There are many bolts that the manual says BMW says you should replace. Suspension component nuts and bolts are just one. I've reused them with no ill effects. I recently had my seats out and put them back in. The manual calls for them to be tightened to a specific torque plus 90 degrees. The "bolts that the nuts are going on are welded to the body. That tells me that TTA is not the same as TTY. If TTA is the same as TTY, then the seat bolts would need to be replaced. But they don't. Personally, I think BMW's recommendation to replace all the different bolts and nuts they do is a money maker for them.