I'll reword it then; I thought they were ONLY using Firestone tires on Firebirds in 1968.
and when I bought my 68 Firebird 350 in 1969 , a 6 mo old used car...It had redlines on it, not sure which brand they were...but they were "original".....I hope they were not Firestones*.... but no idea....
*you could buy those on "blow out sales" a few yrs ago, remember?