I don't think these would be suitable for the bus. Home speakers are 8 ohms, and car speakers are 4 ohms, so there would need to be a converter involved. But the bigger issue is that the tolerances are much tighter on a home speaker, so the vibrations that would occur while in transit wouldn't be good for the voice coil.
You're better off looking at speakers from a place that specializes in car audio. Kromer Radio downtown would be a good place to start.