Harvick raises tyre blister concerns at Michigan

The Richard Childress Racing driver was one of a handful who experienced problems with blistering left-side tyres during Thursday's testing session ahead of Sunday's race, the first to be held on the new surface of the two-mile venue.

The new asphalt is providing plenty of grip, increasing cornering and top speeds while leading to previously unseen averages above 200 mph, which some drivers have been wary about if any kind of failure sends a car against the barrier.

Although NASCAR officials have been confident about speeds dropping as the weekend goes, with rising temperatures and more rubber on the track, Greg Biffle topped 204.7 mph on a qualifying simulation late during Friday's afternoon final practice, setting a new unofficial benchmark for the venue.

"Yes, they were blisters, mainly on the left-side tyres more on the left-front than the left-rear and along with the right-rear," said Harvick at Michigan on Friday. "That is our biggest concern right now as we've seen several of those situations through the garage.

"I don't know that many people ran enough laps to really get to the blistering point. It's either going to come down to the race track getting more rubber on it and the speeds slowing down or it's just going to come down to you slowing down and managing the pace to keep the tyres on the car."

Goodyear advised competitors to run their tyres through a heat cycle in order to try to control the problem. A number of teams scrubbed sets during practice on Friday as a result.

Harvick said he could understand Goodyear's problems given that the compound it is using was based upon a test at the circuit in April, when temperatures were much lower.

"The hardest thing that Goodyear has to deal with is [coming] to a new race track and testing a couple of months before the race and you try to do the best job that you can to get the speeds where they need to be," said Harvick.

"I think [Thursday] we ran a second faster than what they ran at the test. I think they tested and it was 40 or 50 degrees up here. [This weekend] it's going to be 90. You are looking at a 40 degree swing - that is virtually impossible [to anticipate] until you get on the race track."