Half-lives of β + decay and electron capture are studied in some selected superheavy nuclei produced in hot-fusion reactions, namely, 290 Fl, 293 Mc, 294 Lv, and 295 Ts. The nuclear structure is described microscopically from deformed self-consistent Skyrme Hartree-Fock mean-field calculations that include pairing correlations. The sensitivity of the half-lives to deformation and to the QEC energies, which are still not determined experimentally, are studied. The results are compared with phenomenological α-decay half-lives, showing that the latter decay mode is dominant in this mass region.