P.M. BRIEFING : GM Plans Summer Plant Shutdown

General Motors Corp. said today that it plans to shut down some of its assembly plants for a month or longer this summer to help reduce inventories and provide time for plant retooling.

There has been speculation that GM, Ford Motor Co. and Chrysler Corp. would have longer-than-normal changeover times because of slow sales and ambitious production during the first three months of the year.

GM spokeswoman Marcia McGee said today that the company’s plant in Flint, Mich., will be closed between June 13 and Aug. 7 and that plants in Wentzville, Mo., and Orion Township in Oakland County will shut down for about a month each during June and July.

She called the shutdown time normal.