Anything that was created from hydrocarbons (tires, plastic computer cases, plastic drink containers, plastic cups, plastic bags, etc etc) can be turned back into fuels ... the challenge is separating out the types of fuels (you get lighter and heavier fuels after the pyrolysis) and the 'other stuff' that comes with the process. Yes, the fuel is 'clean' due to the distillation process, but it sounds like there can be other chemical 'nasties' in the fuel.
Check out
How to turn plastic waste into diesel fuel cheaply for an interesting discussion...