Bob, I know what you say is correct. I spent a lot of career time associated with tire rubber tech service folks and picked up that same wisdom there. But does that mean everyone's two color tires are made that way and also not a good idea. Or are some two compound constructions better designed, formulated, and built. Like perhaps just a think color overlay (non-structural, just decorative). White wall auto tires, for example, never caused much of a problem during their hey day, and that was when tire compound formulation was much less sophisticated. Of course they were, like the two tone bike tires today, totally unnecessary, but they still worked pretty well. I have never heard of issues with Michelin or Conti two tone tires. Thanks for the input. - Robert