Speaking of tires and air...
I once had a friend over years ago, and we got to talking about cars (I then knew alittle about them), and he told me his car shook at speeds over 45mph. In a serious, professional voice, I told him I once had that problem, and then I asked him "when was the last time you changed the air in your tires?"
He was unaware you had to do this, so I made up something to the fact that the air becomes stale over the years, and causes the tires to rotate improperly. I told him I change mine reularly, and sent him to the gass station with a valve stem remover. Needless to say he came back about 20 minutes later, not a happy camper (got 3 tires empty, before the attendant ask wtf are you doing?).
Sorry, this thread reminded me of that. Thought you might get a kick out of it!