After the design of the body and motor mounts I can get an idea of what kind of wheels I need. The things that are important to consider is the width and diameter. Both are restricted by the dimensions of the the minisumo. In my case, since the motor shaft is offset, I can go with a smaller diameter wheel and not worry about the bottom clearance of the robot. But since the motors are somewhat long, I can't go with a really wide wheel. With this in mind I figured that a wheel diameter of 40mm and a width of roughly 20mm would suffice.