I'm pretty sure that getting your wheels engineered isnt just for custom built cars...

As for wheels 'poking', i have heard of people whose wheel is outside the guards slightly, but suspension travel doesnt allow it to touch the guard; I mean i understand that it should be illegal because if you allow wheels that are 2cm out, then there would be nothing stopping people with open wheeler race cars riding around on the roads... but i hardly think 2cm is a threat to society!