We present a kinetic transport model for hot electrons and hot phonons in metallic single-wall carbon nanotubes. The transport model is based on a coupled system of Boltzmann equations of linearly dispersive electrons and optical phonons. An efficient and accurate deterministic numerical scheme is developed to solve the set of kinetic equations. With this numerical tool we study in detail the high-field transport properties of ohmically contacted molecular nanotube wires lying on a substrate. The simulations demonstrate that the optical phonons are strongly driven out of thermal equilibrium. Nonequilibrium optical phonons are found to influence considerably the electron transport in the high-field regime. We observe that the steady-state current at high bias is sensitive to the anharmonic lifetime of the optical phonons and to the phonon group velocities. Comparisons of experimental current-voltage characteristics with the theoretical results obtained with electron-phonon coupling coefficients as predicted by density functional calculations exhibit very good agreement.