Yeah, the glue part was gooey and there were loads of threads through it - just like duct tape that's been left on something for a while and fallen apart. The wheels and tyres are fully 80s (Dura Ace hubs and Mavic Gel 280 rims) so I was thinking that it was some kind of old school rim tape. Most of it came off with the acetone, my fingernails and a teaspoon. After it all dried off I glued over the remaining bits of glue and hopefully that will be alright.

11.4 and Ceya - thanks for the tips. I might try and get something a bit stronger than acetone for the front wheel. I'm more worried about the tub rolling on the front so I'll probably try a bit harder to get all the old glue off.

The good thing was that, after spending 45 minutes cleaning all the old glue off, the new tub went on easily without too much mess.