On my 2nd build I used inexpensive dept. store aluminum 26" x 1.75" (equivalent) rims/14G spokes. However I rebuilt the rear with a Tomos moped hub & 11G spokes.
Front tire = 26" x 2.125", rear = Boa G 26" x 3.45". Running a big Greyhound 200 engine/Comet Torque-o-verter, and so far no issues directly related to that.
-Kirk