10 cars have tire issues in final practice (Update)

UPDATE A Goodyear official said there were 10 incidents with tires during practice at Auto Club Speedway the past two days as some Sprint Cup teams struggled to adapt setups. With new suspension rules leading to increased speeds and downforce, tires were facing more stress than ever on a 2-mile oval whose abrasive surface already causes as much wear as any track in NASCAR's premier series. "I think everyone is trying to be aggressive and get as much grip as possible," Goodyear's director of race tire sales Greg Stucker said after the final session Saturday afternoon for the Auto Club 400. "A couple of guys had more problems than others."

Team Penske was most affected with five tire problems between the Fords of #22-Joey Logano and #2-Brad Keselowski. Logano will start from the rear of Sunday's race in a backup car after hitting the wall, as will Furniture Row's Martin Truex Jr., who suffered a left-rear flat in his # 78 Chevrolet when entering turn 1.

Stucker said teams' problems predominantly stemmed from left-rear tires that were run under the minimum recommended air pressure of 20 pounds. Teams push the limits on air pressure for better handling and speed, and Stucker said there were other teams that were below the minimum pressure that didn't have problems. Stucker said the same tire was used the past two seasons at Fontana, and Goodyear believed it was structurally sound for use after teams adjusted to this season's changes to the Gen 6 car. "It's not just air pressure, it's what else is under the car, and that's what everyone is trying to get a handle on," Stucker said. "Let's face it: We have a different race car than last year. I'm confident everyone will adjust." USA Today

03/23/14 Final practice was anything but 'Happy Hour' for Team Penske, as the organization's two cars suffered multiple tire failures over the course of the session.

In the opening minutes of the session, Brad Keselowski slowed with a flat left rear tire, which brought out the red flag as he was pushed back to the garage. The issues were far from over, however. With only 15 minutes remaining in the final session of the weekend, Keselowski's teammate Joey Logano suffered another tire failure and hit the outside wall. As a result, the team was forced to pull out the backup car and give up their seventh-place starting spot for Sunday's race. According to Logano and Team Penske competition director Travis Geisler, Goodyear officials seemed to believe the issues was a result of low air pressures and increased camber, not a problem with the tire.

In all, the Team Penske cars had five tire failures over the course of the two practice sessions.

Goodyear's Director of Race Tire Sales Greg Stucker said the left-rear tire problems were caused by a combination of too-low air pressure and too much camber in the left rear. And those two factors put too much load on the tires.

"It's not a lack of grip and it's not a wear situation, it's a load situation," said Stucker. "The tire needs air to support that kind of load, so they're just trying to get as much grip as they can with taking the air pressure down."

The Team Penske cars were not the only ones to have tire failures in practice, though. Stewart-Haas Racing teammates Danica Patrick and Kurt Busch also slowed with flat tires, but were able to avoid any contact with the wall.

In Saturday's first practice session, Martin Truex Jr. cut a left rear tire and made hard contact with the outside wall. The driver of the No. 78 Furniture Row Chevrolet was also forced to a backup car as a result of the contact. Fox Sports