Hate to admit how many miles I put on Used Tires. When I was young & poorer, I would pick Tires out of used piles behind shops. It seems many more affluent riders would change up at the mere mention of a latest zippy tire, leaving ME some excellent nearly new tire finds. I always took care to spot flaws cupping bulges etc. Even rode some K70's with sidewall cracks at ridiculous speeds. I survived, doing my own mounting & bubble balancing.
Now that I am 67, I buy New K70's, & have them professionally mounted. I can get both wheels off my bikes at the same time, using my Harbor Freight Big Red Platform Lift to it's best advantage, & save a little $$ there.