Avon tyres have got a scheme called the Road Hazard Warranty.
If one of their radial tyres becomes damaged or punctured they will replace it free of charge, as long as there's no more than 1mm of wear on the centre of the tread.
To make a claim, call Avon Customer Services on: 01225-357750. They will direct you to a participating dealer who has got a replacement in stock and can check your rubber meets the requirements.
All you have to pay for is the fitting costs.