Speedo readings

[tony_ack]

15'' tyres OK but what is their aspect ratio? 195/50, 205/45  etc., it makes a difference to the overall tyre diameter. There's a calculator for the + or - error from standard fit somewhere........?

This is my favourite, as it actually shows the tyres change size before your eyes!

http://www.kouki.co.uk/utilities/visual-tyre-size-calculator

There is an opportunity to enter your tyre size in the gear ratio calculator however, so you don't need to do any fancy calculations.

To check the accuracy of the speedo, my first suggestion is now actually useful (!) - compare the speedo reading to that on a sat nav.

Most importantly, as jezza mentioned, make sure you do have a 2y gearbox!

[fishnchipsx2]

When comparing the speedo to the satnav, you should find that the speedo reads 10% higher - this is what I've found on every car I've used a satnav in.

(My theory is that car manufacturers by law have to calibrate the speedo to within +/- 10%: they go for as high as possible, to make their cars seem faster to customers, and so they don't get people trying to sue them over speeding tickets...)

... That's what I reckon anyway!