OKay I notice that some people say they lower the pressure in their tires to achieve a faster 0-60 or 1/4 time. Well is it because of rotational mass? Less weight the wheels have to spin=speed reached faster over all? Thanx.

 

It is about traction. But you are increasing your friction and actually making it a bit slower. Your traps will be lower, but your ETs might go down a bit.

 

Unless you're running a drag radial, no street tire is going to get significantly better traction from decreased air pressure. Lowering the pressure will decrease the radius of your tire and give you the effect of lowering the final gear ratio. Many people erroneously credit the effects of lower gearing to better traction.