So cracking of rubber is bad, it means its too hard and won't hook up in the rain as spec'd. It also indicates its either old, been in the sun to long, or the compound is not right. After putting in my goretex patches on my headlights I took notice of cracks on my front AD07 tires and not happy. It hasn't been raining in Cali as much as it should, however to my own QA knowledge this is a FAIL and a safety concern to ALL who're running these! Please inspect your tires and ensure you don't have cracks! I'll email [email protected] the Tire Rack and let him know soon. High performance tires should NOT be cracking.