Frontline gardai were unable to respond to a rape victim over Christmas because their patrol cars were not fitted with snow tyres.
One member of the force was called upon to use his own 4x4 to get to the victim in Co Donegal and take a statement.
Sergeant Paul Wallace, based at Letterkenny Garda station, said the ordeal was just one example of the major difficulties they experienced during the big freeze.
"Around Christmas, a victim made an allegation of rape," he said.
"But we were unable to get to the victim because of the weather conditions. A member had to use his own private car to get to her and take her statement."
Sgt Wallace, speaking at the Association of Garda Sergeants and Inspectors (Agsi) conference, said the force's fleet was not adequate for dealing with emergencies in extreme weather.
"We had a major difficulty coping with the snow," he said.
"We were given snow socks to put on our tyres. They are fine for heavy falls of snow, but on hard packed ice you need snow tyres, like other police forces have."
During the worst of the winter weather, Donegal gardai had to call in a mountain rescue team because they did not have the vehicles to get to certain parts of the county, said Sgt Wallace.
Officers are increasingly having to use their own private cars to carry out everyday duties as part of their work in the force during treacherous conditions, he said.