I already have a good spare wheel carrier on my trailer but I couldn't find just the mounting brackets so I bought it for the mounting brackets. Obviously they don't want people to do that, which is why they use off-thread. They use 7/16 - 20. Good luck finding carriage bolts or nuts in this thread to use the brackets as is. I ended up just drilling them out and threading them to 1/2 - 13 so I can use them with the screws I bought. I could do 1/2 - 20 standard but I've already bought new screws.