How to center rear wheels in weel well

What does this mean...Please explain what you are saying. best informed before than learned after

This is about where the rear end of the car is compared to the front end in a lane, and when you lay into the throttle where the direction of the force is compared to the rest of the car.
Your car can go down the road slightly sideways, and/or when on the throttle it can push sideways on the front end making the steering different from right to left.
I test this by using full throttle in second gear during a sweeping turn left and right.
If one direction tries to fight the steering a bit more or feel like it tries to dig in more on one side than the other there is a problem with the centerline thrust.
When you move one side of the rear end this can get thrown off or made worse.

The best informed statement just meant you might need to know about that before you move something permanently only for the sake of visual differences between the two sides.

I have found that most people never consider this, or even know about it.