DARLINGTON, S.C. -- They may have been "white-of-your-eyes" fast during a test earlier this week, but don't expect those same outrageous speeds when NASCAR returns to Michigan International Speedway to race.
Five drivers took part in a two-day Goodyear tire test at the 2-mile oval, with a few of them taking to social media to report speeds that crept toward the 220 mph mark. Dale Earnhardt Jr. posted to Twitter a photo of a telemetry readout showing 215.2 mph, and Clint Bowyer tweeted that his top speed was 217. "That's white-of-your-eyes fast," the Michael Waltrip Racing driver wrote.
Indeed, it was. But Greg Biffle, who also took part in the test -- and told a TV reporter that he topped 220 mph on the straightaway -- said Friday morning at Darlington Raceway that highs were in the 40s with a track temperature of around 66. Those colder conditions provided plenty of grip, and promised to be much different from what Sprint Cup Series teams will experience when they return in June for the first of its two annual events at the facility in Brooklyn, Mich. And teams won't race on the tire that generated those eye-popping speeds, he added.
"They put a tire on the car that we are not going to race that went that fast," Biffle added. "So on the standard tire, I think the mph was down maybe three or four mph from that."
The track record at Michigan is 203.949 mph, set by Joey Logano in qualifying last year. The big oval has become lightning-fast since a resurfacing was completed in 2012, with three out of four pole winners cracking 200 mph in the time since. Although speeds in excess of that number are not uncommon during practice at Michigan, Dale Jr. doesn't expect drivers to be going quite that fast during the race.
"The track should slow down as it rubbers up, tightens up, get slicker," Earnhardt, who also took part in the test, said at Darlington. "The seams will get slicker. So I don't think we will see those kinds of speeds. That is basically what we saw in practice there last time. We may see those speeds in practice, but I doubt we will see those in the race. The race will slow down quite a bit, or enough."
Trevor Bayne and Ryan Newman also took part in the test, where drivers experimented with different types tires including the dual-zone treads that Goodyear has already employed at Atlanta, Kansas, and Texas, and plans to use at Richmond.
Multi-zone tread tires feature one compound on the outside 10 inches of the tire designed for traction, and another compound on the inside two inches designed for wear. The inside compound is more durable because that part withstands more heat and abuse.
The focus on tires at Michigan intensified after a race weekend there in June of 2012, when Goodyear switched left-side compounds after experiencing severe and unexpected blistering. Earnhardt said Goodyear tried about eight different types of compounds in this week's test at Michigan, including two different dual-zone tread configurations. "It was a productive test," the two-time Daytona 500 champion added, and Biffle echoed that he was pleased with the initial results.
"Goodyear is trying to come up with a little more reliable tire, and I think they have done that," Biffle added. "I am thinking they are going with the dual-zone tread, possibly, or at least that is what they were leaning toward. We will see what they come up with after all the data. I think that is a better tire, because it puts a little margin in the right front. They don't want to blow a right front at that track."
Although many teams have experienced tire issues this season, NASCAR and Goodyear have maintained those problems stem primarily from teams running air pressures lower than recommended -- an assertion backed up Friday by Biffle.
"A lot of it is team-oriented. The tire hasn't changed from last year. What has changed, then? The ride-height rule has changed, and the car has a lot more downforce on it. That is what has changed the tire issue," the two-time Darlington winner said.
"We will probably have to continue to come up a little bit on left-side tire pressure. The tire is getting so much load on it when it is on low air, because the car is sucked to the ground so hard and has more downforce than it ever did. That is probably most likely what is causing these tire issues. The cars have more speed and more downforce. I would say that could potentially be a problem at any place we are going that fast and put that much load on the tire and low air. That can be a deal anywhere."
FULL SERIES COVERAGE
- Motor Racing
- Sports & Recreation