According to the EPA, burning tires to make cement is better than landfilling them. 2500 degree fire leaves little residual ash.
Tires also burn cleaner than most coal.
The exception is on earth day when individual tires are burned on front lawns.
No doubt. Better, on average, than piling them yugely up in mosquito sanctuaries.
Still, there has to be some nasty compounds in the exhaust gas.
[SO2 comes to mind as a big one]