I had just put them on earlier this year, but the rear tire was my spare that had been sitting in my closet for at least 2 years (front was brand new). I'm wondering if the cuts on the inside were really cracking from the tire being folded/packaged for so long, and I got the outside cuts on this ride which let the air out. The tire was never stored out in the elements (was inside in a dark closet) so it shouldn't have had any issues, but who knows how old it was when I got it. Needless to say it went in the trash and I put a new (recently purchased) tire on.