MT Drag radial air pressure?

I've found every car, and tire brand is different. If I change tire brands, I'll find a clean area of concrete, launch the car (not a burn out), then go back and check the patch. You want a soild black area across the width, if it's darker on the edges add 2lbs of pressure, do another launch etc. If it's darker in the center lose air pressure, and do another launch etc. It works for me!