The MPH will either read higher or lower than what the vehicle is actually traveling.
.When changing tire size or axle gear ratios your original speedometer gear will not register the same MPH as it did with the stock gears and tires. Blue;NP231 transfer case;38 teeth;Must purchase 6035709 separately or reuse factory o-ring;California Residents: WARNING Crown Automotive Speedometer 38 Teeth Gear - 52067638 Use the Tire and Gear Ratio Chart to determine which Tooth Gear you will need to correct your MPH speedometer reading. You will need to change the speedometer transfer case gear to the correct tooth count to obtain the proper MPH reading on your Speedometer.