FONTANA, Calif. -- Adam Stevens, crew chief for Kyle Busch, said his team hasn’t resolved a left rear tire wear issue that surfaced during Saturday’s NASCAR Sprint Cup Series practice sessions at Auto Club Speedway.
"I don’t know what it was," Stevens said. "We tried multiple things to remedy it and it’s getting better, but it’s not like it’s gone. We still have some concerns after final practice."
Goodyear officials said the problem was traced to air pressures and camber settings, but Stevens said his No. 18 Joe Gibbs Racing team was not “out of the box on any one of those things compared to every car that we’re capable of looking at and past history.”
"But we’re the only ones that seem to be having a problem," he said. "I don’t know what to do to fix it because everybody else is quite similar."
Busch qualified sixth for Sunday’s Auto Club 400 (3:30 p.m. ET, FOX, MRN, SiriusXM Radio). He was fourth fastest in Saturday’s opening practice under cool conditions and 16th in Happy Hour after track temperatures had increased.
The wear improved in the final practice, according to Stevens, "but you (still) saw excessive wear," he said.
"When it gets hot and gets slick and slows down, a lot of those problems tend to go away," he said. "I don’t know that anything that we’ve done has made it any better, other than just the normal rubbering in of the track and the lap times falling off to be honest."
"It’s a worn surface, guys are searching for grip; one of the ways they’ve attacked that in the past and are doing it still is (by) trying to reduce air pressures, trying to run a little bit more camber,” Goodyear’s Greg Stucker said. “Just trying to push the envelope and get as much as they can."
Stucker said Goodyear has "gone, in very general terms … softer at every track."
"One of the goals was increased falloff and we certainly have seen that, significantly more at Atlanta," he said. "About the same (falloff) at Las Vegas. … More at Phoenix and we’re trending right now at least as much if not more here."
As for the No. 18 team, Stucker said officials "are over there working with them and trying to make sure they know where they stand … what kind of changes they’re making.
"It’s just one of those levers that they pull," he said. "(NASCAR) took aero away so they are going to go about getting grip back mechanically and that’s one way they do it."
Stevens said his team didn’t see the wear issues here last season, but a similar problem did surface at Atlanta earlier this year.
"A lot of times you’ll see (that) when it’s real fast and gripped up," he said. "It was (at Atlanta); it was a concern the entire race. And it’ll be a concern tomorrow until we get a couple of sets across it tomorrow, too."