when a converter is fitted it changes kmh to mph and km to miles so if u got 55000 km then a converter fitted, now it reads 90000, that 35000 gained will be in miles so simple maths convert 35000 miles to km = 56000 add that to your orignal 55000 before it was converted and u got yourself 111000 km in total mileage! or 69000 miles what ever u want!