Best way to actually know how much raise is needed is to pull the trailer wheels up onto boards until the trailer is level, then measure the boards and rail clearance on the truck. We have 7" rail clearance and there have been times when we were glad that we had it. We added MORRyde SRE4000 rubberized equalizers to our trailer--they raise it about 1 1/4" at the wheels. We also replaced the OEM Chinese tires (235/80R16) with Goodyear Endurance trailer tires in the 235/85R16 size which raises a theoretical .45" at the wheels for almost 2" total. LT tires also come in that size. The SRE4000 is amazing in how it smooths the trailer ride and is just as easy as replacing a solid equalizer. MORRyde recommends on of their X-Factor braces on the center pair of spring hangers when using the SRE4000.