I bought some Vittorias packed folded in little boxes; out of the box these tires are "flat", ie. they don't have that C profile. This is a first for me! I can't install them the way I'm accustomed to, ie. by putting a slightly filled inner tube inside the tire and slipping them on the rim together, since the tire has no "inside" that could hold the inner tube. How does one install this kind of tires?