If you had a front wheel drive or rear wheel drive (instead of all wheel drive), then you would only have to match the tread depth on the two tires on the drive axle.
For example, if Ruby Sue was front wheel drive (instead of AWD), you could move you existing rear wheels and tires onto the front (they have the same tread depth), move your good front wheel and tire to the rear, and replace your bad tire with a new one, and put it on the rear on the other side.