Lately I've been rolling with what feels best. I don't want to feel or be aware of any part of my bike. If the tires are rock hard and jarring my wrists, it's not good. If they are soft and I can feel them rolling around under me, it's not good. As far as bunnyhopping goes, I feel like I can hop higher with hard tires since they are absorbing less of my energy. I haven't every checked though--its just a seat-of-the-pants feeling.