I use either the rolled method (Diablo Scott) or just fold them, depending on
the tires, some of mine just don't roll right.
I always keep spares in a tubular bag, the Jandd one as shown above. I carry
one spare and knock wood, haven't needed to use it. I do rotate out the spare
every few months. I will put the recently removed tire on a spare rim for stretching
and replace the glue when I fold it and put it back into use.