hey i dont know if this will help but last time i went out i took my stockos and changed from my 18s while i was there. i just left my 18's with the jack under a sheet i put in my car so not to dirty the seats and left them on the grass around other parked cars and people. I was worried first and kept checking up on them but i quickly relised they were fine. Although now ive posted this on the net it might be a different story, nobody get any ideas.... lol