30 years ago, Washington department of transportation tried experiment of ground up tires being used in the making of Asphalt. The highway held up fine until the runber content spontaneously combusted. It smoldered for several years until they removed that section of the freeway outside of Spokane
Yup, that's the fix, although I would think the risk of spontaneous combustion can be mitigated by formulation. It doesn't happen so often that the benefits aren't worth the hazard. Further, it turns out that gas mileage on rubberized roads should be a bit better. Economically, that would be a win.
I don't know a better way to handle the problem.
I believe it was the steel plies that caused the issue during oxidation. It is no easy task separating the belts from the vulcanized rubber. Best solution... Start filling up the San Francisco Bay with old windmill blades and old tires. Let them enjoy the monument of trash to remind them they are saving the planet.