i think its more of a drag thing, or just for looks. but if it were to serve a purpose at all it would be more drag. longer swingarm is longer wheelbase, more "weight" for the bike to lift off the ground for wheelie. so instead of that power being wasted lifting the bike up for wheelie, all or most of it is used in propelling the bike forward due to that added weight. its all physics. and then the larger tire, would be for a larger contact patch to transfer the power to teh ground.