Can anyone help me get the right values to set the speedo?

Im using a speedo sensor that plugs into the speedo cable. Think it came from Burton
It gives 8 pulses per revolution of the speedo cable.

I set the speedo to 8000 pulses per mile but it's reading too fast

Then realised my wheels are probably not the standard sierra

The size is 185 60 r14

Anyone know how many pulses per revolution I need to set?

http://www.locostbuilders.co.uk/viewthread.php?tid=93588

Cheers Myke, that thread has baffled me a bit more but I think I've worked out how many times the wheel goes round per mile so just think I need to sus out how many time the cable turns each time the wheel turns