[I]This is what happens when you don't drive your car, keep the tyres unused in hot weather for too long.
Dunlop Direzza DZ101 bought fresh in 2011 and approximately 7500 KMs used. Developed cracks, gone hard as nuts and reduced traction. And guess what? I never knew until I got them off to try another rim. Please keep your tyre healthy by using them and by dressing them. It's the MOST IMPORTANT investment one makes in his car. Choose sensibly.