Here you go. When you get up to 4mm wall thickness it is a good candidate! This is how I get my luck. With enough product in the tube for some side wall protection. Sombody else will have a tire liner for you? I don't use these enough to say I know anything about them.
Cannot say I have not used any 20'' combinations to lead you anywhere specific? I stay 24 inch or 26 inch. On my Large Marge rimes with 24 inch tires. I found a awsome motorcycle tube. Nice commercial grade. 4mm thick or better I remember right. That tube combo was perfect. The tube was the right size IME as it did not streach at all to meet the tire. ''Remaining in facto a thick tube''
Now a twenty inch tube in the right tire combo can use a commercial grade moped/motorcycle tube. If a fellow was to look around I know a flawless cobo exist out here!