Total consumer credit rose $13.5 billion to $3.25 trillion in August, the Federal Reserve said on Tuesday. Economists polled by Reuters had expected consumer credit to increase $20 billion in August. The weak reading could bolster the view that economic growth downshifted in the third quarter from the pace clocked in the prior three months. The slowdown in credit growth in August was due primarily to a $207.5 million drop in revolving credit, which mostly measures credit card use.