[DISCLAIMER] I do not live in NC, do not have my trailer regsitered in NC, and am not a lwamaker/law enforcer in NC [\end disclaimer]
My home made car hauler trailer also rides on mobile home axles.
I have replaced the tires, but have been unable to find any tires that do not say mobile home use only, and the tires were HELLA EXPENSIVE.
In hindisght, I could have ordered brand new axles rims and tires from Northern for what I spent on 4 tires and brake replacement parts for the MH units.
Now in fairness when I needed this done I was out of town and did all part locating through wife/internet and bought first found items and didnt ahve a lot of time to price shop.
Tires were $175/each...I probably got screwed here but have not even bother to research because I dont wanna know how bad
But the 13.5 rims size is pretty specific and not very common. I have heard there are 14 inch MH axles out there, I have lookd at every set I see and only come across the 13.5s
Brake parts were a whole nother...They were bought off the net fro some yahoo that shipped them inside a 24-pack buweiser box, taped all to hell and I paid $150 for one axle worth of drums,pads, and parts.
At the time I had posted on here someon recomended rednecktrailersupply.com
I contacted those folks and they said they did not sell MH axle parts.
I have since had that recommendation reaffirmed by several others who say they HAVE BOUGHT from them...not sure if this is any help but worth noting.
All that said and out of the way.
Stopped last week in NC by DOT officials. We were let go (after 1 hour and 45 minutes of roadside chitchat) because we were from SC and were 2 miles from state line but were told that those axles were not legal in NC and I could be cited for reckless driving for pulling an unsafe trailer.