First attempt to replace the tube on the rear wheel failed. After mounting the tire+tube, I pumped it up but didn't even reach 100psi before I heard a loud pop. Blast. Tube failed.
Bought another tube from a different place, tried mounting it. As I pumped it up, I noticed a bulge coming through the sidewall of the tire like a rubber hernia. Oh #$%^@, the sidewall has lost integrity.
While I contemplated buying 1 or 2 new tires, I thought, why go through all this, when all I want to do (for now) is just spin on my trainer. So tonight, I rotated tire+tube from front wheel onto the rear wheel, mounted it, and inflated.