A fatal auto accident in Pennsylvania has stirred concerns about another potentially hazardous Chinese product in wide use in the U.S.: tires. About 450,000 Chinese-made tires sold in the U.S. -- and possibly many more -- may lack an important safety feature, according to federal regulators and the U.S. distributor that helped design them. But the task of identifying who bought the defective tires and getting them off the road has been complicated by litigation and holes in the nation's product-recall system. The tire defect comes in the wake of several other high-profile safety problems involving Chinese products, including the...