[84GT350-1]

I need two auto drags for the rear of my 89 LX coupe but not sure what size to buy. I see they have a 15x7 and 15x8.5 with 4 7/8 backspace. I also will be converting to 5 lug. Also what is about the biggest tire I can get without doing any wheel well work on an auto drag wheel. Thanks for your help...