The 3.25 with the .87 OD gives a final ratio of just under 2.83. Use this calculator and plug in your values to see what RPM you’ll be turning at a certain speed. The tire diameter is the outside diameter of the tire not the wheel size. I suspect you'll have enough HP to use that setup. If you do go that route, let us know how it works.
http://www.advanced-ev.com/Calculators/TireSize/