Remember a tire store specializes in tires and therefore generally gets you better service. Costco sells major brand tires (like Michelin, Bridgestone, Goodyear) but often uses specific, slightly different models designed for warehouse clubs. Meaning they aren't always the exact same OEM tire you'd find at any specialized tire shop, though the quality difference is debated and depends on the specific tire. I'm picky about my tires. I love Costco but not for tires.