For the third time the tire stem has ripped causing my tire to completely deflate. The first couple times I was either on the highway, or just gotten off the highway. Both of those times the tires were ruined. This time I had only driven a couple blocks before I realized something was amiss and stopped so I'm hoping the tire could be saved. The rubber valve stems just rip right at where it goes through the wheel. No, I don't grind my wheels against curbs or anything that would damage them, so I'm kind of clueless. Could it be that they were just cheapo valve stems that were installed?