MIDDLESBROUGH, England (March 20)—Polyurethane tire maker Green Tyre Co. is investing $1.7 million to expand production at its plant in Middlesbrough. The investment will cover a 53,800-sq.-ft. expansion and new machinery to produce water-blown PU tires for wheelchairs, bicycles, recreational and industrial uses, according to Green Tyre Managing Director Colin Scarsi. The expansion will require a doubling of the work force, to about 80, Scarsi said. With annual sales nearing $2.8 million, Green Tyre has been experiencing growing worldwide demand for its products, which are mostly sold overseas, Scarsi said. Founded in 1992, Green Tyre produces around 1 million units a year, around 70 percent of which are for the medical market.