"Radial tubes" are meant to be used in tube type radial tires, not in tubeless tires. I have personally seen what happens when a tube is put in a tubeless tire, especially when they are run a highway speeds. The friction between the tube ans tire inner liner causes exsessive heat, which leads to sidewall and tube failure, usually within 100 miles at highway speeds.
It should also be noted that with current DOT regulations, it is illegal to install tubes in tubless tires. That is why most tire shops (including the one I work at) will not do it.

Bill Burmeister