Originally Posted by
dabac
Inflate tube outside tire to about double size.
Does it swell evenly or with lumps and bumps?
A tube that looks like a recently fed snake will have uneven tube wall thickness and may well explain your problems.
I went through a bad batch of Geax tubes some years ago. When I cut one open the differences in wall thickness became obvious.
If you inflate a tube to double its size, the tube is being stretched a certain amount right? If you then stuff it into a vessel that constrains it to less than that stretched size, the tube is experiencing less stretching right?
Let me illustrate the differences in loading, you may want to follow along with a physical experiment.
1. take a Kleenex tissue paper and completely wet it. Carefully wrap it over the top of a bowl where it can cover top. Hold it where it wraps around edge. Place an orange or heavy object over the wet tissue. What happens?
2. take another Kleenex tissue paper and completely wet it. Lay it out on a tabletop. Place an orange or heavy object over the wet tissue. What happens?