Parameters are accessed with C4DAtom::GetParameter()/ C4DAtom::SetParameter(). See page_maxonapi_getting_started_foundations_cinema_parameters.
Parameter: Outer Radius
PRIM_TUBE_ORAD
Parameter: Inner Radius
PRIM_TUBE_IRAD
Parameter: Rotation Segments
PRIM_TUBE_SEG
Parameter: Cap Segments
PRIM_TUBE_CSUB
Parameter: Height
PRIM_TUBE_HEIGHT
Parameter: Height Segments
PRIM_TUBE_HSUB
Parameter: Fillet
PRIM_TUBE_FILLET
Parameter: Fillet Segments
PRIM_TUBE_FSUB
Parameter: Fillet Radius
PRIM_TUBE_FILLET_RADIUS
Parameter: Switch to Updated Tube
PRIM_TUBE_SWITCH_TO_UPDATED