I've looked into euthanasia, and it seems that any inert
gas -- helium, nitrogen, argon -- will work about the same.
Simply drift off to sleep, painlessly, and no feeling of
suffocation since these gasses don't combine with
hemoglobin and form carbon dioxide, triggering the
sensors in the carotid artery..... Simply a little hose
to a plastic bag over one's head...... a good plan to
have in one's back pocket.....
Regarding the original poster about tires... I'd fill them
full of fart gas so that people wouldn't park so close
and dogs wouldn't pee on the tires.... Harbor Freight
sells a transfer pump that one can insert to pump out
the farts into a plastic bag connected to a compressor
input, and re-fill the tires from there. Use caution, tho,
and don't turn on the compressor pump with the transfer
pump hose still inserted.... you might lose your tongue
and your ears....