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uploaded 3/12/2008

Goodyear's Bad Decisions at Atlanta

The NASCAR drivers are right! Goodyear made a really dumb decision when they brought only one tire to run on the Nationwide and Sprint Cup cars at Atlanta.

These cars are now way too different to use the same tire. The tire was fine for the older car design but unstable on the new car. As a result the teams couldn't find a setup that gave the driver a car that was balanced for an entire stint. It doesn't help that these tires give-up two seconds a lap during the first 20 laps of a tire stint.

Some drivers were more vocal than others but I'm glad they spoke up. The real problem here was not bad tires but a badly managed program. Goodyear and NASCAR both need to be more respectful of the drivers and teams. The tire is the most critical component in the system by far and the loads applied during racing on high banks at close to 200mph are huge.

I'm also glad to hear that Texas Motor Speedway has announced the Atlanta tire will not be used at their track. If NASCAR and Goodyear make poor decisions then other stake holders in the racing industry need to step up and protect their interests.

Goodyear's press release touting, "...our engineering, research and tire development is second to none." is ridiculous. They make good tires but their R&D is second rate compared to Bridgestone and Michelin.

Goodyear also says that Tony Stewart was wrong when he said. "They exited out of Formula One. They exited out of IRL. They exited out of World of Outlaws and there is a reason for that. Goodyear can't build a tire that is worth a crap." The Goodyear press release blames escalating costs as their reason for ending competition in CART and F1 racing.

In my book, The Racing & High-Performance Tire, I explained how Bridgestone reentered racing with the CART series in 1994 and quickly forced Goodyear to the back of the pack. Bridgestone won races with tires that were almost as fast as Goodyear but they gave up much less during a tire stint than Goodyear tires.

Here is an excerpt from the book that explains how two very different tire tread compounds respond to the abuses of a race car.

Tire Give-Up

Rubber abrasion is mainly caused by two mechanisms working simultaneously: 1) abrasion due to rubber fracture and 2) mechanical/chemical degradation of the rubber surface. The fracturing mechanism is actually two processes. A loss of "fine-scale" rubber in very small particles removed from the areas between the peaks in the patterns and "larger-scale" particles abraded from the upper sides of the ridges.

The mechanical/chemical degradation is what's interesting. This type of abrasion is caused by large frictional forces on the surface of the rubber. These forces cause rapid elongation of the polymer chains resulting in rupture of some individual chains. When a chain breaks the broken ends produced are chemically active and will reattach somewhere if they get the chance.

What happens next depends on the chemical nature of the compound. Broken chains in natural rubbers and styrene-butadiene rubbers look for a free radical and usually find oxygen, since wear is a tread surface process. A combination with oxygen stabilizes the ends of the broken chains, resulting in a tendency toward shorter chains and a lower molecular weight in the compound, producing a sticky, oily residue. That's what a hot Goodyear tire looked like during the CART tire war.

Other rubbers, polybutadiene for example, join with other chains after breakage, resulting in additional crosslinks. A higher percentage of crosslinks is a tendency toward a higher molecular weight, producing an abraded material that is dry and powdery. That's how the hot Firestone tires looked.

What myself and other people saw during the CART Firestone/Goodyear tire war were tires that looked very different when they were hot. The Goodyears got black and wet looking. They seemed oily and abraded rubber rolled off in greasy hunks. The Firestone tires looked dry and gray. Their debris was dry and powdery.

Years ago I had a conversation with a Firestone engineer who shall remain nameless and the subject of that talk fits into this discussion. I was doing my usual deal of asking different people the same question and comparing the answers to try to piece together some relevant information. The subject was what's going on with tire give-up and I said something like this. "I guess a tire working hard on a racecar is getting some intense heating and mechanical working. I'd think this would break some of the polymer chains and crosslinks. Is that what causes give up?"

This engineer said something like, "Yes, I think so, but there are things you can put in the compound that encourage the broken chains to reattach and that retards the degradation of the compound." That fits with the process I described above.

The question remains why Goodyear continued to make tires that got hot and greasy instead of gray and dry. Of course I could be wrong about this oily/dry difference, but even so the question remains. Why didn't Goodyear respond?

Either it didn't know how, or it didn't have the money to develop the technology. Goodyear was trying as hard as it could with the materials and processes available. Firestone had its own materials and processes which Goodyear was unable to duplicate. It was obvious at the time that Goodyear had no recourse and had to quit rather than be repeatedly beaten on the track.

There's a lot of misinformation about tires. People say "Hard running forces the oils out of the rubber." I think this oily residue is what they're talking about but I don't think it actually has anything to do with the oils used as extenders in rubber compounds.

That's the end of the excerpt.

Back then if Goodyear had been able to produce a winning tire they would have! Bridgestone entered competition in Formula 1 also and Goodyear had to quit or be soundly beaten.

Leo Mehl, Goodyear's Worldwide Director of Racing, retired during this time. He never spoke on the record about why he quit but those of us who talked to him figure he wouldn't have left Goodyear if he had been given the financial and technical support necessary to compete.



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