Negotiators for the United Rubber Workers union and B.F. Goodrich Co. reached tentative agreement yesterday on a new three-year contract that appears to exceed President Carter's 7 percent wage guideline by a substantial margin.

If it wins further union approval, the pact could set a pattern for the rubber industry and end a five-week strike against Uniroyal, the nation's third largest and financially weakest tire maker.

Neither the NRW nor Goodrich would give details of the pact's cost but both agreed it was "substantial."

Chief Goodrich negotiator Peter J. Pestillo acknowledged the cost would exceed 7 percent a year, the administration's nominal standard for annual wage, benefit and cost-of-living increases. "A flat 7 percent? The answer is no," he said.

But Prestillo said compliance would hinge on the government's interpretation of guideline exemptions, which was sufficiently liberal in the recent Teamster contract bargaining to sanction costs estimated at more than 30 percent compounded over three years. "It may well be" in compliance, he said, adding that "there are certain issues which we'll raise that have to do with the various exceptions."

Thus the aministration appears to face a crucial test of the firmness it will apply in weighing wage increases against the 9-month-old voluntary guidelines, which have already been weakened by the Teamster settlement, soaring prices and a judicial decision banning economic sanctions against violators.

The court ruling is now being appealed. The appeal, coupled with the adminstration's handling of the Goodrich settlement and a recent machinists' contract with United Airlines, could be pivotal in the important negotiation later this year in the huge electrical manufacturing and automaking industries.

The tentative Goodrich contract will be submitted Monday to the URW's "big four" bargaining advisory committee. The committee will decide whether it is to be used as a pattern for an industrywide settlment embracing Uniroyal, Goodyear and Firestone as well as Goodrich, the smallest of the four firms.

If the contract then is accepted by the other companies, it will be submitted for ratification votes by the union's 55,000 members at the four firms.

"We honestly feel the other three major companies will follow," said URW President Peter Bommarito, although he said he was uncertain over Uniroyal workers' reaction in light of the union's bitter dispute with the company.

The union struck Uniroyal May 9 after accusing the company of reneging on an earlier agreement under pressure from administration inflation-fighting officals.

President Carter summoned rubber industry executives to the White House in late April for some "jawboning" by his inflation fighters after the union reported a tentative agreement that was so expensive, in the words of one official, that it would have "devastated" the guidelines.

Uniroyal denied it reached an agreement and, in subsequent fruitless negotiations with the union, stuck by the guidelines.

Finally, faced with a bargaining deadlock between the URW and Uniroyal, chief fedeal mediator Wayne L. Horvitz opened a second bargaining front with Goodrich, a company that enjoys good relations with the union. We invited the two sides to exploratory talks here a week ago, and formal negotiations opened Tuesday. Aside from one angry dispute in a marathon session Wednesday that nearly brought on a strike against Goodrich, both sides moved determinedly - and seemingly smoothly - to a settlement.

At a press conference to announce the tentative settlement last night, Horvitz praised both sides for working "very hard under very trying conditions" and said he had "every confidence" the pact would be ratified by the 9,600 URW members at Goodrich.

Pestillo noted it was the first time in five rounds of negotiations with the URW that the company and union settled without a strike.

Two of the union's main bargaining goals included a hands-off policy toward union organizing of new plants, along the general lines of an earlier agreement between the United Auto Workers and General Motors Corp., and an expansion of cost-of-living benefits.

Bommarito said the contract includes some neutrality guarantees to prohibit the company from opposing union organizing drives at nonunion plants. While all of Goodrich's tire plants are unionized, some of its other operations are not. The other rubber companies have nonunion tire operations as well.

The pact is also understood to include a gradual move toward a cost-of-living formula that would reimburse workers fully for wages lost to inflation - in contrast to the current formula that recovers 85 percent of lost wages, according to union estimates. This is also a major bargaining goal of the UAW in its upcoming negotiations with the "Big Three" auto companies.

URW workers at Goodrich currently are paid about $8 an hour, plus more than $3 in health, welfare and pension benefits. The union won its first cost-of-living clause three years ago after a nearly four-month strike.

There was only one sour note to the windup of the Goodrich-Uniroyal talks. As the bargainers prepared for their press conference at the Federal Mediation and Conciliation Service offices at 21st and K Streets N.W., a policeman descended on two Goodrich leased limousines waiting outside in a no parking zone and ticketed one of them. But they didn't get away before they were observed to be riding on Goodyear tires. CAPTION: Picture, Announcing tentative agreement are B.F. Goodrich's Pestillo, left, mediator Horvitz and URW's Bommarito. AP