Actually I can get through one of my suppliers up to 160 mm ID with a 4:1 shrink ratio. The main problem with heat shrink is flexability. Wall thickness varies depending the amount shrinkage involved. I use heat shrink in place of tape on many wiring repairs. For additional thickness you just shrink the first tube and then add an additional tube to build up the recovered thickness if needed. Works very well when space is very limited where splice connectors are too bulky or where can can't get in to crimp them such as very short wires.
You just buy based what the recovered ID needs to be that way you get the maximum thickness.
