We report microscopic calculations of the thermal conductivity, diffusion constant and thermal diffusion constant for classical solutions of 3 He in superfluid 4 He at temperatures T < ∼ 0.6 K, where phonons are the dominant excitations of the 4 He. We focus on solutions with 3 He concentrations < ∼ 10 −3 , for which the main scattering mechanisms are phonon-phonon scattering via 3-phonon Landau and Beliaev processes, which maintain the phonons in a drifting equilibrium distribution, and the slower process of 3 He-phonon scattering, which is crucial for determining the 3 He distribution function in transport. We use the fact that the relative changes in the energy and momentum of a 3 He atom in a collision with a phonon are small to derive a Fokker-Planck equation for the 3 He distribution function, which we show has an analytical solution in terms of Sonine polynomials. We also calculate the corrections to the Fokker-Planck results for the transport coefficients.