If you're going to tape the tires, get some Gorilla tape on ebay - normal gaffa tape simply won't do the job properly.. Make sure you clean the inside of the tires too, bit of soapy water and a scrub, then rinse off and let'em dry, helps the tape to stay stuck. Use 2 complete rounds of tape on the inside of each tire.
Tire choice comes down to what you're doing with the truck. For all purpose tires the stock HPI GT-2's are fine, will take a good battering on and off-road. For off-road only, I think that the HPI Dirt Claws are very good, or some Badlands http://prolineracing.com/tires/badlands-3.8-traxxas-style-bead-all-terrain-truck-tires/ (now only available with traxxas style beading, so you have to get wheels like the Desperados). The older HPI GT tires aren't bad either, and pretty cheap. If you want to go BIG then Proline Trenchers (the traxxas style ones) and again Desperado wheels http://prolineracing.com/tires/trencher-3.8-all-terrain-tires-mounted-on-desperado-black-wheels/ look good to me and people seem to like them, but they weigh loads, like all big tires, and put more strain on the truck. Fine for speeding about the place but not great for jumping.
Hope that helps