interesting thing about those tire treads,, we often call them "gators"
they are from new tires
not recaps. there is a very low recap failure rate on comercial truck tires
, most of what you see are trailer tires that went flat and the driver can't feel it. they heat up and fall
some areas you will see a lot of them,,,other places you never see them. it mostly reflectsthe amount of truck traffic on a given road.