Trucking industry and Teamster Union representatives are going to Chicago today to talk about living together in a new era of free enterprise.

The industry and the union had benefited from 45 years of government regulation that effectively allowed trucking firms to subsidize higher wages by charging shippers higher prices.

But all of that ended last July 1 when President Carter signed the Motor Carrier Act of 1980, deregulating the industry.

Now worried executives of many unionized trucking firms would like the Teamsters to sacrifice some of the union's 1979 contract gains. Concessions are needed to keep the unionized companies competitive in a deregulated environment, the industry representatives say.

That is what the Chicago meeting is all about.

"We're going to sit down and explore with the industry what it says its problems are under deregulation," said Duke Zeller, Teamsters spokesman.

"The industry called for this meeting. We didn't. We have a contract," Zeller said.

Article 27 of that contract. The National Master Freight Agreement, allows "reopener" talks "in the event of war . . . or a federal agency action which has a significantly adverse effect on the financial structure of the trucking industry."

According to officials of Trucking Management Inc., the industry's bargaining arm, deregulation is having that effect.

"Available data clearly indicates that the recently enacted Motor Carrier Act of 1980 has had a significantly adverse effect upon the financial stability of the industry," the TMI officials said in Aug. 20 letter to Teamster President Frank E. Fitzisimmons, calling for "reopener" talks.

The TMI officials did not list the "available data" that allegedly shows the ruinous effects of deregulation -- a claim complicated by the current, recession's effects on trucking and other industries. But they did list "areas to be discussed" in any contract reopening.

Those areas include cost of living allowance (COLA) payments that, by next April, could add nearly $1 to the current average hourly salary of $11.50 for unionized truckers. The industry representatives said they are also interested in the possibility of lowering certain wage scales, and eliminating several work rules, the loss of which could result in the loss of jobs.

"No one knows what, if anything, might be negotiated. But we need relief," one industry spokesman said.

Both sides have agreed that there will be no strikes or lockouts resulting from the reopener talks. If no agreement is reached, or if an agreement is not ratified by the general membership of either side, the current contract will remain effective until its expiration on March 31, 1982.

The "no-strike, no-lockout" basis for the talks angers dissident Teamsters who fear that the leaders of their 2.3-million member union -- the nation's largest -- will enter the talks "umprotected."

"The industry has made its demands and the union is going into negotiations without any demands or anything to back it up," said Ken Paff, spokesman for the 10,000-member Teamsters for a Democratic Union, the dissident group.

Paff said dissident Teamsters "will not stand for" any reduction in current COLA provisions.

General truck freight tonnage dropped 16 percentage points in the first six months of this year and is runing nearly 30 percent below levels this time a year ago. About 60,000 of the 300,000 Teamster drivers and warehouse workers are unemployed.

But a spokesman for the American Trucking Associations, which won't be involved in the Teamster-TMI talks, said yesterday that it is difficult now to say how much of that decline is attributable to deregulation.

"Everything is so mixed up with the recession right now," he said.

Deregulation, however, makes it possible for more nonunion firms to compete for a share of the $108 billion-a-year trucking industry. That especially worries unionized trucking executives who were able to afford hefty wage settlements in the past, largely because of collective rate-making which allowed them to pass through wage increases to shippers.

"With that gone, we're at a decided disadvantage," one unionized trucking official said. "The nonunion people just don't have our expenses," he said.