And seems to me when I had 33's on it before my lift it was off by 2-3 mph. I had 265's on it before that.Take it out and do 60mph, see how close to 1 minute you are at 1 mile according to the road signs. then adjust your speed to make 1 mile in a minute. when I had 35's and stock 3.73 gears I was off by about 5mph.
Perfect tool!