Tires
Tires are incredibly important on a race car. They are what hold the car on the track in a turn and they transmit the power of the engine to the ground. Tires are so important that, in a single race, a car can go through 40 tires. And each tire costs about $400! When you add it up, a team spends about $20,000 per race just on replacing the tires.

You're probably wondering, "Why do they go through so many tires?" First, race tires are incredibly thin -- only about one quarter of an inch thick. They're so thin to keep from overheating. The tires create friction on the track. The friction creates heat. Thick rubber would hold the heat and melt.

Photo courtesy Action Sports Photography, Inc.

Second, race tires are soft - a lot like the softness of a pencil eraser. There is no tread pattern on NASCAR race car tires because tires can generate more traction if more of their sticky rubber is in contact with the ground. Although the soft rubber gives the tires a lot more grip, it also causes them to wear out fast.

Because the tires are thin and soft, they can burst. For added safety, on racetracks over a mile long, NASCAR requires an inner tire. There's actually a second tire inside the tire you see. If the outer tire bursts, the inner tire lets the driver make a controlled stop.

Now that you know why they go through so many tires, you're probably wondering, "How do they go through them?" It's pretty amazing. In 12 to 14 seconds, seven people manage to completely refuel the car and change all four tires. This requires incredible hand-eye coordination, but there are a couple of tricks the teams use to make things a little easier. When the new tire is placed onto the car, the five lug nuts are already attached to the wheel by some sticky stuff. The studs are long and have no threads for the first three-quarters of an inch. This keeps the lug nuts from getting cross-threaded, making it easier for the tire to be put in the right place.