A South Korean tire manufacturer plans to add almost 400 jobs in a third expansion of its Tennessee operations. The state Department of Economic and Community Development says Hankook Tire & Technology Co. is planning to add the jobs over five years at its Clarksville campus. The company plans to finish a previous expansion to double U.S. production of passenger car and light truck tires. Hankook will invest $612 million in the third expansion, which will add the company’s first U.S. production line of truck and bus radial tires. Hankook has relocated its North American headquarters to Nashville. The new Clarksville expansion will bring the company’s workforce to about 2,300 people across Tennessee.