Firestone doesn't make the Firehawks anymore so you're SOL there.

You might try using Summit's search and compare feature to look at tires.

BFG is still an available choice. Others are MT-SR, Mastercraft Avenger, Hankook Ventus, Cooper Cobra, a couple of Nitto versions, Hoosier...there are still some 15" tires out there although most will be S or T rated cruisers or drag tires.