Here is a use for those old tires....which normally get tossed in the garbage. Save those sidewalls! A sliced open sidewall while out riding trails is never a good thing. Either you are prepared for it....or not. And if you are not.....the long walk ensues.....followed my a lot of swearing. Those old sidewalls can actually serve as an emergency tire boot!
Take those old worn out tires and cut out the sidewalls to custom lengths to use as a tire boot. They are small, weigh nothing, and fit in a seat bag or hydration pack very easily! Plus, it is a ton cheaper than buying pre-made sidewall repair kits.
BAM! One tire boot....that I never hope I have to use. I carried 4 assorted sizes of cut sidewalls off old tires on CTR for those 'just in case' moments.