A congressional commission stalemated yesterday in trying to decide whether America's deregulated truckers need continued antitrust immunity to set rates for hauling freight.

The 5-to-5 vote of the Motor Carrier Ratemaking Study Commission came on a staff recommendation that antitrust immunity be eliminated for all collective ratemaking on both single-carrier and interline truck shipments, effective Jan. 1, 1984.

The staff's draft report found that, among other things, the prices truckers charge shippers are higher than they would be "in the absence of collective ratemaking."

If the commission's stalemate continues past Jan. 1, truckers will be permitted under the trucking deregulation act to continue meeting and setting rates for single-line shipments until July 1, 1984, a six-month extension from the present scheduled termination of antitrust immunity.

The deregulation legislation does not address immunity for joint rates on shipments involving more than one carrier, although the staff thought they should not continue either. Rate bureaus -- whose members are individual trucking companies -- have been blessed with antitrust immunity since 1948.

The truckers' fear is that if all antitrust immunity is removed, there would be nothing to keep a private party from bringing an antitrust suit in a rate case even if the Justice Department remained aloof. Further, there's nothing to prevent a new Justice Department some years down the road from taking a different view of joint ratemaking and bringing an antitrust case.

The staff recommendations were supported in strong letters from the Justice Department, the Transportation Department and the Federal Trade Commission.

The commission consists of six members of Congress, two truckers and two shippers. With no compromise apparently available after the tie vote, commission chairman Sen. Bob Packwood (R-Ore.) adjourned the meeting.

Packwood said he will seek another meeting this year to see if a compromise can be found, but time is short, especially with six members of the commission involved in the last days of the lame-duck session of Congress.

The lack of action was seen as at least a temporary victory for the old-line regulated truckers such as those represented by the American Trucking Associations (ATA). Assuming the commission's report cannot be issued before Jan. 1, truckers automatically get another six months of immunity, which they want and which is also time that can be used on Capitol Hill to seek changes in the law.

The commission's vote came at the same time Congress is contemplating major increases in road use taxes on heavy trucks as part of the administration's tax package for highway reconstruction. ATA lobbyists have been busy explaining that the proposal is unfair, unacceptable and comes at a time when truckers cannot afford it.

Many of the same reasons ATA is using in those discussions were mentioned at the commission table yesterday. Because of the difficulty of attracting business in a recession and the freedom to set prices granted under trucking deregulation, rate-setting bureaus "are just giving us the list price," said commission member Stephen P. Murphy, a senior vice president of Yellow Freight Systems. "We're all discounting."

Ross C. Gaussoin, ATA board chairman, said later that individual trucking companies are engaged in "predatory pricing" just to stay alive. About 40 percent of trucking capacity today is excess, Gaussoin said.

The point of those arguments is that competition exists despite the continuation of the rate bureaus, as Sen. Howard Cannon (D-Nev.) argued. Cannon, a commission member, said that easier, speedier access to markets for new trucking companies was the key, not the abolition of rate bureaus.

Antitrust immunity makes it possible for rate bureaus to confer on prices without fear of prosecution. Further, the Justice Department has said that, even in the absence of immunity, truckers could meet to set interline rates as many of them do now.

Since trucking deregulation took effect in July 1980, according to ATA statistics, 196 regulated trucking companies have gone bankrupt. At the same time, the ATA estimates, between 7,000 and 8,000 companies have been formed.

Cannon voted with ATA's pro-rate bureau position yesterday. A subsidiary issue is who will replace Cannon, defeated in November's election, as a member of the commission.