[Formerly Steve Wilkinson]

Those areas near off-ramps, especially if you drive a bit off the regularly traveled pavement, are filled with all sorts of junk that's flung there by passing cars--pieces of metal, big nuts and bolts, glass.

The most dangerous area of all, in terms of getting punctures, is the vee-shaped area between the off-ramp and the highway. It's a minefield for tires. Often when people just miss their exit, they pull into that area, and its surprising--well, no it isn't--how often they get flats from running over the junk that inevitably collects there.

I don't carry a spare, since I have a fuel cell up front. My tires all contain Ride-On, which is _not_ the common flat-fixer slime. Go to their website, which as I remember is rideon.com.