Austintatious, your trailer must sit higher or something in order for the 15" wheels to fit. I looked at mine, and the 13" barely fit. I also found a big problem, the tire has scrapped the upper wheel well. Also have a dent on the frame where the u-bolt hit it. Apparently I bottomed out the suspension on this one section of highway that has a nasty, but barely visible bump on it, and doing 55mph, I did not see it until I hit it with the truck. Yeah, the trailer did bounce.
So it looks like I'm going to have to flip the axle just to get some more clearance.