Racing legend Mario Andretti remembers running low on time during a tire test session in California around 1970. In those days, engineers for tire companies created grooves in Indy racing tires by hand, thought to better handle dust and debris on the track. But time was short this testing day and engineers wanted to try a new tire construction but didn’t have time to create grooves. “They sent me out in slicks,” Andretti told Popular Mechanics. “They told me to take it careful and I went out there and set a record. It took a couple of years where we were doing less and less grooving and going faster and faster until we said let’s not groove at all. It was that primitive to some degree, but it all had to be proven on the track.” Proving tires on the track has turned into a mainstay of the racing world. For over 100 years, we’ve seen changes in construction and compounds. But every change traces its history back to the same starting point—the 1911 Indy 500. Ever 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 fast...