Actually tires on bikes are replaced more often because of cuts and damage than because they wear out. If you ride in a benign area then in theory you could rotate your tires and get a few thousand more miles by doing so. In practice it rarely works out.
I stopped doing it mostly because I thought for awhile 20mm tires were a good idea, ended up with a bunch and I use them on the front at least until I run out, down to one now. 23mm are my tire size of choice. Also spend about half my time on a bent. Stev