Im just wondering if i could have my plate mounted vertical or down it need to be horizontal, right now i have it mounted vertical on my nightster with the factory side mount, but im just checking to be sure this is leagal to have it mounted this way

 

I'm no legal expert, but as far as I can tell, it needs to be mounted horizontally. See section 341.15 of the link below. Now whether they choose to enforce this on a motorcycle or not is another question. My guess would be that if they are looking for a reason to pull you over, this would give it to them.

http://www.legis.state.wi.us/statutes/Stat0341.pdf

 

Do not take this to the bank but , in beer city we would go through the city early on a Sunday am gust to rattle the windows and set off car alarms. Needless to say when you pass a bike you drop your arm to wave because the cop comeing at you is doing the same thing.

 

I have mine mounted horizontally under my saddlebag on my Road Glide. My friend has his vertically on his Night Train and he has had no problems.