2005 Ram 5.7 speedo adjust

I am trying to adjust speedo in 05 Ram ECU and Tech support says they don't support the gear/tire pulldown for this application. what would the proper route be to adjust to 4.88 gears and a 35" tall tire.. 1/2 the reason I bought this was for gear and tire changes. My trans is confused as hell right now and short shifting on me. FYI- this is in a 2003 Wrangler using Ram ECU

Probably will need access to a factory tool and get as close as possible using the tire sizes and gear choices that are in factory avail. should get you there.