Bought a set (4) of S637 ST235/85R-16 from SimpleTire as suggested by many here on Moc. Had one with slow leak, took to shop for repair, could not find leak so they broke it down and had a defect on inside edge of tire where it seals at the wheel rim. A 6-7" strip of rubber was missing causing very slow leak. I called Sailun (my mistake) they said to call SimpleTire and they would send me a new one right away....I thought maybe I was getting the run-a-round...called SimpleTire and before I could even tell my whole story the young lady said she was sending me a new one and I would get it in 3-4 days!!!! And they are picking up the defective one tomorrow! WOW! what service! I was so happy that I went ahead and bought another one for my spare. Yep, Sailun & SimpleTire were great.