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uploaded 10/16/2005

Tire Troubles at Lowe's Motor Speedway

The NASCAR Nextel Cup race at Lowe's Motor Speedway last night was a good example of the general lack of knowledge of how tires work and how they interact with cars and road surfaces. Tires are very complex devices. A change in operating conditions, track surface texture for example, can destroy a tire quickly. They were giving up at 20 laps last night in Charlotte.

The NASCAR Cup and Busch cars are heavy at 3,400 pounds and the tires are undersized in width for the huge stresses developed on high-banks at near 200 mph.

My weight goes up and down with diet and exercise variations but I never know I'm getting fat until my pants get tight. I'm always surprised when all-of-a-sudden I have trouble buttoning my pants. This weekend at Lowe's the tires went from "no problem" to "look out!"

The Lowe's track was ground last Spring and there were some tire problems at the first NASCAR race this season but nothing scary. I'm told more grinding was done later in the year. The resulting texture obviously develops more grip. The track is also smoother probably making the drivers more comfortable at speed.

The result is speeds rose from 190 mph to 195 mph. The lateral force the tires produce goes up with the square of the speed through the corners. That means when the speed doubles the forces quadruple. That five mph increase is a 5% rise in lateral forces at those speeds.

For a tire higher forces means more distortion, more heat, and higher fatigue stresses. At Charlotte last night it was too much!

Need to know more about tires?

Go back to the Home Page and check out The Tire Book.



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