These Firestone Dirt Track rear tires are sized at 1100-15, giving you the tall and wide look for the rear of your hot rod or vintage sprint car. These tires were originally used on sprint cars in the 1960’s and were made popular by the double diamond tread pattern. Originally, the sizing was 1100-16, but we decided to expand our sizing to include 1100-15, giving hot rodders many more wheel fitment options. Many famous street rods featured Firestone Dirt Track tires.