Are you spreading the tire at all? I've found fatbike tires to be some of the easiest to mount and seat. So far I've mounted hüsker du's, jumbo jims, bud, lou and al mighty's with a track pump. My rims are MOBD with a double layer of full wide tape and one layer of somewhat narrower tape to keep the main tape from peeling off so nothing special there. Also the bud was defective with a large hop and still mounted no problem.