TALLADEGA, Ala. -- Sunday's Amp Energy 500 set records for 64 official lead changes among 28 drivers, featured a confusing finish between a veteran driver who had never won a Sprint Cup race at Talladega Superspeedway and a rookie who had never won at this level, period.

And yet, much of the focus of the day was on Goodyear's tires -- again.

Hamlin to hospital

Denny Hamlin was taken to a Birmingham hospital Sunday after a tire failure led to a hard crash at Talladega Superspeedway.

NASCAR said Hamlin was alert and awake, but was transported for futher observation. Hamlin was complaining of a headache and was favoring his right foot after his slow exit from his crumpled car.

"The tire went down and it was quite a shot," Joe Gibbs Racing president J.D. Gibbs said. "He's got a little headache, so they're just going to watch him. It was a scary deal, but it's at least nice that he's alert and with it."

Hamlin was leading midway through the race when his right-front tire failed and his Toyota shot into the outside wall. He said nothing over his in-car radio after the hit and was slow to get out of the car.

Crew chief Mike Ford said he was unsure what happened to the tire, and did not have a chance to speak to Hamlin.

"But it happened so fast, I doubt he even knows," Ford said.

-- The Associated Press

With no fewer than five accidents directly related to tires, including one that sent Denny Hamlin to a hospital for observation, and one in Friday's Happy Hour practice that seemed to set the tone for the weekend, Goodyear's investigators will have yet another mystery to solve, just like Indianapolis and Atlanta.

"There was nothing you could definitely point a finger at," Goodyear product manager Rick Heinrich said. "We've still got a lot of tire material that we need to go over and definitely need to send all this material back to Akron. Our research department can look at these tires and do a much better job of evaluation."

And what is most confusing about this one is that there may be no common thread, no smoking gun, that can explain why a tire compound that functioned so well in the spring exploded "like a shotgun going off," according to Martin Truex Jr.

The track is billiard table smooth. The weather was almost perfect, partly cloudy and warm. Camber settings for NASCAR's largest oval are minimal. Air pressures, for the most part, were within parameters. There was nothing odd at all about Sunday's race.

But tires exploded on the right front, on the right rear, on short runs and long runs, leaving Goodyear's folks scratching their heads. Heinrich was at a loss to explain things.

"That's the perplexing thing, the lack of commonality," Heinrich said. "We've had [tire problems with] right fronts, right rears, some of the tires looked different. So that's what we're trying to put together right now is to try and find some things that correlate, come together to point to an explanation."

But it was an issue that was in the back of drivers' minds all race, like for Jimmie Johnson.

"I was worried all the way back on Friday when the 88 blew a tire," Johnson said. "When they explode like that, my immediate concern was that something went wrong with the tire and caused it to explode. I watched the ARCA race [Friday] and they had problems."

David Reutimann's blown right rear on Lap 53 wrecked Jeff Gordon's championship chances (watch video) -- and according to Heinrich, was the only incident that could be attributed 100 percent to being cut by debris or a fender rub.

Fifteen laps later, another blowout -- this time on the right front of Brian Vickers' car while he was running directly behind the leaders in the tri-oval -- sent nine cars to the garage with heavy damage (watch video). On Lap 81, it was Mike Wallace who blew a tire on the backstretch, but was able to keep his car going straight and avoid another multi-car crash.

Hamlin was leading on Lap 98 when the right front blew, sending him careening from the low groove all the way into the outside retaining wall (watch video). After a few minutes, Hamlin was able to climb from his car, was placed on a stretcher and taken first to the infield medical center and then to a local hospital for further evaluation.

Then things seemed to settle down, until Jamie McMurray's right rear let go with a handful of laps remaining, setting up the final shootout that resulted in Tony Stewart's win (or was it Regan Smith?).

"There's a lot of questions we have to ask, a lot of things that have to be considered when you have a performance issue with a tire," Heinrich said. "The individual setups that the teams have decided on, the track conditions, that's what we're doing right now is we're downloading all those facts.

"We're looking at what material was coming off the racetrack, tire parts and tires that were coming off the cars, trying to put everything together, trying to find some correlation, trying to come up with a definite explanation."

So if the tire construction wasn't to blame for Sunday's troubles, what could it be?

"It does suggest to us that something is influencing the tire," Heinrich said, "because we've seen too many tires that looked too good, and we have really good conditions for tires. The ambient temperature is reasonable. The tires haven't shown any signs of heat or stress."

And Goodyear officials had to once again answer questions about their product, something that perhaps Heinrich is tiring of doing this season.

"I guess it goes with the territory," Heinrich said. "Tires are a really important component of this car and a very important part of the suspension, so we have to continue to develop our products so teams can develop their racecars.

"Right now, what we've done is put our nose to the grindstone and we're going to work our tails off until we're putting a tire on these cars that performs like you would expect."