Dear mid-60s Buick owners with other daily-drivers,
One has to be a bit cautious when Costco claims to have a deal on anything including tires. Last year, they had some Michelin deals on very exotic tires that didn't seem worth the extra money. However, this month they $70 off a purchase of a set of 4 Michelin tires including the Defender T&H. The following link might get you to the sale after you select a local tire center - it worked for me.
https://www.costco.com/WarehouseTiresLocatorView?storeId=10301&catalogId=10701&langId=-1When I did a price check on a set of 4 tires for your 2000 Buick Century it came in at about $420. In contrast, our local Big-O Tire center wanted a bit over $600 for the very same tires. That's a savings of $180 or 30%!! The order for the tires has to be placed before Sunday, April 29. However, the tires need to be shipped to your local Costco, you the installation probably couldn't be done before the second or third week of May.
Bargain hunters have at it! 
Cheers, Edouard
P.S. Those of you pondering if a Costco membership is worth it . . . . well that's another incentive!
