I recently completed some updated research on 15" ST radial tires 295/50-15s & 245/60-15s over the past few months, and made a few phone calls to confirm bits of information I picked up around product sources and relationships between Avon Tire (Co.), Cooper Tires, Mickey Thompson STs, Cooper Cobras, Mastercraft Tires, Dick Cepek tires, and a few others. Its all public info, you just have to piece it together to see what I'm referring to.
With regard to the street ST radials, a few might be surprised to learn how
some parent companies actually manufacture tires for other brands/labels made right in the exact same factories, with the exact same materials and compounds, just using different tread designs and names on the sidewalls!
I picked up a set of generics myself recently just to try it and see, and confirmed its the same same thing (functionally) as another brand or size that may be sold out because people are familiar with one name vs. another. What's in a name any more...