28. The circumferential rib includes transverse grooves which extend over at least 50% of its width. The transverse grooves include at least one curvilinear section, have a width less than that of the circumferential grooves and at least one of the circumferential grooves including the circumferential rib has at least one side wall defining an undulating profile.