CHAPTER 8: TIRES, TUBES, AND WHEELS
The tires are ideally the only contact your bicycle has with the ground, so be sure and pay attention to them.
The common clincher tire is made up of three parts: a wire bead, a fabric core (sometimes called the last), and a rubber coating on top.
The smaller your contact patch (the area of your tire that contacts the road) the less rolling resistance your tire has. So, as your tire gets wider and wider, it becomes harder and harder to pedal the same distance on the same bicycle. On the flip side, as a tire becomes wider, it also holds more air, which provides more cushion for impacts. ...