Okay, good. The OEM rear wheel actually has the 'tubeless retainer ridges' (or, whatever they're called) built into the rim, while the front does not. This means that seating a 'tubeless' tire on the rear rim will require both more lube and more air pressure to 'pop' the bead, because of the ridge, and the way a tubeless tire fits more closely to the rim to eliminate air leaks. Regardless, the number of rim penetrations for spike nipple holes means you still have to run a tube. Most motorcycle tubes have a straight threaded stem, in a standard diameter and of various lengths - most any will work on a KLR so long as the actual tube size is correct. Standard would be a 90/90-21 front (2.75/3.00-21 in inch sizing) for the front and a 130/80-17 (5.00/5.11-17 in inch sizing) rear for both tires and tubes.