I just completed the 15" upgrade doing the lift and changing to Maxxis 225 75R 15 Load Range E. I'll be running them at 70 psi and the first spin that I took with them, I could not notice any difference in "bounce". Here is a link to the Maxxis Tire Inflation chart.
http://www.maxxis.com/trailer/traile...nflation-chart
According to this, the load rating at 70 psi is 2620#'s which is about what the wheel rating is, 2600#'s. Also it's over the trailers rating which gives me a warm fuzzy.
Checking out the WDH after installation, I didn't have to do anything to the adjustment there. Everything seemed right on the money.
I did have to add about a 3/4" drop to the spare tire carrier but that was no big deal.