Originally Posted by
haaseg
The patches do not stretch. They fully dry when the tube is inflated, and then when the air pressure drops, the tube underneath shrinks but the patch does not - causing the adhesion to break and wrinkles to form. A proper patch made out of rubber will dry before stretched and stretch with the tire.
...which doesn't explain why some patches work just fine and others don't - out of the same package, sometimes on the same tube...