Defeated by Nobby Nics!

[Peachy!]

Or…..
Use a citrus based adhesive remover, it will attack the contact adhesive but not the rubber.

https://www.ebay.co.uk/itm/165061992378
Tensorgrip C101 is my preference.

 

[greencat]

I think I'm just going to leave the Nobby Nics where they are, a tad more rolling resistance than I'd like, but they're decent enough tyres when you get on the trail.

Thanks for all the input.

Probably best solution. Just pray you don't have to fix a puncture with a tube one day!

I have ended up cutting off one particularly stubborn set of tyres. You can try all of the tools, techniques etc suggested but sometimes your time and sanity is worth more than saving a tyre.