WASHINGTON, D.C. — The National Transportation Safety Board (NTSB) is investigating two fatal crashes in February that involved tire failure — in one case leading the vehicle to collide with a school bus.

The first crash occurred on Feb. 15 near Centerville, La. According to the NTSB, the driver of a 2004 Kia Sorento lost control of the SUV after the left rear tire experienced a tire tread sidewall separation and rapid air loss. The SUV veered across a grassy median area and collided with a school bus that was carrying a high school baseball team and traveling in the opposite direction.

The SUV driver and three rear passengers were killed. The fourth SUV passenger was seriously injured. Of the 36 school bus occupants, 31 received injuries, ranging from minor to serious.

The NTSB said that the tire involved in the Louisiana crash, a 10-year-old Michelin Cross Terrain, had not been the subject of a product recall. However, another recent crash that the agency is investigating did involve the failure of a tire that was part of a product recall.

The second crash occurred on Feb. 21 in Lake City, Fla. The driver of a church van — a 2002 Ford E-350 XLT 15-passenger model — lost control after the tread separated from the left rear tire. The van rolled over, and two adults and two juveniles were ejected from the vehicle.

The two ejected adults died. The remaining occupants, one adult and seven children, were all injured.

The tire, a two-year-old BFGoodrich Commercial T/A A/S, was part of a July 2012 product recall initiated by BFGoodrich for approximately 794,000 tires typically found on commercial light trucks and full-size heavy-duty vans.

The safety recall notice sent to tire owners in July 2012 said that “it is possible that any one of the tires being recalled may experience tread loss and/or rapid air loss resulting from tread belt separation. This condition may increase the risk of a vehicle crash.”

The NTSB said that it will examine the tire and review the effectiveness of the product recall process to determine whether the church that operated the van ever received the safety recall notice.

The failed tires involved in both accidents will undergo a laboratory analysis to identify the factors involved in the tread separations.

A preliminary NTSB report on the Louisiana accident is available here.

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