The land is owned by Warren Hyslop - and his wife Angelique Hyde read a victim impact statement in court.
Hyde said when the fire started she and Hyslop had "no chance to stop it".
All they could do was "wait and watch" which was "soul destroying".
The couple had been committed to shifting the tyre pile and she said due to Grimmer's "unlawful act" that work was now much more significant and extensive.
She said the stress of the situation had caused her to consider suicide and retreat from society.
"My life has become a rollercoaster… you Mr Grimmer have ruined my life," she said.
"You're not fit to be in society."
She said had Grimmer been jailed for the first fire he lit at the site the second never would have happened.
It would now take them until at least 2023 to get the tyres off the property and clean it up.
The court heard that Grimmer had an alcohol dependency and mental health issues.
"It's led to him fixating, having an obsession with this tyre pile that led to him setting it on fire."
Grimmer, through his lawyer, publicly apologised for his actions.
He apologised to the land owners as well as the wider community and said he was keen to address his personal issues so he could return to that community and contribute positively.
Grimmer was also convicted of arson after setting fire to the tyres on February 26, 2018.
He lives across the road from the property and the court heard he "snapped" and torched them after watching in horror for two years as the massive black tyre dump grew on leased farmland.
Grimmer - and others in the community - feared that the old tyres were contaminating the land, and could be jeopardising the town's underground water supply.
When Grimmer saw trucks delivering thousands of old tyres he became concerned.
Grimmer phoned authorities and reported his concerns but felt not enough was done in response.
He then took petrol and paper from home, crossed the road and lit a fire in a smaller pile of about 20,000 tyres beside the main pile of 400,000.
The massive took two days to put out.
Police told the court today that Grimmer, having been convicted of an identical offence earlier, knew better than anyone the risk involved in setting the tyres on fire.
Judge Gilbert accepted that Grimmer had mental health issues and his life had "unravelled".
But that was no excuse for his offending.
He noted that the last time Grimmer was sentenced the judge opted for a rehabilitative course of action.
Grimmer then "fell off the wagon" and committed arson a second time.
"It didn't take long for you to light a second and much bigger and more damaging fire," the judge said.
After considering all the matters before him Judge Gilbert said he had to come at the sentencing from a place of "denunciation and deterrence" rather than rehabilitation.