My tyres are £140+ a pop, so I'd pay the £40 - £80 to insure all 4 tyres.
In the South of England there is continuous, 365 days a year building and development work taking place with new housing estates, lorry depots and offices been constructed. This has led to loads of loose builders rubbish and tools being stroon on the roads. The amount of screws and blades I've had in tyres due to careless builders not securing their van gear/rubbish is not funny. As soon as one development starts and I change routes to avoid it, another starts somewhere else.
And there's the loose rubble chipping my car paint......can't have nice things.