Motorbikes don't have quite the same weight concerns so more material is easy to add without putting much strain on decently powered engine rather than some tired legs. Tread pattern is ment to make less difference to rolling resistance than you'd imagine, sounds and feels rough on a road though. Casing and compound is where it's at, a load of extra rubber all over might slow things down more then some extra knobs.
Motorbikes don't have quite the same weight concerns so more material is easy to add without putting much strain on decently powered engine rather than some tired legs. Tread pattern is ment to make less difference to rolling resistance than you'd imagine, sounds and feels rough on a road though. Casing and compound is where it's at, a load of extra rubber all over might slow things down more then some extra knobs.