# The science behind the massive 48-pound Top Fuel tires | 2018 NHRA DRAG RACING

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## Bruno Massel walks you through how the massive tires on Top Fuel cars work.

- One of the more distinguishing characteristics of a top fuel car is the massive Goodyear eagle that is mounted on back. So today, let's talk tires, top fuel tires. Now, this is a massive unit to begin with it. It is 36 inches tall, measures 17 and 1/2 inches wide, which is almost double what a production high-performance tire would be and is mounted on a 16 inch wheel. Now the tire itself weighs 48 pounds, and it has a rollout, which is the overall circumference of the tire, about 115 inches. You'll get some variation.

What's really cool about it is what this tire does during the course of a run. Now when they come up to the starting line, they'll have about six pounds of tire pressure in it. Basically, it's almost flat. Because what they want this tire to do, at the hit of the throttle, is to squat and plant out. This way they get a big footprint on the starting line to grab that rubber and accelerate the car forward.

What you'll see next is a big wrinkle in the sidewall of the tire as this car starts to accelerate. It gets really cool is when you get to the half-track point. Because now the tire is fighting two massive forces-- the force of downforce from the wing, which is putting 5,000 pounds of pressure, just flattening out the bottom half of the tire versus the centrifugal force of going 330 miles an hour. The tire will start to grow. You'll see those two forces combating each other on the back of the tire as it squares itself off.

Trying to figure out how tall the tire gets through the course of run, well, that took some work. So what I did is got with some of the teams, looked at some of the ride height sensors, and did some mathematical equations. What we found is that about five to seven inches taller from the finish line to the starting line. That's how much this tire grows.

We talk about numbers. \$917 for one of these tires. You're not going to get the kind of mileage you would out of a high-performance tire, 20,000 to 30,000 miles. It's going to be more like a mile and a half to two miles per tire. But if you ask me, it's still a great value because this, in my estimation, is the only tire that comes with a speed rating of 330 miles an hour.