A kinetic model is presented for the generation of proton heat flux tails and double beams by Coulomb collisions in the solar wind. The combined action of the large-scale interplanetary magnetic field (mirror effect) and of the collisional scattering (runaway) is shown to be able to produce variously skewed velocity distributions. All intermediate cases between the exospheric and isotropic adiabatic expansion can be simulated as a function of the collisionality of the plasma. Good qualitative agreement is achieved between in situ measurements and model results in the collisional domains of the solar wind. ¿ American Geophysical Union 1987