I'm sure you read the instructions.
Warning:
Using wheels wider than 7” with more than 3-1/2” of backspacing may cause the
right front tire to rub on the steering box. This will vary depending on the vehicle
ride height.
Nothing in
here about centerline of axle measurement. Instructions revised 1/14/2015. What revision do you have? Call/email and ask if the one I linked has good dimensions or is the latest advise to use axle centerline.
