Tire Purchase

In the past 20 some years, I purchased whatever tires my mechanic would recommend. Recently I deviated from the norm, and purchased tires based on a $70 savings advertisement on four Michelin tires at Costco. I've never had Michelins before and have always heard they were reputable wheels. Well, Costco fills their tires with nitrogen air, none of that regular air for them. They don't tell you if your brakes are near death, what your rods are doing, whether you need a wheel alignment or what the new ride will be like with the new wheels. The brakes died soon after installation of the tires. All of my tires have had to be filled with nitrogen air multiple times since late November. One wheel has lost up to 15 pounds of pressure in a week's time. Today I had these Michelin tires rotated and supposedly the errant tire fixed. The ride is still kind of rough. Now why would Michelin tires be so crappy? Were they made in China and that's why Costco could sell them for cheaper prices?I almost never have had trouble with my previous tire purchases other than the occasional low pressure and accidental nail in a tire. This will be my last experiment with either a) Michelin tires, b) Costco installed tires or c) both a and b.