CHARLESTON, SC (WCSC) - South Carolina's school bus fleet carries hundreds of thousands of students to and from their homes.
But more than 5500 hundred buses come with a bunch of potential problems related to age.
Buses in our state are the oldest in the U.S. More than 60 percent are at least 15 years old, and about 1200 have been on the road more than 21 years.
Lawmakers approved $18 million in spending this year to replace older buses. But even new busses can still have another issue, old tires.
It starts where the rubber meets the road. And in many parts of the country, including South Carolina, the condition of that rubber could mean the difference between life and death.
"An aged tire is nothing more than a ticking time bomb," said Georgia attorney Matt Wetherington who specializes in defective product litigation; he's also the founder of the Tire Safety Group.
It's an organization aiming to prevent wrecks due to bad tires.
"Tires age dangerously and they age from the chemical process called oxidation," Wetherington said."They also age from the mechanical process of the tires flexing and fatiguing over time. A tire that is in use will have a cumulative effect for every impact it ever encounters. And so over time, tires are absolutely dangerous as they reached an advanced age."
Nowhere could that be a more critical issue than with tires on school buses.
Yet in some places here and in other states, students may be riding on rubber well past its prime.
Over the past few months, our Raycom Investigative team has been spot-checking bus tires in districts around the state.
You can't always tell the condition of a tire just by looking at it. Researchers say what appears to be a new or low-mileage tire might be more prone to failure based on several factors.
Underinflation for instance or if the vehicle has been operated in a hot climate over a long period of time, and some say, if the tire is more than six years old.
There's a way to determine when the tire was made. It requires finding and reading a four digit code on the sidewall.The code is contained in an oval to the right of the letters DOT.
The first two numbers tell you the week the tire was manufactured. The second two indicate the year.
So the code, 0407 means a Clarendon District 2 bus tire was produced in the fourth week of 2007.
One problem, the code is often only molded into one side. If the tire is mounted with that sidewall facing underneath the bus, the code can be hard to see.
That was the case in roughly half the buses in the investigation. Even so, we did find 25 tires more than six years old.
Sean Kane of Massachusetts-based Safety Research and Strategies is among experts who say tires six years or older start to become risky even if they've spent much of that time sitting in a warehouse.
"No one is saying that at six years and one day, your tire is going to fail," Kane said."But at six years, those tires represent a much increased risk. And that is based in science."
But tire makers argue that science is very much in dispute.
"There's no data to support that chronological age is a primary factor in tire safety performance," said Dan Zielinksi, a spokesman for the Rubber Manufactures Association."What data does support is that proper maintenance and the use of a tire have a much stronger impact on a tire's safety performance."
A spokesman for the South Carolina Department of Education declined repeated requests for an on-camera interview. In emails however, Dino Teppara said state law requires each school bus to undergo a thorough annual inspection.
This includes tire tread depth, proper inflation, mounting hardware and a check for possible cracks. In addition, he says tires are removed and examined every six weeks, and that bus drivers are supposed to inspect their tires daily.
But Kane says when it comes to old tires, even those procedures might not be enough.
Tire failures can occur regardless of the age of the tire.
A ten year old tire can be perfectly safe if it's been properly used and maintained. A one year old tire can be an accident waiting to happen if it's not been maintained, or if it's been damaged and not removed from service.
We contacted 19 districts for permission to check bus tires. Eight districts gave us that permission.
We were only able to see the manufacturing date code on 920 tires. But of that group, we found just 25 to be six years old or older.
That's less than three percent.
Again, if tire manufacturers are to be believed even that number is meaningless without taking into consideration use, maintenance and operating conditions.