The guys at Goodyear said they've seen this problem quite often and when I took it to the Buick Dealer for diagnosis (said check engine light) & repair, they told me they had seen it quite a bit also. I asked what made it crack & they said warming & cooling this winter. I have owned alot of cars & never had this problem before. Before the part was rubber - now plastic. Defective parts if you ask me. I contacted Buick & they wouldn't reimburse me.