The last set i saw(13" tryes) were just on a year old and i had to provide a set of photo's to Avon before they would even consider sending new tyres!! They were originally purchased from Caterham but they refused to have anything to do with the problem. I thought the contract was with the purchaser ie Caterham but that cut no ice at all- told to contact Avon. Seen far more 15" tyres with this problem than the 13" size.
Regards
Richard