Biggest tire under a stock suspension dart????

Looking for the widest 15" tire (about 26-27" tall) on a 8" rim that I can put under a 69 Dart with stock suspension. Looking for pics as well if you have some. After putting my new 428HP 340 in my 69 swinger. 4 speed w 3:55s and 235/60/14s it has major traction issues. Thinking wider, taller tire with 3:91s will help