That formula would give you the absolute top speed that you could possibly go if you didn't change the gearings in the car, negligent drag and horsepower. Basically, it's just a mathematical formula to figure out what speed you would be going if you were to be at the rev limit. It has nothing to do with what a car would actually run in the real world.
Cause in the real world, it wouldn't matter if your overall diameter of your tires are 20 inches or 30 inches, it's the drag and horsepower that will limit your topspeed.
For example, if you could achieve 125 with a total wheel diameter of 20 inches, upgrading to a 30 inch diameter wouldn't change your top speed at all. Your car simply could not push thru the atmosphere any more than what your HP and drag will allow you to.
And for all practical purposes, weight really doesn't matter all that much in a top speed test given enough room to get the car up to speed. You could have a totally gutted out Intrepid that weighs 1000 lbs less (given the same HP and Drag Coefficient numbers) the car would achieve the same Top Speed. The difference is that the gutted out model would get there faster (accelerate faster). The main factors are still the power it has available to push it thru the atmosphere.