Which will just mean that people stop tossing them places they're easy to see and instead throw them into bodies of water or holes in the ground.

You wanna stop people littering tires, make it easy/cheap to get rid of them the right way. Pretty much all the problems in the municipal solid waste industry trace back to some shortsighted "environmentalists" trying to financially punish people for not behaving how they prefer, distorting the market and thereby keeping various types of waste from getting into the hands of the relevant disposal industries.