The L.A. area economy will grow 8.6% in 1986.

The predicted 8.6% growth in the gross regional product for the five-county Southern California area--Los Angeles, Orange, Riverside, San Bernardino and Ventura counties--is down slightly from the 9.1% gain expected for 1985, the Los Angeles Area Chamber of Commerce forecast. The counties will add about 200,000 new jobs in 1986, but jobless rates will remain in the 7.3% to 8% range in all but Orange County, the chamber predicted.