Editor's note: Dale Harrigle, chief engineer for Bridgestone America’s Motorsports and manager of race tire development, highlights the testing that went into development of the new rain tire for the Verizon IndyCar Series in "The Engineers' Spin" -- a behind-the-scenes look at Firestone Racing's program from the perspective of the people that make the tires roll.

After a challenging series of oval events in the Verizon IndyCar Series, it is back to the picturesque hills of Lexington, Ohio, for the road course event at Mid-Ohio Sports Car Course.

Mid-Ohio is considered a home race for Firestone Racing as the track is located about 70 miles from our America’s Support Center in Akron, Ohio, where all of our tires are designed and built. One of the nice things about the race at Mid-Ohio is that many of the Firestone Racing personnel who don’t travel to races get to see the Firestone Firehawks perform on track.

This weekend’s Honda Indy 200 at Mid-Ohio is especially important for Firestone Racing as it will mark the debut of our new rain tire. Our engineers have spent more than a year designing and testing a new compound and construction for the rain tire, and we are sure the drivers are going to like the additional grip that this new tire will afford them.

As mentioned, more than a year of development work went into this new tire. Compound testing began in the laboratory, as it does for all of our new tires, but in this case we took the additional step of building sample, small-scale “tires” for use on a friction tester. These small-scale tests allowed us to evaluate each compound for wet traction before building a full-sized race tire. 

After small-scale testing was complete, we selected the most promising compounds and built experimental race tires for testing, both indoors and outdoors, to measure grip levels on wet surfaces. Once all of the test data was compiled and analyzed, the tread compound with the best overall performance was chosen for the new tire.

Our engineering team followed a similar process for the construction of the new tire. Using feedback from the drivers and teams, our engineers identified what was working well and where the biggest opportunities for improvement were. Once we had a direction for the new construction, we virtually tested nearly 50 different tires before deciding on the final construction of the new tire.

Perhaps the biggest development with the new tire is the one we made for the fans. The new rain tire will feature a gray sidewall, similar to the red sidewall on the alternate tires, which will make it easier for fans to tell when cars are running on the wet tire versus the black-sidewall primary tire.

One of the great strategy decisions in Indy car racing is when the drivers and teams need to decide their timing to switch from dry-to-wet or wet-to-dry tires in changing conditions. Hopefully, this new gray-sidewall tire will make it immediately obvious to the fans which of the wet-tire strategies each team is running.

We are excited about the debut of this new tire this weekend at Mid-Ohio, and while no one likes the threat of rain during a race, we look forward to the opportunity to finally have this new tire out on track during a Verizon IndyCar Series event.