Another Tire Recall, But No Warning About Tread separation?

 Hercules Tire & Rubber Company is recalling certain radial truck tires, size 315/80R22.5 Load Range J. The affected H502 tires were manufactured between December 25, 2011 and May 26, 2012 in China by Sailun Tire Corp.
 
According to NHTSA’s announcement, Hercules Tire & Rubber Company believes 1,222 tires may have inadequate inner liner thickness due to malfunctioning equipment used during the tire building process. The announcement says that insufficient inner liner gauge can cause “voids” to form causing a risk of sidewall separation. 
 
NHTSA announced that the Hercules recall will begin on August 17, 2012, when the tire maker will send notifications to specified Hercules tire owners regarding the recall. The defective tires will be replaced and new tires will be mounted and balanced free of charge.
 
The announcement did not say whether there have been any accidents or injuries related to the problem. 
 
Reading the recall announcement, it’s interesting to note that there is no mention of the more traditional problem caused by defective inner liners – tread separation.   Tread separation is the most common tire failure mode with steel belted radial tires.
 
The inner liner – which is typically made from dense rubber containing halobutyl rubber (which is a very expensive rubber) is designed to act as a barrier between the pressurized air inside the tire and the internal components of the tire – including the “skim stock” which coats the steel belts and helps them stick together during use.  If the inner liner is thin, or poorly made, it allows oxygen to penetrate through the inner liner and deteriorate the tire’s internal components. Which is bad.
 
Oxygen deteriorates rubber.  Over time this deterioration can cause cracks to form between the steel belts and eventually can lead to a tread separation.  A tread separation occurs when the bonds that hold the two belts together are ripped apart by centrifugal force, causing the tire’s tread to tear partially or completely off from the rest of the tire.  Because tread separation is usually a catastrophic and sudden event that happens at highway speeds, it can be extremely dangerous. 
 
So, while the Hercules recall is commendable – as is any recall by a manufacturer when they become aware that their product might be defective and put the public in harms way – it might not tell the whole story about the entire scope of risk posed by the defective inner liners.   
 
Time will tell.  Hopefully all of the bad tires will be pulled off the shelf and road.    
 
For more information, owners may contact Hercules Tire & Rubber Company toll-free at 1-800-677-3573 or the National Highway Traffic Safety Administration (NHTSA) Vehicle Safety Hotline at 1-888-327-4236. Consumers may also visit safercar.gov.