Stock Car Science

Goodyear has figured out (or at least thinks they have a good idea) what the problem was with the Indy tires. They confirmed that the tire compound was indeed the one they intended to use and identical to the one they’ve run there the last two years. They double checks for mistakes with the formulation or processing. They contacted every one of their suppliers to make sure that none of them had changed the raw materials they provided. I’ve had that happen to me when doing chemical synthesis: you buy the same chemical from the same company, but it’s a different lot and all of a sudden, the synthesis doesn’t work. Any of you who knit or crochet know that you can get subtle variations from dye lot to dye lot. Same thing goes for chemicals.

The conclusion they came to is that the drivers are driving differently. Because the new car is so hard to turn, the drivers drive into the corners differently than they used to. It’s not just that the higher center of gravity is shifting more weight to the right-side tires, which would make you think that both right sides would wear and not just the right rears. According to David Poole’s blog, recounting an interview he did with Goodyear’s Stu Grant:

"Grant said drivers were pitching the car into the corner and then sliding the right-rear tire as they tried to get the new car to turn."

The track at Indy has grooves cut in it to allow the lighter Indy cars to get enough grip to race. Remember that Indy is a very flat track. As David goes on to point out, the sliding means that means that instead of the right rear tire riding along parallel to the grooves in the track, it was riding perpendicular to the grooves.

Get out your box grater and a piece of Parmesan cheese (the closest edible thing in my house to tire rubber). Use the largest holes and compare what happens when you grate in one direction to what you get when you grate 90 degrees perpendicular to that direction. You get very different wear. That’s what Goodyear thinks caused the fine powder that wouldn’t stick to the track. It’s not so surprising that Goodyear didn’t get that from the tire test they did–the drivers might not have figured out that sliding is the best way to get the car to turn. Some drivers might have picked it up race weekend.

Why didn’t Goodyear coming up with a reason get as much coverage as the problems at the race? Trying searching for this story on Google. What you’ll get are all the columns with people complaining that Goodyear screwed up. Then Goodyear actually comes out with a reasonable explanation that makes sense and gives them a place to start for next year and you have to dig for it. It’s like printing retractions in legal-sized font in the back of the newspaper. I’m pretty religious about reading through the jayski.com headlines once a day (more when I’m trying to put off tasks I don’t want to do) and I didn’t see a whole lot about Grant’s quotes. Thanks very much to the reporters who take the time to post transcripts so fans can get the whole story and not just “breaking news” soundbites. For example, Claire B. Lang had an in-depth interview with Grant about the tire situation that really gets into the complexity of the problem and gives you a chance to hear about the strategy that Goodyear used to determine the problem. This is a great lesson in problem solving if nothing else.

Now that they have a candidate problem, they at least know what direction they should head in trying to come up with a really good tire for next year. I don’t envy the folks who work at Goodyear!