6. Measure the distance from the hub assembly to the drop line of the weighted bob and record your findings. Our measurement was 4-1/2inches. To create what we call a no-rub zone, subtract 1 to 1-1/2 inches from that number. We subtracted 1-1/4 inches just to make things simple, giving us a whole number of 3 inches. This number is the maximum amount of outboard space for our wheels.