Tubolito S-Tubo MTB Tube - 27.5/29 x 1.8-2.5" 42mm Presta Valve OrangeTubolito S Tubo MTB Tube 27. 5 29 x 1. 8 2. 5" 42mm Presta Valve Orange. The S Tubo MTB was developed to have a minimum possible packaging size making it an ideal spare tube. With a removable valve stem the tubes have a size of only 35cm x 5cm height when packaged. Not only intended as a spare the S Tubo has the puncture resistance as a standard butyl rubber tube but at a significantly reduced weight. S Tubo series tubes are intended for spare tube