Hankook Tire Co., South Korea\'s largest tire maker, said Friday its operating profit in the global market dropped 8.8 percent last year from a year earlier due to rising raw material prices. The operating profit of the tire maker\'s overseas operations came to 566.3 billion won (US$493.1 million) in 2011, compared with 620.9 billion the previous year, the company said in a regulatory filing.