From member Glen Martin:
Here is a way to insure that all your road wheels on your armor project will touch your tracks when you put them on. When putting on your roadwheels to the under carriage bogey assemblies, use a plate glass base. A section of plate glass, about a 1/4 inch thick, will keep your wheels vertically perpendicular to the base, while keeping the bottoms of the wheels on the same flat horizontal plane (surface). This helps to eliminate "floater" wheels by having one too high off the track. You can pick-up a piece of plate glass from a local glass store, pretty cheap for what you need.