They used the only working tiger tank in the world, pulled it out of the museum just for this movie. They had the real tanks for 95% of the scenes, and built replicas specifically for when the tanks explode or get knocked out on screen. They made a replica Tiger and replica Shermans to destroy. They made replicas for destroying tanks on-screen; that has nothing to do with Tiger 131 being used for other scenes.They used practical effects when it got killed. Look up the behind the scenes blogs and vids; you can see them welding a prop tiger to blow up.
April, 1945. As the Allies make their final push in the European Theatre, a battle-hardened army sergeant named Wardaddy commands a Sherman tank and her five-man crew on a deadly mission behind enemy lines. Out-numbered, out-gunned, and with a rookie soldier thrust into their platoon, Wardaddy and his men face overwhelming odds in their heroic attempts to strike at the heart of Nazi Germany.