Rain tires are meant for wet racetracks. Slick tires drive best on a dry course. It doesn't take a Firestone engineer to figure that out.
What had Ryan Hunter-Reay muttering a prayer to Mother Nature early in Sunday's IndyCar Series Grand Prix of Baltimore, though, was the fact that only one tire type is equipped to safely handle both surfaces. And they weren't the ones zipping his Andretti Autosport car around a wet Baltimore course at nearly 90 mph.
"These cars are very stiffly sprung and they're 700 horsepower, and to put that down on a city street when it's wet is one of the tougher things in racing, I think," Hunter-Reay said minutes after a controversial first-place finish. "I'm just glad I got through that. That was very nerve-wracking. I enjoy racing in the wet, but I prefer rain tires when it's wet, for sure."
Rain didn't soak the 2.04-mile course for long Sunday — Lap 16 marked the first in which a driver swapped dry tires for wet ones, and Lap 28 saw the final reversal to the status quo — but when it did, things got interesting.
For one, the heavens opened up on only certain parts of the course. A soaked Turn 12 quickly became a treacherous right-angle hook, and Turns 6 and 10 weren't much more forgiving. Through it all, "the concrete had decent grip, which was surprising a bit," said runner-up Ryan Briscoe.
Still, few teams wanted to risk their rides, or the points a "DNF" would forfeit. E.J. Viso and Bruno Junqueira opted for the grooved tires first, and before long the race's frontrunners had joined them.
As it turned out, they didn't have much use for them, although there were nine caution flags that resulted in 24 laps being run under caution. Will Power sacrificed an early lead for the safety of his car when he pitted in Lap 19, and the nine caution laps he subsequently drove with the slower tires proved crucial.
"Today, I lost it on the weather," he said, slamming his fist down on the podium in mock exclamation.
Power might've been the quickest driver on the course, as he asserted afterward, but he wasn't on the fastest tires the longest.
That was Hunter-Reay, whose team anticipated mid-afternoon showers but nonetheless planned to move to the front of the field while the ominous rain clouds passed.
"We took a little bit of a gamble," Andretti Autosport owner Michael Andretti said. "… But we saw that the rain was going to stop. We thought if we can get through one restart and get through three or four corners — because we thought there was going to be another yellow right away — that, 'You know what, let's just go forward.'
"We told Ryan, 'Just keep it on the track. Don't try to beat anyone, but just keep it on the track.' We think if we do that, it's going to go yellow again and then he's going have time to try it out.' And, in fact, that's what happened, so it was nice when a plan comes together. I think that was the difference of the race."
As Hunter-Reay chased Power in the IndyCar Series standings, he quickly distanced himself from the race's pole sitter and any worries that the rain would drown his dreams. Hunter-Reay picked up the lead Power lost mid-tire change, and his first pit stop was for new dry tires, not wet ones.
Those few laps of limbo produced "unbelievable emotions in your car," Hunter-Reay said afterward. To be sure, there were thoughts of, What am I doing? There were hopes that these raindrops were the last of the afternoon. Ultimately, though, there was elation over the successful experiment and his still-intact car.
"We thought that it was just going to sprinkle and that I'd have to live through a little bit of a wet track and hopefully that sprinkle would end. And it did," Hunter-Reay said. "We never came in for rain tires. That was absolutely critical to our win today."