used tires good or bad idea??

These used tires were on a local ambulance service and there maint. schedule is as stringent as UPS,, every day tire and oil inspections, so I doubt they have ever been run low. Here in Milton Fl where I live we have very good roads no pot holes or rough surface. One thing that convenience me to go with used tires is that these tires have no uneven wear or checking so that tells me the rotation and balance is part of their maint, program they actually ride as smooth as new tires. In my opinion the thickness of the thread has nothing to do with a blow out,, its the condition of the inner part of the tire is where the tire gets it strength so a tire that has a dot code of 0613 ((as mine do))is as stable as a tire with only 10,000 miles on it with a code of 0613. If I change these tires every two years and each time they have a one year code date on them that means that every 2 years I will have a fresh set of tires ((with some wear agreed)) but I will have only spent 480.00 over a 6 year period ,or I cld spend 1000.00 dollars for a new set of tires go around the block 3 times and will be running a USED set of tires for 6 years. Makes sense to me.