Greg Allen, 43, of Seacoast Road, Bellarena, County Londonderry, was convicted along with another man for breaching waste and marine laws.
He plans to appeal the sentence, but not the conviction.
Mr Allen said he has lost at least six acres to the sea over three decades.
He estimates that the land washed away could be worth up to £50,000 and said he was trying to prevent further erosion.
The bales of tyres were put in place to protect a motocross track developed on his ground at the edge of Lough Foyle.
Mr Allen said at least 15 neighbouring farmers are suffering the same problem as him with coastal erosion.
And he questioned why farm land further along the coast was being protected with proper sea defences built and maintained out of the public purse.
"The more ground you lose, the more our income drops," he said.
"If a farmer loses ground for a roadway, he's compensated. We're not, and we're not being allowed to do anything about it either."
Mr Allen said he has been told that to put in a properly licensed sea defence along 100 metres of shoreline would cost up to £90,000 - if it were to be approved.
He must now remove the tyres, which he said will cost him more than £15,000.
Baled tyres have been trialled as potential sea defence material by the authorities in England.
It has not become a mainstream practice.

When Shatner asked if Cmdr Hadfield was tweeting from space, the astronaut replied: "Yes, Standard Orbit, Captain. And we're detecting signs of life on the surface".
The message presumably refers to earth.
Cmdr Hadfield arrived at the International Space Station on 21 December for a five-month mission.
The exchange, which astronaut Buzz Aldrin also participated in, delighted Star Trek fans.
Space and science blogger Jason Major tweeted: "Looks like @WilliamShatner has opened a hailing frequency to the #ISS and @Cmdr-Hadfield answered! #cool", in reaction to the Twitter exchange.
Cmdr Hadfield has been tweeting images of earth, including photographs of snow-covered rice fields in Japan and the coast of Italy.
The Canadian Space Agency has offered to arrange a live tweeting session between the actor and the astronaut.
A farmer given a suspended four-month prison sentence last week for having 20,000 tyres along the shore fronting his farm, has said he was trying to protect his land from coastal erosion.
[NEXT_CONCEPT]
Canadian astronaut Chris Hadfield has exchanged tweets from space with William Shatner, who played Captain Kirk in Star Trek.