Yes, in the late '60s some Firestone tires were used on A-bodies.

Firestone was used for the STANDARD performance tire (D70-14 & E70-14) on Formula S, 'Cuda, GTS & Swinger. Not sure if it was exclusive?

The OPTIONAL "fiberglass-belted" E70-14 tire was Goodyear Polyglas.

Coker Tire's Firestone "Wide Oval" reproductions have been around since the mid-'80s & have always been less expensive and have a much larger distribution network than Kelsey Tire's Goodyear Speedway and/or Goodyear Polyglas reproductions that have been around about half as long.

The Firestone "Wide Oval" name stayed constant through the years although the type of tire construction changed. These dates are estimates - used to demonstrate the changes. The "Wide Oval" was built as nylon-cord ('67-'69), fiberglass-belted ('70+), and steel belted ('74+). The reproduction's sidewall reads "SUP-R-BELT" which was the steel belted version, the current tire is fiberglass-belted and is manufactured at the same plant as the reproduction Goodyears.