The interaction cross-sections of neutron-deficient Ar and Kr isotopes were precisely measured using the fragment separator FRS at relativistic energies. Based on Glauber model analysis, effective root-mean-square matter radii of these nuclei were determined. Using charge radii obtained from isotope-shift measurements, an evolution of proton skins for Ar isotopes is clearly shown. A systematics of the matter radii in the mass region A similar to 70 is also discussed.