Back in the day when it was Good Year, Firestone, General, Continental, Michelin and a very few other players, compacency in quality was rather rampant - the latest (that I know of) being the Firestone debacle with Ford's Explorers. Firestone, thankfully, is part of Bridgestone, even though Firesteone tires are what I consider a marginally acceptable substitute for driving on the wheel rim.
Considering that Uniroyal and B.F. Goodrich (and probably others) are owned by Michelin, I suspect that regardless of what plant in what country the tires are made, Michelin 'eyes' will be watching over the entire process. In this age of global manufacturing, marketing, and distribution, I doubt that no major company worth its salt will knowingly let its quality go into the tank.
Then again, we had the GM cars of the 70s and 80s, so I guess anything is possible.