HANOVER, Germany (April 3)—Continental Tire North America Inc. suffered an 84.4-percent drop in operating earnings last year to $10.6 million, as rising raw materials prices, falling tire prices and an unfavorable peso-dollar exchange rate ate into the profit margin, the company said. The drop included a $17 million operating loss in the fourth quarter. Continental Tire´s sales (adjusted for currency exchange rate influences) rose 2.4 percent to $1.63 billion, while unit sales of car and commercial vehicle tires grew 11 and 8 percent to more than 30 million and 2.7 million units, respectively, the company said. More than 40 percent of the firm´s passenger car tire business is with original equipment customers. Continental plans to counter this trend by improving manufacturing efficiencies and launching new tire lines and expanding existing ones, including a full range of sizes for its ContiTrac sport-utility vehicle and truck tires.