I'm a former Wally World employee and here's how tires work. "Seconds" cannot be sold in the United States, they either comply with DOT regs or they don't.
The manufacturer makes millions of tires, they go to wholesaling warehouses where they sit for months and sometimes years. As it gets unfeasable to make money off selling smaller lots these wholesalers will sell large lots to on-line resalers or discount places like Wal-Mart.
The tires that the on-line sellers and Wally world have may have sat in a warehouse for years undergoing several "heat cold" cycles. These cycles tend to break down the viability of the vulcanized rubber compounds by leaching out the plastisizers used to manufacture them. Would you mount a tire on your bike that had sat in your garage for seven years? Not me! EVERY time I buy tires I check the manufacturing codes on the actual tires I'm getting and make the dealer show me the code book so I know when my tires were manufactured. I WILL NOT use a tire manufactured more than two years prior to mounting. Since you Standard and Classic riders pay so much for bike tires or use tire not intended for your application, it behooves you to make what you ARE buying is the best you can get for your money.
I hope I helped
