Tech Talk · Mike Neff · Monday October 15, 2012
Goodyear Tire and Rubber Company has been making racing tires for as long as there has been racing. In 1914 every competitor in the Indianapolis 500 raced on Goodyear tires. Over the company’s long history they have continually advanced tire technology to new heights that some would argue might be too advanced for what their product is supposed to do. Whatever your opinion, the fact of the matter is that Goodyear is the top manufacturer of tires in the United States and they have developed racing tires that are the most durable that we’ve ever seen in our sport.
Goodyear Engineer Justin Vanthozen sat down with Frontstretch to discuss tires; how they are constructed, the most important characteristics in race tires, the construction compounds (without divulging industry secrets of course) and more. As the series heads into Kansas with their newly repaved surface, tires will most certainly be at the forefront of the conversation, and Vanthozen helped to clarify that picture.
Mike Neff: Getting ready to go to Kansas and they have repaved the track. When Goodyear gets ready to head to a newly repaved track, what are the things that you focus on the most? Are you worried about wear, grip or do you concern yourselves with the entire package?
Justin Vanthozen: When we head to a newly repaved track the most important thing to manage is heat. We try to balance everything you just mentioned. Not only the grip, but also the heat and the wear. Normally, when we go to a repave it is real smooth, real flat, the binder that they have been using in recent repaves has been real tight. The aggregate is really tight so you see very minimal wear. When you have minimal wear you end up with a lot of heat and we try to manage that heat when we’re testing a tire for a track.
Mike Neff: When the time comes for you to prepare a tire for any track, but especially for this trip to Kansas, is there a time frame or a number of laps that you envision for the tire to last or are you more worried about managing the heat? And as long as the heat is dissipated, does it matter how long the tires last?
Justin Vanthozen: We always worry about how long they last and for that equation we look at a gas stop and a half. That is our typical duration, whether it is a new repave or whether we’re changing the recommendation to go back to the same facility, but we’re always trying to go a gas stop and a half.
Mike Neff: Why did you settle on a gas stop and a half vs. maybe having them wear out short of a gas stop?
Justin Vanthozen: We always want to make sure there is enough treadwear and there is enough life and enough heat resistance to make it through that gas stop and we want to give crew chiefs a chance to employ a little gamesmanship. Do they want to go a little more distance, do they want to pit short, where do they want to pit relative to the field, and that gives them a little room to play with it.
Mike Neff: When you talk about tire wear, I know when we had the whole fiasco at Indy and at Michigan when they switched the left side tire, it was because the tire was wearing as dust rather than bigger pieces. What is it, when you’re building a tire, that determines how that rubber sloughs off of the tires? Is it a specific component or is it a combination of things that determines how that rubber wears off?
Justin Vanthozen: There were two different issues. Indianapolis was an aggressive wear situation where Michigan was heat. When the cars gained the extra speed when we went back for the actual race vs. the test, we saw the excess heat which is what drove us to bring in the different left side tire. Indianapolis was an aggressive wear situation. The mechanism of wear comes down to everything that goes into a tire. Whether it is the rubber compound, the actual mold shape (the tread profile if you will), and the construction itself can actually lead to how the tire wears and as it sheds the rubber and leaves it on the race track.
Mike Neff: When we went from bias-ply to radials, stagger growth pretty much went away because you don’t get the tire growth due to the steel belts so they don’t change in size very much. That brought spring rate of the sidewalls into things. Considering sidewalls, is there anything done with concern to the sidewalls to help dissipate heat or is it the tread of the tire that handles all of the dissipation?
Justin Vanthozen: If we just focus on heat, we don’t have any steel from a belt perspective in the tires. You mentioned steel belts but that is more of a consumer/commercial application for road cars. In racing, at least with stock cars, there is so much heat that we cannot put steel in them because that retains the heat and we want to dissipate it. We’ll use a range of fabrics to keep the strength and the rigidity of the design of a belt package but not have the steel or any other metal in there to hold the heat in. So, when you come down to sidewall flex and you come down to the different setups that the guys are using then you surely have to look at the spring rate of what the tire is and what the dissipation of heat is through all of the package, through the whole box, and then the components that we will incorporate into the sidewall itself.
Mike Neff: Hopefully it won’t come into play at Kansas but when we talk about heat and tires we think of places like Martinsville where the brake heat can get so high that it melts the bead. In a situation where you’re going to have excessive heat like on the new pavement at Kansas, is there something that Goodyear does to try and strengthen the bead or is it pretty much as strong as you can make it and it is just a matter of how you design the entire tire?
Justin Vanthozen: It goes back to the sidewall flex vs. how much rubber you put into it. It is always that constant give and take. We normally don’t see brake heat issues or melted beads at mile and a half race tracks. You can if a guy or gal is driving it that way but typically that is not a factor at the faster, bigger race tracks.
Mike Neff: When they construct these tires in Akron, is it still a hands on process or is it mechanized now? I’ve always heard these are built by hand. I know there are machines involved, but is it fully mechanized or is hand craftsmanship still a major part of it?
Justin Vanthozen: If you look on the sidewall of a tire, you’ll see “Proudly Built By” and then the name of the person who built the tire. There is a tremendous amount of hands on labor. We take a lot of pride in the guys and gals that put the labor into it and bring the product to the race track.
Mike Neff: When you have a situation like you have at Michigan, where you had to change out the tires being used. Is there facility where you store tires that can be utilized in an emergency situation like that?
Justin Vanthozen: Absolutely, that is the only way we were able to pull off Michigan. We have tires, whether they are in one of multiple locations, where we can hit the button and put the wheels in motion and be able to pull off such a change.
As a follow-up to this interview, Goodyear noted that there is a contingency plan in place for every race on the schedule. They have multiple options to replace tires anywhere in the country if any kind of scenario develops where the tire that is currently chosen needs to be replaced.
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