Agree Must UNDER read now..... when new.
Variables: New tyres v's worn tyres induces an error & Tyre profile changes induces error.
Smaller diameter over reads, larger diameter under reads.
As of the
1st of July, 2006; all new model motor vehicles in Australia must comply with ADR 18/03 which is aligned with UNECE Regulation ... Which is an 8 kph variance, @ 24.5 c, with a 75 kg driver, an unladen vehicle, level road surface, read with a check instrument with a +/- 5% accuracy.......Yadda Yadda....
What's the average age of registered vehicles in W.a?
Interesting read:
http://www.trafficlaw.com.au/speedos.html