They said Ford told Firestone to add a nylon ply to the tires it manufactured in Venezuela for additional strength . Ford changed the suspension to Explorers available in Venezuela . The report went on to indicate that Ford also had a major role in the problems stating that The Ford Motor Company had instructed Firestone to add a nylon ply to the tires it manufactured in Venezuela for additional strength and that Ford had made suspension changes to the Explorer model available in Venezuela .