EDIT: I just realized that the plastic jaws have a different setting that gives you 2 inches more movement, reducing the max rim size by 6 inches overall! This makes the rim difficult to fit in the jaw, but I was able to replace the 4" bogie. I am very happy with them. Fit with zero modification. My Corghi machine makes a 10" rim on the outside. With all adapter settings set to maximum, it now works with 6" rims. Works like a charm on a zero spin front wheel. Remember that if your car only shrinks to 12-13 inches, you can only use 8-9 inch tires.