Astra digi-dash pulses

[ukhozi]

Anyone know how many pluses per Km (or mile) are needed for a Astra digi-dash.

I'm OK with transducers and the electrical side of things etc and I am using a three wire one which will count the number of gaps in a wheel or disc but I need to know how many pulses per Km or mile go up speedo wire. From that I can adjust the wheel/disc to give the correct number of pulses to suit tyres/wheel size etc. (in addition to the two red switches on the top of the speedo).
I guess the gearbox transducer counts the number of gaps in a gear in the gearbox rather than a spinning sensor such as the MG Maestro one I had which gives 4 pulses per rev of the unit.

Any help gratefully received.