Nankangs were s**t on a 1.1 FIAT, just so you know. They're not called ditchfinders for no reason.
remove it then fill with sand or dry rice. Shake the hell out of it.cant find new replacements, problem with it being 31 years old i guess. plus just spent a silly amount of money on wheels, polishing and tyres so really must make sure i just buy the essentials now... exhaust being key now