VDO replica gauge calibration

I'm interested in a set of the VDO replica gauges, as sold by Vintage Speedsters.

Does anyone know what diameter/radius of tyre they are calibrated for ? I'm running 195/60x15s at the moment, and want to know if they will be accurate.

Can they be recalibrated, or is the calibration fixed ?

Does nobody have a set of these gauges ?

I'm sure they are set for the OEM size tires 165/75x15. Go to:

www.miata.net/garage/tirecalc.html

and you'll see difference - which is not enough to bother with IMHO.

165 has dia of 24.7", circ 77.7, 815 rev-mile while the 195 has dia of 24.2", circ 72.1, 833 rev-mile. So when speedo reads 60 you will actually be doing 58.7. Only a 2.1% difference.

I've found the above site very handy despite the Miata monicker!

Thanks, I agree the difference doesn't sound like a problem.

This site is also very useful:

www.chris-longhurst.com/carbibles/index.html?menu.html&tyre_bible.html