They call the extra tax a "Disposal" fee for getting rid of the old tires here in Illinois... I believe you have to pay it even if you want to keep your old tires... So much for the disposal thing...
ya. charging for disposal is optional here. i pay a guy to come and take my tires. some of them. some, i take to the local hazmat drop off. the balk at it, but they take em.
i also have the option of letting you take your own tires back when i put the new ones on...and you can put them out in your trash. in nj, most townships will take 2 per week.