Did you take off the little clips that hold on the brake rotors? Aftermarket wheels don't always clear those clips, and will cause the car to feel like the tires are not balanced. If you haven't removed those, try taking them off and see if that helps.
I can't speak for jdm, but I know I removed them for sure. The wobble you get with those in there is much worse than the minor vibration that I get with my AM wheels and tires. (ask me how I know . . . )