Don't need to, you can switch back and forth on the fly to see which way you like it best.
It's intended use is for loads that are close to or over 3/4 of the trucks tow rating, but you can use it anytime, even empty. I use it to slow down w/o hitting the brakes.
It's intended use is for loads that are close to or over 3/4 of the trucks tow rating, but you can use it anytime, even empty. I use it to slow down w/o hitting the brakes.
