That would be the most idiotic law ever created, another ridiculous and unnecessary law that could never be policed. Another stupid law to make criminals out of folks just trying to survive. "Used Tire" does not always mean something five years old and worn down to the nub, a used tire can also be a month old with a couple thousand miles on it.
If you can't buy a good used tire, and you can't afford to buy a new tire, do you know what happens? You continue to drive on your old worn tires until they will no longer hold air. My bet is a law like that would create even more bad tires on the road, not less.
Think about all the accidents each day where cars with good tires are totaled out, damaged beyond repair. Or vehicles with many good parts like tires that develop expensive mechanical problems where fixing the vehicle is not practical. Four tires per car that's likely tens of thousands of tires every day. You can't sell all these good used tires, even though they might be just like new. That means they would get ground up to make asphalt, buried in a landfill or burned for fuel. Sounds like a massive waste of usable resources to me.