CHARLOTTE, N.C. — A top NASCAR Sprint Cup Series official apologized Tuesday for the tire issues that marred Sunday's Allstate 400 at the Brickyard and said NASCAR and Goodyear have started working on avoiding another similar debacle.

"I can't say enough how sorry we are," said Robin Pemberton, NASCAR Sprint Cup Series vice president for competition. "It's our responsibility being NASCAR that we don't go through this situation again."

Pemberton's comments on a teleconference with reporters made him the second top NASCAR official in two days to apologize for the race Sunday at Indianapolis Motor Speedway, in which teams were unable to run more than about 10 laps before tires wore out beyond use.

Jim Hunter, NASCAR's vice president of corporate communications, also apologized Monday.

Pemberton said NASCAR and Goodyear officials had a long conference call Tuesday morning to begin assessing what went wrong.

"We're still working on it," Pemberton said. "We're trying to find out what was different, if anything, but everybody's pointing toward the fact that the rubber looked to be a little bit drier or a little bit dustier."

Goodyear officials say the right-side tires, which caused the problems at Indy, were made from the same tread compound as the tires used in the same race a year ago. Unlike last year, Sunday's race used the "car of tomorrow."

Track chairman Tony George said in an interview with The Indianapolis Star the surface was not a factor. Pemberton agreed.

Pemberton said Sunday's race was a disappointment to everyone who worked to stage it for NASCAR.