Originally Posted by
cyccommute
A rubber tube would expand and elongate much more than a TPU tube which isn’t very stretchy at all, contrary to what has been written above. The instructions on the TPU tubes say not to inflate them too much outside of the tire or the tube will be damaged.
The relevant property here, is that TPU tubes don't UN-stretch as much as butyl after you've over-inflated them. So they're always a little more difficult to install, doubly so when you've stretched them. Good news is they're pretty tough so even if you pinch or fold it going in, it'll still probably work at least as a spare... might be lumpy.