Yeah, I just can't believe the notion that a first-line tire manufacturer (such as Bridgestone, Goodyear, Michelin) would send "defects" or "seconds" to certain retailers. That fails on a number of points, all of which I believe are significant:
1) The tire manufacturer stands a huge chance of very poor publicity if any of this is true and reaches the media. Even rumors of it being true likely push some folks away -- away from the tire maker and away from the retailer.
2) Potential lawsuits are always around the corner, wherever you look, and that'd certainly be the case here. Sending tires with known issues is way too much of a liability. Most places don't even sell "scratch and dent" tires (only cosmetic blemishes) because the potential for a lawsuit is too great to risk the chance.
3) You'd have to have a completely separate distribution chain/warehouse system...the "firsts" go here and the "seconds" go over there. I'd think the logistics of that would be way more than it's worth.
4) What about the tires that are specific to certain stores. Examples: the Michelin X Radial at Sam's Club, the Michelin WeatherWise II at Sears, the Bridgestone Dueler RVT at Walmart, etc. If discount retailers only get "seconds", then where do the "firsts" for these tires go? Nobody else sells them!
Now...I would completely buy the notion that lesser tire brands (especially associate brands) may not have the same control over quality that first-line tires enjoy. In addition, this rumor (that warehouse clubs or Walmart) get only "seconds" may come from the fact that older tire models are often sold there. For instance, Sam's Club sells the Bridgestone Potenza G009. That tire has been replaced by the G019 Grid...but Sam's still sells the older version. In addition, it's my understanding that the Turanza LS-T has been generally discontinued at most outlets, but this is a tire that Walmart still sells. The same may become true of the Michelin Symmetry. I don't know how many Michelin or local retailers still carry this tire, but it's very prominently displayed at Walmart and Sam's Club.