Nailed it, deepblonde. Which is why I won't calibrate the speedo to be precise (with respect to a GPS i.e. true speed) on worn tyres - that could result in a Speedo reason low when new tyres are fitted.

Of course, this isn't what we are talking about here - we are only talking about making the speedo dial match the calculated velocity value - and it's that calculated velocity value that I'm not sure about.

And I don't think that the calculated velocity value is adjustable - or at least not in the way we are discussing. So it's all rather academic.

__________________
Wayne
2005 BMW X5 3.0d (b 02/05)
2001 BMW F650GS Dakar (b 06/01)