jmatta33
New member
Hate when Superchips is wrong
look at it this way. if you fully inflate your tire off of your vehicle and measure the circumference it will add up to be X inches. now imagine you put a ratchet strap the same width as the tire and you tighten it so its exerting say 1500lbs of force. measure the corcumference again and it will certainly be less than the original X inches. measuring to the top of the tire adds more height because the air gets pushed up from the weight of the vehicle on the tires. this is also why you measure from the center of the vehicle to the ground and not just any other point on your tire. feel free to test it out on your own. unless you are severely over inflated, the distance from center wheel to the bottom will be less than center wheel to the top. while the amount of difference may only be 1/2 inch or so, that 1/2 inch becomes exponentially greater with calculating speed and mileage.