Tyres are only made to last for a couple of years perhaps 25,000miles in average use. BMW recommend changing your tyres at 6 years irrespective of mileage, however my neighbours BMWs tyres were cracking at 4 years though not worn out so he changed them.
I changed my Morgan tyres at 7 years and 13,000 miles. Not expensive and worth it for peace of mind.
Similar on our Mini Clubman. Front tyre walls near tread edge showing signs of cracks after three years and 25,000 miles. 225 ZV7 's fitted late last year with noticeable turn-in improvement although its was very good before.
