TPU means thermoplastic polyurethane, a material used for lightweight bicycle inner tubes. Schwalbe’s Aerothan, for example, was developed with BASF and is made into tubes using a patented welding process. Changing the material also changes the handling requirements.
Tubolito’s instructions explain that an inflated tube does not return to its original shape and size. A used tube should not simply be transferred into a differently sized tire. Choose a model matching the tire and rim width, and check for twisting or pinching beneath the tire bead during installation. Correctly fitted rim tape is required even on tubeless rims.
Inflation limits outside the tire differ: no more than 0.3 bar for Aerothan and 0.5 bar for Tubolito. These are not riding pressures. Check the particular model’s approval for rim brakes, too. Use the specified repair kit: Tubolito calls for its Tubo-Patch Kit, and ordinary butyl-tube patches are incompatible.