Noah Gragson fastest in Friday's Cup Series practice at Iowa

NEWTON, Iowa — Noah Gragson posted the fastest lap in Friday‘s inaugural NASCAR Cup Series practice at Iowa Speedway, but the speed of his No. 10 Stewart-Haas Racing Ford wasn‘t quite the main attraction.

Five drivers incurred flat tires during the full field‘s 50-minute session ahead of Sunday‘s Iowa Corn 350: Ty Gibbs, Christopher Bell, Ross Chastain, Austin Cindric and Tyler Reddick.

RELATED: Practice results | At-track photos

Gragson was fastest at 137.988 mph over Gibbs, Alex Bowman, Justin Haley and Chase Elliott. Chastain, Harrison Burton, Denny Hamlin, Austin Dillon and Chase Briscoe completed the top 10 in quickest single-lap speeds.

Gibbs was the first to experience an issue, suffering a flat right-front tire entering Turn 3 after 24 laps of practice.

Bell, Gibbs‘ teammate at Joe Gibbs Racing, posted the quickest lap early in the session. But Bell, who participated in a Goodyear tire test at the 0.875-mile oval in late May, slammed the outside SAFER barrier in Turn 4 after a right-front tire flattened on corner exit after 19 laps.

“I‘m perfectly fine, just obviously a big disappointment and something that I didn‘t see coming at all,” Bell said upon being evaluated and released from the infield care center. “It hurt. Whenever we were here for the tire test, we did 50-lap runs like they were going out of style. I don‘t even know how many laps I did, but it couldn‘t have been any more than 20.”

MORE: Bell slams wall during practice

Chastain and Cindric had their issues later in the session. Chastain‘s left-rear tire went down, necessitating a two-tow-truck dolly lift back to the garage area. Like the two Gibbs Toyotas, Cindric‘s No. 2 Team Penske Ford had a right-front tire go down, sending him into the Turn 2 wall. Bell and Cindric will both start from the rear in Sunday‘s race (7 p.m. ET, USA Network, MRN Radio, NBC Sports App, SiriusXM NASCAR Radio).

Reddick, who was fastest on the 10-lap averages in practice, had a right-front tire down as well but wheeled his No. 45 23XI Racing Toyota back to pit road without issue.

Chastain, who sits 10th in points entering the 17th race of the season, was not overly concerned about his issues or others‘.

“I mean there’s no telling what happened,” Chastain said. “We went back out and made more laps on another set, so I went out ran my fastest lap like five laps later.”

On the contrary, Bell was quick to admit raised eyebrows as the Cup Series hits Iowa for the first time. Bell‘s was among three teams to partake in the tire test last month, joined by RFK Racing‘s Brad Keselowski and Hendrick Motorsports‘ Kyle Larson. Friday‘s session was set under a scorching sun, but Bell wasn‘t of the belief that added heat was a factor in the numerous tire issues.

“If anything, it should make it better,” Bell said, “because the more heat that you have, the more rubber gets laid down and typically the less wear you have on the tire. So I mean, certainly it’s a difference. And that’s something that I’m sure they’re talking about. But yeah, it’s strange, very strange.”

Reddick, fourth in points and 49 markers back of Larson for the regular-season standings lead, theorized the fresh pavement in each set of corners may also have played a more natural role.

“You could kind of see where the track was really starting to wear in a little bit too,” Reddick said. “From the start of practice to the end, (it) was starting to lighten up a little bit. You know, fresh asphalt was almost pitch-black looking and it was starting to gray up a little bit where we’re running. So I don’t know if it’s already kind of know if … is it already starting to knock that top layer off a little bit and that’s some of it? I’m not totally sure.

“But as we kept going, I mean … the grip just kept getting better and better and better.”

Larson, who made his share of laps here testing tires in May, was less concerned — and borderline excited for the challenges ahead.

“Honestly, the unknown of everything I think makes things exciting and competitive and all that,” Larson said. “It’s gonna be fun. I think teams are probably gonna have to study a lot and not sleep a lot the next couple nights.”