2002 BMW 325 User Comment / Complaint

My husband has 2 sets of tires one for summer and one for winter. the summer tires are the ones with the defect. the tires have only been used for 2 summers and the car is not driven a lot. the tires still have about 60% thread on them. recently we noticed that the tires are bubbled on the inside and previously one cracked. i don't know what to do. i feel like the tires should still be good for another 2 years, but with the bubbles i'm afraid they'll blow up. the tires are dunlop w10 18" 235/4018. please help, i've looked on their website and there is not contact. the store where we purchase them is closed.