While Goodyear and Michelin are fighting each other in the radial tire arena, they have pooled their technology to produce a strategic synthetic rubber at a joint venture in Le Havre, France.

The plant produces polyisoprenic synthetic rubber or "IR," the only synthetic that almost exactly duplicates the rubber from Asian trees. The joint venture is a good example of how modern multinationals often compete in one area of technology while cooperating in others.

The strategic importance of IR can be seen from the fact that the Soviet Union has pinned its hopes of becoming self-sufficient in rubber by the mid 1980s on doubling its present production of 500,000 tons of IR a year. The Soviet Union is by far the largest IR producer in the world.

The joint industrial venture by the largest American and European tire companies was the result of a power play by the government of French President Charles de Gaulle in 1966.

When Goodyear announced its intention to expand its existing Le Havre synthetic rubber plant to produce IR, the plan was delayed by the French government.

"We don't know whether it was Michelin or the French government that actually was blocking us but when we agreed to do this as a joint venture with Michelin, approval was forthcoming," said a Goodyear official.

At the time, Michelin's Asian rubber plantations were threatened by the war in Indochina, and Michelin did not have technical capability for producing IR, which is the synthetic that is most easy to substitute for natural rubber in tire compounds.

The technical, logistical and financial difficulties Goodyear and Michelin subsequently experienced at Le Havre may explain why the West Has not followed the Soviet Union's lead in pinning its hopes on IR.

Prospective deals for obtaining isoprenes -- the feedstock needed to make IR -- from French company Rhones-Alpes, the West German company Bayer, and the British company ICI all fell through.

It was not until 1972 that the partners obtained the isoprene materials from several chemical companies in Japan.

In 1974, Goodyear began producing the isoprene raw materials with its own process in Le Havre, thereby giving Michelin access to the highest technology in the field.

Nevertheless, technical and economic problems have continued.

In late 1974, a Goodyear facility for manufacturing the isoprene feedstock at Beaumont, Tex., was wrecked by an explosion in which two persons were killed.

Supplies of chemicals for the Le Havre facility also may become tighter, Goodyear officials say. If European gasoline prices continue to rise, oil companies might be inclined to divert more of their naptha supplies from the facility to gasoline production.