Poppy's 5th Wheel wrote:
Here's where I bought mine when I did the same upgrade on my last trailer. They're very friendly and helpful if you have questions.
http://www.trailertiresandwheels.com/
The biggest thing is to make certain you will still have at least 3" between the top of the new wheel/tire combination and the floor of the trailer. I did not do this and it was a real problem. Solution was having a 2" sub-frame fabricated and welded in place between the trailer frame and new hangers.
So had you been told by the dealer that the trailer had been constructed to fit the 16 inch wheels? How level did your rig sit with the 15's and /or the 16's. My truck is the 2005GMC duramax 4x4.