Of the five biggest U.S. tire firms in 1970, today only Goodyear remains independent, due to the challenge posed by radial tire technology, and the varied responses. At the time, the entire U.S. tire industry produced the older bias-ply technology. Estimates to fit the factories with new machinery and tools for making this new product were between $600 million and $900 million. This was a substantial amount in a low margin business with sales revenue in the low billions. The U.S. market was slowly shifting towards the radial tire, as had already been the case in Europe and Asia. In 1968, Consumer Reports, an influential American magazine, acknowledged the superiority of radial construction, which had been developed in 1946 by Michelin.