My mother has a 1st March 2007 Peugoet 307 SW with Pirelli P7 tyes on 16" alloys. it has now done 26,500 miles - I can see very minor cracks on the side walls of the tyres.

I would like to know if I should think about replacing these tyres? The treads themselves are well within the required limits, but I worry that the tyre walls may become prone to blowout, particularly as the car does not do too many miles each year.