Does what it says it will do
If getting your speedometer to read correctly after changing to larger tires is a must, like it is for me, than this is the right tool. Just be prepared to make multiple adjustments. I'm running 35" tires and played around with the tire size setting until the calibration thinks I'm running 33.25" tires. In the end I don't care what the calibration thinks I'm running as long as the speedometer is dead on.... and now it is. So I recommend this highly just be prepared to make a lot of adjustments.