The driver told the Otago Daily Times he was travelling to a hedge-cutting job on Three Miles Hill Road when he did a shoulder check to see if he needed to pull over for traffic.
"The back window was a bit foggy ... and I was like ‘eh, that’s not normal’.
"Then I opened the window ... to see what it was and realised it was smoke."
The driver was uninjured and the cause of the fire remains a mystery.
Whether the tractor was a total loss was also still unknown, he said.
"It’s just one of those things that happen ... just got to get on with it."
Firefighters from Roslyn and Mosgiel stations, as well as a water tanker from Dunedin, were called to assist.
The tractor was "fully involved" upon arrival, but did not pose a risk to anything else and no vegetation had caught fire.
A fire investigator was called to the scene, but the blaze had not been flagged as suspicious, the spokesman said.
