Just for shets and giggles.
Raise the bike up on a jack, making sure that the jack is perfectly level and the bike sits perfectly level on the jack, us a good level!!. Now set the front wheel to perfect center and keep it there by cross tying the handle bars so that the front wheel can't move, it needs to be perfect. Now take a string, butcher twine works well, and run it from the front wheel to the back wheel. The line should start and stop on the opposite side of where you run it. There can be no obstructions between the tires, so you'll have to be low enough to pass any issues, but the higher the better. Now the string should be touching 4 points on the tires on the measuring side. If not, then something is out. Adjust as necessary, but I wouldn't know how.
Now that the bike is level you can also put a level on the wheels to check for plumb, but don't go by the tires, use the wheel only, because the tires will not be perfectly the same size at every point in their circumference.