Contact your local Sam's club, or Costco. They literally charge customers for disposal and pay someone else to haul them away. They would probably give you four old crappy ones if you asked, especially if you ask in person
Guys - Thanks for the tips, but . . . due to stated "liability" concerns, no retail outlets (Costco/Walmart etc.) will sell me used tires. I have asked in person. Also - the car will be worth much more if it has wheels and tires and can be towed. I've checked. Still need those crappy 16" tires!