Velox Rim Tape - Wide x2

You're going to cut the tape after you go around it (it doesn't have to be flush, in fact overlap it a little; I did by an inch or so).

As far as tubes, the stock tires at 20" x 1.5". It's important to note that when they use the decimal rating it's different than the fractional (1/8") meaning. Bike tire companies are weird.