Originally Posted by prathmann

It's not just the weight savings since a thinner tube will reduce the rolling resistance. As the wheel rolls the area near the contact point of the tire is compressed and energy is lost bending the tire sidewall and the tube. The more flexible these are, the lower the energy losses. But yes, the downside is that thinner tubes (and esp. latex) will let air diffuse through more readily so you need to pump up more often.

Some rolling resistance comparisons were cited here:
http://www.powertri.com/index.asp?Pa...ROD&ProdID=648
"Let's look at that all-around good rolling resistance tire, the Michelin Pro 2 Light. With a latex tube, a rolling resistance of 0.0026, or 342.7 watts using that same rider at 24.6 miler per hour. If you were to switch to a standard Bontrager butyl tube, your rolling resistance goes from 0.00266 to 0.00322, 347.7 watts. A full 5 watts slower, which would equal about 9 seconds over a 40K time trial."