I just discovered (or re-discovered) that my GP4000's have a "Rotation ===>" marking on them. The front tire of one of my bikes is pointing the wrong direction. I will confess that this is why I've been so slow lately.

And I have another confession...I didn't realize until just this moment that I can simply remove the skewer and turn the wheel around instead of removing and re-mounting the tire! Of course, I'll have to switch my computer magnet over also but that's a lot easier than remounting the tire!