  We investigate linear and nonlinear transport in interacting single wall
carbon nanotubes (SWCNTs) that are weakly attached to ferromagnetic leads. For
the reduced density matrix of a SWCNT quantum dot, equations of motion which
account for an arbitrarily vectored polarisation of the contacts are derived.
We focus on the case of large diameter nanotubes where exchange effects
emerging from short-ranged processes can be excluded and the four-electron
periodicity at low bias can be observed. This yields in principle four distinct
resonant tunnelling regimes, but due to symmetries in the involved
groundstates, each two possess a mirror-symmetry. With a non-collinear
configuration, we recover at the 4N <-> 4N+1 / 4N+3 <-> 4N resonances the
analytical results known for the angular dependence of the conductance of a
single level quantum dot or a metallic island. The two other cases are treated
numerically and show on the first glance similar, yet not analytically
describable dependences. In the nonlinear regime, negative differential
conductance features occur for non-collinear lead magnetisations.
