The Teamsters union has offered Pan American World Airways an estimated $25 million in wage and work rules concessions as part of a $180 million package of labor cost savings the airline has demanded.

The Teamsters yesterday told the National Mediation Board it would be willing to accept arbitration to settle its contract disputes with Pan Am's management. The company has yet to respond to the board's arbitration offer.

The Teamsters organization is one of two unions that have not agreed to Pan Am's demands for concessions that it says are needed to keep the airline in operation. The other is the Transport Workers Union, which represents mechanics at the airline.

Pan Am announced Tuesday that three other unions -- the Flight Engineers International Association, Independent Union of Flight Attendants and the Airline Pilots Association -- had agreed to concessions worth $110 million. The biggest concessions were made by the pilots, who were asked to give up $60 million in benefits.

Publicly, the Teamsters have said they will strike at the end of a government-imposed 30-day cooling off period that would begin if either the union or the company rejects arbitration.

Pan Am has said it would keep operating if the Teamsters did strike.

It was unclear yesterday whether the Teamsters were willing to continue bargaining or whether Tuesday's proposal was the union's final offer.

Sources said yesterday that the Teamsters made their concession offer at a 4 a.m. bargaining session Tuesday, just hours before a scheduled meeting of the Pan Am board. The offer was rejected by the company as inadequate.

In seeking concessions, Pan Am has given its unions a "term sheet" spelling out how much it expected each one to give up. In the case of the Teamsters, Pan Am demanded $35 million in concessions. It also demanded concessions worth $35 million from the TWU. The flight attendants have agreed to $31 million in concessions and the flight engineers to $19 million.

Sources said yesterday that the Teamster proposal was $8 million to $10 million short of the $35 million demanded by Pan Am.

One source said the union was not willing to make the full wage concessions agreed to by other unions and was not willing to make similar cuts in its health plan.

At the start of the current round of concession bargaining all the unions told Pan Am that if any one union makes a better deal with the company then, as one union negotiator put it yesterday, "all bets are off."

If negotiations are successfully concluded, Pan Am's board is expected to turn its attention to leadership changes, including the ouster of chairman C. Edward Acker and vice chairman Martin R. Shugrue.

The airline's unions, which would not be sorry to see Acker leave, have worked with Shugrue in attempts to find a buyer for the airline that would keep the carrier intact.

Industry analysts said yesterday that if Pan Am wins the concessions it seeks it may be able to stabilize operations and become profitable.

The airline's parent company is anticipating a loss for 1987 "significantly" in excess of $90 million.

Unless the U.S. economy falls into a serious recession, Pan Am operations should be able to stabilize "and make themselves profitable and make themselves more attractive in the future for a buyout by a better-heeled airline," said Louis Marckesano, an airline analyst with Janney Montgomery Scott Inc.