Will Tire Limits Improve Racing?

Will 2017 Tire Limit Rules Require Harder Tires?

Back in the day, the only thing that limited how many sets of tires you could use in Cup-level racing was your budget.

It was different in the lower level series, because Cup teams that also ran XFINITY (for example) had much larger budgets than the XFINITY-only teams. Limiting the number of sets of tires kept costs down and evened things out just a little.

Because teams will push any limit to its furthest extreme, NASCAR eventually introduced limits on the number of tires because otherwise teams could just keep putting on new tires. Then whoever got the most time on newer tires would win.

In 2017, NASCAR has enacted new rules that change the tire limits for most of the races in the season.

Where We Were in 2016

Note that when we say limit, we’re not talking about giving a team three sets of tires for a 500-mile race. Anytime you want to understand change, you first have to understand how things were before the change. So here’s a plot of how many tires were allowed in 2016 for race and practice.


NASCAR arrived at these numbers by taking into account things like the condition of the racetrack, speeds and loads on the tires. Atlanta gets the largest number of tires (13 sets) because, well, Atlanta eats tires. The road courses have the smallest allotment: 5 sets.

Daytona is an interesting case because you get more tires in February (9 sets) than you do in July (6 sets). Yes, the July race is shorter, but only by 100 miles. That’s more than just scaling the miles – it has to do with the importance of the 500 and the difference in the track between Spring and Summer.


Let’s put this in context. When we talk NASCAR implementing limits, we’re not talking about giving a team three sets of tires for a 500-mile race.

Just to give you an idea of the orders of magnitude we’re talking about: In 2015, the cost to lease tires for race or practice was $493 per tire — so roughly $2000 a set . If we use that number (it’s gone up, but I don’t know how much), we’re talking:

If a team used all its allotted tires for race and practice in 2016, we’re talking about 2040 tires – which comes to a tire bill of more than one million dollars.

2017 Rules: Fewer Tires

Among the many rules changes for 2017, NASCAR has decreased how many tires teams will have available to them at all but 6 tracks.

The tracks that aren’t having any changes are:

Bristol Darlington Loudon
Sonoma Talladega Watkins Glen
Daytona – July race only

Fewer tires will be allowed for the Daytona 500, but the July race allotment will remain the same.

The rest of the tracks will have a decrease, ranging from 1 to 3 sets of tires for each race.  I plotted this a couple of different ways, but the one that showed the most information was arranging the graph in terms of track size, from left to right.

How Many Fewer?

Note the following:

  • Every single 1.5-mile track is affected. I outlined those in yellow. Since the 1.5 mile tracks are the ones NASCAR has the hardest time with passing at, you can start to get an idea of why this change is being made.
  • Neither of the road courses are affected.
  • Of the four superspeedway races, only the Daytona 500 is affected.
  • Let’s compare the number of tires allowed for 2016 vs 2017.

It’s a net drop of 38 sets of tires per season — a savings of about $76,000. That seems huge to me, but when you’re talking a million dollars a year tire bill, the savings is about 7.6%.

2016 vs 2017

Let’s compare 2016 and 2017. This graph shows you that the excluded tracks (with the exception of Bristol and Darlington) are pretty much those tracks that already have a low number of tires sets — they’re on the left side of the chart.

So Tires Have to Last Longer?

Theoretically, yes. Below, I show you the change in the number of miles each set of tires must handle.

This is a little confusing, so two more graphs. The first is how many more miles each set of tires is going to have to handle. This ranges from three miles (at Atlanta) to 15 miles (at Daytona) .

The second is how many more laps each set of tires will have to handle. This ranges from 2 (Atlanta) to 12.5 (Martinsville).

If They Have to Last Longer, They Have to be Harder, Right?

Does this require Goodyear to make the tires harder so they can last longer? That’s an issue because harder tires have less grip. They make the car harder to driver and slow down speed.

Could that be the point of the new rule? We know NASCAR and Goodyear have both said they want softer tires that will wear faster, even with the reduced downforce.

How Teams Use Their Tires?

Note that there’s also a new rule that you must start the race on your qualifying tires. When we talk tire limit, your first set of tires aren’t included.

Example 1: Martinsville

Teams will have two fewer sets of tires at Martinsville (8 vs 10) this year. If you used all 10 sets of tires, each tire would need to run an average of 27 laps. If you used 8 sets of tires, that increases to 33 laps.

Last year (April race), almost all the teams made 6 or 7 stops (three cars made 8 stops and one made 10 stops). So, on average, here’s how many miles and laps the tires actually ran at Martinsville. (Again, this is on average. Some were more, some were less.)

Number of Stops Miles per tire run Laps per tire run
6 43 82
7 38 70

They ran a lot more laps than the average. Even though we don’t know whether teams changed tires on every stop or if they took two or four, these numbers tell us that most teams aren’t using all their sets of tires at Martinsville.

Example 2: Daytona 500

Daytona will go from 9 sets of tires to 7 for the Daytona 500 only. Looking at last year’s race, here’s the distribution of pit stops. I excluded cars that dropped out of the race before halfway.

Number of Stops Number of cars Miles per tire run Laps per tire run
5 11 100 40
6 5 83 33
7 9 71 28
8 5 62 25
10 4 50 20
11 1 45 18
12 2 42 16

Requiring the tires at Dayton to be capable of running another 15 miles per set isn’t asking much . Again, not every pit stop is a four-tire change, but it’s possible that a few teams (those that had 10, 11 or 12 stops) might have issues with tires. But still, most teams aren’t getting close to using their full tire allotment.

Example 3: Chicago

When you look at the mile-and-a-half tracks, things get interesting. At Chicago last year, over half the field made 7 or 8 stops. Last year, they had 10 sets of tires to work with. This year, they’ll only have 8. Now it’s starting to look like tires might play more of an issue in the race.

Number of Stops Number of cars Miles per tire run Laps per tire run
6 5 67 44
7 17 57 38
8 5 50 33

These examples show that Goodyear doesn’t have to make tires harder even with the new tire limits.

Example 4: Bristol

I was wondering about the exceptions – the tracks that have a lot of tires available, but didn’t get a decrease. So I looked at Bristol. They have 9 sets now and will continue to have 9 sets.

In 2016, teams made anywhere from 11 to 26 pit stops. Clearly, there are other factors at play here and tires are not a huge part of the racing strategy. Hence, no changes in the rules.

Then, uh… Why The Rule?

To make the Crew Chiefs’ lives a living hell in retaliation for them figuring out how to get all the downforce NASCAR took away from the cars back so quickly.

That’s probably not actually the reason, but it is going to greatly complicate the Crew Chief’s job. They will have to develop a totally new tire management strategy because of the new format: There are three segments, with each of the first two being about half the length of the third.

Now that they’re racing for points at the end of each segment, crew chiefs will be more aggressive about the last laps of those races. If they treat the ends of the segments like the ends of races, look for them to change tires at the end of each segment, which would make two additional tire changes they probably wouldn’t make with the old format.

There will be two cautions between the segments. Most teams will change tires during those cautions, especially if they ran the tires really hard trying to get points in the segments.  That’s four sets of tires spoken for. (I know every team won’t make these choices every time, but I wanted to show you how it adds up.)

So if you have eight sets of tires and you pretty much know where you’d like five sets to go (I’m assuming you’ll want to change tires at the end of the race), then you’ve really only got three sets to deal with — and that’s not a lot when you have all the unexpected things that can happen: accidents, running over something, even flat spotting the tires avoiding someone else’s accident.

One Crew Chief might be in a position to get points at the ends of the first two segments, but use a lot of tires to do it. That leaves him in a vulnerable position because he doesn’t have as many tires left toward the end.

You can think of it sort of like football teams and time outs. Do you use them strategically during the game and then you get in trouble because you don’t have any left at the end? Or do you save them up, miss out on something at the beginning, then have them at the end and maybe you don’t need them?


Here’s something else to keep in mind. There are two major limiting factors on how long a car can stay on track: tires and fuel. We’ve looked here at the tires, but the fuel is also important.

Track Fuel Run in Laps Fuel Run in Miles
Daytona 42 100
Martinsville 125-135 66-72
Chicago 54 81

If the tires are really hard, then they don’t wear and the length of the fuel run determines your strategy.

I wouldn’t be surprised if NASCAR decided to decrease the size of the fuel tank to make the tires even more important, but I suspect they are waiting to do that until Goodyear has a chance to come up with an optimized tire for the new downforce. This is how you make changes when everything depends on everything else.

They’re not done.

Also published on Medium.

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