When we speak of a speedometer calibration, then we are not referring to changing the speedometer. A speedometer calibration is virtually always necessary as soon as you change the tyre size or wheel size of your Ford Ranger, VW Amarok, Mitsubishi L200 or other vehicles. In other words: You are using a different size than that specified in your vehicle documents. It must be noted that with a speedometer calibration contrary to changing, the driven kilometers are not changed. According to the legislature, a speed variance is only allowed if it falls above the actual driving speed. The speedometer is allowed to show a higher speed than is actually driven, but under no circumstances may it fall below the actual speed. The variance percentage is also specified. For vehicles registered before 1991, the variance of seven per cent from the real value is permissible. If the registration is after 1991, the speed may exceed the real value by ten per cent plus one extra increase of four kilometres per hour.