I have a tire that goes flat every few days. I thought neighborhood kids were messing with me so I inflated it to 35psi and put it in the trunk. Two days later it's at 18psi. I don't see any punctures on the tread or sidewall. There might be a patch on the inside that's failing. But first I'd like to replace the valve.

1) Can I swap valve innards with the spare or does removing the innards ruin them? I've done this with bicycle valves.

2) Can I replace the entire valve with basic tools? I have a tool to pull and seat a new valve but can I press the bead off the rim without damaging the tire or myself? I'm 99.44% sure my compressor will [re]seat the bead.

Thanks,
Sixto
MB-less