This is probably a stupid question, but I'll never know till I ask I just got new wheels/tires that were shipped mounted and balanced along with a set of Zenki racing lugs in black, which also includes black valve stems. The stems that are currently on the tires are stainless steel. To switch them, does the tire have to be off the wheel? In other words, am I not going to be able to use the new stems since they came mounted? It's not a big deal, the silver is fine, but I can't quite see how they get put on.l