Dr. Diandra: Darlington tire fall-off — the good kind


Engineers call the effects of tire wear ‘tire fall-off’. This can lead to confusion, especially when NASCAR is dealing with tires literally falling off cars.

Tire fall-off — the good kind — played an important role in last week’s Dover race. Given Darlington’s aggressive track surface, expect it to have a major impact on this week’s race, too.

What is tire fall-off?

Friction with the track wears down tires. Rubber sticks to the track, balls up to form marbles, or gloms back onto the tires during cautions. Tire wear requires teams to use multiple sets of tires during a race.

The ideal tire would grip like crazy and never wear out. Unfortunately — like perpetual motion machines and universal solvents — the laws of physics preclude the perfect tire.

That means Goodyear faces the classic Goldilocks problem at each track. Tires that are too soft wear out too quickly and become a safety issue. Tires that are too hard don’t wear out, but they also don’t offer much grip.

Visualizing tire wear

The best way to “see” tire fall-off is by examining lap times. Let’s use Chase Elliott‘s race from Dover last week as an example. Below, I plot his lap times and running position as functions of lap number. I’ve also shown where cautions occurred by shading those laps yellow.

Two scatter plots showing the lap times (upper) and running position (lower) for Chase Elliott in the Spring 2022 Dover race

Lap times trend upward for each green-flag run of more than a handful of laps. There are variations from lap to lap, of course. That’s why I include running position. A driver’s lap times are highly dependent on whether he’s driving in traffic or not.

Elliott changed tires six times, during pit stops on laps 42, 123, 160, 191, 244 and 326. You can tell tire changes because there’s a sharp, one-lap blip upward in his running position.

Elliott led the last 52 green-flag laps of the race, mostly unimpeded by traffic. Let’s isolate these laps and, since he ran P1 the entire time, we can ditch the track position graph.

I’m also inverting the y-axis so that down means slower.

A scatter plot showing Chase Elliott's lap times for the last 50 laps of the spring 2022 Dover race

Flipping the axis makes the graph a little more intuitive because now you really see the times falling off.

If you’re wondering why I plot time instead of average lap speed, it’s because NASCAR measures time. They infer speed by dividing track length by time. Because drivers don’t drive the same distance around the track each lap, lap time is a more accurate quantity.

You’ll hear people talk about ‘two seconds of tire fall-off.’ Be careful. That’s doesn’t tell you anything. Fall-off is how much lap time increases over some number of laps. It’s a rate, just like miles per hour or revolutions per minute.

Elliott’s last run at Dover started with a lap time of about 23.4 seconds at Lap 350 and increased to about 24.4 seconds at Lap 400. That’s one second of drop-off over 50 laps. Elliott had a big lead at this point and didn’t have to push his tires very hard. A driver using up his tires trying to pass or defend a position can experience even higher fall-off.

In this year’s Martinsville race, where abnormally cold temperatures hurt tire performance, Elliott lost only one second of lap time in the course of leading 90 laps.

What determines how much tire fall-off there is?

An asphalt track is composed of an aggregate mix (rocks) and a binder (the black tarry stuff holding the rocks together.) As a track ages, the binder erodes and the aggregate edges round. Aging changes the grip and how the surface wears tires.

Many variables contribute to tire fall-off, but Goodyear director of race tire sales Greg Stucker explains that “the biggest factor in tire fall-off is the track surface.” For example: Concrete is less porous, so it wears rubber from tires differently than an asphalt track.

But every asphalt track is different as well.

NASCAR ran the same tire set-ups in 2021 at Darlington, Charlotte and Homestead. The 1.5-mile Charlotte track produced about one second of fall-off in 40 laps. Homestead is also a 1.5-mile track, but drivers there experienced about 3 seconds of fall-off in 60 laps. Darlington, with its rough, 2008-era surface, resulted in 3 seconds of fall-off in 30 laps.

The upside

High tire fall-off introduces lots of strategic possibilities.

If new tires aren’t much of an advantage (i.e. not a lot of fall-off), then there’s no point pitting unless you need fuel. But if new tires can give you a tenth-of-a-second advantage per lap, it might be worth short pitting. Short pitting is coming in for tires in the middle of a fuel run hoping to gain positions by virtue of having new rubber.

The crew chief must balance the risk and reward of pitting. How many positions will the team likely lose by coming in? How do other teams pitting (or not pitting) affect the plan? That decision will also depend on how many laps are left in a stage or the race.

The decision is complicated by the fact that tire fall-off isn’t uniform. That, Stucker says, is because there are so many different variables involved.

“In some cases, tire wear is linear,” Stucker explains. “In others, we see a rapid decline, then a slower decline.”

But even two different drivers on the same track with the same tires can experience different fall-off rates depending on their cars’ set up and how aggressively they’re driving.

Although Chase Elliott’s tire fall-off may be one second over 50 laps, that doesn’t mean he loses the same amount every lap. At Dover, tires wear faster in the first stages of a run, then the fall-off decreases a little.

I’ve tried to illustrate this by drawing two straight lines in Elliott’s Dover data. The left line was fit to the first 20 laps and the right line to the last 20 laps.

A scatter plot of Chase Elliott's lap times, with a linear fit to the start and the end of the green-flag Dover run.

The first line is steeper than the second, indicating that the tire fall-off is faster in the early part of the green-flag run than in the later part.

But again, if another driver had closed the gap in the last 20 laps of the race, Elliott’s tire fall-off might have gone up because he would have had to race harder to preserve his lead.

This non-linearity makes the crew chief’s decision even more complicated. If the tires wear really quickly in the first 10 laps, the advantage of new tires lasts for a shorter time. Can the driver get to the front before he’s worn out the tires enough that someone else can pass him?

Tire fall-off may make crew chiefs pull out their hair, but it’s a good thing for those of us watching the race because it adds one more complication to the competition.

Friday 5: Legacy MC seeks to stand out as Trackhouse did in ’22


While the celebration continued after Erik Jones’ Southern 500 victory last September, executives of what is now Legacy MC already were looking ahead.

“(September) and October, decisions we make on people are going to affect how we race next (February), March and April,” Mike Beam, team president, told NBC Sports that night.

Noah Gragson had been announced as the team’s second driver for 2023 less than a month before Jones’ win. 

But bigger news was to come. 

The team announced Nov. 4 that Jimmie Johnson would become a co-owner, lifting the profile of a team that carries Richard Petty’s No. 43 on Jones’ cars.

As February approaches and racing resumes, a question this season is how far can Legacy MC climb. Can this team mimic the breakout season Trackhouse Racing had last year?

“I think everybody looks for Trackhouse for … maybe the way of doing things a bit different,” Jones told NBC Sports. “Obviously, starting with the name. We’ve kind of gone that same direction with Legacy MC and then on down from there, kind of how a program can be built and run in a short amount of time.

“There’s some growth in the back end that we still have to do to probably be totally to that level, but our goal is definitely to be on that same trajectory that Trackhouse was over the last two seasons.”

Trackhouse Racing debuted in 2021 with Daniel Suarez. He finished 25th in the points. The organization added Ross Chastain and several team members from Chip Ganassi Racing to form a two-car team last year. Chastain won two races and finished second in the points, while Suarez won once and was 10th in the standings. 

Legacy MC co-owner Maury Gallagher purchased a majority interest in Richard Petty Motorsports in December 2021 and merged the two teams. Jones won one race and placed 18th in points last year. Ty Dillon was winless, finishing 29th in points and was replaced by Gragson after the season. 

“Legitimately, we were a pretty new team last year coming in,” Jones said. “There were a handful of Richard Petty Motorsports guys who came over, but, for the most part, it was a brand new team.

“I think what we built in one year and done is similar to Trackhouse in their first year. I think maybe even we were a step ahead of where they were in their first year.”

Legacy MC looks for more with Jones, Gragson and Johnson, who will run a limited schedule this year. Johnson will seek to make the Daytona 500 field.

Jones said Johnson has infused the team with energy. Gragson has been trying to soak up as much as he can from Johnson.

Gragson told NBC Sports that having Johnson as a teammate is “going to be an incredible opportunity for a young guy like myself, first year in the Cup series, a rookie, to be able to lean on a seven-time champion.

“Incredible person, friend, mentor that Jimmie has become for myself. He’s probably going to be pretty over me by the time we get to the Daytona 500 because I just keep wearing him out with questions and trying … pick his brain.”

2. Kyle Busch’s impact

Car owner Richard Childress says that Kyle Busch already is making an impact at RCR.

Busch joins the organization after having spent the past 15 seasons driving for Joe Gibbs Racing. Busch will pilot the No. 8 Chevrolet for RCR this year.

He took part in a World Racing League endurance race at Circuit of the Americas in December with Austin Dillon and Sheldon Creed. The trio won one of those races.

“I was down there for that, just watching how (Busch) gets in there and works with everybody,” Childress said. “He’s a racer. He wants to win. That’s what I love about him.”

Childress sees the influence Busch can have on an organization that has won six Cup titles — but none since Dale Earnhardt’s last crown in 1994 — and 113 series races.

“He brings a lot of experience and knowledge,” Childress said of Busch. “I think he’ll help Austin a lot in his career. I think he can help our whole organization from a standpoint of what do we need … to go faster.

Dillon told NBC Sports that the team has changed some things it does in its meetings based on feedback from Busch. Dillon also said that he and Busch have similar driving styles — more similar than Dillon has had with past teammates. 

“I think as we go throughout the year and he gets to drive our race cars, he’ll have some new thoughts that he’ll bring,” Dillon said of Busch. “I think we’re already bringing some new thoughts to him, too.”

3. New role for Kevin Harvick

Kevin Harvick, entering his final Cup season, has joined the Drivers Advisory Council, a move Joey Logano said is important for the group.

“Kevin is necessary to the sport, even post-driving career,” Logano told NBC Sports. “He’s necessary for our sport’s success. Kevin sees it and does something about it. 

“He’s always been vocal, right? He’s always been very brash, and like, boom in your face. That’s what people love about Kevin Harvick. Something I like about him as well is that you know where you stand. You know where the weaknesses are. 

“He’s going to push until something happens. That’s great. There’s nothing wrong with that. Having him on the Advisory Council now for the drivers, his experience, but also his willingness to push, is important.”

Jeff Burton again will lead the group as Director of the Council. The Board of Directors is: Harvick, Logano, Kyle Petty, Austin Dillon, Daniel Suarez, Corey LaJoie, Kurt Busch and Tom Buis.

Logano, Petty, Dillon, Suarez, LaJoie and Busch all return. Buis, a board member of Growth Energy after having previously been the company’s CEO, joins the drivers group and provides a business background. 

4. Finding one’s voice

Chase Briscoe’s contract extension with Stewart-Haas Racing means he could be the longest tenured driver there in the near future.

The 28-year Briscoe enters his third Cup season at SHR, but the landscape is changing. This will be Kevin Harvick’s final season in Cup. Ryan Preece is in his first season driving in Cup for the team. Aric Almirola was supposed to have retired last year but came back. How long he remains is to be determined.

Those changes could soon leave Briscoe as the team’s senior driver.

“It’s a role that is crazy, truthfully, to think about because that could be me in the next year or two, being I wouldn’t say that flagship guy, but being a leader as far as the drivers go in an organization,” Briscoe said.

“Truthfully, I feel like that’s something I want to be. I’ve always enjoyed that kind of leader, team building type of stuff. So, yeah, if that role is kind of placed on me naturally, then that’s one that I would love to have and try to do it to the best of my ability. I feel like that’s a role that you don’t choose, it kind of chooses you.”

Briscoe, who won the spring Phoenix race and made the playoffs last year, said that he’s becoming more comfortable speaking up in team meetings. 

“I look back, especially on my rookie year, we’d go into our competition meeting on Tuesday and, truthfully, I wouldn’t really talk much,” he said. “I would say kind of what we thought for the weekend, but outside of that I would just kind of sit there and listen.  

“This past year, I definitely talked a lot more, and I’d bring up ideas and kind of say things I wanted to get off my chest, where in the past I wouldn’t have done that. I feel like as I’ve gotten more confident in myself and my position, I’ve gotten to the point where I speak my mind a little bit more and, I guess, be a little bit more of a leader.”

5. Busch Clash field

NASCAR released the preliminary entry list for the Feb. 5 Busch Clash. No surprise, the entry list features only the 36 charter teams. Those teams are required to be entered.

With 27 cars in the feature — which is expanded by four cars from last year’s race — there’s no guarantee a non-charter car could make the field. That’s a lot of money to go across country and face the chance of missing the main event.

The Daytona 500 field has four spots for non-charter cars. With that race’s payoff significantly more, it will attract at least five cars for those spots: Jimmie Johnson (Legacy MC), Zane Smith (Front Row Motorsports), Chandler Smith (Kaulig Racing), Austin Hill (Beard Motorsports) and Travis Pastrana (23XI Racing). Helio Castroneves confirmed Thursday that he will not enter the 500. He had been in talks with the team co-owned by boxer Floyd Mayweather.

Helio Castroneves rules out Daytona 500

Helio Castroneves Daytona 500
Robert Scheer/Indy Star/USA TODAY NETWORK

DAYTONA BEACH, Fla. – Helio Castroneves might be at the 2023 Daytona 500, but the four-time Indy 500 winner won’t be in a race car.

During a news conference Thursday at Daytona International Speedway, Castroneves confirmed in response to a question from NBC Sports that he essentially has ruled out attempting to make his NASCAR Cup Series debut in the Feb. 19 season opener.

As recently as last Thursday at Rolex 24 Media Day, Castroneves, 47, said he still was working on trying to piece together a deal.

The Brazilian had been negotiating with the Cup team co-owned by boxer Floyd Mayweather and would have been in an “open” entry that lacked guaranteed entry to the Great American Race. That potentially would leave him in the precarious position of needing to make the race on qualifying speed or a qualifying race finish (as action sports star Travis Pastrana likely might need in his Cup debut).

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“Unfortunately for me, lack of experience, no testing,” Castroneves said. “A lot of things. I believe it would be a little bit tough throwing myself in such a short notice, and to go in a place that you’ve got to race yourself into it. So as of right now, yes, it’s not going to happen.

“But we did have an opportunity. We just got to elaborate a little bit more to give me a little more experience on that. So there is more things to come ahead of us, but as of right now, I want to focus on the IndyCar program as well and (the Rolex 24 at Daytona).”

Castroneves, who has a residence in Key Biscayne, said he still might attend the Daytona 500

“I might just come and see and watch it and continue to take a look and see what’s going to be in the future,” he said.

Castroneves enters Saturday’s Rolex 24 at Daytona having won the event the past two years. He made his signature fence-climb after winning last year with Meyer Shank Racing, which he will be driving for full time in the NTT IndyCar Series this year. He became the fourth four-time Indy 500 winner in history in his 2021 debut with Meyer Shank Racing.

The 2020 IMSA WeatherTech SportsCar champion also has indicated an interest in Trackhouse Racing’s Project 91 car that aims to place international drivers in a Cup ride (such as Kimi Raikkonen at Watkins Glen International last year). Team co-owner Justin Marks recently tweeted Trackhouse wouldn’t field the Project 91 car at the Daytona 500.

After winning the 2022 Superstar Racing Experience opener, SRX CEO Don Hawk had promised he would help secure a Daytona 500 ride for Castroneves.

Castroneves has been angling for a NASCAR ride for years, dating to when he drove for Team Penske from 2000-20. After winning the Rolex 24 last year, he said he had been lobbying Ray Evernham and Tony Stewart for help with getting in a Cup car.

Though Castroneves is out, Sports Business Journal’s Adam Stern reported that Mayweather’s The Money Team Racing still is considering IndyCar driver Conor Daly for its seat.

Fire at Reaume Brothers Racing shop injures three


A Thursday fire at the Reaume Brothers Racing shop in Mooresville, North Carolina, injured three individuals, according to Mooresville (North Carolina) Fire-Rescue.

Firefighters were dispatched to the shop, which is scheduled to field entries for driver Mason Massey in the NASCAR Craftsman Truck Series this season, at about 11:30 a.m. Thursday.

The fire department extinguished the blaze quickly. The department stated on its Facebook page that one individual was transported to Lake Norman Regional hospital for smoke inhalation, and another was transported to Baptist Hospital in Winston-Salem, N.C. with burn injuries. A third was treated and released.

The team stated Thursday night on social media that Taylor Collier and Devin Fokin had been treated and released. The team stated that Taylor was treated for smoke inhalation and Fokin was treated “for serious burns.”

The Mooresville Fire Marshall’s office is investigating the cause of the fire. The fire department said the shop sustained “significant fire damage.”

In a tweet, the team said it is determining the extent of damage to the building. “More importantly,” it said, “a few of our team members did sustain injuries during the fire and are being transported for medical treatment.”


Trackhouse, RFK Racing, Front Row Motorsports sign sponsorship deals


Trackhouse Racing, RFK Racing and Front Row Motorsports announced sponsorship deals Thursday morning.

Trackhouse said WWEX, a Dallas-based global logistics group, will increase its sponsorship presence with the team this year, serving as the primary sponsor in 21 races for drivers Ross Chastain and Daniel Suarez.

WWEX will appear on Chastain’s Chevrolets in 19 races and will sponsor Suarez twice. The organization was a Trackhouse sponsor in 11 events in 2022, which was a breakout season for both Chastain and Suarez.

RFK announced that Solomon Plumbing, which joined the team last season, will expand its presence this season and in future years. The Michigan-based company will serve as the primary sponsor for several races on driver Brad Keselowski‘s No. 6 Ford.

MORE: Chase Briscoe signs contract extension with Stewart-Haas

Solomon specializes in plumbing and fire services for new development and construction. It initially sponsored Keselowski last season in the dirt race at Bristol Motor Speedway.

Front Row Motorsports has signed Quincy Compressor, a Bay Minette, Ala.-based compressor manufacturer, as a sponsor for four races.

Quincy will sponsor Todd Gilliland‘s No. 38 team in three events and Michael McDowell‘s No. 34 team in one race.