The hyperfine structure splittings (hfs) and isotope shifts (IS) in the atomic transitions 5s 2 5p 2 ~So ~5s 2 5p6s 1.3p~ have been measured for the radioactive isotopes lo8 ~l~Sn and all stable ones. The tin isotopes were prepared as fast atomic beams for collinear laser spectroscopy at the GSI online mass separator following a fusion reaction. Nuclear spins, magnetic dipole, electric quadrupole moments and changes in mean square charge radii have been determined. In a~ the spin I=5/2 was measured for the nuclear ground state (Tt/2= 18 min) in contradiction to the literature value. The mean square charge radii show a parabolic behaviour with a maximum at N = 66. This is interpreted by collective effects, which are considerably stronger than accounted for by the B(E2)values.