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Why Do NASCAR Drivers Swerve/Zig Zag? (Explained)

When you turn on a race, you will notice NASCAR drivers swerve and zig zag before the initial green flag drops. While this looks pointless to new NASCAR fans, those who have spent time around the sport know otherwise. There are several reasons drivers swerve when under caution.

NASCAR drivers swerve to warm up their tires, as is common in other motorsports. As a race progresses and cautions occur either because of on-track incidents or following a stage, they will also swerve to shed marble-like substances that accumulate on the tires.

NASCAR drivers zigzag for a variety of reasons, which we’ll talk about in the article below. We’ll discuss that, while it’s ideal for drivers to warm up their tires, warm tires will also lead to faster tire wear, and the ways experienced drivers can delay the onset of worn tires.

Why Do NASCAR Drivers Swerve Back And Forth?

NASCAR drivers swerve back and forth so they can warm up their tires and get rid of the rubber “marbles” that accumulate on the tires as they wear down. Warm tires provide better grip than cold tires and marbles make it harder for the drivers to control their car.

Think about football or basketball players taking part in drills and other forms of practice when they have a game starting within the hour. They do so because they need to warm up their muscles, joints, and particular motor functions. For drivers, the swerving warms up their tires and prepares them for the race ahead.

However, drivers need to do more than just keep tires warm. They also need to keep other parts of the car, like the brakes, at an ideal temperature. When the cars reach such a temperature, they are easier to handle and give the drivers a better chance of performing well.

Do NASCAR Drivers Warm Up Their Tires At Each Stage?

NASCAR drivers will warm up their tires at each stage of the race. Think of the end of each stage as NASCAR’s version of an intermission or halftime. Once the yellow flag drops and cars take their respective pit stops, they will once again warm up their tires and brakes.

Returning to the live game analogy, you may recall football and basketball teams taking extended time off via an intermission or halftime. When they return to the field or court, they once again go through a regimen of warmups to get their body ready for the next stage.

NASCAR drivers do the same thing for their cars. NASCAR Cup races are broken into three stages, with Stages One and Two lasting for a quarter of the respective number of laps. In a 300-lap race, Stages One and Two last 75 laps each. The third stage is made up of the final half of the race. Longer races, like the 600-mile race at Charlotte Motor Speedway, are comprised of four stages.

Why Do NASCAR Cars Need Warm Tires?

NASCAR cars need warm tires for better grip and handling. Safety is the top priority in NASCAR, and the warmer a car’s tires are at the race start, the more likely they are to grip the racetrack and avoid accidents. Before everything else, warmer tires mean safer tires.

While drivers maximize speed with warm tires, it’s also a double-edged sword because those tires will wear faster as they heat up. As tires wear, the car becomes slower and tougher to control. This explains why drivers must make multiple pit stops throughout a race for fresh tires.

If a driver attempted to run an entire race on worn, heated tires, the tires would blow, and they would likely crash out of the race. On the other hand, if a driver doesn’t swerve to warm up their tires, their starting set of Goodyear Eagles would last longer, but they wouldn’t be able to keep up with the pack. Their car would also be tougher to steer and brake.

What Is A Heat Cycle?

In NASCAR, heat cycles cause tires to get harder, leading them to lose their grip on the track. When a driver gains enough experience, they will master the art of keeping their tires warm but slowing down heat cycles. This will allow them to delay tire wear and race at an optimal speed while maintaining their grip.

Less-experienced drivers have a tough time slowing heat cycles. Pay attention to rookies and drivers with lesser NASCAR Cup Series experience. Even if they start near the front or on pole, they are susceptible to losing positions because they haven’t mastered mitigating heat cycles.

What Are Marbles In NASCAR?

Marbles in NASCAR are small, rubbery balls that form on tires as they heat up and wear down. It’s very difficult to race on tires with a lot of marbles and one of the reasons NASCAR drivers swerve during a race is to shed the tires of them. When marbles form, drivers need to consider new tires.

You may notice NASCAR’s Goodyear Eagles are not the same tires you see at your local Goodyear branch. Their tread is different from that on the average road car, and they are even made from different materials. While they both come from rubber, NASCAR tires are made of various different compounds.

The longer a driver races on these tires, the hotter they get. When the tires reach a certain temperature, and as a natural result of the friction forces put through the tires as the cars race, parts of the tire begin to wear down, and small bits of rubber will fall off the tire. These chunks of rubber collect on the track and are known as marbles.

Where You Will See Marbles

Marbles become visible on tracks as the race progresses. The next time you tune into a race, pay attention to the track surface. You will see small black dots that are slightly raised. Those are marbles. Drivers reported that they feel like they are driving over marbles, hence their name. They are not good to drive over, but in the heat of a race, drivers cannot avoid them.

Marbles are very slippery, and they may cause accidents. This is because they interfere with the smooth contact patch of the tires with the track surface. Decreased surface area means decreased grip.

NASCAR drivers swerve and zig zag under caution to shed marbles from their own tires and onto the track. When you look for marbles, you will find them located on the outer portions of the track, close to the SAFER barriers.

What Are Grooves In NASCAR?

Grooves in NASCAR are the result of rubber accumulating on the track as drivers complete lap after lap. They look like black strips on the track. Because of the extra rubber, grooves have more grip than any other location on the track and drivers will naturally gravitate toward them.

If you hear the broadcast say “find the groove,” it’s because former drivers calling a race from the booth realize how much a groove can improve a car’s performance throughout a race. Just like worn tires, however, if too much rubber accumulates onto a groove, they can negatively affect a car’s handling. In that case, drivers will find what’s called a secondary groove and ride it.

Much like rubbered in tracks in other racing series like Formula 1, when cars drive repeatedly over the same bits of track lap after lap, some of the rubber that wears off their tires sticks to the track (while other bits become marbles as mentioned above). This rubber provides extra grip for cars that drive over it, but it can become very dangerous and slippery when wet.

Final Thoughts

NASCAR drivers swerve and zig zag during cautions and before the initial green flag because it warms up the tires for better grip. However, warmer tires will also increase tire wear, which in turn causes marbles to form. As the race progresses, drivers will swerve to shed their tires of marbles.