MILAN, Italy (May 9)—Pirelli S.p.A. recorded a 38-percent increase in operating profit during its first quarter, ended March 31, while sales rose 9.7 percent. Pirelli's tire sector contributed to both improvements, registering a 3-percent gain in sales and a 5.6-percent rise in profits, according to the company. Tire sector sales of $671 million resulted from a 3.7-percent rise in units sold and a slight improvement in product mix, Pirelli said, while pricing and exchange rates had slightly negative effects. Tire sector operating profit was $52.5 million. Overall, Pirelli's corporate sales grew to $1.78 billion, as acquisitions in its cables and systems sector were accounted for the first time. Operating earnings grew to $123.5 million, or 6.9 percent of sales.