EARNS GOODYEAR

Four people were killed in Louisiana back in February, after the tread separated on a ten-year-old SUV tire.

There are a number of questions surrounding the tire industry following an investigation by ABC News into its attempts at blocking legislation that would require tires be inspected on the basis of age. The legislation comes as the National Transportation Safety Board is investigating the relationship between a tire's age and tread separation, following a crash involving a ten-year-old tire in Louisiana that killed four people.

According to ABC, the Rubber Manufacturers of America have spent $36,000 in a lobbying effort to defeat legislation in Massachusetts that would have included tire age as part of a regular vehicle inspection. Similar efforts have been made in seven other states, despite the arguments of safety consultants like Sean Kane.

"Over time, they become less elastic," Kane, who has been hired by both states and lawyers to go against tire manufacturers, told ABC News. "And once [a tire is] put into service it represents a significant hazard."

The RMA, though, disagrees on the safety of aging tires, arguing that there are other, more important factors at play. "We oppose legislation that have some sort of age limit on tires," said Dan Zielinski, executive director of Rubber Manufacturers of America. "It's more important how a tire is used, whether it's maintained and how it's stored."

As the NTSB continues its investigation, though, it's looking to side with Kane, as its lead investigator explained. "Aging does potentially play a role in the degradation of the internal structure of the tire," said Don Karol, the NTSB's lead investigator.

"Aging does potentially play a role in the degradation of the internal structure of the tire." – NTSB

Automakers and even tire manufacturers have their own warnings about the age of tires. According to ABC, General Motors, Ford and Chrysler all recommend tires be replaced six years after their date of manufacture, while Michelin recommends a ten-year shelf life, even if a tire has never actually seen the road. "If we are thinking about a universal practice that inherently keeps you safe, six years is a good place to go," Kane told ABC.

According to Kane, figuring out the age of a tire has been made almost purposefully difficult. While we enthusiasts might know how to read a tire's four-digit age code – the first two digits are the week of manufacture, while the last two are the year – that vital piece of information may just be another bit of gibberish on the tire's sidewall for the average driver.

"They did not want to put a date code on tires, specifically because they did not want to give the impression that tires might actually have a service life," Kane said.

What do you think? Should there be limits on tire age? Should the information on a tire's sidewall be made clearer? Should a check of a tire's age be a regular part of service? Take a look below at the investigation from this morning's Good Morning America, then scroll down into Comments and let us know what you think.