Quality ??
They are made by Michelin for Costo, but are they made to costo specs or Michelin specs? They may look the same, but are they the same quality, number of plies, cords, belts and all that other tire crap.
Same reason I dont shop at Les Schwab. Good company, great service, but other than Toyo who as ever heard of the brands they carry. Who actually believes that Z800 Ultra's are the best radial tire ever made.
Personally I pay more and like it when my tires say BFG, Dunlop, Michelin, Pirelli, Goodyear, etc. right there on the side. -- Dunlops on the wifes car, soon to be BFG's on the truck.