I didn't roughen the rubber tread, that might be a good idea as the tried UHU glue seems to come off quite easily.
I have access to some Evo-stik non drip contact adhesive which I will try. I've seem a dried glue (on something that's been glued) that's really rubbery but I don't know what it is.
Scotch Grip 847 seems to be quite hard to get hold and expensive as well.