The increase of width and decrease of diameters changes the aspect ratio of the tire, allowing for more grip with stiffness, Adams says. The original small tread width and large rim diameter has, over time, started to change. A track forcing drivers to always turn left requires a transferring of load into the outside tire, requiring a thicker tire with more air pressure and stiffness. The right-side construction of a tire to run on an oval requires more durability. Today, Firestone intentionally creates stagger in the designs. FirestoneĪnd it wasn’t long before tire manufacturers were making different molds for different tire positions.

The Firehawk race tire from Firestone is the tire of choice for the Indy 500 race teams, but each tire location on a car comes with a slightly different makeup. Incremental changes took place for the next few decades, even as tire manufactures reduced fabric use in tires in lieu of ply (layered) construction, but still only minutely widening the tire. The story starts in 1911, with the first tires to win the Indy 500, 4.5-inch-wide Firestone tires with just 2.5 inches of actual tread hitting the road when cornering. “The science that goes into tires, when you talk about back in the day to today, it is amazing when you see the chemistry and science that goes into each tire,” says Jay Frye, Ind圜ar president.

The diameters and widths of the tire have changed, the styles have slickened, construction has morphed, and compounds have evolved. Bettmann // Getty ImagesĮver since the first set of 4.5-inch-wide tires rolled into the winner’s circle on Ray Harroun’s car at the Indianapolis Motor Speedway in 1911, tire manufacturers have worked to improve construction to get the cars moving faster. His car, the Marmon Wasp, averaged a total speed of 74.59 mph. Ray Harrounis the first winner of the Indy Race in 1911.

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