I don't see why you couldn't open your C4D model in C4D, pose it, and export as wavefront object. Open Poser, file/import/wavefront object, select your C4D export and import into Poser as a static prop. Of course I imagine that scaling (the model will be HUGE in poser more than likely) and materials in Poser will need attending to, welded or not the file should still have it's material zone assignations, and perhaps it's groups(?)... depends on your setting or prefs upon export from C4D.

_keep in mind that your exported .obj from C4D is going to be a static prop in poser and so will no longer be posable as it was. For vehicles and mechanical objects it's best to have all of the moveable parts as separate objects/children parented to a main object or in a hierarchy and then movement manipulations done via translations and rotations of the comprising objects... Rather than trying such with morphs, which may result in peculiar and unpredictable transformations.