"Radial tubes" are intended for tube type radial tires, not for tubless radials. Running tubes in modern radial tires is a recipe for disaster. Causes too much friction internally, which causes sidewall failure. This is especially true when the tires are run at highway speeds. Should also be noted that all current tire manufacturers state that use of tubes in their tires voids any warrantees.
I've been in the tire industry for almost 20 years, and have seen firsthand what happens when a tube is used in a tubeless tire. When it fails, it isn't pretty.
