I have the movement keys for the tank configured to UP, DOWN, LEFT, RIGHT.
The keys W,S,A,D are remapped to fill in other tasks. These keys are not used for movement at all in my config setup (so also infantry, planes, helicopters, submarines have been set to use UP, DOWN, LEFT, RIGHT instead of W, S, A, D).
Despite this remapping it seems the keys W,S,A,D are fixed to giving moving instructions to the tank.