Thanks, that seems sensible. In terms of the strength of the tyre (resisting the pressure from the inner tube) my hunch was that the carcass does the heavy lifting and it's too much of a coincidence that the crack is at the colour boundary. Presumably the risk you're referring to is of the carcass also being old and brittle rather than a cascade failure of the rubber then the carcass.
Thanks, that seems sensible. In terms of the strength of the tyre (resisting the pressure from the inner tube) my hunch was that the carcass does the heavy lifting and it's too much of a coincidence that the crack is at the colour boundary. Presumably the risk you're referring to is of the carcass also being old and brittle rather than a cascade failure of the rubber then the carcass.