I just spotted that BLACK HAT MINIATURES have released a couple of really nice tracked steamtanks in 15mm scale!
They would make perfect Dwarven Steamtanks in 15mm scale! The lighter one would be ideal for either the Thunderhammer, Iron Drake or Rapier battletanks (with minor conversion) while the larger one would make a good Ironclad!
At £6 each they are a bit pricy but look great!
All the best!