Need suggestions for tire sizes.

I hate to but in.I also could use some advice on tire sizes. What is the tallest,widest tire that will fit on a factory 14" Small bolt ralley? I want to stuff the most in the rear to get some traction. My duster has a healthy 340 4 speed and spins in first,second and starts to hook in third! Can someone let me know. I don't want to change from factory size rims.. Craig.