Hmm... it seems there's a misunderstanding. The wheel isn't out of true. It's not a question of spoke tension. The wheel is perfectly round and true. The problem is only at one point, the seam, where apparently the two halves of the rim are slightly misaligned (which apparently happens to some rims during the manufacture?). I don't believe spoke tension can change this. I've had wheels out of true 2-3mm that didn't make the "thump" noise when I braked, indicating that it's a misaligned joint, not a tension question.