A Ramble on Tires, Push and the Future

As the season reaches the halfway point the future of indycar is starting to look quite bright. Something as simple as an in-depth look at the odd link between downforce, pushy racecars and tires, a bone of contention in their current iteration, easily leads to package improvements simply by going faster at Indianapolis.

After a 2012 season of having the sticky red and more durable black tire compounds just a bit too close in grip and construction, Firestone made a few changes coming into the 2013 season. The gap was widened and the tires, if managed properly, are able to do their jobs. The reds are noticeably quicker through the first half of a run all while losing grip and normalizing somewhere below the blacks nearer to the end of the run. The black side walls have been more or less bullet proof. You can push and push without too much damage taken by the tires. Although starting slower, the more consistent grip allows faster times to be turned all through a run.

However, the cars look planted. The DW12 is an inherently pushy chassis. It has a hard time establishing front end grip on initial turn in and want to pull out to the wall on corner exit. The teams have had to do rethink their setup sheets to break the rear end loose and free up the chassis. Because of this, drivers have adjusted their driving styles to lay more in line with the natural tendencies of the chassis instead of using a compromised setup to bring the car closer to the driver.

This has led to a full field of “easier” to drive racecars in the name of tire longevity and rethought setup sheets. “Loose is fast” is an often quoted line that holds more truth than could be understood. Loose equals rotation, faster cornering, and machines that must be man handled to extract the most from the equipment. It has been noted that we have had a relatively clean season in terms of crash damage on both the ovals and road and street circuits. I do not feel this is a sign that our drivers are improving, rather it is more indicative that the cars are a bit easier to hold on to this year.

Downforce is known to be high on the twisties, but decreasing wing angles won’t necessarily lead to looser racecars; the chassis will still have its natural push tendencies. With all of that said, the confidence that these cars instill on the drivers is evident by the moves and risks that these guys have been willing to take. The racing has been top level so it is hard to fault anyone on the way these machines handle the roads. Maybe in the future Dallara will be able to work back to a more balanced chassis when, or if, the league and manufacturer decide to revise the basic DW12 once speeds at Indy start ramping up.

On the ovals, the story is totally different. The single tire compound seems to only have a handful of laps in them before grip starts to drastically decrease. At Texas, drivers were unable to drive quickly, let alone push, for an entire fuel run. Tires dictated pit strategy, and the race was an evening of drivers trying to find their way into the wall on corner exit.

Iowa and Milwaukee were better in terms of tire degradation, but this leads me to believe that the increased tire life was due to increased downforce instead of better compounds. The league mandated the use of a modified road and street course kit for these two short ovals. The billboard wings produce more aerogrip, thus reducing sliding and increasing tire life. The cars still wanted to push into the wall, but drivers could still run to the edge of grip for most of the fuel stint and manage that push effectively.

This leads to Indianapolis where the same basic aerokit was used as Texas, but speeds were 10-20 miles an hour faster on average per lap. This defines the concept of an aero lull, a grip valley, or whatever you want to call it. For a winged racecar to work effectively there must be enough air passing over the aerodynamic elements to “turn on” and do their job of pressing the car into the track. At Indy, there was enough speed to produce stability, downforce and grip leading to better use of the tires. At Texas, with the shorter straights, once a driver lifted there was no chance to recover the speed. Grip at the next corner would suffer, as would exit speed and therefore straight line speed. This led to a very quickly, downward spiraling cycle of available aero grip causing sliding and the dreaded cheese grater effect on the tires.

The contrast between how well the package is designed on the twisties, verse ovals is staggering. The Indy, Milwaukee and Iowa tire could display the same characteristics as seen in Texas, but the downforce levels work more harmoniously with the tire.

The long straits of Pocono and the wide, sweeping corners of Fontana should give the chassis just enough speed to stay in that aero sweet spot. But it may be time for Firestone to rethink their oval compounds now that we are in year two of a totally different chassis than the type these tires were designed for.

Personally, I like where downforce levels are at. I like seeing the cars blast down the straights and lift or brake when entering a corner, but the tires need to be more sympathetic for the new style of oval racing we are attempting to create. They “got it” on the twisties and there is no reason to think the same thing won’t happen on the ovals. Again, when speeds ramp up at Indy in the coming years, Firestones hand may be forced anyway.

We are tantalizingly close to a complete season technical package.  Oddly enough, the bits and bobs for the twistie portion of the schedule are pretty well nailed down. Ironically, considering where the current iteration of American open-wheel racing came from, the oval package still needs a bit of work. But as a whole, the series has come a long way in terms of giving the cars back to the drivers, even if they are inherently more stable than we would like.

The entire package is primed for the performance increases laid out for the coming years and it will take the combined effort of Honda, Chevy, Dallara, Firestone and Indycar to make these goals happen. After a few races of having Derrick Walker at the technical helm, I am convinced we are in good hands moving forward. Instead of having a huge problem (breaking up pack racing with the IR07) with little to no solutions, we have a few niggling issues that are already being handled in a professional and sporting way.

The tire, chassis, downforce and even the pining for more power are all being actively evaluated by looking to the future and higher speeds at Indianapolis. The simple act of adding ten miles per hour in qualifying trim at Indy will hone an already stellar all around package. For the first time in a very long time, the future looks bright for indycar racing. It’s been a long time coming, now let’s hope people tune in to see it.

Eric Hall

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