Upgrading Tires from 15" to 16"- 2006 Cougar 285 EFS

I did this in 2009 with my old 5th wheel, a 2001 McKenzie Lakota. Like you the only clearance issue I had was from the top of the tire to the bottom of the wheel well, my axles were already flipped so I had 2 inch solid steel blocks added to rise the trailer and that gave me the clearance I needed. I had at least 6 blowouts with the ST tires, after changing to the BFG Commercial T/A's I had none.