my speedo reads 35mph but the satnav says 31 and at 65mph the satnav says 60 but in my other car (which is practically the same) the readings are bang on, well 70 is 69 on satnav, '91 + '92 gti's btw, the car with the readings out is on 15" wheels whereas the other is on 17" wheels but there is only 6mm difference in outside dia between them(17's slightly bigger), anybody got similar problem or a cure?
swap the wheels over and see if problem changes to the other vehicle and fixes on the problem car this will eliminate the wheel / tyre combo as potential fault
Speedos always over read, manufacturers do it to cover their arses, imagine how miffed you would be if you got caught over the limit and yet your speedo told you you were under. They'd get sued left, right and centre
Bigger wheels will make your speedo "slower" and smaller wheels will make your speedo "faster", so the bigger wheels are compensating for the over-reading.
mine reads about the same as yours, its about right for a mk2 with the correct size wheels on. as above, they over-read a little as std
can tell you work at a research centre with every problem heading to an experiment and a good one too, talking to other mk2 owners assures me that mine is about normal, tonight i shall sleep!
