I have been lead to believe that if the number plate is viewable from a 45 degree angle whilst standing at the rear of the bike then it's legal. I've seen others the sit further down on the axle that were passed as well. Im open for suggestions ( other then go f**k myself) for ideas to clean up the rear of my FXSB breakout. 

I found this: https://www.google.com.au/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CBwQFjAA&url=https%3A%2F%2Fwww.sa.gov.au%2F__data%2Fassets%2Fpdf_file%2F0019%2F19153%2FMR808-Motorcycle-and-Sidecars-9.13.pdf&ei=OnHnU7mLIZTroAS3pIHgBg&usg=AFQjCNE6OuQRiiz0aXoWUh0Wa7beS6ntEg&bvm=bv.72676100,d.cGU

 

and this is for choppers: http://www.google.com.au/url?sa=t&rct=j&q=&esrc=s&source=web&cd=5&cad=rja&uact=8&ved=0CD0QFjAE&url=http%3A%2F%2Fwww.rms.nsw.gov.au%2Fregistration%2Fdownloads%2Fvsi%2Fvsi28.pdf&ei=UXDnU5D8NYPyoAT86YGYBg&usg=AFQjCNF6FDxWcZ3AhTd1OgHi9Iu8p8MmuQ&bvm=bv.72676100,d.cGU

They both have information about the rear guard on motorcycles , with any luck somone who knows which one would apply to your bike will reply.

I read (on this site) recently that it depends on which state you are in, but someone else said the ADRs (so Australia wide) do not allow side plates, vertical or not. I can't be fucked looking up the ADRs since I'm not doing it

Best way to find out would be to contact your State Roads Authority, eg. Vic Roads if your in Victoria. etc.

Thanks. I seen one at a dealer here in NSW. I commented about he plate and was to that it passed as it was visible from 45 degrees if you stood at the back of the bike. I get onto the RTA and see what they say.
Thanks for the help fellas.

http://www.rms.nsw.gov.au/registration/downloads/vsi/vsi_58_number_plate_visibility_march_2011.pdf

Looking at the diagram at the RMS site that plate position would be legal. Thanks again for the help gentlemen.

Yeah, its got be on the rear Guard.

Of course not Big Dave, Its a yankee plate ya goose! jeez i gotta tell ya.

No. Simple.  In Vicbloodytoria you would be lucky to see the day out before copping a defect.  Shit, I'm willing to put a slab down you would'nt last a week down here!  Australian Road Rider Mag had a big article on this and their legal guy was of the opinion its no go.

and as it aint my bike, why would you want to "clean up" the back of your bike by adding the street sign.