tubes in a tubeless tire, in a word
NO
A tubeless tire has a thin membrane (interestingly enough called the inner liner) a bout a red, you know what hair thick. The entire purpose of this inner liner is to prevent air from seeping out. The inner liner is composed of synthetic rubber as opposed to the natural rubber on the outside of the tire. The purpose being , the synthetic rubber is not as permeable to the air in the tire as natural rubber would be. However, synthetic rubber does a piss poor job of rejecting heat (to which natural rubber is far superior). Now onto the problem this creates. By placing a tube in a tubeless tire, you have two items rubing against each other, building up heat and neither one being very good at rejecting it. As the heat builds the inner liner and tube begin to deteriorate at a greater degree than if used properly. This can lead to catastrophic failure of the tire (which could at best lead to inconvience or worse a life threatening situation).
Most people get lucky (including stupid me before I gleaned a sliver of knowledge on the subject) and get away with using a tube in a tubeless tire, however remeber your in a lose/lose situation here if you do decide to mount a tube in a tire
