Ron, I'm not certain which wire in the speakers you're asking about. If you're including the wire in the drivers themselves, Axiom along with every other manufacturer uses well over 100 feet of copper wire with gauges in the 20s and 30s(note this
article for a discussion on the point).
As to the short lengths of wire inside preceding the drivers, 20ga would be fine and would have little effect on the overall resistance between the amp and drivers. The thicknesses of wire in common use are adequate for 10 watts or 1,000 watts.