Panto needs one for the back but the rest of my ten would be spares.
Actually second hand ones could well be a waste of money, they may only have one more tug in them, but if no new ones are available what do you do?
Well when I looked into getting a new one when I first got PTP fiat had none and neither did anywhere else I tried. I had a brief thought of using my good one as a template and using an old car tyre to make one out of. Thankfully I got one second hand though.