Ford Motor and Firestone have made considerable progress in their investigations into the tyre-related crashes that have killed more than 100 Americans, mostly in Ford Explorers, but they remain divided on some basic issues, people close to the inquiries said, The New York Times said on Friday. Ford's newest finding is that a Firestone factory in Decatur, Illinois followed procedures different from those at other factories in handling rubber and other incoming materials, and these procedures may have allowed the quality of the materials to degrade, a person involved in the inquiry said. The steel-belted radial tyres made in Decatur have had a much higher failure rate than tyres of the same brands made elsewhere, according to both companies.