MIAMI, Okla. (AP) _ B.F. Goodrich Co. announced Friday it will close the company's tire plant here in February, a move that will cost 1,900 jobs and idle the area's largest employer.

The company cited increased competition from imports and declining demand for large vehicle tires for the closure, which has been rumored here for months.

The 40-year-old factory produces about 10,000 farm equipment tires, off- the-road vehicle tires and radial heavy-duty truck tires each day in this community of 15,000 residents.

''The decision to close the Miami plant was obviously an extremely difficult one because of the effect it will have on employees and the community,'' said B.F. Goodrich Tire Group President Robert A. Eisentrout.

The company has been losing money on its large-tire operations, primarily because of depressed market conditions and increased imports, he said.

''More than 50 percent of off-the-road tires and radial heavy-duty truck tires sold in the replacement market in this country are imported,'' Eisentrout said.

Ferrell Alsbury, a 16-year employee, said the announcement was not a surprise and that his co-workers were subdued when they were told of the decision.

''They just listened and accepted it,'' said Alsbury, who is 50. ''It's not a rumor any more ... It was nice, the company informing us of their plans. They could have just shut it down in one day.''

''A lot of long faces leaving here today,'' said security officer K. B. Sparks of Miami, a 10-year employee. ''A lot of long faces all over Miami.''

The company has hired a firm to help employees find other jobs, said plant spokeswoman Beverly Pierce. She said she did not know whether the shutdown would be gradual or if all workers would remain on the job through February.

The local Chamber of Commerce scheduled a meeting with state Department of Economic Development officials for Tuesday to discuss the closing.

B.F. Goodrich has been unable to find a buyer for the plant, but will continue to work with civic leaders to find another use for the factory, Eisentrout said.

''We have to try and take up the slack before it gets away from us,'' said Chamber of Commerce Manager Joe Thompson. ''We must go about the business of creating a viable economic package of the plant.''

The state was considering tax exemptions, investment tax credits and vocational training for any company that would agree to keep the plant operating, said Grover Phillips, director of the state Department of Economic Development's industrial division.

Ottawa County's unemployment rate was 9.9 percent in July.

The plant had been closed for a week in July, with officials citing a weak tire market. Company officials at that time denied rumors of a permanent shutdown.

Goodrich's tire group, which produces tires at three other domestic locations, had revenue of $1.5 billion and operating income of $93 million in 1984.