On Nov. 11, 2007, Sara Monk got a phone call that changed her life forever.

"I received a phone call around 4 p.m.," Monk said.

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A bystander had called, telling Monk her husband, Robert "Chip" Monk, had been in a serious car accident.

"I called his cell phone and he did not answer, and still I'm thinking it's not him," Monk said.

At the time Sara was six months pregnant and she and "Chip" were planning for the arrival of a new baby. However, just a few hours later the reality of what had happened began to set in.

"It wasn't until four hours later, at night that the police actually came," said Monk.

On his way to a job in Georgia, Chip's Ford Explorer spun out of control on Interstate 75 near Ocala. The crash killed him instantly.

"You know one day we are getting ready to shop for baby stuff, the next day I am sitting in a room full of strangers being asked do I think that my husband would prefer to be buried or cremated,'" said Monk.

At her husband's funeral questions of how and why this happened began to mount.

"His friends at the funeral got together to tell me I might want to talk to a lawyer," said Monk.

She then hired attorney Rich Newsome.

"When we found out, it was a shock," said Newsome.

Newsome and his team of investigators quickly got to work.

They quickly zeroed in on a tiny part located on Chip's back right tire -- a car part many of us might not think to check -- the tire valve stem.

"I have never seen a case where the cause of the failure was a valve stem," said Newsome.

Newsome came to the conclusion that the tiny crack is what caused Chip's tire to blow out, claiming his life on I-75. Newsome's next goal was to track down where Chip got this defective tire valve stem.

Chip got his tires changed locally one month before the wreck.

Newsome's search for the source took him all the way to North Carolina.

"We started to work up stream to find out where the valve stem was manufactured," said Newsome. "We learned that it was a company called Dill out of North Carolina."

WESH 2 called Dill Air Control Product and found that the company received the defective valve stems from their parent company in China in 2006.

"We learned through the info that Dill told the government that they knew about this problem in the summer of 2007," said Newsome.

Dill admits it knew about the defective tire stems in the summer of 2007, but the company did not notify the public or the government right away.

Dill's general manager said the company waited until May 2 to issue a public advisory because they did not have enough complaints or an exact product number to issue a consumer warning.

Around this time Dill also contacted The National Highway Transportation Safety Administration. NHTSA launched an investigation that is still ongoing.

Dill now knows the lot numbers of the defective stems, but once installed, they are impossible to track.

So, any car on the road that has set of tires less than three years old could be driving around with this defective part.

This is one reason Monk is speaking out.

Millions of vehicles could be affected -- especially if your tires were changed in August 2006 or since then or if you have a 2007 model Ford.

Many of those models hit the showroom floor with the defective valve stems. If your falls into these categories, the experts advise getting your tires checked right away.