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It depends how much voltage drop you can tolerate. Even a 25 mil wide trace can take quite a few amps without burning open. I also recommend you use 2 oz. copper but that limits how narrow a trace you can put down for logic components. I have run 40 amps on four 80 mill wide traces with 2 oz. copper. I use a trace on both sides of the board and it was driving two loads. Traces were very short so voltage drop was minimal.
You can compute the resistance of the trace by computing the circular mill area and length.