ORANGE COUNTY, Fla. -- Something could be very wrong with your tires. A cracked tire stem is blamed for killing an Orlando man and a federal investigation has been launched to see how widespread the problem might be.

---

DOCUMENTS: Manufacturer's Warning | NHTSA Report

---

The stems in question are cracking, allowing air to rush out. If that happens while driving on an interstate, safety experts say it can be deadly.

The tire stem is the capped tube used to inflate the tires, but in Robert Monk's case, that stem fell apart and allegedly caused him to crash. Monk died on I-75 in Gainesville when his right tire blew out and caused his Ford Explorer to rollover. He was on his way home to Orlando to see his pregnant wife.

"There was a crack in his valve stem on his tire that led to a loss of air pressure. When that happened, his tires failed and he lost control," said Richard Newsome, the attorney representing the Monk family.

A year before the crash, Monk bought new tires at Discount Tire on John Young Parkway. His attorney says three tires had cracked valve stems.

"It's a hidden, dirty little secret the public just doesn't know about," added Newsome.

The valve stems in question were made in China and distributed by Dill Air Controls of North Carolina. Dill thinks its stems are cracking and leaking air because of ozone exposure.

The federal government is investigating and Dill sent an advisory to major tire retailers, but local stores don't know anything about it.

"You informed me this morning. I had no idea," said Craig Smyth.

Craig Smyth manages Formula One Firestone in Longwood. He says he's seen an increase in customers with tires that have leaking valve stems.

"It's not uncommon. We just chalked it up to an old valve stem," he said.

Thirty million suspect valves were shipped to the U.S. between August 2006 and February 2007.

If you replaced a tire after July 2006, safety experts say you need to have your valve stems checked for signs of cracking. The tire must be removed so you have to take you car to experts who say the Florida heat only accelerates the cracking.

Valve stems cost about $2 each. You can have them switched out for about $15 including labor. The government is investigating Dill valve stems, but safety experts are reporting cracks in other brands, as well.