The term "tire track eel' can get rather confusing, There are actually several spiny eels that are called Tire Track Eels, and so are often mis-identified. This is a common name that is used for 3, sometimes 4 different species. Besides being used for M. armatus and M. favus, it is also a common name used for the Half-banded Spiny Eel Macrognathus circumcinctus, and occasionally for the Black Spotted Eel Mastacembelus dayi.
Fire Eel - Mastacembelus erythrotaenia - around 22" in Aquarium
Tire Track Eel - Mastacembelus armatus - around 20" in Aquarium
Half-banded Spiny Eel - Macrognathus circumcinctu - around 6" in Aquarium