If Kyle Larson has any hope of factoring into the closing laps of his maiden Indianapolis 500 – let alone becoming the first rookie winner since 2016 – the NASCAR Cup series champion is going to have to find the limit.

Monday night, Larson toed the line.

Near the end of his solo, 172-lap lesson under the lights at Phoenix Raceway Monday evening, Larson said his hybrid team of mechanics, engineers and timing stand officials from Arroew McLaren and Hendrick Motorsports sent the 31-year-old out on a rare long run on his final of five sets of tires. Larson told reporters Tuesday he felt the car getting progressively “tighter” throughout the test, but to help jumpstart his feedback process, the NASCAR regular’s team wasn’t always filling him in on the changes they’d make during his frequent stops.

Both sides, Larson admitted, have a ways to go in the three-plus months to learn to better speak each other’s languages. Throwing Larson on-track blind, and then seeing what he would eventually diagnose would help, both sides hoped, speed that process up.

“We had different air pressures to start (that late run), so the car felt a lot different early-on, but I kinda had my mind made up that it was going to keep building tighter, but it was starting to get pretty loose pretty quickly,” Larson told IndyStar on Tuesday during a media call to debrief on his second test day on-track in an Indy car. “I was a bit confused. I wasn’t expecting that, I guess. I was trying to make adjustments on the weight-jacker, and I just got caught off guard a little bit.

“I’d had some warnings a few laps before, but I went into Turn 1, got a little going into the corner, hit the apex, and then when I was leaving the bottom, it started to go sideways.”

Lucky for Larson, he kept it off the wall.

“I definitely could tell I was getting close to the limit, and when the balance started getting free, I could feel it coming. I felt like I was getting close to having a moment, and then I did. But I do really like that what my brain was registering actually happened, and what I was feeling in the car on the other runs, I felt like I was starting to feel the balance well and describe it.”

More: Kyle Larson gets first taste of IndyCar, Indy 500 speeds in IMS rookie test

The hours Larson logged in the cockpit of David Malukas’s No. 6 Chevy Monday evening felt almost night-and-day different from the NASCAR veteran’s first (and up until Monday, only) day he’d spent on-track in an Indy car back in October at the Indianapolis Motor Speedway, where he breezed through his Rookie Orientation Program.

And for good reason.

Larson’s first taste of an Indy car came on the long straights of IMS’s 2.5-mile oval, where even while traveling at speeds around 230 mph, he could give his brain a moment to think, to digest what he was feeling as he learned the weight of the steering wheel and the car’s tendency to pull to the right ever so slightly. That day, too, Arrow McLaren had downforce piled onto the car in order to help Larson easily keep speeds low during the initial stages of his ROP. By the end, he was full-throttle and still ticking off laps with average speeds under 218 mph.

On the 1-mile tri-oval outside Phoenix on Monday evening, Larson said, the balance of his car – likely by design, via changes engineers could deliver through the car’s general setup or its tire pressures – was often pretty uncomfortable, forcing the Hendrick Motorsports driver to experiment with his weight-jacker and bars. Back in October, Larson hardly familiarized himself with either of them because of how seamless the car had been to drive.

Learning how to get comfortable being “uncomfortable” – and quickly targeting how to get back to level – was one of his biggest and most important lessons learned Monday.

“It was a smaller track, so things are happening quicker, and you’re having to lift off the throttle a little bit. At Indy when we were wide-open, it’s pretty easy by yourself, but yesterday was fun to have to work on the timing of the corner and work through some of the balance things,” he said. “The balance definitely wasn’t perfect, which was good to feel at 180 or 190 mph in the corner, compared to going 220 mph at Indy and having a moment and being surprised by something.

“I’m not used to having cockpit adjusters, but that’s what you have to do a lot in an Indy car, so it was really good to do that stuff, log some notes in my brain and hopefully make that transition when I get back to Indy smoother and quicker, so I can get to working on the important stuff once we get to the month of May.”

From October: Here are Larson's lap by lap speeds he used to pass his Indy 500 ROP

Larson also noted the importance of getting to run live pitstops with his crew Monday, allowing him to fine-tune a part of his craft he felt he had the most left to learn. It’s those tiny details, having accidentally thrown his car into anti-stall mode multiple times leaving the pits at IMS last year, Larson knows could make or break the first half of his ‘Hendrick 1100’ on May 26.

“It even comes down to pulling in and out of your pit box. The steering wheel is so small, the cockpit is so tight and the steering is so slow in turning, that you have to turn it way farther than normal, and then quick back the other way. Just getting all that timing down is going to be difficult,” Larson said. “These live stops are quite a bit quicker than I’m used to.

“In a stock car, you’re really just worried about popping into neutral, coasting in, holding the brake pedal, and then they drop the car and you put it into first (gear) and take off. Now, I’m listening to tones in my headphones for when (the fueler) unplugs, because I can’t go into first (gear) until they do. The timing window of all that is just so much smaller, and it feels like it’s all happening so fast.”

Even as he’s built repetitions on-track and in the pits with nearly 250 laps in an Indy car under his belt, Larson admitted he’s still a bit uneasy on just where that progress stacks him up with the rest of the field. Among the 31 drivers formally confirmed for May’s 500, seven have won the race and just six (Larson included) will be making their debuts at the Greatest Spectacle in Racing. Turning laps by himself during his first two tests have given Larson the freedom to not have to worry about perfecting his drafting techniques, making passes or defending yet, but those gaps in his preparation ahead of the two-day Open Test in mid-April still leave a fair bit of unknowns for Larson to uncover.

Like every step in this process, it’ll be a trial by fire of sorts. He can only hope his years and years of hopping from one car to the next, a skill that has made him one of the most versatile racing drivers on the planet, can help him keep it off the wall again when he finds himself starting to slide while searching for those final fractions of a second.

“I could still be a half-second or more off the pace. I just have no clue when I’m out there just judging off myself. I feel like I’m coming up to speed okay, but I don’t really know,” Larson said. “But right now, it is good to have that free-ness of learning on my own.

“When my car was balanced, I still think there was room, at times, to go another tenth (of a second) or two faster, and that’s just about me being confident and committing to the throttle, and knowing and trusting that the car was going to stay gripped.”

This article originally appeared on Indianapolis Star: Indy 500: Kyle Larson gets loose, learns in Phoenix IndyCar test