Folks, I agree with everything that is being said about the affect of ozone on rubber and etc. but I am still convinced that Avon has, or had, a problem. Over the years, my bike has sat through the winter in the same exact place with no differences from year to year and my last set of Avons were the only ones that have ever cracked like that. I've had Dunlop and Michelins before and none of them cracked. I took a chance and replaced them with another set of Avons and so far, they seem to be doing OK. Haven't looked at them closely though. Will do so before the riding season starts. I really like the Avons but if this set cracks, it will be my last ones.