I just bolted up a set of 13" galvanized rims with ST175/80D13 tires (24" diameter). 4 on 4 bolt pattern. Bought them on Amazon for $121 delivered. These replace the 21" diameter 4.80-12 rims/tires that came on my trailer.
As you know, this tire is wider and therefore there's less clearance between the sidewall and the frame/bolt heads. I removed the steel hinge and replaced it with 1/4" aluminum flat bar. Due to that, I only have about 1/4" of clearance between the sidewall and the bolt heads. So...going to do two things to make this better.
1. Change out the stock hex head bolts for tapered head bolts that will sit flush with the flat bar - net gain of 0.25"
2. Install 1/4" wheel spacers between the hubs and rim - net gain of 0.25" (these will be cut on my CNC at work, but they can be bought online for $10-20 each)
All in, the sidewall will have 0.700" - 0.750" of clearance. Should be plenty.
I know that spacers change the pressure on the bearings. Pretty sure 1/4" isn't going to make any real-world difference.