A congressional committee today called for the recall of every Firestone steel-belted Radial 500 tire still on the road, citing new company data it claims shows that one out of every six of the tires sold has been returned by consumers.

In addition, the committee claims one out of every 500 tires and sold has suffered "tread separations, a type of tire failure that frequently leads to blowouts."

Meanwhile, there were new indications that Firestone's troubles continued to mount. Tire industry sources said that General Motors Corp., the nation's largest auto maker, it considering cutting back on the number of tires it normally buys from Firestone for use on its new-model cars.

And, a confidential study done for a rival tire maker by an outside firms claims that consumer confidence in the Firestone 500 has eroded seriously in recent weeks amidst government allegations that the tire is unsafe.

The report today by the House Commerce Committee's subcommittee on oversight and investigations follows a lengthy investigation and four days of hearings this summer. Besides calling for the company to voluntarily recall all of the tires at its expense, the report reaches the following conclusions:

Failing a voluntary recall, the National Highway Traffic Safety Administration should press for a mandatory recall and maximum civil penalties for Firestone.

Congress should amend the National Traffic and Motor Vehilce Safety Act to broaden. NHTSA's powers to subpoena information it considers necessary for its investigations and extend the period of time tire manufacturers are liable for recall from the present three years to five. Under existing rules, NHTSA can order a manufacturer to recall only tires sold within the past three years.

NHTSA should attempt to upgrade the minimum safety requirements for passenger car tires "to avoid a recurrence of another case like the Firestone 500 steel-belted radical tire."

Calling Firestone "an entrenched and recalcitrant manufacturer," subcommittee Chairman John Moss (D-Cal.) said that the company's refusal to take remedial action in the face of growing evidence of problems with the "500" was "reprehensible in the extreme."

Under the direction of Administrator Joan Claybrook, NHTSA made an "initial determination" two months ago that the "500" has a "safety-related defect" and called on the company to recall the estimated 13 million "500s" still on the road. The company refused, and testified at a subsequent NHTSA hearing that the tire was "safe and dependable," and that the agency hadn't shown that there were any inherent safety defects in the tire.

NHTSA is expected to reach a final determination on whether to order the company to recall the tires within the next few weeks - an action that industry analysts say could cost Firestone anywhere from $100 million to $200 million.

In the meantime, Firestone has hired Washington attorney Clark Clifford in an attempt to negotiate a possible settlement with the government agency that might limit the scope and expense of the recall.

But the Moss report claims even more damaging indications of widespread failures of the "500" than had been disclosed previously.

The report states that the Firestone 500's adjustment rate - the number of tires returned by consumers to Firestone prior to wearing out - is 17.5 percent, "three times the rate for all other steel-belted radial tires made by Firestone.

"It is also considerably higher than the 7.4 percent rate previously disclosed by Firestone," the report states.

Firestone manufactured more than 23.5 million steel-belted 500s from 1972 until early 1978 when the line was discontinued, and estimates that as many as 13 million are still on the road, the subcommittee said. But many more "500s" were made by Firestone for Montgomery Ward, Shell Oil Co. and other retail companies under their own brand names.

The report did not address the question of whether the millions of tires manufactured directly for auto companies to put on new cars would or could be affected by the recall. An estimated 10 million steel-belted radial "TPC" tires - a tire similar to the "500" but made to specification for General Motors - still are on the road. There is no information available about possible blowout problems with these tires.

And, tire industry sources say, GM is likely to cut back on future orders of Firestone tires because of complaints from many of its dealers who are reluctant to take delivery on new cars with Firestone tires.

The sources said GM has not yet decided how much business it will give each of the tire manufacturers during the coming year. But that breakdown - which is traditionally one of the industry's best kept secrets - is usually decided much earlier in the production stage of the coming model year.

GM refused to comment on its purchasing decisions, which a spokesman classified as "highly confidential," except to say that "we are still buying Firestone tires."

An elaborate confidential consumer survey conducted for one of Firestone's competitors, and made available to the Washington Post, claims that 20 percent of approximately 20,000 consumers surveyed earlier this month indicted they would not buy Firestone tires. A month earlier, that number was 15 percent, while in June it was 8 percent, the survey showed.

The survey also claimed that 55 percent of Firestone 500 users were "dissatisfied" with the tire - more than twice the number unhappy with any other tire brand.

Of great concern to other tire makers was the fact that the study also showed that the number of people who refused to buy any steel-belted radial tire had virtually doubled from 3 to 6 percent of those questioned during the past three months.

Finally, the survey indicated that the tire manufacturers likely to profit with increased sales from the problems besetting Firestone were Michelin and Goodyear, the leading domestic tire manufacturer. Both have high-quality reputations.

A firestone spokesman here said yesterday "we disagree with the conclusions of the Moss committee report. Our company cooperated fully with the committee in its investigation, presented testimony during the public hearings and furnished huge quantities of additional documentation which we respectfully believe make the report's conclusion unjustified. We will continue to work with NHTSA in seeking a resolution of the matter which will be fair to the public and to our company."

Moss commended Firestone for its cooperation with his investigation, but added that "this cooperation in no way diminished the seriousness of the '500's' problems."