in less than 2 months, four flats.
so new inner tubes, outer (between tube and tire) and inner (between tube and rim) liners.
a day later: pop.... one of my new tubes blew open, a defective tube it seems.
kevlar--you know the stuff they make bullet-proof vests out of? they also make tires--that may be my next purchase; in the meantime I've borrowed one of my wife's bikes.