7. Here, we measured from the ground to the bottom of the frame to figure out the height of our notch. Steve used a simple formula which goes as follows: Ground plus 1/2 overall tire height, plus 1/2 of the axle diameter, plus 1/2-inch for clearance, plus 1/8-inch for bottom notch plate equals the bottom of the notch. Our calculations looked like this for example:14-inches + 13.5-inches + 1.5-inches + .5-inches + 1/8-inch plate =29 5/8-inches to the bottom of the notch. This was running a 27-inch tire with a 3-inch rear end.